Search for decaying neutralions at HERA and clustering optimisation for the ZEUS micro vertex detector

International Nuclear Information System (INIS)

Blohm, Christian

2010-03-01

A search for gravitinos produced in supersymmetric events in electron proton collision has been performed with data recorded with the ZEUS detector at HERA in the years 2003 to 2007. In R-parity violating supersymmetric models a neutralino can be produced by t-channel exchange of a selectron between the incoming electron and a quark of the proton. In the Gauge Mediated Supersymmetry Breaking model (GMSB), where the gravitino is the lightest supersymmetric particle, the neutralino in large regions of the parameter space dominantly decays into a gravitino and a photon, leading to events with an isolated high energetic photon and large missing transverse momentum. To separate signal and background, a multi-variate discriminant method was used. No evidence for supersymmetry was found, and limits were derived for the R-parity violating coupling strength and the messes of the selectron and the lightest neutralino. Moreover, the cluster position reconstruction system of the ZEUS experiment was improved by modifying and implementing an algorithm which uses estimated track angle and impact position from the pattern recognition phase of the tracking system to yield a better position resolution. (orig.)

Measurement of beauty quark production from dimuon events with the ZEUS detector at HERA II

International Nuclear Information System (INIS)

Bot, Danny

2011-10-01

In this thesis, a measurement of beauty quark production via the process ep→e'b anti bX→e'μμX in electron-proton collisions at HERA using a data sample recorded by the ZEUS detector in the years 2003-2007, corresponding to an integrated luminosity of 376 pb -1 , is presented. A low transverse momentum threshold for muon identification in combination with the large rapidity coverage of the ZEUS muon-detection system gives access to essentially the full phase space for beauty quark production. Dimuon charge correlations as well as hadronic isolation and the mass of the dimuon system were used to separate the beauty signal from backgrounds. Visible, differential and total cross sections for beauty quark production were measured and compared to next-to-leading order QCD calculations and previous measurements. In addition, a first search for QCD instanton-induced processes containing both a charm- and beauty-quark pair in dimuon events was performed. In order to differentiate between beauty and instanton events, discriminating observables sensitive to the hadronic final state, so-called event shape variables, were used in combination with the dimuon requirement. As technical part of this thesis, the reconstruction algorithm for so-called energy flow objects (EFOs) was modified. EFOs contain the combined information of primary and secondary vertex-fitted tracks as well as CAL energy measurements. The modification considers additional tracks close to but not fitted to the primary vertex and which fulfill reasonable track and impact parameter requirements. As a result, the efficiency to reconstruct muon candidates with high impact parameter values as energy flow objects was increased. (orig.)

Measurement of beauty quark production from dimuon events with the ZEUS detector at HERA II

Energy Technology Data Exchange (ETDEWEB)

Bot, Danny

2011-10-15

In this thesis, a measurement of beauty quark production via the process ep{yields}e'b anti bX{yields}e'{mu}{mu}X in electron-proton collisions at HERA using a data sample recorded by the ZEUS detector in the years 2003-2007, corresponding to an integrated luminosity of 376 pb{sup -1}, is presented. A low transverse momentum threshold for muon identification in combination with the large rapidity coverage of the ZEUS muon-detection system gives access to essentially the full phase space for beauty quark production. Dimuon charge correlations as well as hadronic isolation and the mass of the dimuon system were used to separate the beauty signal from backgrounds. Visible, differential and total cross sections for beauty quark production were measured and compared to next-to-leading order QCD calculations and previous measurements. In addition, a first search for QCD instanton-induced processes containing both a charm- and beauty-quark pair in dimuon events was performed. In order to differentiate between beauty and instanton events, discriminating observables sensitive to the hadronic final state, so-called event shape variables, were used in combination with the dimuon requirement. As technical part of this thesis, the reconstruction algorithm for so-called energy flow objects (EFOs) was modified. EFOs contain the combined information of primary and secondary vertex-fitted tracks as well as CAL energy measurements. The modification considers additional tracks close to but not fitted to the primary vertex and which fulfill reasonable track and impact parameter requirements. As a result, the efficiency to reconstruct muon candidates with high impact parameter values as energy flow objects was increased. (orig.)

Deep inelastic cross-section measurements at large y with the ZEUS detector at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2014-04-01

The reduced cross sections for e + p deep inelastic scattering have been measured with the ZEUS detector at HERA at three different centre-of-mass energies, 318, 251 and 225 GeV. The cross sections, measured double differentially in Bjorken x and the virtuality, Q 2 , were obtained in the region 0.13≤y≤0.75, where y denotes the inelasticity and 5≤Q 2 ≤110 GeV 2 . The proton structure functions F 2 and F L were extracted from the measured cross sections.

Design and Tests of the Silicon Sensors for the ZEUS Micro Vertex Detector

OpenAIRE

Dannheim, D.; Koetz, U.; Coldewey, C.; Fretwurst, E.; Garfagnini, A.; Klanner, R.; Martens, J.; Koffeman, E.; Tiecke, H.; Carlin, R.

2002-01-01

To fully exploit the HERA-II upgrade,the ZEUS experiment has installed a Micro Vertex Detector (MVD) using n-type, single-sided, silicon micro-strip sensors with capacitive charge division. The sensors have a readout pitch of 120 micrometers, with five intermediate strips (20 micrometer strip pitch). The designs of the silicon sensors and of the test structures used to verify the technological parameters, are presented. Results on the electrical measurements are discussed. A total of 1123 sen...

Precision calculation of processes used for luminosity measurement at the ZEUS experiment

International Nuclear Information System (INIS)

Haas, T.; Makarenko, V.

2010-09-01

The process pe ± → pe ± γ with the photon emitted along the electron beam axis is used for luminosity measurement at HERA. In this paper the process is calculated including one-loop QED radiative corrections. In the ZEUS experiment, both the electron and the photon can be detected. Therefore both photon and electron spectra with and without the γ-e coincidence are analyzed. We also calculate the process pe ± → pe ± l - l + which contributes to the background in the electron tagger. (orig.)

Charm photoproduction using electron taggers with the Zeus detector at HERA

International Nuclear Information System (INIS)

Aghuzumtsyan, G.

2006-07-01

Charm production has been studied at a centre-of-mass energy of √(s)=318 GeV in the ZEUS experiment at the electron-proton collider HERA. The data from the years 1998-2000 are used. Photoproduction is identified by reconstructing the D * (2010) meson via the decay chain D *+ →K - π + π + (+c.c.) and by selecting the scattered electron in one of the dedicated electron taggers located 44m and 35m away from the interaction point. The total visible cross section and differential cross sections as a function of p T (D * ), η(D * ) and W were measured in the restricted phase space: -1.0 * ) T (D * )>1.5 GeV, 80 GeV 2 2 in case of the 44m tagger sample, and -1.5 * ) T (D * )>2.0 GeV, 200 GeV 2 2 in case of the 35m tagger sample. Next-to-leading-order QCD predictions were calculated in the same kinematic region as the data. The comparison of the theoretical predictions with the data shows good agreement within the theoretical uncertainties. Total charm cross sections were calculated by extrapolating the visible cross sections in the limited (p T (D * ), η(D * )) phase space to the full kinematic region. The measurements with the 35m tagger overlap with previous untagged data while the 44m tagger data are used to study a new intermediate region 80 GeV 44m <120 GeV between fixed target and and the other HERA measurements. The comparison of the NLO QCD predictions with the data shows good agreement. (orig.)

Microprocessor-based data acquisition systems for Hera experiments

International Nuclear Information System (INIS)

Haynes, W.J.

1989-09-01

Sophisticated multi-microprocessor configurations are envisaged to cope with the technical challenges of the HERA electron-proton collider and the high data rates from the two large experiments H1 and ZEUS. These lecture notes concentrate on many of the techniques employed, with much emphasis being placed on the use of the IEEE standard VMEbus as a unifying element. The role of modern 32-bit CISC and RISC microprocessors, in the handling of data and the filtering of physics information, is highlighted together with the integration of personal computer stations for monitoring and control. (author)

Leading Hadron Production at HERA

Directory of Open Access Journals (Sweden)

Buniatyan Armen

2013-06-01

Full Text Available Data from the recent measurements of very forward baryon and photon production with the H1 and ZEUS detectors at electron-proton collider HERA are presented and compared to the theoretical calculations and Monte Carlo models. Results are presented of the production of leading protons, neutrons and photons in deep inelastic scattering (ep → e' pX, ep → e'nX, ep → e'γX as well as the leading neutron production in the photoproduction of dijets (ep → ejjXn. The forward baryon and photon results from the H1 and ZEUS Experiments are compared also with the models of the hadronic interactions of high energy Cosmic Rays. The sensitivity of the HERA data to the differences between the models is demonstrated.

Optimising of design parameters of the TESLA vertex detector and search for events with isolated leptons and large missing transverse momentum with the ZEUS-experiment (HERA II)

International Nuclear Information System (INIS)

Adler, V.

2006-06-01

In this thesis, a search for events with isolated leptons and large missing transverse momentum at HERA is presented. Data with an integrated luminosity of 40.76 pb -1 of e + p-collisions collected with the ZEUS detector at a CMS energy of 318 GeV during the HERA II running period in the years 2003 and 2004 were used. Some extensions of the SM contain FCNC processes at tree level, which could lead to a significantly enhanced rate of singly produced t-quarks at HERA (e ± p → e ± tX). The signature of interest originates from the decay t → bW + with a subsequent leptonic decay of the W-boson (W + → e + ν e , μ + ν μ , τ + ν τ ). After the final selection, one event was found in data in the combined e- and μ-channels, where 1.27±0.15 were expected from SM predictions. The selection efficiency in these channels was 13.4 +1.8 -0.8 % for a t-quark mass of 175 GeV. In combination with independent searches in HERA I data in both, the leptonic and hadronic channel, limits on the FCNC couplings through photon and Z-boson exchange were derived. The NLO limit κ tuγ +0.014 -0.012 at 95% CL for a t-quark mass of 175 GeV is the most stringent so far. Together with the most stingent limit on v tuz of 0.37, an upper cross section limit of σ single t +0.029 -0.012 pb was obtained.Also a limit on the cross section of single W-boson production of σ single W +0.67 -0.41 pb was obtained at 95% CL. In this thesis, also a simulation study to optimise design parameters of a MAPS based vertex detector for a future ILC is presented. The study was based on the TESLA TDR. In order to evaluate the effect of different design options for the vertex detector on the physics performance of the whole detector, the reconstruction of the t-quark mass from the signal process e + e - →t anti t in the all-hadronic decay channel was used. The fast simulation program SGV was equipped with a neural-network based heavy-flavour tagging, where the b-tagging achieved a purity of 86% at an

The data-acquisition and second level trigger system for the ZEUS calorimeter

International Nuclear Information System (INIS)

Lugt, H.J. van der.

1993-01-01

ZEUS and HERA are introduced in chapter 1 with emphasis on the ZEUS Calorimeter and the ZEUS trigger system. The analog and digital electronics developed for the readout of the Calorimeter signals, and the hardware for the Calorimeter Second Level Trigger and data-acquisition system, is described in chapter 2. Emphasis is put on the hardware developed at NIKHEF, which is based on the transputer as the main processing element. The ZEUS trigger and data-acquisition environment as well as the calibration procedures needed for the Calorimeter impose several requirements on the design of the data-acquisition system. The requirements, their implications for the design of the transputer network architecture and the design itself, are described in detail in chapter 3. The software developed for the Calorimeter data-acquisition is described in chapter 4. It includes both the software for the Calorimeter data-acquisition as that required for the calibration of the Calorimeter. First experiences with the CAL-SLT algorithms, obtained during the 1992 HERA running periods, are presented in chapter 5. Chapter 6 discusses the performance of the Calorimeter data-acquisition system. (orig.)

Heavy Flavour Production at HERA

International Nuclear Information System (INIS)

Bailey, D.

2001-01-01

ZEUS and H1 results on heavy quark production using the HERA data from 1995 to 2000 are summarised with emphasis on unresolved problems. The HERA upgrade and its impact on future heavy flavour measurements is briefly discussed

Exclusive photoproduction of Υ mesons at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2009-03-01

The exclusive photoproduction reaction γ p → Υ p has been studied with the ZEUS experiment in ep collisions at HERA using an integrated luminosity of 468 pb -1 . The measurement covers the kinematic range 60 2 2 , where W is the photon-proton centre-of-mass energy and Q 2 is the photon virtuality. These results, which represent the analysis of the full ZEUS data sample for this channel, are compared to predictions based on perturbative QCD. (orig.)

Optimising of design parameters of the TESLA vertex detector and search for events with isolated leptons and large missing transverse momentum with the ZEUS-experiment (HERA II)

Energy Technology Data Exchange (ETDEWEB)

Adler, V.

2006-06-15

In this thesis, a search for events with isolated leptons and large missing transverse momentum at HERA is presented. Data with an integrated luminosity of 40.76 pb{sup -1} of e{sup +}p-collisions collected with the ZEUS detector at a CMS energy of 318 GeV during the HERA II running period in the years 2003 and 2004 were used. Some extensions of the SM contain FCNC processes at tree level, which could lead to a significantly enhanced rate of singly produced t-quarks at HERA (e{sup {+-}}p {yields} e{sup {+-}}tX). The signature of interest originates from the decay t {yields} bW{sup +} with a subsequent leptonic decay of the W-boson (W{sup +} {yields} e{sup +}{nu}{sub e}, {mu}{sup +}{nu}{sub {mu}}, {tau}{sup +}{nu}{sub {tau}}). After the final selection, one event was found in data in the combined e- and {mu}-channels, where 1.27{+-}0.15 were expected from SM predictions. The selection efficiency in these channels was 13.4{sup +1.8}{sub -0.8}% for a t-quark mass of 175 GeV. In combination with independent searches in HERA I data in both, the leptonic and hadronic channel, limits on the FCNC couplings through photon and Z-boson exchange were derived. The NLO limit {kappa}{sub tu{gamma}}<0.160{sup +0.014}{sub -0.012} at 95% CL for a t-quark mass of 175 GeV is the most stringent so far. Together with the most stingent limit on v{sub tuz} of 0.37, an upper cross section limit of {sigma}{sub single} {sub t}<0.186{sup +0.029}{sub -0.012} pb was obtained.Also a limit on the cross section of single W-boson production of {sigma}{sub single} {sub W}<1.54{sup +0.67}{sub -0.41} pb was obtained at 95% CL. In this thesis, also a simulation study to optimise design parameters of a MAPS based vertex detector for a future ILC is presented. The study was based on the TESLA TDR. In order to evaluate the effect of different design options for the vertex detector on the physics performance of the whole detector, the reconstruction of the t-quark mass from the signal process e{sup +}e

ZEUS contributions to the Real-Time 93 conference, Vancouver, Canada

International Nuclear Information System (INIS)

1993-07-01

This is a collection of the eight contributions of the ZEUS Data Acquisition group, presented at the Eighth Conference on Real-Time Computer Applications in Nuclear, Particle and Plasma Physics, Vancouver, Canada, June 8-11, 1993. This note describes the major parts of the ZEUS Data Acquisition system and the experience gained since the first HERA running in April 1992. Note that the papers are appended in the order of recommended reading, which does not reflect the order of importance. The presenters for the papers are listed in the following. (orig.)

Beam tests of the ZEUS barrel calorimeter

Energy Technology Data Exchange (ETDEWEB)

Bernstein, A; Bienz, T; Caldwell, A; Chen, L; Derrick, M; Gialas, I; Hamri, A; Imlay, R; Kartik, S; Kim, H J; Kinnel, T; Kreutzmann, H; Li, C G; Lim, J N; Loveless, R; Lu, B; Mallik, U; McLean, K W; McNeil, R; Metcalf, W; Musgrave, B; Oh, B Y; Park, S; Parsons, J A; Reeder, D; Repond, J; Ritz, S; Roco, M T.P.; Sandler, P H; Sciulli, F; Smith, W H; Talaga, R L; Tzanakos, G; Wai, L; Wang, M Z; Whitmore, J; Wu, J; Yang, S [Argonne National Lab., IL (United States) Columbia Univ., New York, NY (United States) Nevis Labs., Irvington-on-Hudson, NY (United States) Univ. of Iowa, Iowa City, IA (United States) Louisiana State Univ., Baton Rouge, LA (United States) Ohio State Univ., Columbus, OH (United States) Pennsylvania State Univ., University Park, PA (United States) Virginia Polytechnic Inst., and State Univ., Blacksburg, VA (United States) Univ. of Wisconsin, Madison, WI (United States)

1993-11-15

A fully compensating uranium-scintillator calorimeter was constructed for the ZEUS detector at HERA. Several of the barrel calorimeter modules were subjected to beam tests at Fermilab before shipping them to DESY for installation. The calibrations of the modules used beams of electrons and hadrons, measuring the uniformity of the response, and checking the resolution. The runs also provided opportunity to test a large fraction of the actual ZEUS calorimeter readout system in an integrated beam environment more than one year before HERA turn on. The experiment utilized two computer controlled mechanical structures, one of which was capable of holding up to four modules in order to study shower containment, and a magnetic spectrometer with a high resolution beam tracking system. During two running periods, beams of 6 to 110 GeV containing e, [mu], [pi], and anti p were used. The results show energy resolutions of 35%/[radical]E for hadrons and 19%/[radical]E for electrons, uniformities at the 1% level, energy nonlinearity less than 1%, and equal response for electrons and hadrons. (orig.)

Study of elastic ρ0 photoproduction at HERA using the ZEUS leading proton spectrometer

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magil, S.

1996-08-01

The differential cross section dσ/dt for elastic ρ 0 photoproduction, γp→ρ 0 p(ρ 0 →π + π - ), has been measured in ep interactions at HERA. The squared four-momentum exchanged at the proton vertex, t, has been determined directly by measuring the momentum of the scattered proton using the ZEUS leading proton spectrometer (LPS), a large scale system of silicon micro-strip detectors operating close to the HERA proton beam. The LPS allows the measurement of the momentum of high energy protons scattered at small angles with accuracies of 0.4% for the longitudinal momentum and 5 MeV for the transverse momentum. Photoproduction of ρ 0 mesons has been investigated in the interval 0.073 2 , for photon virtualities q 2 2 and photon-proton centre-of-mass energies between 50 and 100 GeV. In the measured range, the t distribution exhibits an exponential shape with a slope parameter b=9.8±0.8(stat.)±1.1(syst.) GeV -2 . The use of the LPS eliminates the contamination from events with diffractive dissociation of the proton into low mass states. (orig.)

Study of beauty photoproduction with the ZEUS experiment at the electron-proton collider HERA

Energy Technology Data Exchange (ETDEWEB)

Yaguees Molina, Ana Gloria

2008-02-22

This thesis presents a measurement of beauty photoproduction in ep interactions at the HERA collider working at a center of mass energy of {radical}(s)=318 GeV. Two goals are followed in this thesis: first the development of a reliable algorithm (secondary vertex b-tagging) to identify jets originating from b quarks by exploiting exclusively the full micro-vertex-detector potential and the properties of the b quark, and second the determination of its performance by obtaining first measurements of inclusive beauty dijet photoproduction. The main result presented here is based on a data set collected in 2004 corresponding to an integrated luminosity of 35 pb{sup -1}. Events containing at least two jets, each having an identified secondary vertex, are selected. The fraction of events containing b-quarks is extracted using the characteristic distributions of reconstructed decay length and invariant mass of the secondary vertex. The jets are required to be within the pseudorapidity region vertical stroke {eta} vertical stroke <1.5 with transverse momenta p{sub T}>7(6) GeV/c respectively. No requirements are imposed on the b decay final state so that the measurement is kept inclusive. Total and differential cross sections as a function of transverse momentum d{sigma}/dp{sub T} and pseudorapidity d{sigma}/d{eta} of the b-jet are measured. Furthermore, the results on d{sigma}/dp{sub T} were extrapolated to obtain a measurement at the b-quark level. Motivated by the results of this exploratory analysis of beauty quark production using secondary vertex b-tagging and profiting from improvements of the ZEUS tracking software since this first analysis, a more precise measurement became possible. The new analysis, still ongoing, is based on the data set collected in 2005 by the ZEUS detector and profits of higher statistics (L=132.6 pb{sup -1}) as well as of an improved detector alignment and calibration and a better understanding of the tracking/vertexing procedures which

Study of beauty photoproduction with the ZEUS experiment at the electron-proton collider HERA

International Nuclear Information System (INIS)

Yaguees Molina, Ana Gloria

2008-01-01

This thesis presents a measurement of beauty photoproduction in ep interactions at the HERA collider working at a center of mass energy of √(s)=318 GeV. Two goals are followed in this thesis: first the development of a reliable algorithm (secondary vertex b-tagging) to identify jets originating from b quarks by exploiting exclusively the full micro-vertex-detector potential and the properties of the b quark, and second the determination of its performance by obtaining first measurements of inclusive beauty dijet photoproduction. The main result presented here is based on a data set collected in 2004 corresponding to an integrated luminosity of 35 pb -1 . Events containing at least two jets, each having an identified secondary vertex, are selected. The fraction of events containing b-quarks is extracted using the characteristic distributions of reconstructed decay length and invariant mass of the secondary vertex. The jets are required to be within the pseudorapidity region vertical stroke η vertical stroke T >7(6) GeV/c respectively. No requirements are imposed on the b decay final state so that the measurement is kept inclusive. Total and differential cross sections as a function of transverse momentum dσ/dp T and pseudorapidity dσ/dη of the b-jet are measured. Furthermore, the results on dσ/dp T were extrapolated to obtain a measurement at the b-quark level. Motivated by the results of this exploratory analysis of beauty quark production using secondary vertex b-tagging and profiting from improvements of the ZEUS tracking software since this first analysis, a more precise measurement became possible. The new analysis, still ongoing, is based on the data set collected in 2005 by the ZEUS detector and profits of higher statistics (L=132.6 pb -1 ) as well as of an improved detector alignment and calibration and a better understanding of the tracking/vertexing procedures which contribute significantly to the reduction of the uncertainties of the measurements

The performance of the ZEUS calorimeter

International Nuclear Information System (INIS)

Crittenden, J.A.

1994-12-01

The ZEUS experiment has now completed its third year of operation at the electron-proton collider HERA. The uranium/scintillator sampling calorimeter surrounding the inner tracking detectors has proven an essential component for the online triggering algorithms, for offline event-type identification, for kinematic variable reconstruction, and for a ariety of physics analyses. This paper summarizes the experimental context, the operating characteristics, the calibration techniques, and the performance of the calorimeter during its first three years of operation. (orig.)

Charm photoproduction using electron taggers with the zeus detector at HERA

Energy Technology Data Exchange (ETDEWEB)

Aghuzumtsyan, G.

2006-07-15

Charm production has been studied at a centre-of-mass energy of {radical}(s)=318 GeV in the ZEUS experiment at the electron-proton collider HERA. The data from the years 1998-2000 are used. Photoproduction is identified by reconstructing the D{sup *}(2010) meson via the decay chain D{sup *+}{yields}K{sup -}{pi}{sup +}{pi}{sup +} (+c.c.) and by selecting the scattered electron in one of the dedicated electron taggers located 44m and 35m away from the interaction point. The total visible cross section and differential cross sections as a function of p{sub T}(D{sup *}), {eta}(D{sup *}) and W were measured in the restricted phase space: -1.0<{eta}D({sup *})<1.5, p{sub T}(D{sup *})>1.5 GeV, 80 GeV2.0 GeV, 200 GeVHERA measurements. The comparison of the NLO QCD predictions with the data shows good agreement. (orig.)

Exclusive photoproduction of {upsilon} mesons at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2009-03-15

The exclusive photoproduction reaction {gamma} p {yields} {upsilon} p has been studied with the ZEUS experiment in ep collisions at HERA using an integrated luminosity of 468 pb{sup -1}. The measurement covers the kinematic range 60ZEUS data sample for this channel, are compared to predictions based on perturbative QCD. (orig.)

Measurement of the total and differential b cross sections at HERA and CMS tracker alignment at LHC

CERN Document Server

Stefaniuk, Nazar; Gallo, Elisabetta

2017-01-01

This thesis is logically divided into two main parts. The first part present a ZEUS analysis which was performed on the data obtained from electron-proton collisions measured by the ZEUS detector for the 2003-2007 running period. The full HERA-II integrated luminosity of 376 $pb^{−1}$ is used. The ZEUS detector is sensitive to the full phase space of beauty production, since it has cylindrical geometry, covers a wide rapidity range and was able to measure low transverse momentum muons. In this part a measurement of beauty production was studied via the process $ep \\rightarrow {e}'b \\bar{b} \\rightarrow {e}'\\mu \\mu X$. Making full use of the HERA-II detector upgrade, $bX$ secondary vertex information was used to constrain the beauty and charm contribution to this process. The result of this analysis is the measurement of the total, visible and differential cross sections for beauty production. The cross sections are compared to next-to-leading order QCD calculations. Similar to the beauty events, instanton ...

Charm production in ep collisions with the ZEUS detector at HERA

International Nuclear Information System (INIS)

Bargende, A.

1995-02-01

The production of charmed mesons in ep collisions has been studied with the 1993 data from the ZEUS detector at HERA. Charm quarks are produced by the photoproduction process of photon-gluon fusion. Analysing a data sample corresponding to an integrated luminosity of 486 nb -1 D*(2010) ± mesons have been found in two decay channels, D* + →D 0 π + →(K - π + )π + (+c.c.) and D* + →D 0 π + →((K S 0 →π + π - )π + π - )π + . Clear signals in the mass difference ΔM=M(D*)-M(D 0 ) as well as in the M(D 0 ) distribution are found. The ep cross section for D* ± production with Q 2 2 and 115 -9 +4 ) nb in the kinematic region {p T (D*)≥1.7 GeV, vertical stroke η(D*)vertical stroke -0.21 +0.35 μb) at √(s)=296 GeV and 115 -2.9 6.1 ) μb in the range 115 -8.4 +13.1 ) μb in the range 205< W<275 GeV. (orig.)

Measurements of the neutral current e{sup {+-}}p cross sections using longitudinally polarised lepton beams at HERA II

Energy Technology Data Exchange (ETDEWEB)

Nikiforov, A.

2007-01-18

This thesis presents inclusive e{sup {+-}}p single and double differential cross sections for neutral current deep inelastic scattering measured as functions of the four-momentum transfer squared Q{sup 2} and the Bjorken variable x in interactions of longitudinally polarised leptons with unpolarised protons using the H1 detector at HERA II. An overview of the phenomenology of deep inelastic scattering is given and the experimental apparatus as well as the measurement and analysis procedures are described. The analysis is based on e{sup +}p data taken in 2003-04 and e{sup -}p data taken in 2005 at a centre-of-mass energy of {radical}(s)=318 GeV, with integrated luminosities of 47.6 pb{sup -1} and 98.4 pb{sup -1} for the e{sup +}p and e{sup -}p samples, respectively. The cross sections are measured in the range of 200HERA II data are combined together with previously published data from HERA I to determine the structure function xF{sub 3} with improved precision. Furthermore, this measurement is combined with the corresponding ZEUS measurement to provide the most accurate measurement of the interference structure function xF{sup {gamma}}{sup Z}{sub 3}, which is sensitive to the valence quark distributions down to low values of x. The data on polarised cross section asymmetries A{sup {+-}} are also combined with the ZEUS data. This leads to the first observation of parity violation in neutral current e{sup {+-}}p scattering at distances down to 10{sup -18} m. The data are well described by the Standard Model predictions. (orig.)

Measurement of neutral current cross sections at high Bjorken-x with the ZEUS detector at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2006-07-01

A new method is employed to measure the neutral current cross section up to Bjorken-x values of one with the ZEUS detector at HERA using an integrated luminosity of 65.1 pb -1 for e + p collisions and 16.7 pb -1 for e - p collisions at √(s)=318 GeV and 38.6 pb -1 for e + p collisions at √(s)=300 GeV. Cross sections have been extracted for Q 2 ≥648 GeV 2 and are compared to predictions using different parton density functions. For the highest x bins, the data have a tendency to lie above the expectations using recent parton density function parametrizations. (orig.)

Measurement of beauty and charm photoproduction using inclusive secondary vertexing with the ZEUS detector at HERA

International Nuclear Information System (INIS)

Schoenberg, Verena Ellen

2010-04-01

Photoproduction of heavy quarks in events with two jets has been measured with the ZEUS detector at HERA using data recorded in the years 2006-2007 corresponding to an integrated luminosity of 128 pb -1 . The beauty and charm content was extracted using the decay-length significance of the b and c hadrons and the invariant mass of the decay vertices. Differential cross sections as a function of P Jet T and η Jet were compared with the PYTHIA leading order plus parton shower Monte Carlo and QCD predictions calculated at next-to-leading order. In order to study the theoretical description of higher-order effects correlations between the two highest energy jets were also investigated. (orig.)

The ZEUS vertex detector: Design and prototype

International Nuclear Information System (INIS)

Alvisi, C.; Anzivino, G.; Arzarello, F.; Barbagli, G.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, G.; Bruni, P.; Camerini, U.; Cara Romeo, G.; Castellini, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Ciralli, F.; Contin, A.; Costa, M.; D'Auria, S.; Del Papa, C.; De Pasquale, S.; Fiori, F.; Forte, A.; Frasconi, F.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Lisowski, B.; Maccarrone, G.; Margotti, A.; Massam, T.; Nania, R.; O'Shea, V.; Palmonari, F.; Pelfer, P.; Pilastrini, R.; Qian, S.; Sartorelli, G.; Schioppa, M.; Susinno, G.; Timellini, R.; Zichichi, A.; Bologna Univ.; Cosenza Univ.; Florence Univ.; Istituto Nazionale di Fisica Nucleare, Bologna; Istituto Nazionale di Fisica Nucleare, Florence; Istituto Nazionale di Fisica Nucleare, Frascati; Consiglio Nazionale delle Ricerche, Florence

1991-01-01

A gas vertex detector, operated with dimethylether (DME) at atmospheric pressure, is presently being built for the ZEUS experiment at HERA. Its main design features, together with the performances of a prototype measured at various operating voltages, particle rates and geometrical conditions on a CERN Proton Synchrotron test beam, are presented. A spatial resolution down to 35 μm and an average wire efficiency of 96% have been achieved, for a 3 mm gas gap relative to each sense wire. (orig.)

Progress in the NNPDF global analysis and the impact of the legacy HERA combination

NARCIS (Netherlands)

Rojo, Juan

2015-01-01

The H1 and ZEUS collaborations have recently presented their final results for the combination of inclusive cross-section measurements taken during Run I and Run II at the HERA collider. In this contribution, following an overview of recent progress in the NNPDF framework, we quantify the impact of

High PT leptons and single W boson production at HERA

International Nuclear Information System (INIS)

Korcsak-Gorzo, Katherine

2010-12-01

A search for isolated electrons and muons with high transverse momentum in events with large missing transverse momentum has been conducted. The results have been found to be compatible with the Standard Model expectations. The cross section for single W production has been measured and the total cross section in electron-proton collisions at HERA has been found to be σ(ep → eWX) = 0.93 -0.23 +0.26 (stat.)±0.08(syst.) pb. The measurements are based on the complete available ZEUS data sets from the HERA I and II running periods taken between 1994-2007. (orig.)

DESY: HERA looks back, and forward

International Nuclear Information System (INIS)

Anon.

1994-01-01

The HERA electron-proton collider at the DESY Laboratory in Hamburg has completed a successful second year of operation, with achievements and progress so far promising well for 1994. The collider was commissioned in October 1991 and during the winter 1991-92 shutdown the two major experiments (H1 and ZEUS) were installed in the ring. HERA commissioning resumed in April 1992 and by the end of June the experiments had their first meals of electron-proton collisions. 1992 peak luminosity with nine colliding bunches in each ring was roughly 2x10 29 cm -2 s -1 . By the end of that year a total integrated luminosity of 58 nb -1 had been delivered to each of the experiments, with 25 nb -1 recorded

Design, construction and beam tests of the high resolution uranium scintillator calorimeter for ZEUS

International Nuclear Information System (INIS)

Straver, J.A.

1991-01-01

HERA will collide protons and electrons with energies up to 820 GeV and 30 GeV respectively. Therefore it allows measurements at momentum transfers (Q) which greatly surpass the investigations carried out so far. This extended range in Q will allow investigation of the interactions between the quarks and leptons at a distance scale of the order of 10 -18 cm. Two detectors are foreseen at HERA H1 and ZEUS. The design of the ZEUS detector is optimized for the study of neutral and charged current interactions. A calorimeter is a detector which absorbs the total incident energy of a particle while generating a signal proportional to this energy. The ZEUS calorimeter is built of alternating layers of dense absorber plates ( 238 U) and active layers of scintillator material with a fast readout system via wavelength shifters, light guides and photomultiplyers. The main subject of this thesis is the description of this calorimeter and its performance. After a short introduction to HERA and the physics topics, the importance of the quality of a calorimeter is pointed out and a brief overview of the ZEUS detector is given. In ch. 3 the principles of high resolution hadron calorimetry and the studies which led to the design of the ZEUS-calorimeter are discussed. Ch. 4 describes the mechanical design of the ZEUS forward calorimeter, the mechanical finite element calculations, and the production of the calorimeter modules at NIKHEF. Finally ch. 6 and 5 show the results of beam tests of the ZEUS forward calorimeter prototypes and the final full size forward calorimeter modules. (author). 59 refs.; 115 figs.; 29 tabs

Measurement of neutral current cross sections at high Bjorken-x with the ZEUS detector at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2006-07-15

A new method is employed to measure the neutral current cross section up to Bjorken-x values of one with the ZEUS detector at HERA using an integrated luminosity of 65.1 pb{sup -1} for e{sup +}p collisions and 16.7 pb{sup -1} for e{sup -}p collisions at {radical}(s)=318 GeV and 38.6 pb{sup -1} for e{sup +}p collisions at {radical}(s)=300 GeV. Cross sections have been extracted for Q{sup 2}{>=}648 GeV{sup 2} and are compared to predictions using different parton density functions. For the highest x bins, the data have a tendency to lie above the expectations using recent parton density function parametrizations. (orig.)

Measurement of beauty and charm photoproduction using inclusive secondary vertexing with the ZEUS detector at HERA

Energy Technology Data Exchange (ETDEWEB)

Schoenberg, Verena Ellen

2010-04-15

Photoproduction of heavy quarks in events with two jets has been measured with the ZEUS detector at HERA using data recorded in the years 2006-2007 corresponding to an integrated luminosity of 128 pb{sup -1}. The beauty and charm content was extracted using the decay-length significance of the b and c hadrons and the invariant mass of the decay vertices. Differential cross sections as a function of P{sup Jet}{sub T} and {eta}{sup Jet} were compared with the PYTHIA leading order plus parton shower Monte Carlo and QCD predictions calculated at next-to-leading order. In order to study the theoretical description of higher-order effects correlations between the two highest energy jets were also investigated. (orig.)

High P{sub T} leptons and single W boson production at HERA

Energy Technology Data Exchange (ETDEWEB)

Korcsak-Gorzo, Katherine

2010-12-15

A search for isolated electrons and muons with high transverse momentum in events with large missing transverse momentum has been conducted. The results have been found to be compatible with the Standard Model expectations. The cross section for single W production has been measured and the total cross section in electron-proton collisions at HERA has been found to be {sigma}(ep {yields} eWX) = 0.93{sub -0.23}{sup +0.26}(stat.){+-}0.08(syst.) pb. The measurements are based on the complete available ZEUS data sets from the HERA I and II running periods taken between 1994-2007. (orig.)

Review of searches for rare processes and physics beyond the Standard Model at HERA

International Nuclear Information System (INIS)

South, David M.; Turcato, Monica

2016-01-01

The electron-proton collisions collected by the H1 and ZEUS experiments at HERA comprise a unique particle physics data set, and a comprehensive range of measurements has been performed to provide new insight into the structure of the proton. The high centre of mass energy at HERA has also allowed rare processes to be studied, including the production of W and Z 0 bosons and events with multiple leptons in the final state. The data have also opened up a new domain to searches for physics beyond the Standard Model including contact interactions, leptoquarks, excited fermions and a number of supersymmetric models. This review presents a summary of such results, where the analyses reported correspond to an integrated luminosity of up to 1 fb -1 , representing the complete data set recorded by the H1 and ZEUS experiments. (orig.)

The LST analog read-out system of the ZEUS muon detector

International Nuclear Information System (INIS)

De Giorgi, M.; Abbiendi, G.; Bertolin, A.; Borsato, E.; Brugnera, R.; Carlin, R.; Dal Corso, F.; Dosselli, U.; Gasparini, F.; Limentani, S.; Morandin, M.; Pitacco, G.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Zuin, F.

1996-01-01

A muon position detector based on limited streamer tubes has been built for the ZEUS experiment at the HERA e-p collider at Desy. The tubes are arranged in chambers equipped with electronics circuitry providing an analog read-out of induced signals on strips set orthogonal to the tube wires. The electronic module for charge amplification and conversion will be described including some results obtained from the complete system. (orig.)

The pipelined readout for the ZEUS calorimeter

International Nuclear Information System (INIS)

Hervas, L.

1991-01-01

The electron-proton storage ring complex HERA under construction at DESY in Hamburg is the first machine of a new generation of colliders. Since physics to be studied at HERA (covered in chapter 2) base on the precise measurement of kinematic variables over a very large range of energies, a foremost emphasis is set in calorimetry. After long studies and an ambitious test program, the ZEUS collaboration has built a high resolution depleted uranium-scintillator calorimeter with photomultiplier readout, the state of the art in detectors of this type. In chapter 3 the principles of calorimetry are reviewed and the construction of the ZEUS calorimeter is described. Mainly due to the large dynamic range and the short bunch crossing times a novel concept for the readout in an analog pipelined fashion had to be designed. This concept is explained in chapter 4. The solid state implementation of the pipeline required two integrated circuits which were developed specially for the ZEUS calorimeter in collaboration with an electronics research institute and produced by industry. The design and construction of these devices and the detailed testing which has been performed for properties critical in the readout is covered in chapters 5 and 6. The whole pipelined readout is a complicated setup with many steps and collaborating systems. Its implementation and the information to operate it are covered in chapter 7. Finally the concepts presented and the applications discussed have been installed and tested on a test beam calibration experiment. There, the modules of the calorimeter have been calibrated. Chapter 8 presents results from these measurements which show excellent performance of the electronics as well as optimal properties of the calorimeter modules. (orig./HSI)

Measurement of e-p→e-X differential cross sections at high Q2 and of the structure function xF3 with ZEUS at HERA

International Nuclear Information System (INIS)

Kappes, A.

2001-12-01

The 16 pb -1 of e - p data taken with the ZEUS detector during the 1998/99 running period of HERA have been used to measure neutral current single- and double-differential cross sections in deep inelastic e - p scattering in the range 200 GeV 2 2 2 and 3.7.10 -3 2 is visible. A comparison of the measured e - p cross sections to those from e + p clearly reveals the influence of the Z-boson contribution for Q 2 >or∼ M Z 2 . This dependence is exploited to determine the mass of the Z boson, M Z , and by combining the e - p and e + p cross sections the parity violating structure function xF 3 is extracted for the first time in deep-inelastic ep scattering at ZEUS. (orig.)

Leading proton production in deep inelastic scattering at HERA

NARCIS (Netherlands)

Chekanov, S.; Derrick, M.; Magill, S.; Musgrave, B.; Nicholass, D.; Repond, J.; Yoshida, R.; Mattingly, M. C. K.; Antonioli, P.; Bari, G.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cindolo, G. Cara Romeo F.; Corradi, M.; Giusti, P.; Iacobucci, G.; Margotti, A.; Massam, T.; Nania, R.; Polini, A.; Antonelli, S.; Basile, M.; Bindi, M.; Cifarelli, L.; Contin, A.; Palmonari, F.; De Pasquale, S.; Sartorelli, G.; Zichichi, A.; Bartsch, D.; Brock, I.; Hartmann, H.; Hilger, E.; Jakob, H. -P.; Juengst, M.; Nuncio-Quiroz, A. E.; Samson, U.; Schoenberg, V.; Shehzadi, R.; Wlasenko, M.; Brook, N. H.; Heath, G. P.; Kaur, M.; Kaur, P.; Singh, I.; Capua, M.; Fazio, S.; Pellegrino, A.

The semi-inclusive reaction e(+)p -> e(+) Xp was studied with the ZEUS detector at HERA with an integrated luminosity of 12.8 pb(-1). The final-state proton, which was detected with the ZEUS leading proton spectrometer, carried a large fraction of the incoming proton energy, x(L) > 0.32, and its

New experimental results at HERA

International Nuclear Information System (INIS)

Kuhlen, M.

1994-10-01

Recent measurements by the ZEUS and H1 collaborations of the hadronic final state in deep inelastic scattering at HERA are reviewed. QCD is studied by means of charged particle spectra, jet rates and inclusive energy flows. (orig.)

Summary of workshop on future physics with HERA data

International Nuclear Information System (INIS)

Bacchetta, A.; Bluemlein, J.; Behnke, O.

2015-12-01

Recent highlights from the HERA experiments, Hermes, H1 and ZEUS, are reviewed and ideas for future analyses to fully exploit this unique data set are proposed. This document is a summary of a workshop on future physics with HERA data held at DESY, Hamburg at the end of 2014. All areas of HERA physics are covered and contributions from both experimentalists and theorists are included. The document outlines areas where HERA physics can still make a significant contribution, principally in a deeper understanding of QCD, and its relevance to other facilities. Within the framework of the Data Preservation in High Energy Physics, the HERA data have been preserved for analyses to take place over a timescale of 10 years and more. Therefore, although an extensive list of possibilities is presented here, safe storage of the data ensures that it can also be used in the far future should new ideas and analyses be proposed.

Recent results from ep scattering at HERA

International Nuclear Information System (INIS)

Haas, T.

1994-09-01

The HERA experiments, H1 and ZEUS, had their second running period during the summer and fall of 1993 collecting 0.5 pb -1 of data each, a twentyfold increase in statistics over the previous running period. This large increase in statistics together with an improved understanding of the detectors has brought a wide range of physics questions within the reach of the experiments. In this report we give a brief overview of some of the studies performed recently. (orig.)

Measurement of charm production in deep inelastic scattering using lifetime tagging for D± meson decays with the ZEUS detector at HERA

International Nuclear Information System (INIS)

Lisovyi, Mykhailo

2011-10-01

A measurement of charm production in deep inelastic scattering at √(s)=318 GeV at HERA is presented in this thesis. The analysed data were collected with the ZEUS detector during 2005-2007, corresponding to the integrated luminosity of 323 pb -1 . Charm production events were identified by the reconstruction of D ± mesons in the D ± →K -+ π ± π ± decay channel. The phase space of the analysis is defined by 5 2 2 , 0.02 T (D ± ) ± ) vertical stroke 2 is the photon virtuality, y is the inelasticity and p T (D ± ) and η(D ± ) are the D ± transverse momentum and pseudorapidity. Lifetime information was exploited to substantially reduce combinatorial background originating from light flavour production. Single- and double-differential cross sections were measured and compared to next-to-leading order QCD predictions as well as to previously published ZEUS measurements. The charm contribution to the proton structure function F 2 , F c 2 , was extracted. (orig.)

The HERA physics programme

International Nuclear Information System (INIS)

Saxon, D.H.

1991-09-01

The construction of the HERA accelerator and its detectors H1 and ZEUS opens up new physic regimes to explore at high-Q 2 and low-x. The physics interest and methods of exploration are described, starting from the environment provided by the accelerator and the reaction kinematics. (orig.)

Jets and diffraction results from HERA

International Nuclear Information System (INIS)

Buniatyan, A.

2014-01-01

The latest results on precision measurements of jet and diffractive cross sections obtained by the H1 and ZEUS experiments at HERA are reported. The inclusive jet and multi-jet cross-sections are used in QCD calculations at next-to-leading order (NLO) to determine the strong coupling α s . The cross-section measurements for diffractive inclusive DIS processes with a leading proton in the final state are combined for the H1 and ZEUS experiments in order to improve the precision and extend the kinematic range. The di-jet cross sections are measured in diffractive DIS with a leading proton and compared with QCD predictions based on diffractive parton densities in the proton. The cross sections for exclusive heavy vector meson photoproduction are studied in terms of the momentum transfer at the proton vertex and of the photon-proton centre-of-mass energy. (author)

The physics analysis environment of the ZEUS experiment

International Nuclear Information System (INIS)

Bauerdick, L.A.T.; Derugin, O.; Gilkinson, D.; Kasemann, M.; Manczak, O.

1995-12-01

The ZEUS Experiment has over the last three years developed its own model of the central computing environment for physics analysis. This model has been designed to provide ZEUS physicists with powerful and user friendly tools for data analysis as well as to be truly scalable and open. (orig.)

Cross section measurement of vector meson quasi-photoproduction at high four-momentum transfer using the ZEUS detector at the HERA collider

Energy Technology Data Exchange (ETDEWEB)

Klimek, K.H.

2001-11-01

Photoproduction of vector mesons, {gamma}p {yields} VY, where Y is the system into which the proton dissociates, has been measured in e{sup +}p interactions with the ZEUS detector at HERA using an integrated luminosity of 24 pb{sup -1}. The data were taken at a photon-proton center-of-mass energy W {approx_equal} 100 GeV and extend up to -t = 10 GeV{sup 2}, where t is the square of the four-momentum transferred to the vector meson. The differential cross section d{sigma}/dt for {rho}{sup 0}, {phi} and J/{psi} production are compared to the expectations of phenomenological models. (orig.)

Dijets in diffractive photoproduction measured with the ZEUS experiment

International Nuclear Information System (INIS)

Renner, R.

2006-10-01

The diffractive photoproduction of dijets in electron-proton scattering has been studied using 77.1 pb -1 of data taken with the ZEUS detector at HERA. The measurements have been made at a centre-of- mass energy √s=318 GeV in the kinematic range 0.2 P P is the fraction of the proton momentum taken by the diffractive exchange. The jets have been reconstructed using the k T algorithm. The two jets with the highest transversal energy have been required to satisfy E T >7.5 and 6.5 GeV, respectively, and to be in the pseudorapidity range -1.5<η<1.5. Differential cross sections have been measured and been confronted with the predictions from leading order Monte Carlo simulations and next-to-leading order QCD calculations. (orig.)

Observation of two-jet production in deep inelastic scattering at HERA

Science.gov (United States)

Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Repond, J.; Repond, S.; Stanek, R.; Talaga, R. L.; Thron, J.; Arzarello, F.; Ayad, R.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Bruni, P.; Cara Romeo, G.; Castellini, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Ciralli, F.; Contin, A.; D'Auria, S.; Del Papa, C.; Frasconi, F.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Lin, Q.; Lisowski, B.; Maccarrone, G.; Margotti, A.; Massam, T.; Nania, R.; Nemoz, C.; Palmonari, F.; Sartorelli, G.; Timellini, R.; Zamora Garcia, Y.; Zichichi, A.; Bargende, A.; Crittenden, J.; Dabbous, H.; Desch, K.; Diekmann, B.; Doeker, T.; Geerts, M.; Geitz, G.; Gutjahr, B.; Hartmann, H.; Haun, D.; Heinloth, K.; Hilger, E.; Jakob, H.-P.; Kramarczyk, S.; Kückes, M.; Mass, A.; Mengel, S.; Mollen, J.; Monaldi, D.; Müsch, H.; Paul, E.; Schattevoy, R.; Schneider, J.-L.; Wedemeyer, R.; Cassidy, A.; Cussans, D. G.; Dyce, N.; Fawcett, H. F.; Foster, B.; Gilmore, R.; Heath, G. P.; Lancaster, M.; Llewellyn, T. J.; Malos, J.; Morgado, C. J. S.; Tapper, R. J.; Wilson, S. S.; Rau, R. R.; Arneodo, M.; Barillari, T.; Schioppa, M.; Susinno, G.; Bernstein, A.; Caldwell, A.; Gialas, I.; Parsons, J. A.; Ritz, S.; Sciulli, F.; Straub, P. B.; Wai, L.; Yang, S.; Chwastowski, J.; Dwuraźny, A.; Eskreys, A.; Jakubowski, Z.; Niziom̵, B.; Piotrzkowski, K.; Zachara, M.; Zawiejski, L.; Bednarek, B.; Borzemski, P.; Eskreys, K.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Zajaç, J.; Kȩdzierski, T.; Kotański, A.; Przybycień, M.; Bauerdick, L. A. T.; Behrens, U.; Bienlein, J. K.; Coldewey, C.; Dannemann, A.; Drews, G.; Erhard, P.; Flasiński, M.; Fleck, I.; Gläser, R.; Göttlicher, P.; Haas, T.; Hagge, L.; Hain, W.; Hasell, D.; Hultschig, H.; Jahnen, G.; Joos, P.; Kasemann, M.; Klanner, R.; Koch, W.; Kötz, U.; Kowalski, H.; Krüger, J.; Labs, J.; Ladage, A.; Löhr, B.; Löwe, M.; Lüke, D.; Mainusch, J.; Manczak, O.; Momayezi, M.; Ng, J. S. T.; Nickel, S.; Notz, D.; Park, I. H.; Pösnecker, K.-U.; Rohde, M.; Roldán, J.; Ros, E.; Schneekloth, U.; Schroeder, J.; Schulz, W.; Selonke, F.; Stiliaris, E.; Tscheslog, E.; Tsurugai, T.; Turkot, F.; Vogel, W.; Wolf, G.; Youngman, C.; Grabosch, H. J.; Leich, A.; Meyer, A.; Rethfeldt, C.; Schlenstedt, S.; Barbagli, G.; Francescato, A.; Nuti, M.; Pelfer, P.; Anzivino, G.; Casaccia, R.; De Pasquale, S.; Qian, S.; Votano, L.; Bamberger, A.; Freidhof, A.; Poser, T.; Söldner-Rembold, S.; Theisen, G.; Trefzger, T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Forbes, J. R.; Jamieson, V. A.; Raine, C.; Saxon, D. H.; Brückmann, H.; Gloth, G.; Holm, U.; Kammerlocher, H.; Krebs, B.; Neumann, T.; Wick, K.; Fürtjes, A.; Kröger, W.; Lohrmann, E.; Milewski, J.; Nakahata, M.; Pavel, N.; Poelz, G.; Seidman, A.; Schott, W.; Terron, J.; Wiik, B. H.; Zetsche, F.; Bacon, T. C.; Butterworth, I.; Markou, C.; McQuillan, D.; Miller, D. B.; Mobayyen, M. M.; Prinias, A.; Vorvolakos, A.; Bienz, T.; Kreutzmann, H.; Mallik, U.; McCliment, E.; Roco, M.; Wang, M. Z.; Cloth, P.; Filges, D.; Chen, L.; Imlay, R.; Kartik, S.; Kim, H.-J.; McNeil, R. R.; Metcalf, W.; Barreiro, F.; Cases, G.; Hervás, L.; Labarga, L.; del Peso, J.; de Trocóniz, J. F.; Ikraiam, F.; Mayer, J. K.; Smith, G. R.; Corriveau, F.; Gilkinson, D. J.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Meijer Drees, R.; Mitchell, J. W.; Patel, P. M.; Sinclair, L. E.; Stairs, D. G.; Ullmann, R.; Bashindzhagyan, G. L.; Ermolov, P. F.; Gladilin, L. K.; Golubkov, Y. A.; Kuzmin, V. A.; Kuznetsov, E. N.; Savin, A. A.; Voronin, A. G.; Zotov, N. P.; Bentvelsen, S.; Botje, M.; Dake, A.; Engelen, J.; de Jong, P.; de Kamps, M.; Kooijman, P.; Kruse, A.; van der Lugt, H.; O'Dell, V.; Tenner, A.; Tiecke, H.; Uijterwaal, H.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; van Woudenberg, R.; Yoshida, R.; Bylsma, B.; Durkin, L. S.; Honscheid, K.; Li, C.; Ling, T. Y.; McLean, K. W.; Murray, W. N.; Park, S. K.; Romanowski, T. A.; Seidlein, R.; Blair, G. A.; Byrne, A.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Gingrich, D. M.; Hallam-Baker, P. M.; Harnew, N.; Khatri, T.; Long, K. R.; Luffman, P.; McArthur, I.; Morawitz, P.; Nash, J.; Smith, S. J. P.; Roocroft, N. C.; Wilson, F. F.; Abbiendi, G.; Brugnera, R.; Carlin, R.; Dal Corso, F.; De Giorgi, M.; Dosselli, U.; Gasparini, F.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Butterworth, J. M.; Bulmahn, J.; Field, G.; Oh, B. Y.; Whitmore, J.; Contino, U.; D'Agostini, G.; Guida, M.; Iori, M.; Mari, S. M.; Marini, G.; Mattioli, M.; Nigro, A.; Hart, J. C.; McCubbin, N. A.; Prytz, K.; Shah, T. P.; Short, T. L.; Barberis, E.; Cartiglia, N.; Heusch, C.; Hubbard, B.; Leslie, J.; Lockman, W.; O'Shaughnessy, K.; Sadrozinski, H. F.; Seiden, A.; Badura, E.; Biltzinger, J.; Chaves, H.; Rost, M.; Seifert, R. J.; Walenta, A. H.; Weihs, W.; Zech, G.; Dagan, S.; Levy, A.; Zer-Zion, D.; Hasegawa, T.; Hazumi, M.; Ishii, T.; Kasai, S.; Kuze, M.; Nagasawa, Y.; Nakao, M.; Okuno, H.; Tokushuku, K.; Watanabe, T.; Yamada, S.; Chiba, M.; Hamatsu, R.; Hirose, T.; Kitamura, S.; Nagayama, S.; Nakamitsu, Y.; Cirio, R.; Costa, M.; Ferrero, M. I.; Lamberti, L.; Maselli, S.; Peroni, C.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Bandyopadhyay, D.; Benard, F.; Bhadra, S.; Brkic, M.; Burow, B. D.; Chlebana, F. S.; Crombie, M. B.; Hartner, G. F.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Prentice, J. D.; Sampson, C. R.; Stairs, G. G.; Teuscher, R. J.; Yoon, T.-S.; Bullock, F. W.; Catterall, C. D.; Giddings, J. C.; Jones, T. W.; Khan, A. M.; Lane, J. B.; Makkar, P. L.; Shaw, D.; Shulman, J.; Blankenship, K.; Gibaut, D. B.; Kochocki, J.; Lu, B.; Mo, L. W.; Charchum̵a, K.; Ciborowski, J.; Gajewski, J.; Grzelak, G.; Kasprzak, M.; Krzyżanowski, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Stopczyński, A.; Tymieniecka, T.; Walczak, R.; Wróblewski, A. K.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Abramowicz, H.; Eisenberg, Y.; Glasman, C.; Karshon, U.; Montag, A.; Revel, D.; Shapira, A.; Foudas, C.; Fordham, C.; Loveless, R. J.; Goussiou, A.; Ali, I.; Behrens, B.; Dasu, S.; Reeder, D. D.; Smith, W. H.; Silverstein, S.; Frisken, W. R.; Furutani, K. M.; Iga, Y.; ZEUS Collaboration

1993-05-01

A sample of events with two distinct jets, in addition to the proton remnant, has been identified in deep inelastic, neutral current ep interactions recorded at HERA by the ZEUS experiment. For these events, the mass of the hadronic system ranges from 40 to 260 GeV. The salient features of the observed jet production agree with the predictions of higher order QCD.

Exclusive vector meson production at HERA

International Nuclear Information System (INIS)

Szuba, Dorota

2013-01-01

The exclusive photoproduction of Υ has been studied with the ZEUS detector in ep collisions at HERA. The exponential slope, b, of the |t|-dependence of the cross section, where t is the squared four-momentum transfer at the proton vertex, has been measured. This constitutes the first measurement of the |t|-dependence of the γp→Υp cross section. The differential crosssections as a function of t at lower energies of γp centre-of-mass has been studied in exclusive diffractive photoproduction of J/ψ mesons with the H1 detector. The exclusive electroproduction of two pions has been measured by the ZEUS experiment. The two-pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, assuming that the studied mass range includes the contributions of the ρ, ρ′ and . ρ'' vector-meson states.

The presampler for the forward and rear calorimeter in the ZEUS detector

Energy Technology Data Exchange (ETDEWEB)

Bamberger, A; Bornheim, A; Crittenden, J; Grabosch, H -J; Grothe, M; Hervas, L; Hilger, E; Holm, U; Horstmann, D; Kaufmann, V; Kharchilava, A; Koetz, U; Kummerow, D; Mallik, U; Meyer, A; Nowoczyn, M; Ossowski, R; Schlenstedt, S; Tiecke, H; Verkerke, W; Vossebeld, J; Vreeswijk, M; Wang, S M; Wu, J [Bonn Univ. (Germany). Phys. Inst.; [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); [DESY-IfH Zeuthen, Zeuthen (Germany); [Fakultaet fuer Physik der Universitaet Freiburg, Freiburg i.Br. (Germany); [Hamburg University, I. Institute of Exp. Physics, Hamburg (Germany); [University of Iowa Physics and Astronomy Dept, Iowa City (United States); [Univer. Autonoma Madrid, Depto de Fisica Teorica, Madrid (Spain); [NIKHEF and University of Amsterdam, Amsterdam (Netherlands)

1996-11-21

The ZEUS detector at HERA has been supplemented with a presampler detector in front of the forward and rear calorimeters. It consists of a segmented scintillator array read out with wavelength-shifting fibers. We discuss its design, construction and performance. Test beam data obtained with a prototype presampler and the ZEUS prototype calorimeter demonstrate the main function of this detector, i.e. the correction for the energy lost by an electron interacting in inactive material in front of the calorimeter. (orig.).

The performance of the ZEUS central tracking detector z-by-timing electronics in a transputer based data acquisition system

International Nuclear Information System (INIS)

Foster, B.; Heath, G.P.; Llewellyn, T.J.; Gingrich, D.M.; Harnew, N.; Hallam-Baker, P.M.; Khatri, T.; McArthur, I.C.; Morawitz, P.; Nash, J.; Shield, P.D.; Topp-Jorgensen, S.; Wilson, F.F.; Allen, D.B.; Carter, R.C.; Jeffs, M.D.; Morrissey, M.C.; Quinton, S.P.H.; Lane, J.B.; Postranecky, M.

1993-01-01

The Central Tracking Detector of the ZEUS experiment employs a time difference technique to measure the z coordinate of each hit. The method provides fast, three-dimensional space point measurements which are used as input to all levels of the ZEUS trigger. Such a tracking trigger is essential in order to discriminate against events with vertices lying outside the nominal electron-proton interaction region. Since the beam crossing interval of the HERA collider is 96 ns, all data must be pipelined through the front-end readout electronics. Subsequent data aquisition employs a novel technique which utilizes a network of approximately 120 INMOS transputers to process the data in parallel. The z-by-timing method and its data aquisition have been employed successfully in recording and reconstructing tracks from electron-proton interactions in ZEUS. (orig.)

Measurement of D{sup *{+-}} production at low Q{sup 2} with the beam-pipe calorimeter of ZEUS at HERA

Energy Technology Data Exchange (ETDEWEB)

Irrgang, P

2004-12-01

The production of D* mesons in deep-inelastic ep-scattering has been studied using the ZEUS detector at HERA. The total D* production cross-section and the differential cross-sections as functions of Q{sup 2}, y, p{sub t}(D*) and {eta}(D*) have been measured at low Q{sup 2}. The data sample used was collected during the period 1998-2000 and amounts to an integrated luminosity of 82.2 pb{sup -1}. The low Q{sup 2} region could be reached using the beam-pipe calorimeter which measures the scattered electron at very small angles. Therefore special emphasis was put on the calibration of the BPC in order to reconstruct events in the kinematic range 0.05 < Q{sup 2} < 0.7 GeV{sup 2} and 0.02 < y < 0.85. The D* mesons have been identified via the decay into lighter mesons D{sup *}+{yields}K{sup -}{pi}{sup +}{pi}{sup -} and the charged conjugated decay in the kinematic region 1.5ZEUS D* production measurements could be extended towards lower values of Q{sup 2} in agreement with the corresponding perturbative QCD predictions. (orig.)

Exclusive vector meson production at HERA

Energy Technology Data Exchange (ETDEWEB)

Szuba, Dorota [Hamburg University, Hamburg (Germany); Collaboration: H1 Collaboration; ZEUS Collaboration

2013-04-15

The exclusive photoproduction of {Upsilon} has been studied with the ZEUS detector in ep collisions at HERA. The exponential slope, b, of the |t|-dependence of the cross section, where t is the squared four-momentum transfer at the proton vertex, has been measured. This constitutes the first measurement of the |t|-dependence of the {gamma}p{yields}{Upsilon}p cross section. The differential crosssections as a function of t at lower energies of {gamma}p centre-of-mass has been studied in exclusive diffractive photoproduction of J/{psi} mesons with the H1 detector. The exclusive electroproduction of two pions has been measured by the ZEUS experiment. The two-pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, assuming that the studied mass range includes the contributions of the {rho}, {rho} Prime and . {rho}'' vector-meson states.

A two-Transputer VME module for data acquisition and on-line event selection in ZEUS

International Nuclear Information System (INIS)

Boterenbrood, H.; Goble, S.; Jong, S.J. de; Kieft, G.; Lugt, H.J. van der; Uijterwaal, H.A.J.R.; Vermeulen, J.C.; Waard, A. de; Wiggers, L.W.

1993-01-01

For the ZEUS experiment at the HERA e-p collider in Hamburg a versatile and fast VME-based processor module has been developed at NIKHEF-H. The single-slot wide VME module contains two INMOS T800 Transputers, each with private memory, and a triple-port memory (TPM), accessible to both Transputers. Both Transputers have access to the VME bus, while an external master can also access the TPM directly. The VME accesses proceed typically with 10 Mbyte/s. Three application-specific integrated circuits (ASICs) handle the internal and external Transputer interfacing. The module combines the VME environment with the parallel processing and link-oriented environment of the Transputer. Over 200 modules are used in the data acquisition and event selection systems of ZEUS. (orig.)

Signals for supersymmetry at HERA

International Nuclear Information System (INIS)

Dreiner, H.; Morawitz, P.

1994-07-01

We consider the baryon parity signals at HERA for the case of the MSSM production mechanisms and the decays via the lepton number violating couplings L i Q anti D. We can probe very small Yukawa couplings λ'> or ∼3.10 -6 , limited only by the decay length of the LSP. We assume the LSP to be the lightest neutralino and study its decays in detail. We present the matrix element squared for the tree-level decay amplitude of a generally mixed neutralino explicitly. We find that the branching fraction to charged leptons strongly depends on the SUSY parameters and can differ significantly from the naively expected 50%. The SUSY mass reaches of the studied processes in the ZEUS detector at HERA were found to be: (m(e, anti ν)+m( anti q)) ≤ 170 GeV, 195 GeV and 205 GeV for the L t Q anti D, L μ Q anti D and L e Q anti D couplings respectively. These are well above existing limits on R-parity violating (R p ) SUSY from previous experiments. We conclude that HERA offers a very promising discovery potential for R p SUSY. (orig.)

Measurement of D*± production at low Q2 with the beam-pipe calorimeter of ZEUS at HERA

International Nuclear Information System (INIS)

Irrgang, P.

2004-12-01

The production of D* mesons in deep-inelastic ep-scattering has been studied using the ZEUS detector at HERA. The total D* production cross-section and the differential cross-sections as functions of Q 2 , y, p t (D*) and η(D*) have been measured at low Q 2 . The data sample used was collected during the period 1998-2000 and amounts to an integrated luminosity of 82.2 pb -1 . The low Q 2 region could be reached using the beam-pipe calorimeter which measures the scattered electron at very small angles. Therefore special emphasis was put on the calibration of the BPC in order to reconstruct events in the kinematic range 0.05 2 2 and 0.02 * +→K - π + π - and the charged conjugated decay in the kinematic region 1.5 t (D*) 2 in agreement with the corresponding perturbative QCD predictions. (orig.)

Charm production and QCD analysis at HERA and LHC

International Nuclear Information System (INIS)

Zenaiev, Oleksandr

2015-03-01

sections and a 'customised' QCD calculation was introduced in order to improve the agreement between the central values of the theoretical predictions and the data. While the HERA charm data are sensitive to the gluon distribution in the proton at the values of partonic fractions of the proton momenta 10 -4 experiment were used together with the combined inclusive and heavy-flavour production cross sections in deep inelastic scattering at HERA. The heavy-flavour data of the LHCb experiment impose constraints on the gluon and sea-quark distributions at very low partonic fractions of the proton momenta. This kinematic range is currently not covered by other experimental data in QCD fits. As the technical part of this thesis, the ZEUS Event Display program has been modified in the context of the ZEUS data preservation project to become independent of the ZEUS Software. The new program is a pure ROOT application. While it provides the main functionalities that were available in the classic program, it does not require any maintenance.

Search for excited leptons in ep scattering at HERA using the ZEUS detector

International Nuclear Information System (INIS)

Weber, A.

2002-03-01

A search for heavy excited electrons and neutrinos has been performed with the ZEUS detector at HERA. The ep scattering data used were taken at a centre-of-mass energy of 318 GeV in the years 1998-2000. Excited electrons have been searched for in e - p and e + p collisions corresponding to integrated luminosities of 16.7 pb -1 and 66.1 pb -1 , respectively. The decay channels e * → eγ, e * → νW → νqq' and e * → eZ → eqq have been considered. Excited neutrinos have been sought in the e - p data set via the decay channels ν * → νγ, ν * → eW → eqq' and ν * → νZ → νqq. The event selection has been performed employing both fixed cuts and a probability-based method as alternatives, with the latter yielding better overall performance. No evidence for an e * or ν * signal is observed in any of the channels analysed. Upper limits (95% confidence level) as a function of the excited-lepton mass have been set on the cross section times the branching ratio, σ x BR, and on the coupling over the compositeness scale, f/Λ. In many cases, these limits extend up to higher masses and are more stringent than the existing ones. (orig.)

Status of the HERA-B experiment

CERN Document Server

Schmidt, B

2001-01-01

HERA-B is a fixed target experiment using the halo of the 920 GeV proton beam of HERA on an internal wire target. The aim of the experiment is to trigger on rare B to J/ psi decays, using a highly selective trigger system and to measure the CP violating parameter sin (2 beta ). The specific problems of the experiment arise from the extreme background conditions which put unprecedented requirements on the detector components and the triggering and read out system. After 6 years of intense R&D, HERA-B has been finally completed and is now in its commissioning phase.

Dijets in diffractive photoproduction measured with the ZEUS experiment

Energy Technology Data Exchange (ETDEWEB)

Renner, R.

2006-10-15

The diffractive photoproduction of dijets in electron-proton scattering has been studied using 77.1 pb{sup -1} of data taken with the ZEUS detector at HERA. The measurements have been made at a centre-of- mass energy {radical}s=318 GeV in the kinematic range 0.27.5 and 6.5 GeV, respectively, and to be in the pseudorapidity range -1.5<{eta}<1.5. Differential cross sections have been measured and been confronted with the predictions from leading order Monte Carlo simulations and next-to-leading order QCD calculations. (orig.)

Measurement of charm production in deep inelastic scattering using lifetime tagging for D{sup {+-}} meson decays with the ZEUS detector at HERA

Energy Technology Data Exchange (ETDEWEB)

Lisovyi, Mykhailo

2011-10-15

A measurement of charm production in deep inelastic scattering at {radical}(s)=318 GeV at HERA is presented in this thesis. The analysed data were collected with the ZEUS detector during 2005-2007, corresponding to the integrated luminosity of 323 pb{sup -1}. Charm production events were identified by the reconstruction of D{sup {+-}} mesons in the D{sup {+-}}{yields}K{sup -+}{pi}{sup {+-}}{pi}{sup {+-}} decay channel. The phase space of the analysis is defined by 5ZEUS measurements. The charm contribution to the proton structure function F{sub 2}, F{sub c}{sup 2}, was extracted. (orig.)

A search for lepton flavor violating transitions e τ via leptoquarks in e+p scattering with the ZEUS detector at HERA

International Nuclear Information System (INIS)

Kerger, R.

2001-03-01

A search for lepton flavor violation e + p → τX under the leptoquark (LQ) assumption has been performed with the ZEUS detector at HERA using the 1994 to 1997 data corresponding to an integrated luminosity of 47.7 pb -1 . Special effort has been made to identify the hadronic decay modes of the τ. No evidence for lepton flavor violation was found. For resonantly produced leptoquarks, limits on λ eq i x √(BR(LQ → lq j )) as well as on their Yukawa couplings λ eq i and λ τq j as a function of the leptoquark mass have been set. Assuming couplings of electromagnetic strength, λ = 0.3, leptoquarks for masses up to 285 GeV are excluded at 95% C.L. and assuming vice-versa leptoquarks of M LQ = 250 GeV, λ x √(BR) down to 3 . 10 -2 is excluded at 95% C.L. For leptoquarks with M LQ >> √(s), limits are set on the four-fermion contact interaction term λ eq i λ lq j /M LQ 2 . Many of these limits supersede existing limits from low-energy experiments. (orig.)

Calibration of the ZEUS 6 m tagger

Energy Technology Data Exchange (ETDEWEB)

Schroeder, Matthias

2008-11-15

In the last period of the HERA running, data were taken with the ZEUS detector to measure directly the longitudinal structure function of the proton and to determine the total photoproduction cross section. The identification of electrons from photoproduction events, in which an electron interacts with a proton and is scattered at very small angles, is essential for both the measurements. The electrons were detected using a small electromagnetic calorimeter, the 6 m tagger, which as located near the beam pipe at {approx} 6m from the ep interaction point. A method for the calibration and reconstruction of electromagnetic showers in the 6m tagger was developed and the energy acceptance range and the resolution of the 6 m tagger was measured. Furthermore, the photon acceptance and the energy resolution of a different electromagnetic calorimeter used for the luminosity measurement at ZEUS were analyzed using the 6 m tagger. (orig.)

Calibration of the ZEUS 6 m tagger

International Nuclear Information System (INIS)

Schroeder, Matthias

2008-11-01

In the last period of the HERA running, data were taken with the ZEUS detector to measure directly the longitudinal structure function of the proton and to determine the total photoproduction cross section. The identification of electrons from photoproduction events, in which an electron interacts with a proton and is scattered at very small angles, is essential for both the measurements. The electrons were detected using a small electromagnetic calorimeter, the 6 m tagger, which as located near the beam pipe at ∼ 6m from the ep interaction point. A method for the calibration and reconstruction of electromagnetic showers in the 6m tagger was developed and the energy acceptance range and the resolution of the 6 m tagger was measured. Furthermore, the photon acceptance and the energy resolution of a different electromagnetic calorimeter used for the luminosity measurement at ZEUS were analyzed using the 6 m tagger. (orig.)

Scaled momentum spectra in deep inelastic scattering at HERA

NARCIS (Netherlands)

Abramowicz, H.; Abt, I.; Adamczyk, L.; Adamus, M.; Antonelli, S.; Antonioli, P.; Antonov, A.; Arneodo, M.; Aushev, V.; Aushev, Y.; Bachynska, O.; Bamberger, A.; Barakbaev, A. N.; Barbagli, G.; Bari, G.; Barreiro, F.; Bartsch, D.; Basile, M.; Behnke, O.; Behr, J.; Behrens, U.; Bellagamba, L.; Bertolin, A.; Bhadra, S.; Bindi, M.; Blohm, C.; Bold, T.; Boos, E. G.; Borodin, M.; Borras, K.; Boscherini, D.; Boutle, S. K.; Brock, I.; Brownson, E.; Brugnera, R.; Bruemmer, N.; Bruni, A.; Bruni, G.; Brzozowska, B.; Bussey, P. J.; Butterworth, J. M.; Bylsma, B.; Caldwell, A.; Capua, M.; Carlin, R.; Catterall, C. D.; Chekanov, S.; Chwastowski, J.; Ciborowski, J.; Pellegrino, A.

Charged particle production has been studied in neutral current deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 0.44 fb(-1). Distributions of scaled momenta in the Breit frame are presented for particles in the current fragmentation region. The evolution

The design and performance of the ZEUS micro vertex detector

Energy Technology Data Exchange (ETDEWEB)

Polini, A. [Bologna Univ. (Italy)]|[INFN Bologna (Italy); Brock, I.; Goers, S. [Bonn Univ. (DE). Physikalisches Institut] (and others)

2007-08-15

In order to extend the tracking acceptance, to improve the primary and secondary vertex reconstruction and thus enhancing the tagging capabilities for short lived particles, the ZEUS experiment at the HERA Collider at DESY installed a silicon strip vertex detector. The barrel part of the detector is a 63 cm long cylinder with silicon sensors arranged around an elliptical beampipe. The forward part consists of four circular shaped disks. In total just over 200k channels are read out using 2.9 m{sup 2} of silicon. In this report a detailed overview of the design and construction of the detector is given and the performance of the completed system is reviewed. (orig.)

The design and performance of the ZEUS micro vertex detector

International Nuclear Information System (INIS)

Polini, A.; Brock, I.; Goers, S.

2007-08-01

In order to extend the tracking acceptance, to improve the primary and secondary vertex reconstruction and thus enhancing the tagging capabilities for short lived particles, the ZEUS experiment at the HERA Collider at DESY installed a silicon strip vertex detector. The barrel part of the detector is a 63 cm long cylinder with silicon sensors arranged around an elliptical beampipe. The forward part consists of four circular shaped disks. In total just over 200k channels are read out using 2.9 m 2 of silicon. In this report a detailed overview of the design and construction of the detector is given and the performance of the completed system is reviewed. (orig.)

Optimization of the transverse electron polarization of HERA at 26.7 GeV

International Nuclear Information System (INIS)

Grosshauser, C.

1994-08-01

The methods applied for the optimization of the transverse electron polarization were presented in the following and the measurements performed by this extensively described. By these measurements could be shown that in pure electron-beam operation a degree of polarization of P similar 67% can be reached. A adjustment of the electron storage ring determined by this allows also under luminosity conditions without further optimization an only fewly deminuished transverse electron polarization. The measured polarization values where thereby over several hours stable and could also after months be reproduced. An interference of the polarization by electron-proton collisions could not be stated in the framework of the measurements. In an optimization of the electron polarization performed during the luminosity operation polarization values of P similar 67% could be reached. Thereby could be stated that an optimization of the electron polarization can be perforemd parallel to the data taking of the experiments H1 and ZEUS without fearing of extensive interferences for the measurement conditions of the experiments. By means of the resonance depolarization, which was at HERA for the first time successfully applied, the electron energy was determined with a maximal error of similar 3 MeV and an energy calibration of the HERA electron storage ring performed. At this energy calibration a mean deviation of the nominal energy from the energy values, which were determined by means of the depolarization measurements, of similar 35 MeV resulted. By the different studies on the transverse electron polarization and by the production of the worldwide first longitudinally polarized electron beam in a storage ring, in which a degree of polarization of P long ≥55% was observed, could be shown that a data taking of the experiment HERMES can be pursued parallel to the experiments H1 and ZEUS in the electron storage ring HERA

Search for leptoquarks at HERA

Energy Technology Data Exchange (ETDEWEB)

Huettmann, Antje

2009-10-15

A search for first generation leptoquarks was performed in polarized electron-proton collider data recorded with the ZEUS detector at HERA in the years 2003-2007. They were analyzed for final states with an electron and jets or with missing transverse momentum and jets and a search for resonance structures or other deviations from the Standard Model predictions in the spectra of the invariant mass of lepton and jets was performed. No evidence for leptoquark signals was found. The data were combined with the previously taken data at HERA corresponding to an integrated luminosity of 488 pb{sup -1} and limits were set on the Yukawa coupling {lambda} as a function of the leptoquark mass for different leptoquark types within the Buchmueller-Rueckl-Wyler model. (orig.)

The design, status and performance of the ZEUS central tracking detector electronics

International Nuclear Information System (INIS)

Foster, B.; Cussans, D.G.; Fawcett, H.F.; Gilmore, R.S.; Heath, G.P.; Llewellyn, T.J.; Malos, J.; Morgado, C.J.S.; Tapper, R.J.; Gingrich, D.M.; Harnew, N.; Hallam-Baker, P.; Nash, J.; Khatri, T.; Shield, P.D.; McArthur, I.; Topp-Jorgensen, S.; Wilson, F.F.; Allen, D.; Baird, S.A.; Carter, R.; Galagadera, S.; Gibson, M.D.; Hatley, R.S.; Jeffs, M.; Milborrow, R.; Morissey, M.; Quinton, S.P.H.; White, D.J.; Lane, J.; Nixon, G.; Postranecky, M.; Jamdagni, A.K.; Marcou, C.; Miller, D.B.; Toudup, L.

1992-01-01

The readout system developed for the ZEUS central tracking detector (CTD) is described. The CTD is required to provide an accurate measurement of the sagitta and energy loss of charged particles as well as provide fast trigger information. This must be carried out in the HERA environment in which beams cross every 96 ns. The first two aims are achieved by digitizing chamber pulses using a pipelined 104 MHz FADC system. The trigger uses a fast determination of the difference in the arrival times of a pulse at each end of the CTD. It processes this data and gives information to the ZEUS global first level trigger. The modules are housed in custom-built racks and crates and read out using a DAQ system based on Transputer readout controllers. These also monitor data quality and produce data for the ZEUS second level Trigger. (orig.)

Leading proton production in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-12-01

The semi-inclusive reaction e + p→e + Xp was studied with the ZEUS detector at HERA using an integrated luminosity of 12.8 pb -1 . The final-state proton, which was detected with the ZEUS leading proton spectrometer, carried a large fraction of the incoming proton energy, x L >0.32, and its transverse momentum squared satisfied p T 2 2 ; the exchanged photon virtuality, Q 2 , was greater than 3 GeV 2 and the range of the masses of the photon-proton system was 45 L , p T 2 , Q 2 and the Bjorken scaling variable, x. (orig.)

Studies on the prototype of the transition-radiation detector for the Zeus experiment

International Nuclear Information System (INIS)

Munde, A.

1991-04-01

The Zeus detector is currently being built for HERA at Hamburg. One part of the inner detector is the transition radiation detector (TRD). It will identify single electrons inside hadronic jets of deep inelastic ep-collisions. To test the chamber performance and to improve mechanical tools, a prototype of the smallest detector modul (TRD-1) was built. The gasgain of this prototype was measured under several high voltage conditions. The gasgain is about 1.5x10 3 up to 8x10 3 in Argon/Methane 90/10. To test the function of this prototype, the test beam facility at the Bonn 2.5 GeV electron synchrotron was used. The same relative amplification was measured by comparing the beam results with those obtained with a Fe 55 -source. (orig.) [de

Heavy flavours production in DIS events at HERA

International Nuclear Information System (INIS)

Bellan, Paolo

2008-10-01

The estimation of the fraction of events in which an heavy quark is produced in the deeply inelastic electron-proton collisions is the measurement performed in the present analysis. The analysed data sample corresponds to about 130 pb -1 collected during the years 2004-2005 by the ZEUS detector, located in one of the interaction points of the HERA collider in Hamburg. The measured percentages are directly related to the proton structure, formally encoded by the contribution of the heavy quarks to the structure functions F 2 . The tagging of the events in which an heavy quark is produced is achieved by means of the Impact Parameter method. The correlation between the lifetime of the hadrons and the geometrical properties of the relative tracks makes possible to pick out the heavy flavours production form the background. This kind of 'topological' method makes an extensive use of the silicon Micro Vertex Detector (MVD). This essential component of the tracking suite of the ZEUS detector has been the major upgrade realized in the second half of the ZEUS experiment data taking period. The achievement of the physical goal has strongly leaned on its performance and reliability, so a considerable part of the work consisted in feasibility, refinement and optimization studies. (orig.)

Heavy flavours production in DIS events at HERA

Energy Technology Data Exchange (ETDEWEB)

Bellan, Paolo

2008-10-15

The estimation of the fraction of events in which an heavy quark is produced in the deeply inelastic electron-proton collisions is the measurement performed in the present analysis. The analysed data sample corresponds to about 130 pb{sup -1} collected during the years 2004-2005 by the ZEUS detector, located in one of the interaction points of the HERA collider in Hamburg. The measured percentages are directly related to the proton structure, formally encoded by the contribution of the heavy quarks to the structure functions F{sub 2}. The tagging of the events in which an heavy quark is produced is achieved by means of the Impact Parameter method. The correlation between the lifetime of the hadrons and the geometrical properties of the relative tracks makes possible to pick out the heavy flavours production form the background. This kind of 'topological' method makes an extensive use of the silicon Micro Vertex Detector (MVD). This essential component of the tracking suite of the ZEUS detector has been the major upgrade realized in the second half of the ZEUS experiment data taking period. The achievement of the physical goal has strongly leaned on its performance and reliability, so a considerable part of the work consisted in feasibility, refinement and optimization studies. (orig.)

Leading Baryon Production at HERA

International Nuclear Information System (INIS)

Dodonov, V.; Schmitt, S.

2009-01-01

The production of highly energetic forward neutrons has been studied in deep-inelastic scattering. The data were taken with the H1 detector at HERA in the years 2006-2007 and correspond to an integrated luminosity of 117 pb -1 . Semi-inclusive cross sections have been measured in the kinematic region 4 2 2 , 0.7*10 -4 -1 and the fractional momentum of the neutron 0.3 L T and compared to the predictions of models of leading neutron production. Differential cross sections for dijet photoproduction and in association with a leading neutron have been measured in the reaction e + p → e + jet jet X n with the ZEUS detector at HERA using an integrated luminosity of 40pb -1 . The data are consistent with a simple pion exchange model. The ratio of the neutron-tagged and dijet cross sections show violations of factorization of the lepton and photon vertices which can be explained by kinematic effects constraining the phase space for neutron production. Normalised double-differential leading-neutron cross sections have been measured in dijet photoproduction for the first time. The distributions can be fully characterised by only two energy dependent parameters extracted from fits to the data. Absorption effects were studied by comparing the dijet photoproduction measurements and similar results in deep inelastic scattering. No clear effect, not related to kinematics, was observed. In a resolved-enriched dijet photoproduction sample, significantly fewer neutrons were seen than for direct. This depletion can also be accounted for by kinematic constraints. The semi-inclusive reaction e + p → e + X p was studied with the ZEUS detector at HERA using an integrated luminosity of 12.8 pb -1 . The final state proton, which was detected with the ZEUS leading proton spectrometer, carried a large fraction of the incoming proton energy, x L > 0.32, and its transverse momentum squared satisfied p T 2 2 ; the exchanged photon virtuality, Q 2 , was greater than 3 GeV 2 and the range of

A measurement of multijet production in low-x{sub Bj} neutral current deep inelastic scattering with ZEUS at HERA

Energy Technology Data Exchange (ETDEWEB)

Danielson, T.E.

2007-12-15

Inclusive dijet and trijet production in deep inelastic ep scattering has been measured for 10HERA ep collider with center-of-mass energy {radical}(s)=318 GeV using the ZEUS detector and correspond to an integrated luminosity of 82 pb{sup -1}. Jets were identified in the hadronic center-of-mass (HCM) frame using the k{sub T} cluster algorithm in the longitudinally invariant inclusive mode. Measurements of dijet and trijet differential cross sections are presented as functions of Q{sup 2}, x{sub Bj}, jet transverse energy, and jet pseudorapidity. As a further examination of low-x{sub Bj} dynamics, multi-differential cross sections as functions of the jet correlations in transverse momenta, azimuthal angles, and pseudorapidity are also presented. Calculations at O({alpha}{sup 3}{sub s}) generally describe the trijet data well and improve the description of the dijet data compared to the calculation at O({alpha}{sup 2}{sub s}). (orig.)

Design and tests of the silicon sensors for the ZEUS micro vertex detector

International Nuclear Information System (INIS)

Dannheim, D.; Koetz, U.; Coldewey, C.; Fretwurst, E.; Garfagnini, A.; Klanner, R.; Martens, J.; Koffeman, E.; Tiecke, H.; Carlin, R.

2003-01-01

To fully exploit the HERA-II upgrade, the ZEUS experiment has installed a Micro Vertex Detector (MVD) using n-type, single-sided, silicon μ-strip sensors with capacitive charge division. The sensors have a readout pitch of 120 μm, with five intermediate strips (20 μm strip pitch). The designs of the silicon sensors and of the test structures used to verify the technological parameters, are presented. Results on the electrical measurements are discussed. A total of 1123 sensors with three different geometries have been produced by Hamamatsu Photonics K.K. Irradiation tests with reactor neutrons and 60 Co photons have been performed for a small sample of sensors. The results on neutron irradiation (with a fluence of 1x10 13 1 MeV equivalent neutrons/cm 2 ) are well described by empirical formulae for bulk damage. The 60 Co photons (with doses up to 2.9 kGy) show the presence of generation currents in the SiO 2 -Si interface, a large shift of the flatband voltage and a decrease of the hole mobility

Angular correlations in three-jet events in ep collisions at HERA

NARCIS (Netherlands)

Abramowicz, H.; Abt, I.; Adamczyk, L.; Adamus, M.; Aggarwal, R.; Antonelli, S.; Antonioli, P.; Antonov, A.; Arneodo, M.; Aushev, V.; Aushev, Y.; Bachynska, O.; Bamberger, A.; Barakbaev, A. N.; Barbagli, G.; Bari, G.; Barreiro, F.; Bartosik, N.; Bartsch, D.; Basile, M.; Behnke, O.; Behr, J.; Behrens, U.; Bellagamba, L.; Bertolin, A.; Bhadra, S.; Bindi, M.; Blohm, C.; Bokhonov, V.; Bold, T.; Bondarenko, K.; Boos, E. G.; Borras, K.; Boscherini, D.; Brock, I.; Brownson, E.; Brugnera, R.; Bruemmer, N.; Bruni, A.; Bruni, G.; Brzozowska, B.; Bussey, P. J.; Bylsma, B.; Caldwell, A.; Capua, M.; Carlin, R.; Catterall, C. D.; Chekanov, S.; Chwastowski, J.; Pellegrino, A.

2012-01-01

Three-jet production in deep inelastic ep scattering and photoproduction was investigated with the ZEUS detector at HERA using an integrated luminosity of up to 127 pb(-1). Measurements of differential cross sections are presented as functions of angular correlations between the three jets in the

Search for single-top production in ep collisions at HERA

CERN Document Server

Abramowicz, H.

2012-02-14

A search for single-top production, $ep \\rightarrow etX$, has been performed with the ZEUS detector at HERA using data corresponding to an integrated luminosity of $0.37\\fbi$. No evidence for top production was found, consistent with the expectation from the Standard Model. Limits were computed for single-top production via flavour changing neutral current transitions. The result was combined with a previous ZEUS result yielding a total luminosity of 0.50fb-1. A 95% credibility level upper limit of 0.13 pb was obtained for the cross section at the centre-of-mass energy of $\\sqrt{s}=315\\gev$.

Measurement of dijet cross sections in deep inelastic ep scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Theedt, Thorben

2009-11-15

Dijet cross sections have been measured in deep inelastic neutral current electron-proton scattering at HERA. Cross sections have been measured differentially as functions of the photon virtuality, Q{sup 2}, the scaling variable, Bjorken x, the mean transverse jet energy, E{sub T}, the invariant dijet mass, M{sub jj}, the difference in jet pseudorapidity, {eta}'= vertical stroke {eta}{sup jet{sub 1}}-{eta}{sup jet{sub 2}} vertical stroke and the momentum fraction, {xi}. Cross sections as function of {xi} have also been measured in different regions of the photon virtuality. The analysed data were recorded at a centre-of-mass energy of 318 GeV with the ZEUS detector in the years 1998, 1999, and 2000 and correspond to an integrated luminosity of 81.74 pb{sup -1}. The phase space of the analysis is defined by 125ZEUS detector was not described by the HERA II Monte Carlo predictions. The results triggered the so called single pion study, in which single pion events were used to investigate the response of the simulated detector. (orig.)

Angular correlations in three-jet events in ep collisions at HERA

NARCIS (Netherlands)

Abramowicz, H.; et al., [Unknown; Grigorescu, G.; Keramidas, A.; Koffeman, E.; Kooijman, P.; Pellegrino, A.; Tiecke, H.; Vázquez, M.; Wiggers, L.

2012-01-01

Three-jet production in deep inelastic ep scattering and photoproduction was investigated with the ZEUS detector at HERA using an integrated luminosity of up to 127  pb−1. Measurements of differential cross sections are presented as functions of angular correlations between the three jets in the

Angular correlations in three-jet events in ep collisions at HERA

NARCIS (Netherlands)

Abramowicz, H.; Abt, I.; Kooijman, P.; Zotkin, D.S.

2012-01-01

Three-jet production in deep inelastic ep scattering and photoproduction was investigated with the ZEUS detector at HERA using an integrated luminosity of up to 127  pb-1. Measurements of differential cross sections are presented as functions of angular correlations between the three jets in the

Measurement of charm fragmentation fractions in photoproduction at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max-Planck-Institute for Physics, Munich (Germany); Abt, I. [Max-Planck-Institute for Physics, Muinch (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science] [and others; Collaboration: ZEUS Collaboration

2013-06-15

The production of D{sup 0}, D{sup *+}, D{sup +}, D{sub s}{sup +} and {Lambda}{sub c}{sup +} charm hadrons and their antiparticles in ep scattering at HERA has been studied with the ZEUS detector, using a total integrated luminosity of 372 pb{sup -1}. The fractions of charm quarks hadronising into a particular charm hadron were derived. In addition, the ratio of neutral to charged D-meson production rates, the fraction of charged D mesons produced in a vector state, and the strangeness-suppression factor have been determined. The measurements have been performed in the photoproduction regime. The charm hadrons were reconstructed in the range of transverse momentum p{sub T} > 3.8GeV and pseudorapidity vertical stroke {eta} vertical stroke <1.6. The charm fragmentation fractions are compared to previous results from HERA and from e{sup +}e{sup -} experiments. The data support the hypothesis that fragmentation is independent of the production process.

Heavy Quark Production in ep Collisions at HERA

International Nuclear Information System (INIS)

Bloch, I.

2006-01-01

Collisions of electrons with protons at a centre-of-mass energy of 318 GeV are being recorded by the two experiments H1 and ZEUS at the ep accelerator HERA at DESY, Hamburg (Germany). Measurements involving beauty and charm quarks, performed by these experiments, provide a good environment to test perturbative QCD predictions as the large quark mass supplies a hard scale. Recent measurements of beauty and charm production in ep collisions are presented here. QCD predictions at next-to-leading order are found to generally agree with the measurements. Beauty measurements however are sometimes slightly higher than the predicted cross sections. Beauty and charm contributions to the proton structure were also measured and are well described by QCD predictions

The Zeus Copper/Uranium Critical Experiment at NCERC

International Nuclear Information System (INIS)

Sanchez, Rene G.; Hayes, David K.; Bounds, John Alan; Jackman, Kevin R.; Goda, Joetta M.

2012-01-01

A critical experiment was performed to provide nuclear data in a non-thermal neutron spectrum and to reestablish experimental capability relevant to Stockpile Stewardship and Technical Nuclear Forensic programs. Irradiation foils were placed at specific locations in the Zeus all oralloy critical experiment to obtain fission ratios. These ratios were compared with others from other critical assemblies to assess the degree of softness in the neutron spectrum. This critical experiment was performed at the National Criticality Experiments Research Center (NCERC) in Nevada.

Search for single-top production in ep collisions at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (PL). Faculty of Physics and Applied Computer Science] (and others)

2011-11-15

A search for single-top production, ep{yields}etX, has been performed with the ZEUS detector at HERA using data corresponding to an integrated luminosity of 0.37 fb{sup -1}. No evidence for top production was found, consistent with the expectation from the Standard Model. Limits were computed for single-top production via flavour changing neutral current transitions. The result was combined with a previous ZEUS result yielding a total luminosity of 0.50 fb{sup -1}. A 95% credibility level upper limit of 0.13 pb was obtained for the cross section at the centre-of-mass energy of {radical}(s)=315 GeV. (orig.)

Search for single-top production in ep collisions at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2011-11-01

A search for single-top production, ep→etX, has been performed with the ZEUS detector at HERA using data corresponding to an integrated luminosity of 0.37 fb -1 . No evidence for top production was found, consistent with the expectation from the Standard Model. Limits were computed for single-top production via flavour changing neutral current transitions. The result was combined with a previous ZEUS result yielding a total luminosity of 0.50 fb -1 . A 95% credibility level upper limit of 0.13 pb was obtained for the cross section at the centre-of-mass energy of √(s)=315 GeV. (orig.)

Study of charged-current ep interactions at Q2 > 200 GeV2 with the ZEUS detector at HERA

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magill, S.

1996-06-01

Deep inelastic charged-current reactions have been studied in e + p and e - p collisions at a center of mass energy of about 300 GeV in the kinematic region Q 2 >200 GeV 2 and x>0.006 using the ZEUS detector at HERA. The integrated cross sections for Q 2 >200 GeV 2 are found to be σ e + p→ anti νX =30.3 -4.2-2.6 +5.5+1.6 pb and σ e - p→νX =54.7 -9.8-3.4 +15.9+2.8 pb. Differential cross sections have been measured as functions of the variables x, y and Q 2 . From the measured differential cross sections dσ/dQ 2 , the W boson mass is determined to be M W =79 -7-4 +8+4 GeV. Measured jet rates and transverse energy profiles agree with model predictions. A search for charged-current interactions with a large rapidity gap yielded one candidate event, corresponding to a cross section σ e + p→ anti νX (Q 2 >200 GeV 2 ; η max -0.7 +1.8 ±0.1 pb. (orig.)

Measurement of $ D^{*\\pm}$ production in deep inelastic scattering at HERA

CERN Document Server

Abramowicz, H.; Adamczyk, L.; Adamus, M.; Aggarwal, R.; Antonelli, S.; Antonioli, P.; Antonov, A.; Arneodo, M.; Arslan, O.; Aushev, V.; Bachynska, O.; Bamberger, A.; Barakbaev, A.N.; Barbagli, G.; Bari, G.; Barreiro, F.; Bartosik, N.; Bartsch, D.; Basile, M.; Behnke, O.; Behr, J.; Behrens, U.; Bellagamba, L.; Bertolin, A.; Bhadra, S.; Bindi, M.; Blohm, C.; Bokhonov, V.; Bold, T.; Boos, E.G.; Borras, K.; Boscherini, D.; Bot, D.; Brock, I.; Brownson, E.; Brugnera, R.; Brummer, N.; Bruni, A.; Bruni, G.; Brzozowska, B.; Bussey, P.J.; Bylsma, B.; Caldwell, A.; Capua, M.; Carlin, R.; Catterall, C.D.; Chekanov, S.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Cifarelli, L.; Cindolo, F.; Contin, A.; Cooper-Sarkar, A.M.; Coppola, N.; Corradi, M.; Corriveau, F.; Costa, M.; D'Agostini, G.; Dal Corso, F.; del Peso, J.; Dementiev, R.K.; De Pasquale, S.; Derrick, M.; Devenish, R.C.E.; Dobur, D.; Dolinska, G.; Doyle, A.T.; Drugakov, V.; Durkin, L.S.; Dusini, S.; Eisenberg, Y.; Fang, S.; Fazio, S.; Ferrando, J.; Ferrero, M.I.; Figiel, J.; Foster, B.; Gach, G.; Galas, A.; Gallo, E.; Garfagnini, A.; Geiser, A.; Gialas, I.; Gizhko, A.; Gladilin, L.K.; Gladkov, D.; Glasman, C.; Gogota, O.; Golubkov, Yu. A.; Gottlicher, P.; Grabowska-Bold, I.; Grebenyuk, J.; Gregor, I.; Grigorescu, G.; Grzelak, G.; Gueta, O.; Guzik, M.; Gwenlan, C.; Haas, T.; Hain, W.; Hamatsu, R.; Hart, J.C.; Hartmann, H.; Hartner, G.; Hilger, E.; Hochman, D.; Hori, R.; Huttmann, A.; Ibrahim, Z.A.; Iga, Y.; Ingbir, R.; Ishitsuka, M.; Iudin, A.; Jakob, H.P.; Januschek, F.; Jones, T.W.; Jungst, M.; Kadenko, I.; Kahle, B.; Kananov, S.; Kanno, T.; Karshon, U.; Karstens, F.; Katkov, I.I.; Kaur, M.; Kaur, P.; Keramidas, A.; Khein, L.A.; Kim, J.Y.; Kisielewska, D.; Kitamura, S.; Klanner, R.; Klein, U.; Koffeman, E.; Kondrashova, N.; Kononenko, O.; Kooijman, P.; Korol, Ie.; Korzhavina, I.A.; Kotanski, A.; Kotz, U.; Kovalchuk, N.; Kowalski, H.; Kuprash, O.; Kuze, M.; Lee, A.; Levchenko, B.B.; Levy, A.; Libov, V.; Limentani, S.; Ling, T.Y.; Lisovyi, M.; Lobodzinska, E.; Lohmann, W.; Lohr, B.; Lohrmann, E.; Long, K.R.; Longhin, A.; Lontkovskyi, D.; Lukina, O.Yu.; Maeda, J.; Magill, S.; Makarenko, I.; Malka, J.; Mankel, R.; Margotti, A.; Marini, G.; Martin, J.F.; Mastroberardino, A.; Mattingly, M.C.K.; Melzer-Pellmann, I.A.; Mergelmeyer, S.; Miglioranzi, S.; Idris, F.Mohamad; Monaco, V.; Montanari, A.; Morris, J.D.; Mujkic, K.; Musgrave, B.; Nagano, K.; Namsoo, T.; Nania, R.; Nigro, A.; Ning, Y.; Nobe, T.; Notz, D.; Nowak, R.J.; Nuncio-Quiroz, A.E.; Oh, B.Y.; Okazaki, N.; Olkiewicz, K.; Onishchuk, Yu.; Papageorgiu, K.; Parenti, A.; Paul, E.; Pawlak, J.M.; Pawlik, B.; Pelfer, P.G.; Pellegrino, A.; Perlanski, W.; Perrey, H.; Piotrzkowski, K.; Plucinski, P.; Pokrovskiy, N.S.; Polini, A.; Proskuryakov, A.S.; Przybycien, M.; Raval, A.; Reeder, D.D.; Reisert, B.; Ren, Z.; Repond, J.; Ri, Y.D.; Robertson, A.; Roloff, P.; Rubinsky, I.; Ruspa, M.; Sacchi, R.; Samson, U.; Sartorelli, G.; Savin, A.A.; Saxon, D.H.; Schioppa, M.; Schlenstedt, S.; Schleper, P.; Schmidke, W.B.; Schneekloth, U.; Schonberg, V.; Schorner-Sadenius, T.; Schwartz, J.; Sciulli, F.; Shcheglova, L.M.; Shehzadi, R.; Shimizu, S.; Singh, I.; Skillicorn, I.O.; Slominski, W.; Smith, W.H.; Sola, V.; Solano, A.; Son, D.; Sosnovtsev, V.; Spiridonov, A.; Stadie, H.; Stanco, L.; Stefaniuk, N.; Stern, A.; Stewart, T.P.; Stifutkin, A.; Stopa, P.; Suchkov, S.; Susinno, G.; Suszycki, L.; Sztuk-Dambietz, J.; Szuba, D.; Szuba, J.; Tapper, A.D.; Tassi, E.; Terron, J.; Theedt, T.; Tiecke, H.; Tokushuku, K.; Tomaszewska, J.; Trofymov, A.; Trusov, V.; Tsurugai, T.; Turcato, M.; Tymieniecka, T.; Vazquez, M.; Verbytskyi, A.; Viazlo, O.; Vlasov, N.N.; Walczak, R.; Wan Abdullah, W.A.T.; Whitmore, J.J.; Wichmann, K.; Wiggers, L.; Wing, M.; Wlasenko, M.; Wolf, G.; Wolfe, H.; Wrona, K.; Yagues-Molina, A.G.; Yamada, S.; Yamazaki, Y.; Yoshida, R.; Youngman, C.; Zakharchuk, N.; Zarnecki, A.F.; Zawiejski, L.; Zenaiev, O.; Zeuner, W.; Zhautykov, B.O.; Zhmak, N.; Zichichi, A.; Zolkapli, Z.; Zotkin, D.S.

2013-01-01

The production of $D^{*\\pm}$ mesons in deep inelastic $ep$ scattering has been measured for exchanged photon virtualities $ 5ZEUS detector at HERA. Differential cross sections have been measured and compared to next-to-leading-order QCD calculations. The cross-sections are used to extract the charm contribution to the proton structure functions, expressed in terms of the reduced charm cross section, $\\sigma_{\\rm red}^{c\\bar{c}}$. Theoretical calculations based on fits to inclusive HERA data are compared to the results.

B-physics at HERA

International Nuclear Information System (INIS)

Gladilin, L.K.

2000-01-01

The beauty photoproduction cross-section measurements in ep collisions at HERA are reviewed. Data samples of events having a lepton (μ or e) and two jets in the final state, have been collected with the H1 and ZEUS detectors. The beauty signals have been extracted by fitting the p T rel distribution of the data with beauty, charm and light flavor components, where p T rel is the transverse momentum of the lepton relative to the axis of the associated jet. The obtained beauty cross sections are larger than leading order Monte Carlo and next-to-leading order perturbative QCD predictions

Measurement of the t dependence in exclusive photoproduction of Upsilon(1S) mesons at HERA

CERN Document Server

Abramowicz, H.

2012-02-14

The exclusive photoproduction reaction gamma p -> Upsilon(1S) p has been studied with the ZEUS detector in ep collisions at HERA using an integrated luminosity of 468 pb^-1. The measurement covers the kinematic range 60 Upsilon(1S) p cross section.

A measuring facility for the uniformization of the optical readout at the ZEUS calorimeter

International Nuclear Information System (INIS)

Jahnen, G.

1988-10-01

The ZEUS-detector for HERA features a high resolution calorimeter of the sampling type. The passive layers are made of depleted uranium and the active layers are of aromatic scintillator. The layer thicknesses are chosen to yield full compensation, i.e. for a given energy electrons or photons produce the same signal as hadrons or jets. The scintillators are read out via wave length shifter bars. A uniform response of the wave length shifter i.e. a response independent of the entrance position of the scintillator light, is essential to obtain best possible resolution. This diploma thesis concentrates on the apparatus and the procedure to produce wave length shifters for the electromagnetic sections of the ZEUS forward calorimeter to better than ±2%. (orig.) [de

Measurement of the total and differential b cross sections at HERA and CMS tracker alignment at LHC

International Nuclear Information System (INIS)

Stefaniuk, Nazar

2017-09-01

This thesis is logically divided into two main parts. The first part present a ZEUS analysis which was performed on the data obtained from electron-proton collisions measured by the ZEUS detector for the 2003-2007 running period. The full HERA-II integrated luminosity of 376 pb"-"1 is used. The ZEUS detector is sensitive to the full phase space of beauty production, since it has cylindrical geometry, covers a wide rapidity range and was able to measure low transverse momentum muons. In this part a measurement of beauty production was studied via the process ep→e"'b anti bX→e"'μμX. Making full use of the HERA-II detector upgrade, secondary vertex information was used to constrain the beauty and charm contribution to this process. The result of this analysis is the measurement of the total, visible and differential cross sections for beauty production. The cross sections are compared to next-to-leading order QCD calculations. Similar to the beauty events, instanton or instanton-induced events involving heavy flavour can also be a source for non-isolated, both like- and unlike-sign muon pairs. In this analysis, instantons were studied with using QCDINS predictions. The data show no indication for instanton-induced events. The second part is related to CMS tracker alignment. It uses collision and cosmic data samples obtained by the CMS detector at the Large Hadron Collider in 2012. This part consists of studies of the CMS tracker alignment weak modes and a detailed study of the ''z-rescaling'' weak mode. The CMS tracker alignment weak mode study includes the simulation of the weak modes, and the alignment implementation on top of such simulation. This study shows that the alignment procedure of the CMS tracker is stable with regard to the three weak modes: ''Twist, Sagitta and Telescope'' which stand for three types of systematic shifts of the CMS tracker. The ''z-rescaling'' weak mode shows a strong and unexpected shift of some tracker detector components in the

Search for first-generation leptoquarks at HERA

CERN Document Server

Abramowicz, H.; Adamczyk, L.; Adamus, M.; Aggarwal, R.; Antonelli, S.; Antonioli, P.; Antonov, A.; Arneodo, M.; Arslan, O.; Aushev, V.; Aushev, Y.; Bachynska, O.; Bamberger, A.; Barakbaev, A.N.; Barbagli, G.; Bari, G.; Barreiro, F.; Bartosik, N.; Bartsch, D.; Basile, M.; Behnke, O.; Behr, J.; Behrens, U.; Bellagamba, L.; Bertolin, A.; Bhadra, S.; Bindi, M.; Blohm, C.; Bokhonov, V.; Bold, T.; Bondarenko, K.; Boos, E.G.; Borras, K.; Boscherini, D.; Bot, D.; Brock, I.; Brownson, E.; Brugnera, R.; Brummer, N.; Bruni, A.; Bruni, G.; Brzozowska, B.; Bussey, P.J.; Bylsma, B.; Caldwell, A.; Capua, M.; Carlin, R.; Catterall, C.D.; Chekanov, S.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Cifarelli, L.; Cindolo, F.; Contin, A.; Cooper-Sarkar, A.M.; Coppola, N.; Corradi, M.; Corriveau, F.; Costa, M.; D'Agostini, G.; Dal Corso, F.; del Peso, J.; Dementiev, R.K.; De Pasquale, S.; Derrick, M.; Devenish, R.C.E.; Dobur, D.; Dolinska, G.; Doyle, A.T.; Drugakov, V.; Durkin, L.S.; Dusini, S.; Eisenberg, Y.; Fang, S.; Fazio, S.; Ferrando, J.; Ferrero, M.I.; Figiel, J.; Forrest, M.; Foster, B.; Gach, G.; Galas, A.; Gallo, E.; Garfagnini, A.; Geiser, A.; Gialas, I.; Gizhko, A.; Gladilin, L.K.; Gladkov, D.; Glasman, C.; Gogota, O.; Golubkov, Yu.A.; Gottlicher, P.; Grabowska-Bold, I.; Grebenyuk, J.; Gregor, I.; Grigorescu, G.; Grzelak, G.; Gueta, O.; Guzik, M.; Gwenlan, C.; Haas, T.; Hain, W.; Hamatsu, R.; Hart, J.C.; Hartmann, H.; Hartner, G.; Hilger, E.; Hochman, D.; Hori, R.; Horton, K.; Huttmann, A.; Ibrahim, Z.A.; Iga, Y.; Ingbir, R.; Ishitsuka, M.; Jakob, H.P.; Januschek, F.; Jones, T.W.; Jungst, M.; Kadenko, I.; Kahle, B.; Kananov, S.; Kanno, T.; Karshon, U.; Karstens, F.; Katkov, I.I.; Kaur, M.; Kaur, P.; Keramidas, A.; Khein, L.A.; Kim, J.Y.; Kisielewska, D.; Kitamura, S.; Klanner, R.; Klein, U.; Koffeman, E.; Kondrashova, N.; Kononenko, O.; Kooijman, P.; Korol, Ie.; Korzhavina, I.A.; Kotanski, A.; Kotz, U.; Kowalski, H.; Kuprash, O.; Kuze, M.; Lee, A.; Levchenko, B.B.; Levy, A.; Libov, V.; Limentani, S.; Ling, T.Y.; Lisovyi, M.; Lobodzinska, E.; Lohmann, W.; Lohr, B.; Lohrmann, E.; Long, K.R.; Longhin, A.; Lontkovskyi, D.; Lukina, O.Yu.; Maeda, J.; Magill, S.; Makarenko, I.; Malka, J.; Mankel, R.; Margotti, A.; Marini, G.; Martin, J.F.; Mastroberardino, A.; Mattingly, M.C.K.; Melzer-Pellmann, I.A.; Mergelmeyer, S.; Miglioranzi, S.; Idris, F.Mohamad; Monaco, V.; Montanari, A.; Morris, J.D.; Mujkic, K.; Musgrave, B.; Nagano, K.; Namsoo, T.; Nania, R.; Nigro, A.; Ning, Y.; Nobe, T.; Notz, D.; Nowak, R.J.; Nuncio-Quiroz, A.E.; Oh, B.Y.; Okazaki, N.; Oliver, K.; Olkiewicz, K.; Onishchuk, Yu.; Papageorgiu, K.; Parenti, A.; Paul, E.; Pawlak, J.M.; Pawlik, B.; Pelfer, P.G.; Pellegrino, A.; Perlanski, W.; Perrey, H.; Piotrzkowski, K.; Plucinski, P.; Pokrovskiy, N.S.; Polini, A.; Proskuryakov, A.S.; Przybycien, M.; Raval, A.; Reeder, D.D.; Reisert, B.; Ren, Z.; Repond, J.; Ri, Y.D.; Robertson, A.; Roloff, P.; Rubinsky, I.; Ruspa, M.; Sacchi, R.; Samson, U.; Sartorelli, G.; Savin, A.A.; Saxon, D.H.; Schioppa, M.; Schlenstedt, S.; Schleper, P.; Schmidke, W.B.; Schneekloth, U.; Schonberg, V.; Schorner-Sadenius, T.; Schwartz, J.; Sciulli, F.; Shcheglova, L.M.; Shehzadi, R.; Shimizu, S.; Singh, I.; Skillicorn, I.O.; Slominski, W.; Smith, W.H.; Sola, V.; Solano, A.; Son, D.; Sosnovtsev, V.; Spiridonov, A.; Stadie, H.; Stanco, L.; Stefaniuk, N.; Stern, A.; Stewart, T.P.; Stifutkin, A.; Stopa, P.; Suchkov, S.; Susinno, G.; Suszycki, L.; Sztuk-Dambietz, J.; Szuba, D.; Szuba, J.; Tapper, A.D.; Tassi, E.; Terron, J.; Theedt, T.; Tiecke, H.; Tokushuku, K.; Tomaszewska, J.; Trusov, V.; Tsurugai, T.; Turcato, M.; Turkot, O.; Tymieniecka, T.; Vazquez, M.; Verbytskyi, A.; Viazlo, O.; Vlasov, N.N.; Walczak, R.; Wan Abdullah, W.A.T.; Whitmore, J.J.; Wichmann, K.; Wiggers, L.; Wing, M.; Wlasenko, M.; Wolf, G.; Wolfe, H.; Wrona, K.; Yagues-Molina, A.G.; Yamada, S.; Yamazaki, Y.; Yoshida, R.; Youngman, C.; Zabiegalov, O.; Zarnecki, A.F.; Zawiejski, L.; Zenaiev, O.; Zeuner, W.; Zhautykov, B.O.; Zhmak, N.; Zhou, C.; Zichichi, A.; Zolkapli, Z.; Zotkin, D.S.

2012-01-01

A search for first-generation leptoquarks was performed in electron-proton and positron-proton collisions recorded with the ZEUS detector at HERA in 2003-2007 using an integrated luminosity of 366 pb^-1. Final states with an electron and jets or with missing transverse momentum and jets were analysed, searching for resonances or other deviations from the Standard Model predictions. No evidence for any leptoquark signal was found. The data were combined with data previously taken at HERA, resulting in a total integrated luminosity of 498 pb^-1. Limits on the Yukawa coupling, lambda, of leptoquarks were set as a function of the leptoquark mass for different leptoquark types within the Buchmueller-Rueckl-Wyler model. Leptoquarks with a coupling lambda=0.3 are excluded for masses up to 699 GeV.

Search for first-generation leptoquarks at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (PL). Faculty of Physics and Applied Computer Science] (and others)

2012-05-15

A search for first-generation leptoquarks was performed in electron-proton and positron-proton collisions recorded with the ZEUS detector at HERA in 2003-2007 using an integrated luminosity of 366 pb{sup -}1. Final states with an electron and jets or with missing transverse momentum and jets were analysed, searching for resonances or other deviations from the Standard Model predictions. No evidence for any leptoquark signal was found. The data were combined with data previously taken at HERA, resulting in a total integrated luminosity of 498 pb{sup -}1. Limits on the Yukawa coupling, {lambda}, of leptoquarks were set as a function of the leptoquark mass for different leptoquark types within the Buchmueller-Rueckl-Wyler model. Leptoquarks with a coupling {lambda}=0.3 are excluded for masses up to 699 GeV.

Combined inclusive diffractive cross sections measured with forward proton spectrometers at HERA

International Nuclear Information System (INIS)

Ruspa, Marta

2013-01-01

A combination is presented of the inclusive diffractive cross section measurements made by the H1 and ZEUS Collaborations at HERA. The analysis uses samples of diffractive deep inelastic scattering data where leading protons are detected by dedicated spectrometers. Correlations of systematic uncertainties are taken into account by the combination method, resulting in improved precision.

Combined inclusive diffractive cross sections measured with forward proton spectrometers at HERA

Energy Technology Data Exchange (ETDEWEB)

Ruspa, Marta [Univ. Piemonte Orientale, via Solaroli 17, 28100 Novara (Italy); Collaboration: H1 Collaboration; ZEUS Collaboration

2013-04-15

A combination is presented of the inclusive diffractive cross section measurements made by the H1 and ZEUS Collaborations at HERA. The analysis uses samples of diffractive deep inelastic scattering data where leading protons are detected by dedicated spectrometers. Correlations of systematic uncertainties are taken into account by the combination method, resulting in improved precision.

Calibration of the ZEUS forward calorimeter

International Nuclear Information System (INIS)

Kraemer, M.

1990-10-01

The physics at the ep-collider HERA requires high resolution calorimetry calibrated with an accuracy of better than 2%. The ZEUS detector meets these conditions by means of a compensating uranium scintillator sandwich calorimeter with an energy resolution of σ/E = 35%/√E + σ cal , where σ cal is the calibration error. One of the tools to minimize σ cal is the calibration with the signals of the radioactivity of the Uranium plates (UNO). Taking UNO data every 8 hours keeps the calibration stable within ≅ 1%. The muon calibration is done employing an algorithm, that determines the most probable energy loss with a precision of ≅ 1%. The channel-to-channel fluctuations of the ratio μ/UNO for a forward calorimeter (FCAL) prototype show a spread of 5.2% for the electromagnetic calorimeter and ≅ 2.5% for the hadronic sections. Improvements in the construction of the FCAL modules decreased these fluctuations to 2.0% and ≅ 1.8% respectively. The influence of the cracks between the calorimeter modules amounts to ≅ 1.7% on average for the ZEUS geometry, if a 2 mm thick Pb-sheet is introduced between the modules. We conclude that we are able to keep σ cal below 2%. (orig.)

Measurement of the longitudinal proton structure function at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2009-03-01

The reduced cross sections for ep deep inelastic scattering have been measured with the ZEUS detector at HERA at three different centre-of-mass energies, 318, 251 and 225 GeV. From the cross sections, measured double differentially in Bjorken x and the virtuality, Q 2 , the proton structure functions F L and F 2 have been extracted in the region 5 x 10 -4 2 2 . (orig.)

Measurement of D{sup *{+-}} production in deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science] [and others; Collaboration: ZEUS Collaboration

2013-03-15

The production of D{sup *{+-}} mesons in deep inelastic ep scattering has been measured for exchanged photon virtualities 5ZEUS detector at HERA. Differential cross sections have been measured and compared to next-to-leading-order QCD calculations. The cross-sections are used to extract the charm contribution to the proton structure functions, expressed in terms of the reduced charm cross section, {sigma}{sub red}{sup c} {sup anti} {sup c}. Theoretical calculations based on fits to inclusive HERA data are compared to the results.

The ZEUS second level calorimeter trigger

International Nuclear Information System (INIS)

Jong, S.J. de.

1990-01-01

ZEUS is a detector for the HERA ep collider, consisting of several large components. The most important being the inner tracking detectors, which are positioned nearest to the interaction point, the calorimeter surrounding the inner tracking detectors and the muon detectors on the outside of the experimental setup. Each component will deliver a vast amount of information. In order to keep this information manageable, data is preprocessed and condensed per component and then combined to obtain the final global trigger result. The main subject of this thesis is the second level calorimeter trigger processor of the ZEUS detector. In order to be able to reject the unwanted events passing the first level, the topological event signature will have to be used at the second level. The most demanding task of the second level is the recognition of local energy depositions corresponding to isolated electrons and hadron jets. Also part of the work performed by the first level will be repeated with a higher level of accuracy. Additional information not available to the first level trigger will be processed and will be made available to the global second level trigger decision module. For the second level calorimeter trigger processor a special VME module, containing two transputers, has been developed. The second level calorimeter trigger algorithm described in this thesis was tested with simulated events, that were tracked through a computer simulation of the ZEUS detector. A part of this thesis is therefore devoted to the description of the various Monte Carlo models and the justification of the way in which they were used. (author). 132 refs.; 76 figs.; 18 tabs

Charm production and QCD analysis at HERA and LHC

International Nuclear Information System (INIS)

Zenaiev, O.

2017-02-01

This review is devoted to the study of charm production in ep and pp collisions. The total set of measurements obtained by the two collaborations H1 and ZEUS from HERA and their combination is outlined, as well as complementary data obtained by the LHCb collaboration at the LHC. After fitting the parton distribution functions the charm production cross sections are predicted within perturbative QCD at next-to-leading order using the fixed-flavour-number scheme. Agreement with the data is found. The combined HERA charm data are sensitive to the c-quark mass and enabled its accurate determination. The predictions crucially depend upon the knowledge of the gluon distribution function. It is shown that the shape of the gluon distribution based on the HERA data is considerably improved by adding the measurements from LHCb and applicable down to values x of about 10"-"6, where x is the proton momentum fraction carried by a parton.

Charm production and QCD analysis at HERA and LHC

Energy Technology Data Exchange (ETDEWEB)

Zenaiev, O.

2017-02-15

This review is devoted to the study of charm production in ep and pp collisions. The total set of measurements obtained by the two collaborations H1 and ZEUS from HERA and their combination is outlined, as well as complementary data obtained by the LHCb collaboration at the LHC. After fitting the parton distribution functions the charm production cross sections are predicted within perturbative QCD at next-to-leading order using the fixed-flavour-number scheme. Agreement with the data is found. The combined HERA charm data are sensitive to the c-quark mass and enabled its accurate determination. The predictions crucially depend upon the knowledge of the gluon distribution function. It is shown that the shape of the gluon distribution based on the HERA data is considerably improved by adding the measurements from LHCb and applicable down to values x of about 10{sup -6}, where x is the proton momentum fraction carried by a parton.

Charm production and QCD analysis at HERA and LHC

Energy Technology Data Exchange (ETDEWEB)

Zenaiev, O. [DESY, Hamburg (Germany)

2017-03-15

This review is devoted to the study of charm production in ep and pp collisions. The total set of measurements obtained by the two collaborations H1 and ZEUS from HERA and their combination is outlined, as well as complementary data obtained by the LHCb Collaboration at the LHC. After fitting the parton distribution functions the charm-production cross sections are predicted within perturbative QCD at next-to-leading order using the fixed-flavour-number scheme. Agreement with the data is found. The combined HERA charm data are sensitive to the c-quark mass and enabled its accurate determination. The predictions crucially depend upon the knowledge of the gluon distribution function. It is shown that the shape of the gluon distribution based on the HERA data is considerably improved by adding the measurements from LHCb and applicable down to values x of about 10{sup -6}, where x is the proton momentum fraction carried by a parton. (orig.)

Bounds on the maximum attainable equilibrium spin polarization of protons at high energy in HERA

International Nuclear Information System (INIS)

Vogt, M.

2000-12-01

For some years HERA has been supplying longitudinally spin polarised electron and positron (e ± ) beams to the HERMES experiment and in the future longitudinal polarisation will be supplied to the II1 and ZEUS experiments. As a result there has been a development of interest in complementing the polarised e ± beams with polarised protons. In contrast to the case of e ± where spin flip due to synchrotron radiation in the main bending dipoles leads to self polarisation owing to an up-down asymmetry in the spin flip rates (Sokolov-Ternov effect), there is no convincing self polarisation mechanism for protons at high energy. Therefore protons must be polarised almost at rest in a source and then accelerated to the working energy. At HERA, if no special measures are adopted, this means that the spins must cross several thousand ''spin-orbit resonances''. Resonance crossing can lead to loss of polarisation and at high energy such effects are potentially strong since spin precession is very pronounced in the very large magnetic fields needed to contain the proton beam in HERA-p. Moreover simple models which have been successfully used to describe spin motion at low and medium energies are no longer adequate. Instead, careful numerical spin-orbit tracking simulations are needed and a new, mathematically rigorous look at the theoretical concepts is required. This thesis describes the underlying theoretical concepts, the computational tools (SPRINT) and the results of such a study. In particular strong emphasis is put on the concept of the invariant spin field and its non-perturbative construction. The invariant spin field is then used to define the amplitude dependent spin tune and to obtain numerical non-perturbative estimates of the latter. By means of these two key concepts the nature of higher order resonances in the presence of snakes is clarified and their impact on the beam polarisation is analysed. We then go on to discuss the special aspects of the HERA-p ring

Measurement of beauty production from dimuon events at HERA

International Nuclear Information System (INIS)

2009-01-01

Beauty production in events containing two muons in the final state has been measured with the ZEUS detector at HERA using an integrated luminosity of 114 pb -1 . A low transverse-momentum threshold for muon identification, in combination with the large rapidity coverage of the ZEUS muon system, gives access to almost the full phase space for beauty production. The total cross section for beauty production in ep collisions at (s) 1/2 = 318 GeV has been measured to be σ tot (ep → b b-bar X) = 13.9 ± 1.5(stat.) +4.0 -4.3 (syst.) nb. Differential cross sections and a measurement of b b-bar correlations are also obtained, and compared to other beauty cross-section measurements, Monte Carlo models and next-to-leading-order QCD predictions.

Study of the photon remnant in resolved photoproduction at HERA

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magill, S.

1995-01-01

Photoproduction at HERA is studied in ep collisions, with the ZEUS detector, for γp centre-of-mass energies ranging from 130-270 GeV. A sample of events with two high-p T jets (p T >6 GeV, η T with respect to the beam axis is measured to be 2.1±0.2 GeV, which demonstrates substantial mean transverse momenta for the photon remnant. (orig.)

Construction of the Zeus forward/rear calorimeter modules at NIKHEF

International Nuclear Information System (INIS)

Blankers, R.; Engelen, J.; Geerinck, H.; Homma, J.; Hunck, P.; Koning, N. de; Kooijman, P.; Korporaal, A.; Loos, R.; Straver, J.; Tiecke, H.

1990-07-01

ZEUS is one of the two experiments in preparation for studying electron-proton interactions at the HERA e-p collider at DESY in Hamburg. The design value for the energy of the electron beam is 30 GeV and for the proton beam 820 GeV. The asymmetry in the beam particle masses and their energies causes in general a strongly asymmetric energy distribution for the reaction products, in particular most of the energy flow will be in the proton direction. The layout of the ZEUS detector accomodates for this asymmetry. In the proton direction for instance, several wirechambers assure together with the central tracking detector good track reconstruction, in an area where high density of tracks is expected. The tracking detector is placed inside a magnetic field of 1.8 Tesla, provided by a superconducting coil. The interaction point is completely surrounded by a high resolution calorimeter, which in turn is surrounded by a backing calorimeter; this backing calorimeter has to detect late showering particles, has to serve as a muon filter and is also the return yoke for the magnetic field. The ZEUS collaboration has chosen for a type of hadron calorimeter with the best possible energy resolution known to date, a depleted uranium-scintillator sampling calorimeter. The calorimeter has an equal response to electrons and hadrons of the same energy (e/h=1). The sampling thickness is one radiation length. The calorimeter is subdivided in three components, the forward- (in proton direction), the rear- (in electron direction) and the barrel calorimeter, FCAL, RCAL and BCAL. In this report the design and assembly procedure of the FCAL/RCAL is described in detail. Furthermore the transport problems are discussed and the first calibration results obtained with beam particles are shown. (author). 5 refs.; 29 figs.; 1 tab

Measurement of J/{psi} photoproduction at large momentum transfer at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Lab., Argonne, IL (US)] (and others)

2009-09-15

The proton-dissociative diffractive photoproduction of J/{psi} mesons has been studied in ep collisions with the ZEUS detector at HERA using an integrated luminosity of 112 pb{sup -1}. The cross section is presented as a function of the photon- proton centre-of-mass energy and of the squared four-momentum transfer at the proton vertex. The results are compared to perturbative QCD calculations. (orig.)

Measurement of J/ψ photoproduction at large momentum transfer at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2009-09-01

The proton-dissociative diffractive photoproduction of J/ψ mesons has been studied in ep collisions with the ZEUS detector at HERA using an integrated luminosity of 112 pb -1 . The cross section is presented as a function of the photon- proton centre-of-mass energy and of the squared four-momentum transfer at the proton vertex. The results are compared to perturbative QCD calculations. (orig.)

Measurement of J/ψ helicity distributions in inelastic photoproduction at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2009-06-01

The J/ψ decay angular distributions have been measured in inelastic photoproduction in ep collisions with the ZEUS detector at HERA, using an integrated luminosity of 468 pb -1 . The range in photon-proton centre-of-mass energy, W, was 50 + were measured in the J/ψ rest frame and compared to theoretical predictions at leading and next-to-leading order in QCD. (orig.)

Hard photoproduction: An analysis of the first ZEUS data

International Nuclear Information System (INIS)

Feld, L.W.

1993-10-01

The electron-proton storage ring HERA gives the unique opportunity to study photon-proton collisions at center of mass energies around 200 GeV. This analysis covers the extraction of hard photoproduction events from the data taken by the ZEUS-detector in its first year of operation. It is shown, that these events are well described by the Monte Carlo generators PYTHIA and HERWIG. A jet analysis allows to measure the kinematics of the hard subprocess. Clear evidence for both direct and resolved photon processes is seen in the data. In detailed Monte Carlo studies different photon structure functions are compared to the data. (orig.)

Measurement of the total and differential b cross sections at HERA and CMS tracker alignment at LHC

Energy Technology Data Exchange (ETDEWEB)

Stefaniuk, Nazar

2017-09-15

This thesis is logically divided into two main parts. The first part present a ZEUS analysis which was performed on the data obtained from electron-proton collisions measured by the ZEUS detector for the 2003-2007 running period. The full HERA-II integrated luminosity of 376 pb{sup -1} is used. The ZEUS detector is sensitive to the full phase space of beauty production, since it has cylindrical geometry, covers a wide rapidity range and was able to measure low transverse momentum muons. In this part a measurement of beauty production was studied via the process ep→e{sup '}b anti bX→e{sup '}μμX. Making full use of the HERA-II detector upgrade, secondary vertex information was used to constrain the beauty and charm contribution to this process. The result of this analysis is the measurement of the total, visible and differential cross sections for beauty production. The cross sections are compared to next-to-leading order QCD calculations. Similar to the beauty events, instanton or instanton-induced events involving heavy flavour can also be a source for non-isolated, both like- and unlike-sign muon pairs. In this analysis, instantons were studied with using QCDINS predictions. The data show no indication for instanton-induced events. The second part is related to CMS tracker alignment. It uses collision and cosmic data samples obtained by the CMS detector at the Large Hadron Collider in 2012. This part consists of studies of the CMS tracker alignment weak modes and a detailed study of the ''z-rescaling'' weak mode. The CMS tracker alignment weak mode study includes the simulation of the weak modes, and the alignment implementation on top of such simulation. This study shows that the alignment procedure of the CMS tracker is stable with regard to the three weak modes: ''Twist, Sagitta and Telescope'' which stand for three types of systematic shifts of the CMS tracker. The ''z-rescaling'' weak

Measurement of elastic φ photoproduction at HERA

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magill, S.

1996-01-01

The production of φ mesons in the reaction e + p→e + φp(φ→K + K - ) at a median Q 2 of 10 -4 GeV 2 has been studied with the ZEUS detector at HERA. The differential φ photoproduction cross section dσ/dt has an exponential shape and has been determined in the kinematic range 0.1 2 and 60 γp→φp 0.96±0.19 -0.18 +0.21 μb has been obtained by extrapolating to t=0. When compared to lower energy data, the results show a weak energy dependence of both σ γp→φp and the slope of the t distribution. The φ decay angular distributions are consistent with s-channel helicity conservation. From lower energies to HERA energies, the features of φ photoproduction are compatible with those of a soft diffractive process. (orig.)

Study of charm production at HERA using the ZEUS detector

International Nuclear Information System (INIS)

Woudenberg, R. van.

1995-01-01

The subject of this thesis is charm production at HERA, especially in photoproduction (Q 2 ∼0). In lowest order, the production of heavy quarks proceeds via photo-gluon fusion. Thus a measurement of charm production provides a handle on the gluon structure of the proton. (Leading and next-to-leading order processes together result in a total cross section of σ(ep→ec anti cX)≅O(1.0 μb)). (orig./HSI)

Detailed comparison of next-to-leading order predictions for jet photoproduction at HERA.

Energy Technology Data Exchange (ETDEWEB)

Harris, B. W.; Klassen, M.; Vossebeld, J.

1999-06-02

The precision of new HERA data on jet photoproduction opens up the possibility to discriminate between different models of the photon structure. This requires equally precise theoretical predictions from perturbative QCD calculations. In the past years, next-to-leading order calculations for the photoproduction of jets at HERA have become available. Using the kinematic cuts of recent ZEUS analyses, we compare the predictions of three calculations for different dijet and three-jet distributions. We find that in general all three calculations agree within the statistical accuracy of the Monte Carlo integration yielding reliable theoretical predictions. In certain restricted regions of phase space, the calculations differ by up to 5%.

Saturation and forward jets at HERA

International Nuclear Information System (INIS)

Marquet, C.; Peschanski, R.; Royon, C.

2004-01-01

We analyse forward-jet production at HERA in the framework of the Golec-Biernat and Wusthoff saturation models. We obtain a good description of the forward-jet cross-sections measured by the H1 and ZEUS Collaborations in the two-hard-scale region (k T∼ Q >> Λ QCD ) with two different parametrizations with either significant or weak saturation effects. The weak saturation parametrization gives a scale compatible with the one found for the proton structure function F2. We argue that Mueller-Navelet jets at the Tevatron and the LHC could help distinguishing between both options

Measurement of beauty production from dimuon events at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (United States)] (and others)

2008-09-15

Beauty production in events containing two muons in the final state has been measured with the ZEUS detector at HERA using an integrated luminosity of 114 pb{sup -1}. A low transverse-momentum threshold for muon identification, in combination with the large rapidity coverage of the ZEUS muon system, gives access to almost the full phase space for beauty production. The total cross section for beauty production in ep collisions at {radical}(s) = 318 GeV has been measured to be {sigma}{sub tot}(ep {yields} b anti bX) = 13.9 {+-} 1.5(stat.){sub -4.3}{sup +4.0}(syst.) nb. Differential cross sections and a measurement of b anti b correlations are also obtained, and compared to other beauty cross-section measurements, Monte Carlo models and next-to-leading-order QCD predictions. (orig.)

Study of charm production at HERA using the ZEUS detector

Energy Technology Data Exchange (ETDEWEB)

Woudenberg, R van

1995-09-26

The subject of this thesis is charm production at HERA, especially in photoproduction (Q{sup 2}{approx}0). In lowest order, the production of heavy quarks proceeds via photo-gluon fusion. Thus a measurement of charm production provides a handle on the gluon structure of the proton. (Leading and next-to-leading order processes together result in a total cross section of {sigma}(ep{yields}ec anti cX){approx_equal}O(1.0 {mu}b)). (orig./HSI).

Measurement of the longitudinal proton structure function at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2009-03-15

The reduced cross sections for ep deep inelastic scattering have been measured with the ZEUS detector at HERA at three different centre-of-mass energies, 318, 251 and 225 GeV. From the cross sections, measured double differentially in Bjorken x and the virtuality, Q{sup 2}, the proton structure functions F{sub L} and F{sub 2} have been extracted in the region 5 x 10{sup -4}

Measurement of high-Q2 neutral current cross-sections with longitudinally polarised positrons with the ZEUS detector

International Nuclear Information System (INIS)

Stewart, Trevor P.

2012-07-01

The cross sections for neutral current (NC) deep inelastic scattering (DIS) in e + p collisions with a longitudinally polarised positron beam are measured at high momentum transfer squared (Q 2 >185 GeV 2 ) at the ZEUS detector at HERA. The HERA accelerator provides e ± p collisions at a centre-of-mass energy of 318 GeV, which allows the weak contribution to the NC process to be studied at high Q 2 . The measurements are based on a data sample with an integrated luminosity of 135.5 pb -1 collected with the ZEUS detector in 2006 and 2007. The single differential NC cross sections dσ/dQ 2 , dσ/dx and dσ/dy and the reduced cross section σ are measured. The structure function xF 3 is determined by combining the e + p NC reduced cross sections with the previously measured e - p measurements. The interference structure function xF 3 γZ is extracted at Q 2 =1500 GeV 2 . The cross-section asymmetry between the positive and negative polarisation of the positron beam is measured and the parity violation effects of the electroweak interaction are observed. The predictions of the Standard Model of particle physics agree well with the measurements. (orig.)

Production of Z 0 bosons in elastic and quasi-elastic ep collisions at HERA

NARCIS (Netherlands)

Abramowicz, A.; et al., [Unknown; Koffeman, E.; Kooijman, P.

2013-01-01

The production of Z0Z0 bosons in the reaction ep→eZ0p(*)ep→eZ0p(*), where )p(*) stands for a proton or a low-mass nucleon resonance, has been studied in ep collisions at HERA using the ZEUS detector. The analysis is based on a data sample collected between 1996 and 2007, amounting to 496 pb−1496

Production of Z0 bosons in elastic and quasi-elastic ep collisions at HERA

NARCIS (Netherlands)

Abramowicz, H.; Kooijman, P.; Zotkin, D.S.

2013-01-01

The production of Z0 bosons in the reaction ep →eZ0 p(∗), where p(∗) stands for a proton or a lowmass nucleon resonance, has been studied in ep collisions at HERA using the ZEUS detector. The analysis is based on a data sample collected between 1996 and 2007, amounting to 496 pb−1 of integrated

Measurement of the energy dependence of the total photon-proton cross section at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). Raymond and Beverly Sackler Faculty of Exact Sciences; Univ. Coll. London (United Kingdom); Krakow Univ. of Technology (Poland). Faculty of Physics, Mathematics and Applied Computer Science; Abt, I. [Max-Planck-Institut fuer Physik, Muenchen (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Cracow (PL). Faculty of Physics and Applied Computer Science] (and others)

2010-10-15

The energy dependence of the photon-proton total cross section, {sigma}{sub tot}{sup {gamma}}{sup p}, was determined from e{sup +}p scattering data collected with the ZEUS detector at HERA at three values of the center-of-mass energy, W, of the {gamma}p system in the range 194experiment at high W. Parameterizing {sigma}{sub tot}{sup {gamma}}{sup p} {proportional_to} W{sup 2c}, {epsilon}=0.111{+-}0.009 (stat.){+-}0.036 (syst.) was obtained. (orig.)

Scaled momentum distributions of charged particles in dijet photoproduction at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2009-04-01

The scaled momentum distributions of charged particles in jets have been measured for dijet photoproduction with the ZEUS detector at HERA using an integrated luminosity of 359 pb -1 . The distributions are compared to predictions based on perturbative QCD carried out in the framework of the modified leading-logarithmic approximation (MLLA) and assuming local parton-hadron duality (LPHD). The universal MLLA scale, Λ eff , and the LPHD parameter, κ ch , are extracted. (orig.)

Beauty photoproduction using decays into electrons at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2008-05-15

Photoproduction of beauty quarks in events with two jets and an electron associated with one of the jets has been studied with the ZEUS detector at HERA using an integrated luminosity of 120 pb{sup -1}. The fractions of events containing b quarks, and also of events containing c quarks, were extracted from a likelihood fit using variables sensitive to electron identification as well as to semileptonic decays. Total and differential cross sections for beauty and charm production were measured and compared with next-to-leading-order QCD calculations and Monte Carlo models. (orig.)

Beauty photoproduction using decays into electrons at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-05-01

Photoproduction of beauty quarks in events with two jets and an electron associated with one of the jets has been studied with the ZEUS detector at HERA using an integrated luminosity of 120 pb -1 . The fractions of events containing b quarks, and also of events containing c quarks, were extracted from a likelihood fit using variables sensitive to electron identification as well as to semileptonic decays. Total and differential cross sections for beauty and charm production were measured and compared with next-to-leading-order QCD calculations and Monte Carlo models. (orig.)

Analysis of the reaction γp → J/ψp, J/ψ → μ+μ- with the help of the planar drift chambers of the ZEUS detector

International Nuclear Information System (INIS)

Coboeken, K.

2000-03-01

The software for track segment reconstruction in the forward planar drift chambers, FTD1-3, in the ZEUS experiment at the electron-proton storage ring HERA at DESY (Hamburg) has been improved and extended. A global forward track fit has been developed combining the segments in FTD1-3 with track segments in the central drift chamber and the forward muon chambers using Kalman filter techniques. Photoproduction events from the reaction ep→J/ψp, J/ψ→μ + μ - were studied. The reaction cross section as a function of the hadronic mass W in the range from 20 GeV to 130 GeV has been measured. The cross section for W between 20 and 30 GeV has been determined for the first time. This was only possible using the new developed forward track fit. This measurement fills the W gap between fixed target experiments and previous HERA measurements at higher values. (orig.)

The eventbuilder of the ZEUS experiment

International Nuclear Information System (INIS)

Behrens, U.; Hagge, L.; Vogel, W.O.

1993-02-01

The Eventbuilder of the ZEUS experiment is a real-time parallel data formatting and transport system. It combines data flows originating from various detector components and transfers them to the third level trigger processor farm. The Eventbuilder is based on an asynchronous packet-switching transputer network and uses transputer links for bulk data transfer. A high-speed 64x64 custom made crossbar switch allows dynamic linking of any detector component to any branch of third level processor nodes, offering a bandwidth of more than 24 MB/s over a distance of 100 m. The use of structured system development techniques (SA/SD) resulted in a flexible and well-partitioned system structure and guaranteed that all requirements were met. (orig.)

Measurement of high-Q2 deep inelastic scattering cross sections with a longitudinally polarised positron beam at HERA

NARCIS (Netherlands)

Chekanov, S.; Kooijman, P.

2006-01-01

The cross sections for charged and neutral current deep inelastic scattering in e+p collisions with a longitudinally polarised positron beam have been measured using the ZEUS detector at HERA. The results, based on data corresponding to an integrated luminosity of 23.8 pb−1 at , are given for both

Study of tau-pair production at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Cracow (Poland). Faculty of Physics and Applied Computer Science; Adamus, M. [Institute for Nuclear Studies, Warsaw (PL)] (and others)

2010-12-15

A study of events containing two tau leptons with high transverse momentum has been performed with the ZEUS detector at HERA, using a data sample corresponding to an integrated luminosity of 0.33 fb{sup -1}. The tau candidates were identified from their decays into electrons, muons or hadronic jets. The number of tau-pair candidates has been compared with the prediction from the Standard Model, where the largest contribution is expected from Bethe-Heitler processes. The total visible cross section was extracted. Standard Model expectations agree well with the measured distributions, also at high invariant mass of the tau pair. (orig.)

Measurement of D± and D0 production in deep inelastic scattering using a lifetime tag at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-12-01

The production of D ± and D 0 mesons has been measured with the ZEUS detector at HERA using an integrated luminosity of 133.6 pb -1 . The measurements cover the kinematic range 5 2 2 , 0.02 D T D vertical stroke c anti c 2 , to the proton structure function, F 2 . (orig.)

Exclusive production of J/ψ mesons in the ZEUS detector

International Nuclear Information System (INIS)

Tandler, J.

2003-07-01

Exclusive J/ψ production has been studied using the ZEUS detector at HERA. Two ranges of the photon virtuality, Q 2 2 and 0.15 2 2 are examined. The latter is defined by requiring the scattered electron to be detected in the Beam Pipe Calorimeter under low angles. The J/ψ mesons have been identified via the decay J/ψ→e + e - . The cross sections are measured as a function of the photon-proton centre-of-mass energy, W. The data used were taken during the 1999 and 2000 running periods, which yielded an integrated luminosity of 68.7 pb -1 . The measured W dependences are in agreement with each other and the values obtained in high-Q 2 (2 2 2 ) measurements. This leads to the conclusion that J/ψ production is a hard process for all Q 2 values and can be described with models based on perturbative QCD. Electron-pion separation of the ZEUS Transition Radiation Detector is measured. A method to combine TRD information and dE/dx measurements from the central drift chamber is developed and applied to the Q 2 2 J/ψ sample. (orig.)

Scaled momentum distributions of charged particles in dijet photoproduction at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Lab., Argonne, IL (US)] (and others)

2009-04-15

The scaled momentum distributions of charged particles in jets have been measured for dijet photoproduction with the ZEUS detector at HERA using an integrated luminosity of 359 pb{sup -1}. The distributions are compared to predictions based on perturbative QCD carried out in the framework of the modified leading-logarithmic approximation (MLLA) and assuming local parton-hadron duality (LPHD). The universal MLLA scale, {lambda}{sub eff}, and the LPHD parameter, {kappa}{sup ch}, are extracted. (orig.)

Search for stop production in R-parity-violating supersymmetry at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2006-11-01

A search for stop production in R-parity-violating supersymmetry has been performed in e + p interactions with the ZEUS detector at HERA, using an integrated luminosity of 65 pb -1 . At HERA, the R-parity-violating coupling λ' allows resonant squark production, e + d→q. Since the lowest-mass squark state in most supersymmetry models is the light stop, t, this search concentrated on production of t, followed either by a direct R-parity-violating decay, or by the gauge decay to b χ 1 + . No evidence for stop production was found and limits were set on λ 131 ' as a function of the stop mass in the framework of the Minimal Supersymmetric Standard Model. The results have also been interpreted in terms of constraints on the parameters of the minimal Supergravity model. (orig.)

Energy-loss measurement with the ZEUS Central Tracking Detector

International Nuclear Information System (INIS)

Bartsch, D.

2007-05-01

The measurement of the specific energy loss due to ionisation, dE/dx, in a drift chamber is a very important tool for particle identification in final states of reactions between high energetic particles. Such identification requires a well understood dE/dx measurement including a precise knowledge of its uncertainties. Exploiting for the first time the full set of ZEUS data from the HERA operation between 1996 and 2005 twelve detector-related influences affecting the dE/dx measurement of the ZEUS Central Tracking Detector have been identified, separately studied and parameterised. A sophisticated iterative procedure has been developed to correct for these twelve effects, which takes into account the correlations between them. A universal parameterisation of the detector-specific Bethe-Bloch curve valid for all particle species has been extracted. In addition, the various contributions to the measurement uncertainty have been disentangled and determined. This yields the best achievable prediction for the single-track dE/dx resolution. For both the analysis of the measured data and the simulation of detector performance, the detailed understanding of the measurement and resolution of dE/dx gained in this work provides a tool with optimum power for particle identification in a physics studies. (orig.)

Energy-loss measurement with the ZEUS Central Tracking Detector

Energy Technology Data Exchange (ETDEWEB)

Bartsch, D.

2007-05-15

The measurement of the specific energy loss due to ionisation, dE/dx, in a drift chamber is a very important tool for particle identification in final states of reactions between high energetic particles. Such identification requires a well understood dE/dx measurement including a precise knowledge of its uncertainties. Exploiting for the first time the full set of ZEUS data from the HERA operation between 1996 and 2005 twelve detector-related influences affecting the dE/dx measurement of the ZEUS Central Tracking Detector have been identified, separately studied and parameterised. A sophisticated iterative procedure has been developed to correct for these twelve effects, which takes into account the correlations between them. A universal parameterisation of the detector-specific Bethe-Bloch curve valid for all particle species has been extracted. In addition, the various contributions to the measurement uncertainty have been disentangled and determined. This yields the best achievable prediction for the single-track dE/dx resolution. For both the analysis of the measured data and the simulation of detector performance, the detailed understanding of the measurement and resolution of dE/dx gained in this work provides a tool with optimum power for particle identification in a physics studies. (orig.)

Production of the excited charm mesons D1 and D*2 at HERA

International Nuclear Information System (INIS)

Verbytskyi, Andrii

2013-02-01

The production of the excited charm mesons D 1 , D * 2 and D + s1 in ep collisions has been measured with the ZEUS detector at Hera. The data sample taken by the ZEUS detector in the years 2003-2007, corresponding to an integrated luminosity of 373 pb -1 has been used. The masses of the neutral, charged and strange states, the widths of the neutral states, the helicity parameters of D 0 1 and D + s1 were determined and compared with other measurements and with theoretical expectations. The measured helicity parameters of the D 0 1 and D + s1 allows for some mixing of S- and D-waves in their decays to D *± π -+ and D *± K 0 respectively. The measured value of the D 0 1 helicity parameter is also consistent with a pure D-wave decay. Ratios of branching fractions of the two decay modes of the D *0 2 , D *± 2 and D + s1 states were measured and compared with previous measurements. The fractions of charm quarks hadronising into D 1 , D * 2 and D + s1 were measured and are consistent with those obtained in e + e - annihilations. The Grid computing technology has a high importance for modern High Energy Physics. This technology has been successfully used in Zeus experiment for the MC simulations and data analysis. The dedicated infrastructure has been maintained by the author since 2010. In addition to continuous support, the author has upgraded and improved the performance of the Grid MC simulations and contributed to the Zeus data preservation project.

Measruement of beauty production in DIS and F2bantib extraction at ZEUS

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2010-04-01

Beauty production in deep inelastic scattering with events in which a muon and a jet are observed in the final state has been measured with the ZEUS detector at HERA using an integrated luminosity of 114 pb -1 . The fraction of events with beauty quarks in the data was determined using the distribution of the transverse momentum of the muon relative to the jet. The cross section for beauty production was measured in the kinematic range of photon virtuality, Q 2 >2 GeV 2 , and inelasticity, 0.05 2 was extracted and is compared to theoretical predictions. (orig.)

Charm Production and QCD Analysis at HERA and LHC

CERN Document Server

Zenaiev, Oleksandr; Foster, Brian; McNulty, Ronan

2015-01-01

In this thesis the study of charm production in ep and pp collisions is presented. The heavy- quark masses provide a hard scale, allowing the application of perturbative QCD. A measurement of D + -meson production in deep inelastic scattering with the ZEUS detector at HERA is presented. The analysis was performed using a data sample with an integrated luminosity of 354 pb-1. Di erential cross sections were measured as a function of virtuality Q 2 , inelasticity y , transverse momentum and pseudorapidity of the D + mesons. Lifetime infor- mation was used to reduce the combinatorial background significantly. Next-to-leading-order QCD predictions in the fixed-flavour-number scheme were compared to the data. This measurement was combined with other H1 and ZEUS measurements of charm produc- tion. The combination was performed at inclusive level for the reduced charm cross sections, which were obtained from the measured visible cross sections, extrapolated to the full phase space using the shape of the theoretical ...

Hunting Down Interpretations of the HERA Large-$Q^{2}$ data

CERN Document Server

Ellis, John R.

1999-01-01

Possible interpretations of the HERA large-Q^2 data are reviewed briefly. The possibility of statistical fluctuations cannot be ruled out, and it seems premature to argue that the H1 and ZEUS anomalies are incompatible. The data cannot be explained away by modifications of parton distributions, nor do contact interactions help. A leptoquark interpretation would need a large tau-q branching ratio. Several R-violating squark interpretations are still viable despite all the constraints, and offer interesting experimental signatures, but please do not hold your breath.

Measurement of heavy-quark jet photoproduction at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2011-04-01

Photoproduction of beauty and charm quarks in events with at least two jets has been measured with the ZEUS detector at HERA using an integrated luminosity of 133 pb -1 . The fractions of jets containing b and c quarks were extracted using the invariant mass of charged tracks associated with secondary vertices and the decay-length significance of these vertices. Differential cross sections as a function of jet transverse momentum, p jet T , and pseudorapidity, η jet , were measured. The data are compared with previous measurements and are well described by next-to-leading-order QCD predictions. (orig.)

Measurement of heavy-quark jet photoproduction at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max-Planck-Institute for Physics, Munich (Germany); Abt, I. [Max-Planck-Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Cracow (PL). Faculty of Physics and Applied Computer Science] (and others)

2011-04-15

Photoproduction of beauty and charm quarks in events with at least two jets has been measured with the ZEUS detector at HERA using an integrated luminosity of 133 pb{sup -1}. The fractions of jets containing b and c quarks were extracted using the invariant mass of charged tracks associated with secondary vertices and the decay-length significance of these vertices. Differential cross sections as a function of jet transverse momentum, p{sup jet}{sub T}, and pseudorapidity, {eta}{sup jet}, were measured. The data are compared with previous measurements and are well described by next-to-leading-order QCD predictions. (orig.)

The processor farm for online triggering and full event reconstruction of the HERA-B experiment at HERA

International Nuclear Information System (INIS)

Gellrich, A.; Dippel, R.; Gensch, U.; Kowallik, R.; Legrand, I.C.; Leich, H.; Sun, F.; Wegner, P.

1996-01-01

The main goal of the HERA-B experiment which start taking data in 1988 is to study CP violation in B decays. This article describes the concept and the planned implementation of a multi-processor system, called processor farm,as the last part of the data acquisition and trigger system of the HERA B experiment. The third level trigger task and a full online event reconstruction will be performed on this processor farm, consisting of more then 100 powerful RISC processors which are based on commercial hardware boards. The controlling will be done by a real-time operating system which provides a software development environment, including FORTRAN and C compilers. (author)

Photoproduction of isolated photons, inclusively and with a jet, at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2013-12-01

The photoproduction of isolated photons, both inclusive and together with a jet, has been measured with the ZEUS detector at HERA using an integrated luminosity of 374 pb -1 . Differential cross sections are presented in the isolated-photon transverse-energy and pseudorapidity ranges 6 T γ γ T jet jet 2 2 . Differential cross sections are also presented for inclusive isolated photon production as functions of the transverse energy and pseudorapidity of the photon. Higher-order theoretical calculations are compared to the results.

A first measurement of the charged current DIS cross sections with longitudinally polarised electrons in the H1 experiment at HERA

International Nuclear Information System (INIS)

Antunovic, B.

2007-01-01

The analysis presented in this thesis is based on data from electron-proton collisions with longitudinally polarised electron beams at a centre-of-mass energy of √(s)=319 GeV. The data were taken with the H1 detector at the HERA collider in the year 2005 corresponding to two polarisation states: a left-handed electron polarisation of -27% and a right-handed electron polarisation of +37%, corresponding to integrated luminosities of 68.6 pb -1 and 29.6 pb -1 , respectively. The inclusive total deep inelastic charged current cross section and the differential cross sections are measured for both helicities in the kinematic domain Q 2 >400 GeV 2 and y cc 2 has been performed at the H1 experiment for the first time. The measurements are well described by the theoretical expectations based on parton distributions derived from inclusive neutral current measurements in H1, and are in agreement with published data from the ZEUS (e ± p) and CCFR (anti ν μ Fe) experiments. (orig.)

DESY scientific annual report 1987

International Nuclear Information System (INIS)

1988-05-01

This annual report contains a short description of the organization of DESY, extended abstracts concerning the experimental studies at the PETRA and DORIS storage rings, the development of the ZEUS detector, synchrotron-radiation experiments, theory of elementary particles, development of counting electronics, technical developments of the HERA, DORIS II and PETRA II storage rings and the DESY II respectively DESY I/III synchrotron, radiation protection, as well as data processing, and a list of speeches, publications, and theses. (HSI)

Measurement of multijet events at low x{sub Bj} and low Q{sup 2} with the ZEUS detector at HERA

Energy Technology Data Exchange (ETDEWEB)

Gosau, T.

2007-07-15

In this thesis, cross sections of inclusive and differential di- and trijet production in deep inelastic electron-proton scattering at low Bjorken-x have been determined and compared to perturbative QCD calculations at next-to- leading order. The data were taken during the years 1998-2000 with the ZEUS detector at the HERA collider and had an integrated luminosity of 82 pb{sup -1}. The center-of-mass energy was {radical}(s)=318 GeV. The phase space was defined by 10{sup -4}

Measurement of high-Q{sup 2} neutral current cross-sections with longitudinally polarised positrons with the ZEUS detector

Energy Technology Data Exchange (ETDEWEB)

Stewart, Trevor P.

2012-07-15

The cross sections for neutral current (NC) deep inelastic scattering (DIS) in e{sup +}p collisions with a longitudinally polarised positron beam are measured at high momentum transfer squared (Q{sup 2}>185 GeV{sup 2}) at the ZEUS detector at HERA. The HERA accelerator provides e{sup {+-}}p collisions at a centre-of-mass energy of 318 GeV, which allows the weak contribution to the NC process to be studied at high Q{sup 2}. The measurements are based on a data sample with an integrated luminosity of 135.5 pb{sup -1} collected with the ZEUS detector in 2006 and 2007. The single differential NC cross sections d{sigma}/dQ{sup 2}, d{sigma}/dx and d{sigma}/dy and the reduced cross section {sigma} are measured. The structure function xF{sub 3} is determined by combining the e{sup +}p NC reduced cross sections with the previously measured e{sup -}p measurements. The interference structure function xF{sub 3}{sup {gamma}Z} is extracted at Q{sup 2}=1500 GeV{sup 2}. The cross-section asymmetry between the positive and negative polarisation of the positron beam is measured and the parity violation effects of the electroweak interaction are observed. The predictions of the Standard Model of particle physics agree well with the measurements. (orig.)

Beauty photoproduction using decays into muons at HERA

Energy Technology Data Exchange (ETDEWEB)

Samson, U.

2008-05-15

Inclusive cross-sections for the production of open beauty in ep collisions at HERA are measured. The data were recorded with the ZEUS detector between 1996 and 2000. The measurements are restricted to photoproduction processes, i.e. collision events with small four-momentum transfer squared, Q{sup 2}{approx}0. Two jets with transverse momentum p{sub T}>7(6) GeV and pseudo-rapidities vertical stroke {eta} vertical stroke <2.5 are required. The flavour is tagged by the identification of muons from semi-leptonic decays of the beauty quark. The variable used to discriminate between beauty and background is the transverse momentum of the muon with respect to the jet axis. The fraction of beauty is determined by a fit of Monte Carlo templates to the data. Cross-sections have been measured as a function of the muon and jet variables as well as a function of dijet correlation variables. Dijet correlations in beauty production have been measured for the first time in ZEUS and are found in agreement with QCD NLO predictions. (orig.)

Beauty photoproduction using decays into muons at HERA

International Nuclear Information System (INIS)

Samson, U.

2008-05-01

Inclusive cross-sections for the production of open beauty in ep collisions at HERA are measured. The data were recorded with the ZEUS detector between 1996 and 2000. The measurements are restricted to photoproduction processes, i.e. collision events with small four-momentum transfer squared, Q 2 ∼0. Two jets with transverse momentum p T >7(6) GeV and pseudo-rapidities vertical stroke η vertical stroke <2.5 are required. The flavour is tagged by the identification of muons from semi-leptonic decays of the beauty quark. The variable used to discriminate between beauty and background is the transverse momentum of the muon with respect to the jet axis. The fraction of beauty is determined by a fit of Monte Carlo templates to the data. Cross-sections have been measured as a function of the muon and jet variables as well as a function of dijet correlation variables. Dijet correlations in beauty production have been measured for the first time in ZEUS and are found in agreement with QCD NLO predictions. (orig.)

Photoproduction of isolated photons, inclusively and with a jet, at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.; Adamus, M.; Aggarwal, R.; Antonelli, S.; Arslan, O.; Aushev, V.; Aushev, Y.; Bachynska, O.; Barakbaev, A.N.; Bartosik, N.; Behnke, O.; Behr, J.; Behrens, U.; Bertolin, A.; Bhadra, S.; Bloch, I.; Bokhonov, V.; Boos, E.G.

2014-01-01

The photoproduction of isolated photons, both inclusive and together with a jet, has been measured with the ZEUS detector at HERA using an integrated luminosity of 374 pb −1 . Differential cross sections are presented in the isolated-photon transverse-energy and pseudorapidity ranges 6 T γ γ T jet jet 2 2 . Differential cross sections are also presented for inclusive isolated-photon production as functions of the transverse energy and pseudorapidity of the photon. Higher-order theoretical calculations are compared to the results

Photoproduction of events with rapidity gaps between jets with ZEUS at HERA

Energy Technology Data Exchange (ETDEWEB)

Ryan, P.D.

2006-11-15

Cross sections for the photoproduction of dijet events, where the two jets with the highest transverse energy are separated by a large gap in pseudorapidity, have been studied with the ZEUS detector using an integrated luminosity of 38.6 pb{sup -1}. Rapidity-gap events are defined in terms of the energy flow between the jets, such that the total summed transverse energy in this region is less than some value E{sup CUT}{sub T}. The data show a clear excess above the predictions of standard photoproduction models. Models which include color-singlet exchange are able to describe the data. (orig.)

Photoproduction of events with rapidity gaps between jets with ZEUS at HERA

International Nuclear Information System (INIS)

Ryan, P.D.

2006-11-01

Cross sections for the photoproduction of dijet events, where the two jets with the highest transverse energy are separated by a large gap in pseudorapidity, have been studied with the ZEUS detector using an integrated luminosity of 38.6 pb -1 . Rapidity-gap events are defined in terms of the energy flow between the jets, such that the total summed transverse energy in this region is less than some value E CUT T . The data show a clear excess above the predictions of standard photoproduction models. Models which include color-singlet exchange are able to describe the data. (orig.)

Measurement of beauty production in deep inelastic scattering at HERA using decays into electrons

International Nuclear Information System (INIS)

Shehzadi, Ramoona

2011-01-01

The production of beauty quarks in ep interactions has been studied with the ZEUS detector at HERA for exchanged four-momentum squared Q 2 >10 GeV 2 , using an integrated luminosity of 363 pb -1 . The beauty events were identified using electrons from semileptonic b decays with a transverse momentum 0.9 T e e 2 was extracted from the double-differential cross section as a function of Bjorken-x and Q 2 . (orig.)

Measurement of beauty-production in deep inelastic scattering at HERA II

International Nuclear Information System (INIS)

Kahle, B.

2006-04-01

This thesis presents a measurement of beauty quark production in deep inelastic scattering at the ep-collider HERA at √(s)=318 GeV. The measurement is based on data collected at the ZEUS detector in the years 2003/2004, using an integrated luminosity of 39 pb -1 . In the analysis presented in this thesis, events were selected that contain a scattered electron, a jet and a muon inside the jet. The fraction of events from beauty quark production was extracted using the characteristic distribution of the transverse momenta of muons relative to the associated jets. The total visible cross section was measured to be: σ b anti b (ep→eb anti b X→e jetμX')=57.9±5.8(stat.) +3.5 -8.1 (syst.) pb in the kinematic region defined by: Q 2 >4 GeV 2 , y>0.05 und y jet t,lab >5 GeV und -2 jet μ t >1.5 GeV and η μ >-1.6. Differential cross sections were measured in p μ t and η μ , in p jet t and η jet and in Q 2 .Furthermore double differential cross sections d 2 σ/dQ 2 dx were measured. (Orig.)

Multi-jet cross sections in charged current e{sup {+-}}p scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2008-02-15

Jet cross sections were measured in charged current deep inelastic e{sup {+-}}p scattering at high boson virtualities Q{sup 2} with the ZEUS detector at HERA II using an integrated luminosity of 0.36 fb{sup -1}. Differential cross sections are presented for inclusive-jet production as functions of Q{sup 2}, Bjorken x and the jet transverse energy and pseudorapidity. The dijet invariant mass cross section is also presented. Observation of three- and four-jet events in charged-current e{sup {+-}}p processes is reported for the first time. The predictions of next-to-leading-order (NLO) QCD calculations are compared to the measurements. The measured inclusive-jet cross sections are well described in shape and normalization by the NLO predictions. The data have the potential to constrain the u and d valence quark distributions in the proton if included as input to global fits. (orig.)

Multi-jet cross sections in charged current e±p scattering at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-02-01

Jet cross sections were measured in charged current deep inelastic e ± p scattering at high boson virtualities Q 2 with the ZEUS detector at HERA II using an integrated luminosity of 0.36 fb -1 . Differential cross sections are presented for inclusive-jet production as functions of Q 2 , Bjorken x and the jet transverse energy and pseudorapidity. The dijet invariant mass cross section is also presented. Observation of three- and four-jet events in charged-current e ± p processes is reported for the first time. The predictions of next-to-leading-order (NLO) QCD calculations are compared to the measurements. The measured inclusive-jet cross sections are well described in shape and normalization by the NLO predictions. The data have the potential to constrain the u and d valence quark distributions in the proton if included as input to global fits. (orig.)

DESY: First physics from HERA; A wide gap; 30 Years of the HEP-Index

International Nuclear Information System (INIS)

Anon.

1993-01-01

At the HERA collider at DESY, the dreams of electron-proton scattering experiments are becoming reality, with electron-proton collisions at an energy of about 300 GeV opening up new physics. Information about the distribution of quarks, antiquarks and gluons inside the proton can now be obtained with a precision never attained before. But there are many other reactions which could provide surprises at these energies. Collisions between HERA's 820 GeV protons and 26.7 GeV electrons started in June 1992. With a total of about 30 inverse nanobarns of integrated luminosity collected up to the winter shut-down (November 1992), the H1 and ZEUS experiments published results which gave a foretaste of things to come. As most electron-proton interactions take place through the exchange of a photon, this was the first reaction to be studied. When the scattered electron emerges at a very small angle, the mass of the exchanged virtual photon is close to zero and the photon nearly real. This opens up the study of photon proton collisions at energies in the region of 200 GeV. The total cross section for these reactions previously known up to 18 GeV collision energy was 118 micro barn, and was predicted to rise with energy

Measurement of the cross-section ratio σψ(2S)/σJ/ψ(1S) in deep inelastic exclusive ep scattering at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2016-01-01

The exclusive deep inelastic electroproduction of ψ(2S) and J/ψ(1S) at an ep centre-of-mass energy of 317 GeV has been studied with the ZEUS detector at HERA in the kinematic range 2HERA I and HERA II periods and correspond to an integrated luminosity of 468 pb -1 . The decay modes analysed were μ + μ - and J/ψ(1S) π + π - for the ψ(2S) and μ + μ - for the J/ψ(1S). The cross-section ratio σ ψ(2S) /σ J/ψ(1S) has been measured as a function of Q 2 , W and t. The results are compared to predictions of QCD-inspired models of exclusive vector-meson production.

Measurement of J/{psi} helicity distributions in inelastic photoproduction at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Lab., Argonne, IL (US)] (and others)

2009-06-15

The J/{psi} decay angular distributions have been measured in inelastic photoproduction in ep collisions with the ZEUS detector at HERA, using an integrated luminosity of 468 pb{sup -1}. The range in photon-proton centre-of-mass energy, W, was 50

A search for excited fermions in electron-proton collisions at HERA

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magill, S.

1994-10-01

A search for excited states of the standard model fermions was performed using the ZEUS detector at the HERA electron-proton collider, operating at a centre of mass enery of 296 GeV. In a sample corresponding to an integrated luminosity of 0.55 pb -1 , no evidence was found for any resonant state decaying into final states composed of a fermion and a gauge boson. Limits on the coupling strength times branching ratio of excited fermions are presented for masses between 50 GeV and 250 GeV, extending previous search regions significantly. (orig.)

Search for stop production in R-parity-violating supersymmetry at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, IL (US)] (and others)

2006-11-15

A search for stop production in R-parity-violating supersymmetry has been performed in e{sup +}p interactions with the ZEUS detector at HERA, using an integrated luminosity of 65 pb{sup -1}. At HERA, the R-parity-violating coupling {lambda}' allows resonant squark production, e{sup +}d{yields}q. Since the lowest-mass squark state in most supersymmetry models is the light stop, t, this search concentrated on production of t, followed either by a direct R-parity-violating decay, or by the gauge decay to b{sub {chi}{sub 1}}{sup +}. No evidence for stop production was found and limits were set on {lambda}{sub 131}' as a function of the stop mass in the framework of the Minimal Supersymmetric Standard Model. The results have also been interpreted in terms of constraints on the parameters of the minimal Supergravity model. (orig.)

Further development of the ZEUS Expert System: Computer science foundations of design

International Nuclear Information System (INIS)

Flasinski, M.

1994-03-01

The prototype version of the ZEUS Expert System, ZEXP, was diagnosing selected aspects of DAQ System during ZEUS running in 1993. In November 1993 ZEUS decided to extend its scope in order to cover all crucial aspects of operating the ZEUS detector (Run Control, Slow Control, Data Acquisition performance and Data Quality Monitoring). The paper summarizes fundamental assumptions concerning the design of the final version of the ZEUS Expert System, ZEX. Although the theoretical background material relates primarily to ZEX, its elements can be used for constructing other expert systems for HEP experiments. (orig.)

Three- and four-jet final states in photoproduction at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2007-08-01

Three- and four-jet final states have been measured in photoproduction at HERA using the ZEUS detector with an integrated luminosity of 121 pb -1 . The results are presented for jets with transverse energy E jet T >6 GeV and pseudorapidity vertical stroke η jet vertical stroke 2 2 and the inelasticity 0.2≤y≤0.85 and in two mass regions defined as 25≤M nj nj ≥50 GeV, where M nj is the invariant mass of the n-jet system. The four-jet photoproduction cross section has been measured for the first time and represents the highest-order process studied at HERA. Both the three- and four-jet cross sections have been compared with leading-logarithmic parton-shower Monte Carlo models, with and without multi-parton interactions. The three-jet cross sections have been compared to an O(αα 2 s ) perturbative QCD calculation. (orig.)

Measurement of beauty production in deep inelastic scattering at HERA using decays into electrons

International Nuclear Information System (INIS)

Abramowicz, H.; Gueta, O.; Ingbir, R.; Kananov, S.; Levy, A.; Stern, A.

2011-01-01

The production of beauty quarks in ep interactions has been studied with the ZEUS detector at HERA for exchanged four-momentum squared Q 2 >10 GeV 2 , using an integrated luminosity of 363 pb -1 . The beauty events were identified using electrons from semileptonic b decays with a transverse momentum 0.9 T e e vertical stroke 2 was extracted from the double-differential cross section as a function of Bjorken-x and Q 2 . (orig.)

The uranium calorimeter of the ZEUS detector - studies on the uniformity of the energy measurement of electrons

International Nuclear Information System (INIS)

Prange, K.

1991-04-01

To meet the physics goals at the ep-collider HERA, the compensating uranium scintillator sandwich calorimeter for the ZEUS-Detector has an energy resolution σ/E = 35%/√E + σ cal ; the total calibration error σ cal including overall spatial nonuniformity should be less than 2%. Inhomogeneities occur at the edges of scintillator readout segments. They influence the spatial uniformity of the response of EMC-sections within a calorimeter module as well as between adjacent modules. Both items have been investigated in beam measurements with a spatial granularity of about 1 mm. The nonuniformity for electrons due to the EMC-segmentation within a calolrimeter module is less than 8.3%. That effect is observed in a region of ±4 mm [FWHM] for perpendicular electron incidence. The inhomogeneity at the transition of two modules is compensated by a lead foil of 2.6 mm. Investigations with the prototype calorimeter show the effect on average energy measurement for the ZEUS geometry to be below 2%. (orig.) [de

The ZEUS calorimeter first level trigger

Science.gov (United States)

Silverstein, S.; Ali, I.; Behrens, B.; Foudas, C.; Fordham, C.; Goussiou, A.; Jaworski, M.; Lackey, J.; Reeder, D.; Robl, P.; Smith, W. H.; Vaiciulis, A.; Wodarczyk, M.; Dawson, J.; Krakauer, D.; Talaga, R.; Schlereth, J.; Zhang, H.

1995-02-01

An overview of the ZEUS calorimeter first level trigger is presented. The CFLT uses a pipelined architecture to accept and analyze calorimeter data for every 96 ns beam crossing interval. PMT signals are combined by analog electronics into electromagnetic and hadronic sums for 896 trigger towers. The analog sums are then digitized and analyzed. The CFLT determines the total, transverse, and missing transverse energy, identifies isolated electrons and muons, and sums energies in programmable subregions. Calculations are performed in 96 ns steps, and new data are accepted for every beam crossing. Trigger data are forwarded to the global first level trigger (GFLT) after 2 μs, allowing a GFLT accept to be issued 5 μs after the beam crossing which produced the event. Important features of the CFLT include a 12-bit effective dynamic range, extensive use of memory lookup tables for trigger calculations, fast pattern searches for isolated leptons, and low electronics noise. During the 1993 HERA run, the CFLT reduced a 50 kHz background rate to around 100 Hz.

Forward-jet production in deep inelastic ep scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Lab., IL (US)] (and others)

2007-07-15

Forward jet cross sections have been measured in neutral current deep inelastic scattering at low Bjorken-x with the ZEUS detector at HERA using an integrated luminosity of 81.8 pb{sup -1}. Measurements are presented for inclusive forward jets as well as for forward jets accompanied by a dijet system. The explored phase space, with jet pseudorapidity up to 4.3 is expected to be particularly sensitive to the dynamics of QCD parton evolution at low x. The measurements are compared to fixed-order QCD calculations and to leading-order parton-shower Monte Carlo models. (orig.)

Forward-jet production in deep inelastic ep scattering at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2007-07-01

Forward jet cross sections have been measured in neutral current deep inelastic scattering at low Bjorken-x with the ZEUS detector at HERA using an integrated luminosity of 81.8 pb -1 . Measurements are presented for inclusive forward jets as well as for forward jets accompanied by a dijet system. The explored phase space, with jet pseudorapidity up to 4.3 is expected to be particularly sensitive to the dynamics of QCD parton evolution at low x. The measurements are compared to fixed-order QCD calculations and to leading-order parton-shower Monte Carlo models. (orig.)

Measurement of beauty quark mass at HERA and impact on Higgs production in association with beauty quarks at LHC

CERN Document Server

Gizhko, Andrii; Foster, Brian

2016-01-01

Three different, but related topics are the subject of this thesis, performed in the contextof the ZEUS and CMS groups at DESY. The first measurement of the MS beauty-quarkmass mb (mb ) at an electron-proton collider is presented. The measurement is based ona QCD analysis of beauty production cross sections in deep inelastic (DIS) ep scatteringmeasured by ZEUS at HERA, together with inclusive DIS HERA data, using Next-toLeading-Order QCD predictions. The measured value of the running beauty-quark massin the MS scheme was found to bemb (mb ) = 4.07 ± 0.14 (fit)+0.01 (mod.)+0.05 (param.) +0.08 (theo.) GeV, which is in good−0.07−0.00−0.05agreement with the world average Particle Data Group value and previous measurementsat electron-positron colliders. It is also found to be consistent with the expected runningof mb (µ).A first measurement of the charm-quark mass mc (µ) running in the MS scheme ispresented. The measurement is based on a QCD analysis of the published H1 and ZEUScombination of charm cr...

Measurement of elastic ω photoproduction at HERA

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magill, S.

1996-08-01

The reaction γp→ωp (ω→π + π - π 0 and π 0 →γγ) has been studied in ep interactions using the ZEUS detector at photon-proton centre-of-mass energies between 70 and 90 GeV and vertical stroke t vertical stroke 2 , where t is the squared four momentum transferred at the proton vertex. The elastic ω photoproduction cross section has been measured to be σ γp→ωp =1.21±0.12±0.23 μb. The differential cross section dσ γp→ωp /d vertical stroke t vertical stroke has an exponential shape e -b vertical stroke t vertical stroke with a slope b=10.0±1.2±1.3 GeV -2 . The angular distributions of the decay pions are consistent with s-channel helicity conservation. When compared to low energy data, the features of ω photoproduction as measured at HERA energies are in agreement with those of a soft diffractive process. Previous measurements of the ρ 0 and φ photoproduction cross sections at HERA show a similar behaviour. (orig.)

MC rate at NLO for heavy flavour photoproduction at HERA

Energy Technology Data Exchange (ETDEWEB)

Toll, Tobias

2010-02-15

A Monte Carlo at next-to-leading order (MC rate at NLO) has been constructed for the production of heavy quark flavours in photoproduction. As such, it is the rst Monte Carlo event generator with next-to-leading order (NLO) accuracy for a process in lepton hadron scattering. In order to construct such an MC rate at NLO, the matrix element for the process has to be calculated at NLO and then be matched with a parton shower. When doing this, it is important that none of the parton configurations produced are doubly counted. In this thesis, the concept of a Monte Carlo event generator will be explained, with emphasis on the HERWIG parton shower. Also, different techniques of calculating matrix elements at NLO accuracy will be explained. It will then be shown how the NLO calculation can be matched with the HERWIG parton shower in an MC rate at NLO without double counting, producing unweighted events at NLO-accuracy. Many comparisons are made between the MC rate at NLO here constructed, the HERWIG Monte Carlo and the FMNR NLO calculation. Also many comparisons are made to HERA data from the H1 and ZEUS experiments. It is shown that all HERA data with heavy quarks produced in photoproduction can be described by the MC rate at NLO program constructed in this thesis. (orig.)

MC rate at NLO for heavy flavour photoproduction at HERA

International Nuclear Information System (INIS)

Toll, Tobias

2010-02-01

A Monte Carlo at next-to-leading order (MC rate at NLO) has been constructed for the production of heavy quark flavours in photoproduction. As such, it is the rst Monte Carlo event generator with next-to-leading order (NLO) accuracy for a process in lepton hadron scattering. In order to construct such an MC rate at NLO, the matrix element for the process has to be calculated at NLO and then be matched with a parton shower. When doing this, it is important that none of the parton configurations produced are doubly counted. In this thesis, the concept of a Monte Carlo event generator will be explained, with emphasis on the HERWIG parton shower. Also, different techniques of calculating matrix elements at NLO accuracy will be explained. It will then be shown how the NLO calculation can be matched with the HERWIG parton shower in an MC rate at NLO without double counting, producing unweighted events at NLO-accuracy. Many comparisons are made between the MC rate at NLO here constructed, the HERWIG Monte Carlo and the FMNR NLO calculation. Also many comparisons are made to HERA data from the H1 and ZEUS experiments. It is shown that all HERA data with heavy quarks produced in photoproduction can be described by the MC rate at NLO program constructed in this thesis. (orig.)

Multi-lepton production at high transverse momentum at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Lab., Argonne, IL (US)] (and others)

2009-06-15

A search for events containing two or more high-transverse-momentum isolated leptons has been performed in ep collisions with the ZEUS detector at HERA using the full collected data sample, corresponding to an integrated luminosity of 480 pb{sup -1}. The number of observed events has been compared with the prediction from the Standard Model, searching for possible deviations, especially for multi- lepton events with invariant mass larger than 100 GeV. Good agreement with the Standard Model has been observed. Total and differential cross sections for di-lepton production have been measured in a restricted phase space dominated by photon-photon collisions. (orig.)

Multi-lepton production at high transverse momentum at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2009-06-01

A search for events containing two or more high-transverse-momentum isolated leptons has been performed in ep collisions with the ZEUS detector at HERA using the full collected data sample, corresponding to an integrated luminosity of 480 pb -1 . The number of observed events has been compared with the prediction from the Standard Model, searching for possible deviations, especially for multi- lepton events with invariant mass larger than 100 GeV. Good agreement with the Standard Model has been observed. Total and differential cross sections for di-lepton production have been measured in a restricted phase space dominated by photon-photon collisions. (orig.)

Combination of Differential D^{*\\pm} Cross-Section Measurements in Deep-Inelastic ep Scattering at HERA

CERN Document Server

Abramowicz, H.; Adamczyk, L.; Adamus, M.; Andreev, V.; Antonelli, S.; Aushev, V.; Aushev, Y.; Baghdasaryan, A.; Begzsuren, K.; Behnke, O.; Behrens, U.; Belousov, A.; Bertolin, A.; Bloch, I.; Boos, E.G.; Borras, K.; Boudry, V.; Brandt, G.; Brisson, V.; Britzger, D.; Brock, I.; Brook, N.H.; Brugnera, R.; Bruni, A.; Buniatyan, A.; Bussey, P.J.; Bylinkin, A.; Bystritskaya, L.; Caldwell, A.; Campbell, A.J.; Cantun Avila, K.B.; Capua, M.; Catterall, C.D.; Ceccopieri, F.; Cerny, K.; Chekelian, V.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Contreras, J.G.; Cooper-Sarkar, A.M.; Corradi, M.; Corriveau, F.; Cvach, J.; Dainton, J.B.; Daum, K.; Dementiev, R.K.; Devenish, R.C.E.; Diaconu, C.; Dobre, M.; Dodonov, V.; Dolinska, G.; Dusini, S.; Eckerlin, G.; Egli, S.; Elsen, E.; Favart, L.; Fedotov, A.; Feltesse, J.; Ferencei, J.; Figiel, J.; Fleischer, M.; Fomenko, A.; Foster, B.; Gabathuler, E.; Gach, G.; Gallo, E.; Garfagnini, A.; Gayler, J.; Geiser, A.; Ghazaryan, S.; Gizhko, A.; Gladilin, L.K.; Goerlich, L.; Gogitidze, N.; Golubkov, Yu. A.; Gouzevitch, M.; Grab, C.; Grebenyuk, A.; Grebenyuk, J.; Greenshaw, T.; Gregor, I.; Grindhammer, G.; Grzelak, G.; Gueta, O.; Guzik, M.; Haidt, D.; Hain, W.; Henderson, R.C.W.; Hladky, J.; Hochman, D.; Hoffmann, D.; Hori, R.; Horisberger, R.; Hreus, T.; Huber, F.; Ibrahim, Z.A.; Iga, Y.; Ishitsuka, M.; Iudin, A.; Jacquet, M.; Janssen, X.; Januschek, F.; Jomhari, N.Z.; Jung, A.W.; Jung, H.; Kadenko, I.; Kananov, S.; Kapichine, M.; Karshon, U.; Kaur, M.; Kaur, P.; Kiesling, C.; Kisielewska, D.; Klanner, R.; Klein, M.; Klein, U.; Kleinwort, C.; Kogler, R.; Kondrashova, N.; Kononenko, O.; Korol, Ie.; Korzhavina, I.A.; Kostka, P.; Kotanski, A.; Kotz, U.; Kovalchuk, N.; Kowalski, H.; Kretzschmar, J.; Kruger, K.; Krupa, B.; Kuprash, O.; Kuze, M.; Landon, M.P.J.; Lange, W.; Laycock, P.; Lebedev, A.; Levchenko, B.B.; Levonian, S.; Levy, A.; Libov, V.; Limentani, S.; Lipka, K.; Lisovyi, M.; List, B.; List, J.; Lobodzinska, E.; Lobodzinski, B.; Lohr, B.; Lohrmann, E.; Longhin, A.; Lontkovskyi, D.; Lukina, O.Yu.; Makarenko, I.; Malinovski, E.; Malka, J.; Martyn, H.U.; Maxfield, S.J.; Mehta, A.; Mergelmeyer, S.; Meyer, A.B.; Meyer, H.; Meyer, J.; Mikocki, S.; Idris, F.Mohamad; Morozov, A.; Nasir, N.Muhammad; Muller, K.; Myronenko, V.; Nagano, K.; Naumann, Th.; Newman, P.R.; Niebuhr, C.; Nobe, T.; Notz, D.; Nowak, G.; Nowak, R.J.; Olsson, J.E.; Onishchuk, Yu.; Ozerov, D.; Pahl, P.; Pascaud, C.; Patel, G.D.; Paul, E.; Perez, E.; Perlanski, W.; Petrukhin, A.; Picuric, I.; Pirumov, H.; Pitzl, D.; Placakyte, R.; Pokorny, B.; Pokrovskiy, N.S.; Polifka, R.; Przybycien, M.; Radescu, V.; Raicevic, N.; Ravdandorj, T.; Reimer, P.; Rizvi, E.; Robmann, P.; Roloff, P.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Rubinsky, I.; Rusakov, S.; Ruspa, M.; Salek, D.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Saxon, D.H.; Schioppa, M.; Schmidke, W.B.; Schmitt, S.; Schneekloth, U.; Schoeffel, L.; Schoning, A.; Schorner-Sadenius, T.; Sefkow, F.; Shcheglova, L.M.; Shevchenko, R.; Shkola, O.; Shushkevich, S.; Shyrma, Yu.; Singh, I.; Skillicorn, I.O.; Slominski, W.; Solano, A.; Soloviev, Y.; Sopicki, P.; South, D.; Spaskov, V.; Specka, A.; Stanco, L.; Steder, M.; Stefaniuk, N.; Stern, A.; Stopa, P.; Straumann, U.; Sykora, T.; Sztuk-Dambietz, J.; Szuba, D.; Szuba, J.; Tassi, E.; Thompson, P.D.; Tokushuku, K.; Tomaszewska, J.; Traynor, D.; Trofymov, A.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Tsurugai, T.; Turcato, M.; Turkot, O.; Turnau, J.; Tymieniecka, T.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vazdik, Y.; Verbytskyi, A.; Viazlo, O.; Walczak, R.; Wan Abdullah, W.A.T.; Wegener, D.; Wichmann, K.; Wing, M.; Wolf, G.; Wunsch, E.; Yamada, S.; Yamazaki, Y.; Zacek, J.; Zakharchuk, N.; Zarnecki, A.F.; Zawiejski, L.; Zenaiev, O.; Zhang, Z.; Zhautykov, B.O.; Zhmak, N.; Zlebcik, R.; Zohrabyan, H.; Zomer, F.; Zotkin, D.S.

2015-01-01

H1 and ZEUS have published single-differential cross sections for inclusive D^{*\\pm}-meson production in deep-inelastic ep scattering at HERA from their respective final data sets. These cross sections are combined in the common visible phase-space region of photon virtuality Q2 > 5 GeV2, electron inelasticity 0.02 1.5 GeV and pseudorapidity |eta(D^*)| 1.5 GeV2. Perturbative next-to-leadingorder QCD predictions are compared to the results.

Measurement of the proton structure function F2 in ep scattering at HERA

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magill, S.

1993-08-01

This paper presents our first measurement of the F 2 structure function in neutral-current, deep inelastic scattering using the ZEUS detector at HERA, the ep colliding beam facility at DESY. The data correspond to an integrated luminosity of 24.7 nb -1 . Results are presented for data in a range of Q 2 from 10 GeV 2 to 4700 GeV 2 and Bjorken x down to 3.0x10 -4 . The F 2 structure function increases rapidly as x decreases. (orig.)

Real W and Z bosons production at HERA

Directory of Open Access Journals (Sweden)

Nobe Takuya

2014-04-01

Full Text Available The production of real W and Z bosons has been studied in ep collisions at HERA. A combined analysis is performed with the data taken with the H1 and ZEUS detectors corresponding to 0.98 fb−1 of integrated luminosity to search for events containing an isolated electron or muon and missing transverse momentum, which is dominated by single W production. The total single W boson production cross section is measured as 1.06 ± 0.16(stat. ± 0.07(sys. pb, in agreement with the Standard Model (SM expectation of 1.26 ± 0.19 pb. The production of Z bosons has been studied in the reaction ep → eZp(∗, where p(∗ stands for a proton or a low-mass nucleon resonance, using a data sample collected with the ZEUS detector amounting to 0.5 fb−1. The Z is measured in the hadronic decay mode. The cross section of the reaction ep → eZp(∗ is measured to be 0.13 ± 0.06(stat. ± 0.01(syst. pb, in agreement with the SM prediction of 0.16 pb.

Deep inelastic scattering with leading protons or large rapidity gaps at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-12-01

The dissociation of virtual photons, γ * p→ Xp, in events with a large rapidity gap between X and the outgoing proton, as well as in events in which the leading proton was directly measured, has been studied with the ZEUS detector at HERA. The data cover photon virtualities Q 2 > 2 GeV 2 and γ * p centre-of-mass energies 40 X > 2 GeV, where M X is the mass of the hadronic final state, X. Leading protons were detected in the ZEUS leading proton spectrometer. The cross section is presented as a function of t, the squared four-momentum transfer at the proton vertex and Φ, the azimuthal angle between the positron scattering plane and the proton scattering plane. It is also shown as a function of Q 2 and x P , the fraction of the proton's momentum carried by the diffractive exchange, as well as β, the Bjorken variable defined with respect to the diffractive exchange. (orig.)

Combined QCD and electroweak analysis of HERA data

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max-Planck-Institute for Physics, Munich (Germany); Abt, I. [Max-Planck-Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science; Collaboration: ZEUS Collaboration; and others

2016-03-15

A simultaneous fit of parton distribution functions (PDFs) and electroweak parameters to HERA data on deep inelastic scattering is presented. The input data are the neutral current and charged current inclusive cross sections which were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In addition, the polarisation of the electron beam was taken into account for the ZEUS data recorded between 2004 and 2007. Results on the vector and axial-vector couplings of the Z boson to u- and d-type quarks, on the value of the electroweak mixing angle and the mass of the W boson are presented. The values obtained for the electroweak parameters are in agreement with Standard Model predictions.

Subjet distributions in deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Lab., Argonne, IL (US)] (and others)

2008-12-15

Subjet distributions were measured in neutral current deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 81.7 pb{sup -1}. Jets were identified using the k{sub T} cluster algorithm in the laboratory frame. Sub-jets were defined as jet-like substructures identified by a reapplication of the cluster algorithm at a smaller value of the resolution parameter y{sub cut}. Measurements of subjet distributions for jets with exactly two subjets for y{sub cut}=0.05 are presented as functions of observables sensitive to the pattern of parton radiation and to the colour coherence between the initial and final states. Perturbative QCD predictions give an adequate description of the data. (orig.)

Combined QCD and electroweak analysis of HERA data

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2016-03-01

A simultaneous fit of parton distribution functions (PDFs) and electroweak parameters to HERA data on deep inelastic scattering is presented. The input data are the neutral current and charged current inclusive cross sections which were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In addition, the polarisation of the electron beam was taken into account for the ZEUS data recorded between 2004 and 2007. Results on the vector and axial-vector couplings of the Z boson to u- and d-type quarks, on the value of the electroweak mixing angle and the mass of the W boson are presented. The values obtained for the electroweak parameters are in agreement with Standard Model predictions.

Subjet distributions in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-12-01

Subjet distributions were measured in neutral current deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 81.7 pb -1 . Jets were identified using the k T cluster algorithm in the laboratory frame. Sub-jets were defined as jet-like substructures identified by a reapplication of the cluster algorithm at a smaller value of the resolution parameter y cut . Measurements of subjet distributions for jets with exactly two subjets for y cut =0.05 are presented as functions of observables sensitive to the pattern of parton radiation and to the colour coherence between the initial and final states. Perturbative QCD predictions give an adequate description of the data. (orig.)

Combined QCD and electroweak analysis of HERA data

CERN Document Server

Abramowicz, H; Adamczyk, L; Adamus, M; Antonelli, S; Aushev, V; Behnke, O; Behrens, U; Bertolin, A; Bloch, I; Boos, EG; Brock, I; Brook, NH; Brugnera, R; Bruni, A; Bussey, PJ; Caldwell, A; Capua, M; Catterall, CD; Chwastowski, J; Ciborowski, J; Ciesielski, R; Cooper-Sarkar, AM; Corradi, M; Dementiev, RK; Devenish, RCE; Dusini, S; Foster, B; Gach, G; Gallo, E; Garfagnini, A; Geiser, A; Gizhko, A; Gladilin, LK; Golubkov, Yu A; Grzelak, G; Guzik, M; Hain, W; Hochman, D; Hori, R; Ibrahim, ZA; Iga, Y; Ishitsuka, M; Januschek, F; Jomhari, NZ; Kadenko, I; Kananov, S; Karshon, U; Kaur, P; Kisielewska, D; Klanner, R; Klein, U; Korzhavina, IA; Kotański, A; Kötz, U; Kovalchuk, N; Kowalski, H; Krupa, B; Kuprash, O; Kuze, M; Levchenko, BB; Levy, A; Limentani, S; Lisovyi, M; Lobodzinska, E; Löhr, B; Lohrmann, E; Longhin, A; Lontkovskyi, D; Lukina, OYu; Makarenko, I; Malka, J; Mohamad Idris, F; Mohammad Nasir, N; Myronenko, V; Nagano, K; Nobe, T; Nowak, RJ; Onishchuk, Yu; Paul, E; Perlański, W; Pokrovskiy, NS; Przybycien, M; Roloff, P; Ruspa, M; Saxon, DH; Schioppa, M; Schneekloth, U; Schörner-Sadenius, T; Shcheglova, LM; Shevchenko, R; Shkola, O; Shyrma, Yu; Singh, I; Skillicorn, IO; Słomiński, W; Solano, A; Stanco, L; Stefaniuk, N; Stern, A; Stopa, P; Sztuk-Dambietz, J; Tassi, E; Tokushuku, K; Tomaszewska, J; Tsurugai, T; Turcato, M; Turkot, O; Tymieniecka, T; Verbytskyi, A; Wan Abdullah, WAT; Wichmann, K; Wing, M; Yamada, S; Yamazaki, Y; Zakharchuk, N; Żarnecki, AF; Zawiejski, L; Zenaiev, O; Zhautykov, BO; Zotkin, DS; Bhadra, S; Gwenlan, C; Hlushchenko, O; Polini, A; Mastroberardino, A

2016-05-03

A simultaneous fit of parton distribution functions (PDFs) and electroweak parameters to HERA data on deep inelastic scattering is presented. The input data are the neutral current and charged current inclusive cross sections which were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In addition, the polarisation of the electron beam was taken into account for the ZEUS data recorded between 2004 and 2007. Results on the vector and axial-vector couplings of the Z boson to u- and d-type quarks, on the value of the electroweak mixing angle and the mass of the W boson are presented. The values obtained for the electroweak parameters are in agreement with Standard Model predictions.

Review of high energy diffraction in real and virtual photon proton scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Wolf, G.

2009-07-15

The electron-proton collider HERA at DESY opened the door for the study of diffraction in real and virtual photon-proton scattering at center-of-mass energies W up to 250 GeV and for large negative mass squared -Q{sup 2} of the virtual photon up to Q{sup 2}=1600 GeV{sup 2}. At W = 220 GeV and Q{sup 2}=4 GeV{sup 2}, diffraction accounts for about 15% of the total virtual photon proton cross section decreasing to {approx}5% at Q{sup 2}=200 GeV{sup 2}. An overview of the results obtained by the experiments H1 and ZEUS on the production of neutral vector mesons and on inclusive diffraction up to the year 2008 is presented. (orig.)

The ZEUS data preservation project

International Nuclear Information System (INIS)

Malka, Janusz; Wichmann, Katarzyna

2012-01-01

A project to allow long term access and physics analysis of ZEUS data (ZEUS data preservation) has been established in collaboration with the DESY-IT group. In the ZEUS approach the analysis model is based on the Common Ntuple project, under development since 2006. The real data and all presently available Monte Carlo samples are being preserved in a flat ROOT ntuple format. There is ongoing work to provide the ability to simulate new, additional Monte Carlo samples also in the future. The validation framework of such a scheme using virtualisation techniques is being explored. The goal is to validate the frozen ZEUS software against future changes in hardware and operating system. A cooperation between ZEUS, DESY-IT and the library was established for document digitisation and long-term preservation of collaboration web pages. Part of the ZEUS internal documentation has already been stored within the HEP documentation system INSPIRE. Existing digital documentation, needed to perform physics analysis also in the future, is being centralised and completed.

High-ET dijet photoproduction at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2007-06-01

The cross section for high-E T dijet production in photoproduction has been measured with the ZEUS detector at HERA using an integrated luminosity of 81.8 pb -1 . The events were required to have a virtuality of the incoming pho- ton, Q 2 , of less than 1 GeV 2 and a photon-proton centre-of-mass energy in the range 142 γp T jet1 >20 GeV and E T jet2 >15 GeV and pseudorapidity requirements of -1 jet1,2 jet <2.5. The measurements show sensitivity to the parton distributions in the photon and proton and effects beyond next-to-leading order in QCD. Hence these data can be used to constrain further the parton densities in the proton and photon. (orig.)

Phenomenology of leading nucleon production in e p collisions at HERA in the framework of fracture functions

Science.gov (United States)

Shoeibi, Samira; Taghavi-Shahri, F.; Khanpour, Hamzeh; Javidan, Kurosh

2018-04-01

In recent years, several experiments at the e-p collider HERA have collected high precision deep-inelastic scattering (DIS) data on the spectrum of leading nucleon carrying a large fraction of the proton's energy. In this paper, we have analyzed recent experimental data on the production of forward protons and neutrons in DIS at HERA in the framework of a perturbative QCD. We propose a technique based on the fractures functions framework, and extract the nucleon fracture functions (FFs) M2(n /p )(x ,Q2;xL) from global QCD analysis of DIS data measured by the ZEUS Collaboration at HERA. We have shown that an approach based on the fracture functions formalism allows us to phenomenologically parametrize the nucleon FFs. Considering both leading neutron as well as leading proton production data at HERA, we present the results for the separate parton distributions for all parton species, including valence quark densities, the antiquark densities, the strange sea distribution, and the gluon distribution functions. We proposed several parametrizations for the nucleon FFs and open the possibility of these asymmetries. The obtained optimum set of nucleon FFs is accompanied by Hessian uncertainty sets which allow one to propagate uncertainties to other observables interest. The extracted results for the t -integrated leading neutron F2LN (3 )(x ,Q2;xL) and leading proton F2LP (3 )(x ,Q2;xL) structure functions are in good agreement with all data analyzed, for a wide range of fractional momentum variable x as well as the longitudinal momentum fraction xL.

Inclusive K0SK0S resonance production in ep collisions at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-06-01

Inclusive K 0 S K 0 S production in ep collisions at HERA was studied with the ZEUS detector using an integrated luminosity of 0.5 fb -1 . Enhancements in the mass spectrum were observed and are attributed to the production of f 2 (1270)/a 0 2 (1320), f' 2 (1525) and f 0 (1710). The f 0 (1710) state was observed with a statistical significance of 5 standard deviations. Masses and widths were obtained using a fit which takes into account theoretical predictions based on SU(3) symmetry arguments. (orig.)

Inclusive K0SK0S resonance production in ep collisions at HERA

CERN Document Server

AUTHOR|(CDS)2076592; Magill, S.; Musgrave, B.; Nicholass, D.; Repond, J.; Yoshida, R.; Mattingly, M.C.K.; Antonioli, P.; Bari, G.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cindolo, F.; Corradi, M.; Iacobucci, G.; Margotti, A.; Nania, R.; Polini, A.; Antonelli, S.; Basile, M.; Bindi, M.; Cifarelli, L.; Contin, A.; De Pasquale, S.; Sartorelli, G.; Zichichi, A.; Bartsch, D.; Brock, I.; Hartmann, H.; Hilger, E.; Jakob, H.P.; Jungst, M.; Nuncio-Quiroz, A.E.; Paul, E.; Samson, U.; Schonberg, V.; Shehzadi, R.; Wlasenko, M.; Brook, N.H.; Heath, G.P.; Morris, J.D.; Capua, M.; Fazio, S.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Tassi, E.; Kim, J.Y.; Ibrahim, Z.A.; Kamaluddin, B.; Wan Abdullah, W.A.T.; Ning, Y.; Ren, Z.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Galas, A.; Gil, M.; Olkiewicz, K.; Stopa, P.; Zawiejski, L.; Adamczyk, L.; Bold, T.; Grabowska-Bold, I.; Kisielewska, D.; Lukasik, J.; Przybycien, M.; Suszycki, L.; Kotanski, A.; Slominski, W.; Behrens, U.; Blohm, C.; Bonato, A.; Borras, K.; Ciesielski, R.; Coppola, N.; Fang, S.; Fourletova, J.; Geiser, A.; Gottlicher, P.; Grebenyuk, J.; Gregor, I.; Haas, T.; Hain, W.; Huttmann, A.; Januschek, F.; Kahle, B.; Katkov, I.I.; Klein, U.; Kotz, U.; Kowalski, H.; Lobodzinska, E.; Lohr, B.; Mankel, R.; Melzer-Pellmann, I.A.; Miglioranzi, S.; Montanari, A.; Namsoo, T.; Notz, D.; Parenti, A.; Rinaldi, L.; Roloff, P.; Rubinsky, I.; Santamarta, R.; Schneekloth, U.; Spiridonov, A.; Szuba, D.; Szuba, J.; Theedt, T.; Wolf, G.; Wrona, K.; Yagues Molina, A.G.; Youngman, C.; Zeuner, W.; Drugakov, V.; Lohmann, W.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Pelfer, P.G.; Bamberger, A.; Dobur, D.; Karstens, F.; Vlasov, N.N.; Bussey, P.J.; Doyle, A.T.; Dunne, W.; Forrest, M.; Rosin, M.; Saxon, D.H.; Skillicorn, I.O.; Gialas, I.; Papageorgiu, K.; Holm, U.; Klanner, R.; Lohrmann, E.; Schleper, P.; Schorner-Sadenius, T.; Sztuk, J.; Stadie, H.; Turcato, M.; Foudas, C.; Fry, C.; Long, K.R.; Tapper, A.D.; Matsumoto, T.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Barakbaev, A.N.; Boos, E.G.; Pokrovskiy, N.S.; Zhautykov, B.O.; Aushev, V.; Borodin, M.; Kadenko, I.; Kozulia, A.; Libov, V.; Lisovyi, M.; Lontkovskyi, D.; Makarenko, I.; Sorokin, Iu.; Verbytskyi, A.; Volynets, O.; Son, D.; de Favereau, J.; Piotrzkowski, K.; Barreiro, F.; Glasman, C.; Jimenez, M.; Labarga, L.; del Peso, J.; Ron, E.; Soares, M.; Terron, J.; Zambrana, M.; Corriveau, F.; Liu, C.; Schwartz, J.; Walsh, R.; Zhou, C.; Tsurugai, T.; Antonov, A.; Dolgoshein, B.A.; Gladkov, D.; Sosnovtsev, V.; Stifutkin, A.; Suchkov, S.; Dementiev, R.K.; Ermolov, P.F.; Gladilin, L.K.; Golubkov, Yu.A.; Khein, L.A.; Korzhavina, I.A.; Kuzmin, V.A.; Levchenko, B.B.; Lukina, O.Yu.; Proskuryakov, A.S.; Shcheglova, L.M.; Zotkin, D.S.; Abt, I.; Caldwell, A.; Kollar, D.; Reisert, B.; Schmidke, W.B.; Grigorescu, G.; Keramidas, A.; Koffeman, E.; Kooijman, P.; Pellegrino, A.; Tiecke, H.; Vazquez Acosta, Monica Luisa; Wiggers, L.; Brummer, N.; Bylsma, B.; Durkin, L.S.; Lee, A.; Ling, T.Y.; Allfrey, Philip Daniel; Bell, M.A.; Cooper-Sarkar, A.M.; Devenish, R.C.E.; Ferrando, J.; Foster, B.; Korcsak-Gorzo, K.; Oliver, K.; Robertson, A.; Uribe-Estrada, C.; Walczak, R.; Bertolin, A.; Dal Corso, F.; Dusini, S.; Longhin, A.; Stanco, L.; Bellan, P.; Brugnera, R.; Carlin, R.; Garfagnini, A.; Limentani, S.; Oh, B.Y.; Raval, A.; Ukleja, J.; Whitmore, J.J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cole, J.E.; Hart, J.C.; Abramowicz, H.; Ingbir, R.; Kananov, S.; Levy, A.; Stern, A.; Kuze, M.; Maeda, J.; Hori, R.; Kagawa, S.; Okazaki, N.; Shimizu, S.; Tawara, T.; Hamatsu, R.; Kaji, H.; Kitamura, S.; Ota, O.; Ri, Y.D.; Costa, M.; Ferrero, M.I.; Monaco, V.; Sacchi, R.; Solano, A.; Arneodo, M.; Ruspa, M.; Fourletov, S.; Martin, J.F.; Stewart, T.P.; Boutle, S.K.; Butterworth, J.M.; Gwenlan, C.; Jones, T.W.; Loizides, J.H.; Wing, M.; Brzozowska, B.; Ciborowski, J.; Grzelak, G.; Kulinski, P.; Luzniak, P.; Malka, J.; Nowak, R.J.; Pawlak, J.M.; Tymieniecka, T.; Ukleja, A.; zarnecki, A.F.; Adamus, M.; Plucinski, P.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Brownson, E.; Danielson, T.; Everett, A.; Kcira, D.; Reeder, D.D.; Ryan, P.; Savin, A.A.; Smith, W.H.; Wolfe, H.; Bhadra, S.; Catterall, C.D.; Cui, Y.; Hartner, G.; Menary, S.; Noor, U.; Standage, J.; Whyte, J.

2008-01-01

Inclusive K0SK0S production in ep collisions at HERA was studied with the ZEUS detector using an integrated luminosity of 0.5 fb-1. Enhancements in the mass spectrum were observed and are attributed to the production of f2(1270)/a02(1320), f'2(1525) and f0(1710). The f0(1710) state was observed with a statistical significance of 5 standard deviations. Masses and widths were obtained using a fit which takes into account theoretical predictions based on SU(3) symmetry arguments.

Production of the excited charm mesons D{sub 1} and D{sup *}{sub 2} at HERA

Energy Technology Data Exchange (ETDEWEB)

Verbytskyi, Andrii

2013-02-15

The production of the excited charm mesons D{sub 1}, D{sup *}{sub 2} and D{sup +}{sub s1} in ep collisions has been measured with the ZEUS detector at Hera. The data sample taken by the ZEUS detector in the years 2003-2007, corresponding to an integrated luminosity of 373 pb{sup -1} has been used. The masses of the neutral, charged and strange states, the widths of the neutral states, the helicity parameters of D{sup 0}{sub 1} and D{sup +}{sub s1} were determined and compared with other measurements and with theoretical expectations. The measured helicity parameters of the D{sup 0}{sub 1} and D{sup +}{sub s1} allows for some mixing of S- and D-waves in their decays to D{sup *{+-}}{pi}{sup -+} and D{sup *{+-}}K{sup 0} respectively. The measured value of the D{sup 0}{sub 1} helicity parameter is also consistent with a pure D-wave decay. Ratios of branching fractions of the two decay modes of the D{sup *0}{sub 2}, D{sup *{+-}}{sub 2} and D{sup +}{sub s1} states were measured and compared with previous measurements. The fractions of charm quarks hadronising into D{sub 1}, D{sup *}{sub 2} and D{sup +}{sub s1} were measured and are consistent with those obtained in e{sup +}e{sup -} annihilations. The Grid computing technology has a high importance for modern High Energy Physics. This technology has been successfully used in Zeus experiment for the MC simulations and data analysis. The dedicated infrastructure has been maintained by the author since 2010. In addition to continuous support, the author has upgraded and improved the performance of the Grid MC simulations and contributed to the Zeus data preservation project.

HERA: Illuminating Our Early Universe

Science.gov (United States)

DeBoer, David

2014-06-01

The Hydrogen Epoch of Reionization Arrays (HERA) roadmap is a staged plan for using the unique properties of the 21cm line from neutral hydrogen to probe our cosmic dawn, from the birth of the first stars and black holes, through the full reionization of the primordial intergalactic medium (IGM). HERA is a collaboration between the Precision Array Probing the Epoch of Reionization (PAPER), US-Murchison Widefield Array (MWA), and MIT Epoch of Reionization (MITEOR) teams.The first phase of the HERA roadmap entailed the operation of the PAPER and MWA telescopes to explore techniques and designs required to detect the primordial HI signal in the presence of radio continuum foreground emission some four orders of magnitude brighter. Studies with PAPER and the MWA have led to a new understanding of the interplay of foreground and instrumental systematics in the context of a three-dimensional cosmological intensity-mapping experiment. We are now able to remove foregrounds to the limits of our sensitivity with these instruments, culminating in the first physically meaningful upper limits on the power spectrum of 2 cm emission from reionization.Building on this understanding, the next stage of HERA entails a new 14m diameter antenna element that is optimized both for sensitivity and for minimizing foreground systematics. Arranging these elements in a compact hexagonal grid yields an array that facilitates calibration, leverages proven foreground removal techniques, and is scalable to large collecting areas. The HERA phase II will be located in the radio quiet environment of the SKA site in Karoo, South Africa, and have a sensitivity close to two orders of magnitude better than PAPER and the MWA, with broader frequency coverage, HERA can paint an uninterrupted picture through reionization, back to the end of the Dark Ages.This paper will present a summary of the current understanding of the signal characteristics and measurements and describe this planned HERA telescope to

Polarisation at HERA. Reanalysis of the HERA II polarimeter data

Energy Technology Data Exchange (ETDEWEB)

Sobloher, B.; Behnke, T.; Olsson, J.; Pitzl, D.; Schmitt, S.; Tomaszewska, J.; Fabbri, R.

2012-01-15

In this technical note we briefly present the analysis of the HERA polarimeters (transversal and longitudinal) as of summer 2011. We present the final reanalysis of the TPOL data, and discuss the systematic uncertainties. A procedure to combine and average LPOL and TPOL data is presented. (orig.)

Polarisation at HERA. Reanalysis of the HERA II polarimeter data

International Nuclear Information System (INIS)

Sobloher, B.; Behnke, T.; Olsson, J.; Pitzl, D.; Schmitt, S.; Tomaszewska, J.; Fabbri, R.

2012-01-01

In this technical note we briefly present the analysis of the HERA polarimeters (transversal and longitudinal) as of summer 2011. We present the final reanalysis of the TPOL data, and discuss the systematic uncertainties. A procedure to combine and average LPOL and TPOL data is presented. (orig.)

Three- and four-jet final states in photoproduction at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2007-08-15

Three- and four-jet final states have been measured in photoproduction at HERA using the ZEUS detector with an integrated luminosity of 121 pb{sup -1}. The results are presented for jets with transverse energy E{sup jet}{sub T}>6 GeV and pseudorapidity vertical stroke {eta}{sup jet} vertical stroke <2.4, in the kinematic region given by the virtuality of the photon Q{sup 2}<1 GeV{sup 2} and the inelasticity 0.2{<=}y{<=}0.85 and in two mass regions defined as 25{<=}M{sub nj}<50 GeV and M{sub nj}{>=}50 GeV, where M{sub nj} is the invariant mass of the n-jet system. The four-jet photoproduction cross section has been measured for the first time and represents the highest-order process studied at HERA. Both the three- and four-jet cross sections have been compared with leading-logarithmic parton-shower Monte Carlo models, with and without multi-parton interactions. The three-jet cross sections have been compared to an O({alpha}{alpha}{sup 2}{sub s}) perturbative QCD calculation. (orig.)

Measurement of beauty quark cross sections in photoproduction with the ZEUS experiment at the electron-proton collider HERA

International Nuclear Information System (INIS)

Gutsche, O.

2005-03-01

This thesis measures photoproduction cross sections of semi-leptonically decaying beauty quarks into muons in dijet events: ep → ebbX → ejjμX The p T rel method is used in pre- and post-upgrade running periods to identify beauty quarks. Afterwards, these results are used to explore the applicability of the impact parameter method in the post-upgrade running periods. The technical task of this thesis consisted of the development of a new event display for the ZEUS detector incorporating the changes in the detector layout after the upgrade including the new micro-vertex-detector. The new solution providing event displays both for the pre- and post-upgrade running periods is presented by describing the visualisation concept and the implementation. In the following, a brief description of the structure of the cross section measurements and the study of the impact parameter method is given. In the pre-upgrade running periods, a data sample of 110 pb -1 is used to measure cross sections with the p T rel method. A new general muon reconstruction is established to increase the statistics significantly. The experience from the pre-upgrade running periods is then transferred to the post-upgrade running periods to measure first beauty quark cross sections using the p T rel method with the upgraded detector in a data sample of 40 pb -1 . The comparison between pre- and post-upgrade results establishes a post-upgrade event sample with known beauty content which is suitable for comparisons of the two beauty quark identification methods. A first study of the applicability of the impact parameter method concludes the investigation of beauty quark production after the upgrade. (orig.)

Leading neutron energy and pT distributions in deep inelastic scattering and photoproduction at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2007-02-01

The production of energetic neutrons in ep collisions has been studied with the ZEUS detector at HERA. The neutron energy and p T 2 distributions were measured with a forward neutron calorimeter and tracker in a 40 pb -1 sample of inclusive deep inelastic scattering (DIS) data and a 6 pb -1 sample of photoproduction data. The neutron yield in photoproduction is suppressed relative to DIS for the lower neutron energies and the neutrons have a steeper p T 2 distribution, consistent with the expectation from absorption models. The distributions are compared to HERA measurements of leading protons. The neutron energy and transverse-momentum distributions in DIS are compared to Monte Carlo simulations and to the predictions of particle exchange models. Models of pion exchange incorporating absorption and additional secondary meson exchanges give a good description of the data. (orig.)

The ZEUS calorimeter first level trigger

International Nuclear Information System (INIS)

Smith, W.H.; Ali, I.; Behrens, B.; Fordham, C.; Foudas, C.; Goussiou, A.; Jaworski, M.; Kinnel, T.; Lackey, J.; Robl, P.; Silverstein, S.; Dawson, J.W.; Krakauer, D.A.; Talaga, R.L.; Schlereth, J.L.

1994-10-01

The design of the ZEUS Calorimeter First Level Trigger (CFLT) is presented. The CFLT utilizes a pipelined architecture to provide trigger data for a global first leel trigger decision 5 μsec after each beam crossing, occurring every 96 nsec. The charges from 13K phototubes are summed into 1792 trigger tower pulseheights which are digitized by flash ADC's. The digital values are linearized, stored and used for sums and pattern tests. Summary data is forwarded to the Global First Level Trigger for each crossing 2 μsec after the crossing occurred. The CFLT determines the total energy, the total transverse energy, the missing energy, and the energy and number of isolated electrons and muons. It also provides information on the electromagnetic and hadronic energy deposited in various regions of the calorimeter. The CFLT has kept the experimental trigger rate below ∼200 Hz at the highest luminosity experienced at HERA. Performance studies suggest that the CFLT will keep the trigger rate below 1 kHZ against a rate of proton-beam gas interactions on the order of the 100 kHz expected at design luminosity. (orig.)

The data acquisition system for the HERA H1 experiment

International Nuclear Information System (INIS)

Haynes, W.J.

1990-06-01

The HERA ep collider will set new challenges for the acquisition of data from large particle physics experiments. Short bunch-crossing times combined with high data rates imply sophisticated designs based on current technology. This paper describes how a multi-microprocessor system is being used at the H1 experiment. (author)

Measurement of (anti)deuteron and (anti)proton production in DIS at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2007-05-01

The first observation of (anti)deuterons in deep inelastic scattering at HERA has been made with the ZEUS detector at a centre-of-mass energy of 300-318 GeV using an integrated luminosity of 120 pb -1 . The measurement was performed in the central rapidity region for transverse momentum per unit of mass in the range 0.3 T /M<0.7. The particle rates have been extracted and interpreted in terms of the coalescence model. The (anti)deuteron production yield is smaller than the (anti)proton yield by approximately three orders of magnitude, consistent with the world measurements. (orig.)

Multi-Leptons with High Transverse Momentum at HERA

CERN Document Server

Aaron, F.D.; Abt, I.; Adamczyk, L.; Adamus, M.; Aldaya Martin, M.; Alexa, C.; Alimujiang, K.; Andreev, V.; Antonelli, S.; Antonioli, P.; Antonov, A.; Antunovic, B.; Arneodo, M.; Asmone, A.; Aushev, V.; Bachynska, O.; Backovic, S.; Baghdasaryan, A.; Bamberger, A.; Barakbaev, A.N.; Barbagli, G.; Bari, G.; Barreiro, F.; Barrelet, E.; Bartel, W.; Bartsch, D.; Basile, M.; Begzsuren, K.; Behnke, O.; Behr, J.; Behrens, U.; Bellagamba, L.; Belousov, A.; Bertolin, A.; Bhadra, S.; Bindi, M.; Bizot, J.C.; Blohm, C.; Bold, T.; Boos, E.G.; Borodin, M.; Borras, K.; Boscherini, D.; Bot, D.; Boudry, V.; Boutle, S.K.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Brock, I.; Brownson, E.; Brugnera, R.; Brummer, N.; Bruncko, D.; Bruni, A.; Bruni, G.; Brzozowska, B.; Bunyatyan, A.; Buschhorn, G.; Bussey, P.J.; Butterworth, J.M.; Bylsma, B.; Bystritskaya, L.; Caldwell, A.; Campbell, A.J.; Cantun Avila, K.B.; Capua, M.; Carlin, R.; Cassol-Brunner, F.; Catterall, C.D.; Cerny, K.; Cerny, V.; Chekanov, S.; Chekelian, V.; Cholewa, A.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Cifarelli, L.; Cindolo, F.; Contin, A.; Contreras, J.G.; Cooper-Sarkar, A.M.; Coppola, N.; Corradi, M.; Corriveau, F.; Costa, M.; Coughlan, J.A.; Cozzika, G.; Cvach, J.; D'Agostini, G.; Dainton, J.B.; Dal Corso, F.; Daum, K.; Deak, M.; de Boer, Y.; de Favereau, J.; Delcourt, B.; Del Degan, M.; del Peso, J.; Delvax, J.; Dementiev, R.K.; De Pasquale, S.; Derrick, M.; Devenish, R.C.E.; De Wolf, E.A.; Diaconu, C.; Dobur, D.; Dodonov, V.; Dolgoshein, B.A.; Dossanov, A.; Doyle, A.T.; Drugakov, V.; Dubak, A.; Durkin, L.S.; Dusini, S.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eisenberg, Y.; Eliseev, A.; Elsen, E.; Ermolov, P.F.; Eskreys, A.; Falkiewicz, A.; Fang, S.; Favart, L.; Fazio, S.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrando, J.; Ferrero, M.I.; Figiel, J.; Fischer, D.J.; Fleischer, M.; Fomenko, A.; Forrest, M.; Foster, B.; Fourletov, S.; Gabathuler, E.; Galas, A.; Gallo, E.; Garfagnini, A.; Gayler, J.; Geiser, A.; Ghazaryan, S.; Gialas, I.; Gladilin, L.K.; Gladkov, D.; Glasman, C.; Glazov, A.; Glushkov, I.; Goerlich, L.; Gogitidze, N.; Golubkov, Yu.A.; Gottlicher, P.; Gouzevitch, M.; Grab, C.; Grabowska-Bold, I.; Grebenyuk, J.; Greenshaw, T.; Gregor, I.; Grell, B.R.; Grigorescu, G.; Grindhammer, G.; Grzelak, G.; Gwenlan, C.; Haas, T.; Habib, S.; Haidt, D.; Hain, W.; Hamatsu, R.; Hart, J.C.; Hartmann, H.; Hartner, G.; Helebrant, C.; Henderson, R.C.W.; Hennekemper, E.; Henschel, H.; Herbst, M.; Herrera, G.; Hildebrandt, M.; Hilger, E.; Hiller, K.H.; Hochman, D.; Hoffmann, D.; Holm, U.; Hori, R.; Horisberger, R.; Horton, K.; Hreus, T.; Huttmann, A.; Iacobucci, G.; Ibrahim, Z.A.; Iga, Y.; Ingbir, R.; Ishitsuka, M.; Jacquet, M.; Jakob, H.P.; Janssen, M.E.; Janssen, X.; Januschek, F.; Jimenez, M.; Jones, T.W.; Jonsson, L.; Jung, A.W.; Jung, H.; Jungst, M.; Kadenko, I.; Kahle, B.; Kamaluddin, B.; Kananov, S.; Kanno, T.; Kapichine, M.; Karshon, U.; Karstens, F.; Katkov, I.I.; Katzy, J.; Kaur, M.; Kaur, P.; Kenyon, I.R.; Keramidas, A.; Khein, L.A.; Kiesling, C.; Kim, J.Y.; Kisielewska, D.; Kitamura, S.; Klanner, R.; Klein, M.; Klein, U.; Kleinwort, C.; Kluge, T.; Knutsson, A.; Koffeman, E.; Kogler, R.; Kollar, D.; Kooijman, P.; Korzhavina, I.A.; Kostka, P.; Kotanski, A.; Kotz, U.; Kowalski, H.; Kraemer, M.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Kulinski, P.; Kuprash, O.; Kutak, K.; Kuze, M.; Kuzmin, V.A.; Landon, M.P.J.; Lange, W.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Lee, A.; Leibenguth, G.; Lendermann, V.; Levchenko, B.B.; Levonian, S.; Levy, A.; Li, G.; Libov, V.; Limentani, S.; Ling, T.Y.; Lipka, K.; Liptaj, A.; Lisovyi, M.; List, B.; List, J.; Lobodzinska, E.; Lohmann, W.; Lohr, B.; Lohrmann, E.; Loizides, J.H.; Loktionova, N.; Long, K.R.; Longhin, A.; Lontkovskyi, D.; Lopez-Fernandez, R.; Lubimov, V.; Lukasik, J.; Lukina, O.Yu.; Luzniak, P.; Lytkin, L.; Maeda, J.; Magill, S.; Makankine, A.; Makarenko, I.; Malinovski, E.; Malka, J.; Mankel, R.; Marage, P.; Margotti, A.; Marini, G.; Marti, Ll.; Martin, J.F.; Martyn, H.U.; Mastroberardino, A.; Matsumoto, T.; Mattingly, M.C.K.; Maxfield, S.J.; Mehta, A.; Melzer-Pellmann, I.A.; Meyer, A.B.; Meyer, H.; Meyer, H.; Meyer, J.; Michels, V.; Miglioranzi, S.; Mikocki, S.; Milcewicz-Mika, I.; Mohamad Idris, F.; Monaco, V.; Montanari, A.; Moreau, F.; Morozov, A.; Morris, J.D.; Morris, J.V.; Mozer, M.U.; Mudrinic, M.; Muller, K.; Murin, P.; Musgrave, B.; Nagano, K.; Namsoo, T.; Nania, R.; Naumann, Th.; Newman, P.R.; Nicholass, D.; Niebuhr, C.; Nigro, A.; Nikiforov, A.; Ning, Y.; Noor, U.; Notz, D.; Nowak, G.; Nowak, K.; Nowak, R.J.; Nozicka, M.; Nuncio-Quiroz, A.E.; Oh, B.Y.; Okazaki, N.; Oliver, K.; Olivier, B.; Olkiewicz, K.; Olsson, J.E.; Osman, S.; Ota, O.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, Th.; Papageorgiu, K.; Parenti, A.; Pascaud, C.; Patel, G.D.; Paul, E.; Pawlak, J.M.; Pawlik, B.; Pejchal, O.; Pelfer, P.G.; Pellegrino, A.; Perez, E.; Perlanski, W.; Perrey, H.; Petrukhin, A.; Picuric, I.; Piec, S.; Piotrzkowski, K.; Pitzl, D.; Placakythe, R.; Plucinski, P.; Pokorny, B.; Pokrovskiy, N.S.; Polifka, R.; Polini, A.; Povh, B.; Preda, T.; Proskuryakov, A.S.; Przybycien, M.; Radescu, V.; Rahmat, A.J.; Raicevic, N.; Raspiareza, A.; Raval, A.; Ravdandorj, T.; Reeder, D.D.; Reimer, P.; Reisert, B.; Ren, Z.; Repond, J.; Ri, Y.D.; Rizvi, E.; Robertson, A.; Robmann, P.; Roland, B.; Roloff, P.; Ron, E.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Rubinsky, I.; Ruiz Tabasco, J.E.; Rurikova, Z.; Rusakov, S.; Ruspa, M.; Sacchi, R.; Salek, D.; Samson, U.; Sankey, D.P.C.; Sartorelli, G.; Sauter, M.; Sauvan, E.; Savin, A.A.; Saxon, D.H.; Schioppa, M.; Schlenstedt, S.; Schleper, P.; Schmidke, W.B.; Schmitt, S.; Schneekloth, U.; Schoeffel, L.; Schonberg, V.; Schoning, A.; Schorner-Sadenius, T.; Schultz-Coulon, H.C.; Schwartz, J.; Sciulli, F.; Sefkow, F.; Shaw-West, R.N.; Shcheglova, L.M.; Shehzadi, R.; Shimizu, S.; Shtarkov, L.N.; Shushkevich, S.; Singh, I.; Skillicorn, I.O.; Sloan, T.; Slominski, W.; Smiljanic, I.; Smith, W.H.; Sola, V.; Solano, A.; Soloviev, Y.; Son, D.; Sopicki, P.; Sorokin, Iu.; Sosnovtsev, V.; South, D.; Spaskov, V.; Specka, A.; Spiridonov, A.; Stadie, H.; Stanco, L.; Staykova, Z.; Steder, M.; Stella, B.; Stern, A.; Stewart, T.P.; Stifutkin, A.; Stoicea, G.; Stopa, P.; Straumann, U.; Suchkov, S.; Sunar, D.; Susinno, G.; Suszycki, L.; Sykora, T.; Sztuk, J.; Szuba, D.; Szuba, J.; Tapper, A.D.; Tassi, E.; Tchoulakov, V.; Terron, J.; Theedt, T.; Thompson, G.; Thompson, P.D.; Tiecke, H.; Tokushuku, K.; Toll, T.; Tomasz, F.; Tomaszewska, J.; Tran, T.H.; Traynor, D.; Trinh, T.N.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Tsurugai, T.; Turcato, M.; Turnau, J.; Tymieniecka, T.; Urban, K.; Uribe-Estrada, C.; Valkarovha, A.; Vallee, C.; Van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Vazquez, M.; Verbytskyi, A.; Vinokurova, S.; Vlasov, N.N.; Volchinski, V.; Volynets, O.; von den Driesch, M.; Walczak, R.; Wan Abdullah, W.A.T.; Wegener, D.; Whitmore, J.J.; Whyte, J.; Wiggers, L.; Wing, M.; Wissing, Ch.; Wlasenko, M.; Wolf, G.; Wolfe, H.; Wrona, K.; Wunsch, E.; Yagues-Molina, A.G.; Yamada, S.; Yamazaki, Y.; Yoshida, R.; Youngman, C.; Zacek, J.; Zalesak, J.; Zarnecki, A.F.; Zawiejski, L.; Zeuner, W.; Zhang, Z.; Zhautykov, B.O.; Zhokin, A.; Zhou, C.; Zichichi, A.; Zimmermann, T.; Zohrabyan, H.; Zolko, M.; Zomer, F.; Zotkin, D.S.; Zus, R.

2009-01-01

Events with at least two high transverse momentum leptons (electrons or muons) are studied using the H1 and ZEUS detectors at HERA with an integrated luminosity of 0.94 fb^{-1}. The observed numbers of events are in general agreement with the Standard Model predictions. Seven di- and tri-lepton events are observed in e^+p collision data with a scalar sum of the lepton transverse momenta above 100 GeV while 1.94+-0.17 events are expected. Such events are not observed in e^-p collisions for which 1.19+-0.12 are predicted. Total visible and differential di-electron and di-muon photoproduction cross sections are extracted in a restricted phase space dominated by photon-photon collisions.

Multi-leptons with high transverse momentum at HERA

Energy Technology Data Exchange (ETDEWEB)

Aaron, F.D. [National Inst. for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Bucharest Univ. (Romania). Faculty of Physics; Abramowicz, H. [Tel Aviv Univ. (Israel). Raymond and Beverly Sackler Faculty of Exact Sciences; Max-Planck-Inst., Muenchen (Germany); Abt, I. [Max-Planck-Inst., Muenchen (DE)] (and others)

2009-07-15

Events with at least two high transverse momentum leptons (electrons or muons) are studied using the H1 and ZEUS detectors at HERA with an integrated luminosity of 0.94 fb{sup -1}. The observed numbers of events are in general agreement with the Standard Model predictions. Seven di- and tri-lepton events are observed in e{sup +}p collision data with a scalar sum of the lepton transverse momenta above 100 GeV while 1.94{+-}0.17 events are expected. Such events are not observed in e{sup -}p collisions for which 1.19{+-}0.12 are predicted. Total visible and differential di-electron and di-muon photoproduction cross sections are extracted in a restricted phase space dominated by photon-photon collisions. (orig.)

Multi-leptons with high transverse momentum at HERA

International Nuclear Information System (INIS)

Aaron, F.D.; Abt, I.

2009-07-01

Events with at least two high transverse momentum leptons (electrons or muons) are studied using the H1 and ZEUS detectors at HERA with an integrated luminosity of 0.94 fb -1 . The observed numbers of events are in general agreement with the Standard Model predictions. Seven di- and tri-lepton events are observed in e + p collision data with a scalar sum of the lepton transverse momenta above 100 GeV while 1.94±0.17 events are expected. Such events are not observed in e - p collisions for which 1.19±0.12 are predicted. Total visible and differential di-electron and di-muon photoproduction cross sections are extracted in a restricted phase space dominated by photon-photon collisions. (orig.)

Operational experience running the HERA-B database system

International Nuclear Information System (INIS)

Amaral, V.; Amorim, A.; Batista, J.

2001-01-01

The HERA-B database system has been used in the commissioning period of the experiment. The authors present the expertise gathered during this period, covering also the improvements introduced and describing the different classes of problems faced in giving persistency to all non-event information. The author aims to give a global overview of the Database group activities, techniques developed and results based on the running experiment and dealing with large Data Volumes during and after the production phase

An extended study of prompt photon photoproduction at HERA with k{sub T}-factorization

Energy Technology Data Exchange (ETDEWEB)

Lipatov, A.V.; Malyshev, M.A.; Zotov, N.P. [Moskovskij Gosudarstvennyj Univ., Moscow (Russian Federation). Nauchno-Issledovatel' skij Inst. Yadernoj Fiziki

2013-08-15

We reconsider the prompt photon photoproduction at HERA in the framework of the k{sub T}-factorization QCD approach. The proposed method is based on the O({alpha}{sup 2}{alpha}{sub s}) amplitudes for {gamma}q{yields}{gamma}gq and {gamma}g{sup *}{yields}{gamma}q anti q partonic subprocesses. Additionally, we take into account the O({alpha}{sup 2}{alpha}{sub s}{sup 2}) box contributions {gamma}g{yields}{gamma}g to the production cross sections. The unintegrated (or transverse momentum dependent) parton densities in the proton are determined using Kimber-Martin-Ryskin (KMR) prescription. Our consideration covers both inclusive and jet associated prompt photon photoproduction rates. We find that our numerical predictions agree well with the recent data taken by H1 and ZEUS collaborations at HERA. We demonstrate that the box contributions are sizeable and amount up to {proportional_to}15% of the calculated total cross section.

Measurement of the charm fragmentation function in D* photoproduction at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-12-01

The charm fragmentation function has been measured in D * photoproduction with the ZEUS detector at HERA using an integrated luminosity of 120 pb -1 . The fragmentation function is measured versus z=(E+p parallel ) D * /2E jet , where E is the energy of the D * meson and p parallel is the longitudinal momentum of the D * meson relative to the axis of the associated jet of energy E jet . Jets were reconstructed using the k T clustering algorithm and required to have transverse energy larger than 9 GeV. The D * meson associated with the jet was required to have a transverse momentum larger than 2 GeV. The measured function is compared to different fragmentation models incorporated in leading-logarithm Monte Carlo simulations and in a next-to-leading-order QCD calculation. The free parameters in each fragmentation model are fitted to the data. The extracted parameters and the function itself are compared to measurements from e + e - experiments. (orig.)

The readout of the ZEUS forward detector and studies on the ρ' -resonance in the photoproduction of π+π-- pairs

International Nuclear Information System (INIS)

Stamm, J.

1997-12-01

Track finding and reconstruction of charged particles close to the beam-line with the ZEUS-detector at HERA uses three planar drift chambers in the forward (FTDs), and one in rear direction (RTD). In addition two pairs of transition radiation detectors (TRD) are located between the FTDs. In 1993-1995 the TRD and FRTD readout systems were included in the global ZEUS data acquisition. A detailed description of the systems is given. In particular the communication between single modules in the components system and the synchronisation with the global ZEUS trigger components are explained. The analysis of photoproduction events of the reaction ep → π + π - p in the region of M ππ > 1.1 GeV with special respect to the track reconstruction with RTD is described in a second part of this report. In this mass region the ρ'-resonance in the decay channel ρ'→ π + π - is studied. The mass peak at 1.6 GeV is best described with a parametrisation including two resonances. Results are also given on the vertical stroke t vertical stroke - and W-dependence of the cross section as well as the polar angular distribution of the decay pions. (orig.)

The hadronic final state in the deep inelastic electron-proton scattering. A comparison between the ZEUS data measured 1992 and theoretical models

International Nuclear Information System (INIS)

Schneider, J.L.

1993-12-01

The hadronic final state in deep inelastic e - P collisions has been studied with the 1992 data from the ZEUS detector at HERA. The hadronic final state is described by event topology variables like thrust and sphericity and also by variables like multiplicity and transverse momentum. These quantities require the reconstruction of the particle four moments which are calculated from calorimeter cell clusters (condensates). A detailed Monte-Carlo comparison between final state particles and condensates is presented. ZEUS data and model predictions are compared in the γ * P system. Good agreement between data and models is found in the x-Feynman and transverse momentum spectra and in the seagull plot. Mean thrust and sphericity are measured as functions of the invariant mass W of the hadronic final state. They significantly deviate from the model predictions, as do the mean multiplicities, which exceed the model predictions by about 1 unit. (orig.)

Search for events with an isolated lepton and missing transverse momentum and a measurement of W production at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-07-01

A search for events with an isolated high-energy lepton and large missing transverse momentum has been performed with the ZEUS detector at HERA using a total integrated luminosity of 504 pb -1 . The results agree well with Standard Model predictions. The cross section for production of single W bosons in electron-proton collisions with unpolarised electrons is measured to be 0.89 +0.25 -0.22 (stat.)±0.10(syst.) pb. (orig.)

Diffractive photoproduction of D{sup *{+-}}(2010) at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2007-03-15

Diffractive photoproduction of D{sup *{+-}}(2010) mesons was measured with the ZEUS detector at the ep collider HERA, using an integrated luminosity of 78.6 pb{sup -1}. The D{sup *} mesons were reconstructed in the kinematic range: transverse momentum p{sub T}(D{sup *})>1.9 GeV and pseudorapidity vertical stroke {eta}(D{sup *}) vertical stroke <1.6, using the decay D{sup *+} {yields} D{sup 0}{pi}{sup +}{sub s} followed by D{sup 0} {yields} K{sup -}{pi}{sup +}(+c.c.). Diffractive events were identified by a large gap in pseudorapidity between the produced hadronic state and the outgoing proton. Cross sections are reported for photon-proton centre-of-mass energies in the range 130ZEUS Collaboration

Measurement of the Υ meson productin cross section in ep scattering at HERA

International Nuclear Information System (INIS)

Rubinskiy, Igor

2009-04-01

This thesis presents a measurement of Υ meson production in ep collisions with the ZEUS detector at HERA using an integrated luminosity of 468 pb -1 . The Υ mesons were identified using the decay channel Υ→μ + μ - . The measurements were performed for exclusive diffractive production in the kinematic range Q 2 2 , 60 2 2 , 60 2 is virtuality of the exchanged photon and W is the photon-proton centre-of-mass energy. A feasibility study for the Υ meson inelastic production has also been performed. The measured cross sections are compared to and agree well with theoretical predictions within the perturbative QCD framework such as Martin-Ryskin-Teubner two gluon exchange and NRQCD. As the technical part of this thesis, work related to the commissioning of the Straw Tube Tracker (STT) and to the Zeus Event Visualisation (ZEVIS) software package are presented. STT developments include: the STT DSP (Digital Signal Processor) quality monitor was developed, the pattern recognition algorithm was optimised for speed, and used in the Third Level Trigger (TLT) in order to reduce the accepted event rate by rejecting non-physics background. The TLT Charge Current(CC) slot rate was reduced by an order of magnitude, offering a rate reduction for the total accepted TLT rate by ∼2%. ZEVIS developments include: the STT hit visualisation scheme in 2D, 3D and tan(θ)-φ view, and a user-friendly interface called ''EasyTool'' for global ZEUS track and hit visualisation for all ZEUS components. (orig.)

Measurement of D mesons production in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Chakanov, S.; Derrick, M.; Magill, S.

2007-04-01

Charm production in deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 82 pb -1 . Charm has been tagged by reconstructing D *+ , D 0 , D + and D + s (+c.c.) charm mesons. The charm hadrons were measured in the kinematic range p T (D *+ ,D 0 ,D + )>3 GeV, p T (D + s )>2 GeV and vertical stroke η(D) vertical stroke 2 2 and 0.02 T (D) and η(D) in order to determine the open-charm contribution, F c anti c 2 (x,Q 2 ), to the proton structure function F 2 . (orig.)

DESY: focuses on HERA

Energy Technology Data Exchange (ETDEWEB)

Anon.

1992-12-15

On 1 October, a special 'FestKolloquium' at DESY marked the official start of the research programme at the new HERA electron-proton collider, which began operations earlier this year. The timing could not have been better, as HERA performance had improved by a factor of ten during the two weeks beforehand. More than 600 guests assembled in one of the big halls previously used for assembly of major components for HERA experiments.

DESY: focuses on HERA

International Nuclear Information System (INIS)

Anon.

1992-01-01

On 1 October, a special 'FestKolloquium' at DESY marked the official start of the research programme at the new HERA electron-proton collider, which began operations earlier this year. The timing could not have been better, as HERA performance had improved by a factor of ten during the two weeks beforehand. More than 600 guests assembled in one of the big halls previously used for assembly of major components for HERA experiments

Deep inelastic scattering with leading protons or large rapidity gaps at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Lab., Argonne, IL (US)] (and others)

2008-12-15

The dissociation of virtual photons, {gamma}{sup *}p{yields} Xp, in events with a large rapidity gap between X and the outgoing proton, as well as in events in which the leading proton was directly measured, has been studied with the ZEUS detector at HERA. The data cover photon virtualities Q{sup 2}> 2 GeV{sup 2} and {gamma}{sup *}p centre-of-mass energies 40 2 GeV, where M{sub X} is the mass of the hadronic final state, X. Leading protons were detected in the ZEUS leading proton spectrometer. The cross section is presented as a function of t, the squared four-momentum transfer at the proton vertex and {phi}, the azimuthal angle between the positron scattering plane and the proton scattering plane. It is also shown as a function of Q{sup 2} and x{sub P}, the fraction of the proton's momentum carried by the diffractive exchange, as well as {beta}, the Bjorken variable defined with respect to the diffractive exchange. (orig.)

Production of excited charm and charm-strange mesons at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.; Musgrave, B.; Nicholass, D.; Repond, J.; Yoshida, R.; Mattingly, M.C.K.; Antonioli, P.; Bari, G.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cindolo, F.; Corradi, M.; Iacobucci, G.; Margotti, A.; Nania, R.; Polini, A.; Antonelli, S.; Basile, M.; Bindi, M.; Cifarelli, L.; Contin, A.; De Pasquale, S.; Sartorelli, G.; Zichichi, A.; Bartsch, D.; Brock, I.; Hartmann, H.; Hilger, E.; Jakob, H.P.; Juengst, M.; Nuncio-Quiroz, A.E.; Paul, E.; Samson, U.; Schoenberg, V.; Shehzadi, R.; Wlasenko, M.; Brook, N.H.; Heath, G.P.; Morris, J.D.; Capua, M.; Fazio, S.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Tassi, E.; Kim, J.Y.; Ibrahim, Z.A.; Kamaluddin, B.; Wan Abdullah, W.A.T.; Ning, Y.; Ren, Z.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Galas, A.; Gil, M.; Olkiewicz, K.; Stopa, P.; Zawiejski, L.; Adamczyk, L.; Bold, T.; Grabowska-Bold, I.; Kisielewska, D.; Lukasik, J.; Przybycien, M.; Suszycki, L.; Kotanski, A.; Slominski, W.; Behrens, U.; Blohm, C.; Bonato, A.; Borras, K.; Ciesielski, R.; Coppola, N.; Fang, S.; Fourletova, J.; Geiser, A.; Goettlicher, P.; Grebenyuk, J.; Gregor, I.; Haas, T.; Hain, W.; Huettmann, A.; Januschek, F.; Kahle, B.; Katkov, I.I.; Klein, U.; Koetz, U.; Kowalski, H.; Lobodzinska, E.; Loehr, B.; Mankel, R.; Melzer-Pellmann, I.A.; Miglioranzi, S.; Montanari, A.; Namsoo, T.; Notz, D.; Parenti, A.; Rinaldi, L.; Roloff, P.; Rubinsky, I.; Santamarta, R.; Schneekloth, U.; Spiridonov, A.; Szuba, D.; Szuba, J.; Theedt, T.; Wolf, G.; Wrona, K.; Yaguees Molina, A.G.; Youngman, C.; Zeuner, W.; Drugakov, V.; Lohmann, W.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Pelfer, P.G.; Bamberger, A.; Dobur, D.; Karstens, F.; Vlasov, N.N.; Bussey, P.J.; Doyle, A.T.; Dunne, W.; Forrest, M.; Rosin, M.; Saxon, D.H.; Skillicorn, I.O.; Gialas, I.; Papageorgiu, K.; Holm, U.; Klanner, R.; Lohrmann, E.; Schleper, P.; Schoerner-Sadenius, T.; Sztuk, J.; Stadie, H.; Turcato, M.; Foudas, C.; Fry, C.; Long, K.R.; Tapper, A.D.; Matsumoto, T.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Barakbaev, A.N.; Boos, E.G.; Pokrovskiy, N.S.; Zhautykov, B.O.; Aushev, V.; Bachynska, O.; Borodin, M.; Kadenko, I.; Kozulia, A.; Libov, V.; Lisovyi, M.; Lontkovskyi, D.; Makarenko, I.; Sorokin, I.; Verbytskyi, A.; Volynets, O.; Son, D.; Favereau, J. de; Piotrzkowski, K.; Barreiro, F.; Glasman, C.; Jimenez, M.; Labarga, L.; Peso, J. del; Ron, E.; Soares, M.; Terron, J.; Zambrana, M.; Corriveau, F.; Liu, C.; Schwartz, J.; Walsh, R.; Zhou, C.; Tsurugai, T.; Antonov, A.; Dolgoshein, B.A.; Gladkov, D.; Sosnovtsev, V.; Stifutkin, A.; Suchkov, S.; Dementiev, R.K.; Ermolov, P.F.; Gladilin, L.K.; Golubkov, Yu.A.; Khein, L.A.; Korzhavina, I.A.; Kuzmin, V.A.; Levchenko, B.B.; Lukina, O.Yu.; Proskuryakov, A.S.; Shcheglova, L.M.; Zotkin, D.S.; Abt, I.; Caldwell, A.; Kollar, D.; Reisert, B.; Schmidke, W.B.; Grigorescu, G.; Keramidas, A.; Koffeman, E.; Kooijman, P.; Pellegrino, A.; Tiecke, H.; Vazquez, M.; Wiggers, L.; Bruemmer, N.; Bylsma, B.; Durkin, L.S.; Lee, A.; Ling, T.Y.; Allfrey, P.D.; Bell, M.A.; Cooper-Sarkar, A.M.; Devenish, R.C.E.; Ferrando, J.; Foster, B.; Korcsak-Gorzo, K.; Oliver, K.; Robertson, A.; Uribe-Estrada, C.; Walczak, R.; Bertolin, A.; Dal Corso, F.; Dusini, S.; Longhin, A.; Stanco, L.; Bellan, P.; Brugnera, R.; Carlin, R.; Garfagnini, A.; Limentani, S.; Oh, B.Y.; Raval, A.; Ukleja, J.; Whitmore, J.J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cole, J.E.; Hart, J.C.

2009-01-01

The production of excited charm, D 1 (2420) 0 and D 2 * (2460) 0 , and charm-strange, D s 1(2536) ± , mesons in ep collisions was measured with the ZEUS detector at HERA using an integrated luminosity of 126 pb -1 . Masses, widths and helicity parameters were determined. The measured yields were converted to the rates of c quarks hadronising as a given excited charm meson and to the ratios of the dominant D 2 * (2460) 0 and D s1 (2536) ± branching fractions. A search for the radially excited charm meson, D *' (2640) ± , was also performed. The results are compared with those measured previously and with theoretical expectations. (orig.)

Production of excited charm and charm-strange mesons at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-07-01

The production of excited charm, D 1 (2420) 0 and D * 2 (2460) 0 , and charm-strange, D s1 (2536) ± , mesons in ep collisions was measured with the ZEUS detector at HERA using an integrated luminosity of 126 pb -1 . Masses, widths and helicity parameters were determined. The measured yields were converted to the rates of c quarks hadronising as a given excited charm meson and to the ratios of the dominant D * 2 (2460) 0 and D s1 (2536) ± branching fractions. A search for the radially excited charm meson, D *' (2640) ± , was also performed. The results are compared with those measured previously and with theoretical expectations. (orig.)

Dijet angular distributions in direct and resolved photoproduction at HERA

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magill, S.

1996-05-01

Jet photoproduction, where the two highest transverse energy (E T jet ) jets have E T jet above 6 GeV and a jet-jet invariant mass above 23 GeV, has been studied with the ZEUS detector at the HERA ep collider. Resolved and direct photoproduction samples have been separated. The cross section as a function of the angle between the jet-jet axis and the beam direction in the dijet rest frame has been measured for the two samples. The measured angular distributions differ markedly from each other. They agree with the predictions of QCD calculations, where the different angular distributions reflect the different spins of the quark and gluon exchanged in the hard subprocess. (orig.)

Search for events with an isolated lepton and missing transverse momentum and a measurement of W production at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2008-07-15

A search for events with an isolated high-energy lepton and large missing transverse momentum has been performed with the ZEUS detector at HERA using a total integrated luminosity of 504 pb{sup -1}. The results agree well with Standard Model predictions. The cross section for production of single W bosons in electron-proton collisions with unpolarised electrons is measured to be 0.89{sup +0.25}{sub -0.22}(stat.){+-}0.10(syst.) pb. (orig.)

Diffractive photoproduction of dijets in ep collisions at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2007-09-01

Diffractive photoproduction of dijets was measured with the ZEUS detector at the ep collider HERA using an integrated luminosity of 77.2 pb -1 . The measurements were made in the kinematic range Q 2 2 , 0.20 P 2 is the photon virtuality, y is the inelasticity and x P is the fraction of the proton momentum taken by the diffractive exchange. The two jets with the highest transverse energy, E jet T , were required to satisfy E jet T >7.5 and 6.5 GeV, respectively, and to lie in the pseudorapidity range -1.5 jet <1.5. Differential cross sections were compared to perturbative QCD calculations using available parameterisations of diffractive parton distributions of the proton. (orig.)

Production of heavy flavours with associated jets at HERA

International Nuclear Information System (INIS)

Kind, O.M.

2006-12-01

Inclusive cross-sections for the production of open beauty and charm in ep collisions at HERA recorded with the ZEUS detector in the years 1996-2000 are measured. The data is restricted to photoproduction processes, i. e. collision events with small four-momentum transfers squared, Q 2 ∼0. Two associated jets with transverse energies E t >7(6)GeV and pseudo-rapidities vertical stroke η vertical stroke +20 -30 pb for centre-of-mass energies √(S ep )=300 GeV and 1170±130 +30 -100 pb for √(S ep )=318 GeV. The total cross-section for charm production is given as well as differential cross-sections for b anti b and c anti c production. (orig.)

Unintegrated gluon distributions in D*± and dijet associated photoproduction at HERA

International Nuclear Information System (INIS)

Lipatov, A.V.; Zotov, N.P.

2006-01-01

We consider the photoproduction of D *± mesons associated with two hadron jets at HERA collider in the framework of the k T -factorization approach. The unintegrated gluon densities in a proton are obtained from the full CCFM, from unified BFKL-DGLAP evolution equations as well as from the Kimber-Martin-Ryskin prescription. Resolved photon contributions are reproduced by the initial-state gluon radiation. We investigate different production rates and make a comparison with the recent experimental data taken by the ZEUS collaboration. Special attention is given to the specific dijet correlations which can provide unique information about non-collinear gluon evolution dynamics. (orig.)

Energy dependence of the charged multiplicity in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-03-01

The charged multiplicity distributions and the mean charged multiplicity have been investigated in inclusive neutral current deep inelastic ep scattering with the ZEUS detector at HERA, using an integrated luminosity of 38.6 pb -1 . The measurements were performed in the current region of the Breit frame, as well as in the current fragmentation region of the hadronic centre-of-mass frame. The KNO-scaling properties of the data were investigated and the energy dependence was studied using different energy scales. The data are compared to results obtained in e + e - collisions and to previous DIS measurements as well as to leading-logarithm parton-shower Monte Carlo predictions. (orig.)

Measurement of (anti)deuteron and (anti)proton production in DIS at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2007-05-15

The first observation of (anti)deuterons in deep inelastic scattering at HERA has been made with the ZEUS detector at a centre-of-mass energy of 300-318 GeV using an integrated luminosity of 120 pb{sup -1}. The measurement was performed in the central rapidity region for transverse momentum per unit of mass in the range 0.3

ZEUS - standardized macros for the TPA computer

International Nuclear Information System (INIS)

Winde, M.

1976-01-01

An existing cross-assembler with macro-option was modified to allow the usage of the ZEUS macros. The ZEUS macros are understood by the assembler without prior definition by the user. ZEUS macros allow the programmer, who is obliged to code his TPA (PDP-8) programs on the assembler level to formulate his program logic as in a higher level language. ZEUS macros offer all basic elements necessary for structured programming. (author)

Leading neutron energy and p{sub T} distributions in deep inelastic scattering and photoproduction at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2007-02-15

The production of energetic neutrons in ep collisions has been studied with the ZEUS detector at HERA. The neutron energy and p{sub T}{sup 2} distributions were measured with a forward neutron calorimeter and tracker in a 40 pb{sup -1} sample of inclusive deep inelastic scattering (DIS) data and a 6 pb{sup -1} sample of photoproduction data. The neutron yield in photoproduction is suppressed relative to DIS for the lower neutron energies and the neutrons have a steeper p{sub T}{sup 2} distribution, consistent with the expectation from absorption models. The distributions are compared to HERA measurements of leading protons. The neutron energy and transverse-momentum distributions in DIS are compared to Monte Carlo simulations and to the predictions of particle exchange models. Models of pion exchange incorporating absorption and additional secondary meson exchanges give a good description of the data. (orig.)

FPGA-based fast pipeline-parameterized-sorter implementation for first level trigger systems in HEP experiments

CERN Document Server

Pozniak, Krzysztof T

2004-01-01

The paper describes a behavioral model of fast, pipeline sorter dedicated to electronic triggering applications in the experiments of high energy physics (HEP). The sorter was implemented in FPGA for the RPC Muon Detector of CMS experiment (LHC accelerator, CERN) and for Backing Calorimeter (BAC) in ZEUS experiment (HERA accelerator, DESY) . A general principle of the applied sorting algorithm was presented. The implementation results were debated in detail for chosen FPGA chips by ALTERA and XILINX manufactures. The realization costs have been calculated as function of system parameters.

Measurement of beauty-production in deep inelastic scattering at HERA II

Energy Technology Data Exchange (ETDEWEB)

Kahle, B.

2006-04-15

This thesis presents a measurement of beauty quark production in deep inelastic scattering at the ep-collider HERA at {radical}(s)=318 GeV. The measurement is based on data collected at the ZEUS detector in the years 2003/2004, using an integrated luminosity of 39 pb{sup -1}. In the analysis presented in this thesis, events were selected that contain a scattered electron, a jet and a muon inside the jet. The fraction of events from beauty quark production was extracted using the characteristic distribution of the transverse momenta of muons relative to the associated jets. The total visible cross section was measured to be: {sigma}{sup b} {sup anti} {sup b}(ep{yields}eb anti b X{yields}e jet{mu}X')=57.9{+-}5.8(stat.){sup +3.5}{sub -8.1}(syst.) pb in the kinematic region defined by: Q{sup 2}>4 GeV{sup 2}, y>0.05 und y<0.7, one jet originating from a beauty quark with: E{sup jet}{sub t,lab}>5 GeV und -2<{eta}{sup jet}<2.5 and a muon originating from a beauty quark decay (direct or indirect) included in this jet with: p{sup {mu}}{sub t}>1.5 GeV and {eta}{sup {mu}}>-1.6. Differential cross sections were measured in p{sup {mu}}{sub t} and {eta}{sup {mu}}, in p{sup jet}{sub t} and {eta}{sup jet} and in Q{sup 2}.Furthermore double differential cross sections d{sup 2}{sigma}/dQ{sup 2}dx were measured. (Orig.)

Beauty photoproduction at HERA. k{sub T}-factorization versus experimental data

Energy Technology Data Exchange (ETDEWEB)

Lipatov, A.V.; Zotov, N.P. [M.V. Lomonosov Moscow State Univ., Moscow (Russian Federation). D.V. Skobeltsyn Institute of Nuclear Physics

2006-05-15

We present calculations of the beauty photoproduction at HERA collider in the framework of the k{sub T}-factorization approach. Both direct and resolved photon contributions are taken into account. The unintegrated gluon densities in a proton and in a photon are obtained from the full CCFM, from unified BFKL-DGLAP evolution equations as well as from the Kimber-Martin-Ryskin prescription. We investigate different production rates (both inclusive and associated with hadronic jets) and compare our theoretical predictions with the recent experimental data taken by the H1 and ZEUS collaborations. Special attention is put on the x{sup obs}{sub {gamma}} variable which is sensitive to the relative contributions to the beauty production cross section. (Orig.)

The ZEUS central tracking detector. Der zentrale Spuren-Detektor von ZEUS

Energy Technology Data Exchange (ETDEWEB)

Saxon, D H

1989-12-01

The Central Tracking Detector (CTD) of ZEUS covers a wide angular range, whilst the Forward Detector - comprising the Forward Tracking Detector (FTD) and electron identification by transition radiation - concentrates on the important forward cone. The RTD (Rear Tracking Detector) provides accurate angle measurement of the recoil electron and the vertex detector (VXD) aims to find particles from heavy flavour decay. To measure momentum accurately the CTD sits in a high magnetic field (B=1,8 T) within the ZEUS calorimeter. (orig./HSI).

Measurement of beauty quark mass at HERA and impact on Higgs production in association with beauty quarks at LHC

International Nuclear Information System (INIS)

Gizhko, Andrii

2016-06-01

Three different, but related topics are the subject of this thesis, performed in the context of the ZEUS and CMS groups at DESY. The first measurement of the MS beauty-quark mass m b (m b ) at an electron-proton collider is presented. The measurement is based on a QCD analysis of beauty production cross sections in deep inelastic (DIS) ep scattering measured by ZEUS at HERA, together with inclusive DIS HERA data, using Next-to-Leading-Order QCD predictions. The measured value of the running beauty-quark mass in the MS scheme was found to be m b (m b )=4.07±0.14 (fit) +0.01 -0.07 (mod.) +0.05 -0.00 (param.) +0.08 -0.05 ( theo.) GeV, which is in good agreement with the world average Particle Data Group value and previous measurements at electron-positron colliders. It is also found to be consistent with the expected running of m b (μ). A first measurement of the charm-quark mass m c (μ) running in the MS scheme is presented. The measurement is based on a QCD analysis of the published H1 and ZEUS combination of charm cross section measurements in DIS ep scattering at HERA, together with inclusive DIS HERA data, using Next-to-Leading-Order QCD predictions. The running charm-quark mass m c (μ) was measured at different scales μ and is presented in a charm-quark mass running plot with a comparison to the world average Particle Data Group m c (m c ) evolved to higher scales. The running is found to be consistent with the expectations from QCD. The uncertainties of the theoretical predictions for Higgs production in association with beauty-quarks originating from the beauty-quark mass were studied and reduced for massive and massless QCD calculations. The beauty-quark mass measurement m b (m b ) was used to decrease the variation of the beauty-quark mass to 0.17 GeV. It was shown that the uncertainty from the beauty-quark mass m b (m b ) in the case of massive calculations for Hb anti b production at LHC can be reduced to 2%. This makes it negligible compared to other

Measurement of beauty quark mass at HERA and impact on Higgs production in association with beauty quarks at LHC

Energy Technology Data Exchange (ETDEWEB)

Gizhko, Andrii

2016-06-15

Three different, but related topics are the subject of this thesis, performed in the context of the ZEUS and CMS groups at DESY. The first measurement of the MS beauty-quark mass m{sub b}(m{sub b}) at an electron-proton collider is presented. The measurement is based on a QCD analysis of beauty production cross sections in deep inelastic (DIS) ep scattering measured by ZEUS at HERA, together with inclusive DIS HERA data, using Next-to-Leading-Order QCD predictions. The measured value of the running beauty-quark mass in the MS scheme was found to be m{sub b}(m{sub b})=4.07±0.14 (fit){sup +0.01}{sub -0.07}(mod.){sup +0.05}{sub -0.00}(param.){sup +0.08}{sub -0.05}( theo.) GeV, which is in good agreement with the world average Particle Data Group value and previous measurements at electron-positron colliders. It is also found to be consistent with the expected running of m{sub b}(μ). A first measurement of the charm-quark mass m{sub c}(μ) running in the MS scheme is presented. The measurement is based on a QCD analysis of the published H1 and ZEUS combination of charm cross section measurements in DIS ep scattering at HERA, together with inclusive DIS HERA data, using Next-to-Leading-Order QCD predictions. The running charm-quark mass m{sub c}(μ) was measured at different scales μ and is presented in a charm-quark mass running plot with a comparison to the world average Particle Data Group m{sub c}(m{sub c}) evolved to higher scales. The running is found to be consistent with the expectations from QCD. The uncertainties of the theoretical predictions for Higgs production in association with beauty-quarks originating from the beauty-quark mass were studied and reduced for massive and massless QCD calculations. The beauty-quark mass measurement m{sub b}(m{sub b}) was used to decrease the variation of the beauty-quark mass to 0.17 GeV. It was shown that the uncertainty from the beauty-quark mass m{sub b}(m{sub b}) in the case of massive calculations for Hb anti b

Inclusive charged particle distributions in deep inelastic scattering events at HERA

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magill, S.

1995-11-01

A measurement of inclusive charged particle distributions in deep inelastic ep scattering for γ * p centre-of-mass energies 75 2 2 from the ZEUS detector at HERA is presented. The differential charged particle rates in the γ*p centre-of-mass system as a function of the scaled longitudinal momentum, x F , and of the transverse momentum, p* t and t 2 >, as a function of x F , W and Q 2 are given. Separate distributions are shown for events with (LRG) and without (NRG) a rapidity gap with respect to the proton direction. The data are compared with results from experiments at lower beam energies, with the naive quark parton model and with parton models including perturbative QCD corrections. The comparison shows the importance of the higher order QCD processes. Significant differences of the inclusive charged particle rates between NRG and LRG events at the same W are observed. The value of t 2 > for LRG events with a hadronic mass M X , which excludes the forward produced baryonic system, is similar to the t 2 > value observed in fixed target experiments at W∼M X . (orig.)

Production of excited charm and charm-strange mesons at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2008-07-15

The production of excited charm, D{sub 1}(2420){sup 0} and D{sup *}{sub 2}(2460){sup 0}, and charm-strange, D{sub s1}(2536){sup {+-}}, mesons in ep collisions was measured with the ZEUS detector at HERA using an integrated luminosity of 126 pb{sup -1}. Masses, widths and helicity parameters were determined. The measured yields were converted to the rates of c quarks hadronising as a given excited charm meson and to the ratios of the dominant D{sup *}{sub 2}(2460){sup 0} and D{sub s1}(2536){sup {+-}} branching fractions. A search for the radially excited charm meson, D{sup *'}(2640){sup {+-}}, was also performed. The results are compared with those measured previously and with theoretical expectations. (orig.)

Exclusive ρ0 production in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2007-08-01

Exclusive ρ 0 electroproduction at HERA has been studied with the ZEUS detector using 120 pb -1 of integrated luminosity collected during 1996-2000. The analysis was carried out in the kinematic range of photon virtuality 2 2 2 , and γ * p centre-of-mass energy 32 2 and W dependence of the γ * p→ρ 0 p cross section and the distribution of the squared-four-momentum transfer to the proton. The helicity analysis of the decay-matrix elements of the ρ 0 was used to study the ratio of the γ * p cross section for longitudinal and transverse photon as a function of Q 2 and W. Finally, an effective Pomeron trajectory was extracted. The results are compared to various theoretical predictions. (orig.)

Further studies of the photoproduction of isolated photons with a jet at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2014-05-01

In this extended analysis using the ZEUS detector at HERA, the photoproduction of isolated photons together with a jet is measured for different ranges of the fractional photon energy, x γ meas , contributing to the photon-jet final state. Cross sections are evaluated in the photon transverse-energy and pseudorapidity ranges 6 T γ γ T jet jet -1 . The kinematic observables studied comprise the transverse energy and pseudorapidity of the photon and the jet, the azimuthal difference between them, the fraction of proton energy taking part in the interaction, and the difference between the pseudorapidities of the photon and the jet. Higher-order theoretical calculations are compared to the results.

Measurement of open beauty production at HERA in the D*μ final state

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2006-09-01

The production of beauty quarks with a D *± and a muon in the final state has been measured with the ZEUS detector at HERA using an integrated luminosity of 114 pb -1 . Low transverse-momentum thresholds for the muon and D * meson allow a measurement of beauty production closer to the production threshold than previous measurements. The beauty signal was extracted using the charge correlations and angular distributions of the muon with respect to the D * meson. Cross sections for photoproduction and deep inelastic scattering are somewhat higher than, but compatible with, next-to-leading-order QCD predictions, and compatible with other measurements. (orig.)

Inclusive diffractive cross sections in deep inelastic ep scattering at HERA

International Nuclear Information System (INIS)

Sola, Valentina

2012-04-01

Diffractive deep-inelastic scattering events in ep collisions at HERA are the subject of this thesis. The cross sections for inclusive diffraction, ep → eXp, measured by the H1 and ZEUS Collaborations were combined, providing a model-independent check of the data consistency and a cross calibration between the two experiments, and resulting in single data sets with improved accuracy and precision. Two sets of combined results were obtained. The cross sections measured using the proton-spectrometer data were combined, both in the range of t, the squared four-momentum transfer at the proton vertex, common to the two experiments (0.09 2 ) and in the extended t-range vertical stroke t vertical stroke 2 . The resulting cross sections cover the region 2.5≤ Q 2 ≤200 GeV 2 in photon virtualities, 0.0003≤x P ≤0.09 in the proton fractional momentum losses and 0.0018≤ β ≤0.816 in β=x/x P , where x is the Bjorken scaling variable. The cross sections obtained from data with the large rapidity gap signature were also combined in the kinematic range 2.5≤ Q 2 ≤1600 GeV 2 , 0.0003≤x P ≤0.03 and 0.0017≤ β ≤0.8, for masses of the hadronic final state M X >4 GeV. The inclusive diffractive reduced cross section σ r D(3) was measured with data collected by the ZEUS detector, at two different centre-of-mass energies, 318 and 225 GeV. The diffractive data were selected with the large rapidity gap method in the kinematic region 20 2 2 , 0.05 P or similar 0.55), the inelasticity of the interaction.

Inclusive J/{psi} photoproduction and polarization at HERA in the k{sub T}-factorization approach

Energy Technology Data Exchange (ETDEWEB)

Baranov, S.P. [P.N. Lebedev Physics Institute, Moscow (Russian Federation); Lipatov, A.V.; Zotov, N.P. [M.V. Lomonosov Moscow State Univ. (Russian Federation). D.V. Skobeltsyn Institute of Nuclear Physics

2010-12-15

We investigate the inclusive photoproduction of J/{psi} mesons at HERA within the framework of the k{sub T} -factorization QCD approach. Our consideration is based on the color singlet model supplemented with the relevant off-shell matrix elements and the CCFM and KMR unintegrated gluon densities in a proton and in a photon. Both the direct and resolved photon contributions are taken into account. Our predictions are compared with the recent experimental data taken by the H1 and ZEUS collaborations. Special attention is put on the J/{psi} polarization parameters {lambda} and {nu} which are sensitive to the production dynamics. (orig.)

Scaled momentum spectra in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2009-12-01

Charged particle production has been studied in neutral current deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 0.44 fb -1 . Distributions of scaled momenta in the Breit frame are presented for particles in the current fragmentation region. The evolution of these spectra with the photon virtuality, Q 2 , is described in the kinematic region 10 2 2 . Next-to-leading-order and modified leading-log-approximation QCD calculations as well as predictions from Monte Carlo models are compared to the data. The results are also compared to e + e - annihilation data. The dependences of the pseudorapidity distribution of the particles on Q 2 and on the energy in the γp system, W, are presented and interpreted in the context of the hypothesis of limiting fragmentation. (orig.)

Leading proton production in e+p collisions at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Krakauer, D.; Loizides, J.H.; Magill, S.; Musgrave, B.; Repond, J.; Yoshida, R.; Mattingly, M.C.K.; Antonioli, P.; Anzivino, G.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Nemoz, C.; Palmonari, F.; Pesci, A.; Sartorelli, G.; Zamora Garcia, Y.; Zichichi, A.; Aghuzumtsyan, G.; Bartsch, D.; Brock, I.; Crittenden, J.; Goers, S.; Hartmann, H.; Hilger, E.; Irrgang, P.; Jakob, H.-P.; Kappes, A.; Katz, U.F.; Kind, O.; Paul, E.; Rautenberg, J.; Renner, R.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K.C.; Wang, M.; Weber, A.; Bailey, D.S.; Brook, N.H.; Cole, J.E.; Foster, B.; Heath, G.P.; Heath, H.F.; Namsoo, T.; Robins, S.; Rodrigues, E.; Wing, M.; Ayad, R.; Capua, M.; Iannotti, L.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Kim, J.Y.; Kim, Y.K.; Lee, J.H.; Lim, I.T.; Pac, M.Y.; Caldwell, A.; Helbich, M.; Liu, X.; Mellado, B.; Ning, Y.; Paganis, S.; Ren, Z.; Schmidke, W.B.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Olkiewicz, K.; Stopa, P.; Zawiejski, L.; Adamczyk, L.; Bold, T.; Grabowska-Bold, I.; Kisielewska, D.; Kowal, A.M.; Kowal, M.; Kowalski, T.; Przybycien, M.; Suszycki, L.; Szuba, D.; Szuba, J.; Kotanski, A.; Slominski, W.; Bauerdick, L.A.T.; Behrens, U.; Bloch, I.; Borras, K.; Chiochia, V.; Dannheim, D.; Derrick, M.; Drews, G.; Fourletova, J.; Fox-Murphy, A.; Fricke, U.; Geiser, A.; Goebel, F.; Goettlicher, P.; Gutsche, O.; Haas, T.; Hain, W.; Hartner, G.F.; Hillert, S.; Koetz, U.; Kowalski, H.; Kramberger, G.; Labes, H.; Lelas, D.; Loehr, B.; Mankel, R.; Melzer-Pellmann, I.-A.; Moritz, M.; Notz, D.; Petrucci, M.C.; Polini, A.; Raval, A.; Schneekloth, U.; Selonke, F.; Wessoleck, H.; Wichmann, R.; Wolf, G.; Youngman, C.; Zeuner, W.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Genta, C.; Pelfer, P.G.; Bamberger, A.; Benen, A.; Coppola, N.; Raach, H.; Bell, M.; Bussey, P.J.; Doyle, A.T.; Glasman, C.; Hamilton, J.; Hanlon, S.; Lupi, A.; Saxon, D.H.; Skillicorn, I.O.; Gialas, I.; Bodmann, B.; Carli, T.; Holm, U.; Klimek, K.; Krumnack, N.; Lohrmann, E.; Milite, M.; Salehi, H.; Stonjek, S.; Wick, K.; Ziegler, A.; Ziegler, Ar.; Collins-Tooth, C.; Foudas, C.; Goncalo, R.; Long, K.R.; Metlica, F.; Miller, D.B.; Tapper, A.D.; Walker, R.; Cloth, P.; Filges, D.; Kuze, M.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Barakbaev, A.N.; Boos, E.G.; Pokrovskiy, N.S.; Zhautykov, B.O.; Lim, H.; Son, D.; Barreiro, F.; Gonzalez, O.; Labarga, L.; Del Peso, J.; Redondo, I.; Terron, J.; Vazquez, M.; Barbi, M.; Bertolin, A.; Corriveau, F.; Gliga, S.; Lainesse, S.; Padhi, S.; Stairs, D.G.; Tsurugai, T.; Antonov, A.; Danilov, P.; Dolgoshein, B.A.; Gladkov, D.; Sosnovtsev, V.; Suchkov, S.; Dementiev, R.K.; Ermolov, P.F.; Golubkov, Yu.A.; Katkov, I.I.; Khein, L.A.; Korzhavina, I.A.; Kuzmin, V.A.; Levchenko, B.B.; Lukina, O.Yu.; Proskuryakov, A.S.; Shcheglova, L.M.; Vlasov, N.N.; Zotkin, S.A.; Bokel, C.; Engelen, J.; Grijpink, S.; Koffeman, E.; Kooijman, P.; Maddox, E.; Pellegrino, A.; Schagen, S.; Tassi, E.; Tiecke, H.; Tuning, N.; Velthuis, J.J.; Wiggers, L.; de Wolf, E.; Bruemmer, N.; Bylsma, B.; Durkin, L.S.; Gilmore, J.; Ginsburg, C.M.; Kim, C.L.; Ling, T.Y.; Boogert, S.; Cooper-Sarkar, A.M.; Devenish, R.C.E.; Ferrando, J.; Grzelak, G.; Patel, S.; Rigby, M.; Sutton, M.R.; Walczak, R.; Brugnera, R.; Carlin, R.; Dal Corso, F.; Dusini, S.; Garfagnini, A.; Limentani, S.; Longhin, A.; Parenti, A.; Posocco, M.; Stanco, L.; Turcato, M.; Heaphy, E.A.; Oh, B.Y.; Saull, P.R.B.; Whitmore, J.J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cormack, C.; Hart, J.C.; Barberis, E.; Heusch, C.; Lockman, W.; Rahn, J.T.; Sadrozinski, H.F.-W.; Seiden, A.; Williams, D.C.; Park, I.H.; Pavel, N.; Abramowicz, H.; Gabareen, A.; Kananov, S.; Kreisel, A.; Levy, A.; Abe, T.; Fusayasu, T.; Kagawa, S.; Kohno, T.; Tawara, T.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Inuzuka, M.; Kaji, H.; Kitamura, S.; Matsuzawa, K.; Nishimura, T.; Patel, S.; Arneodo, M.; Cartiglia, N.; Cirio, R.; Costa, M.; Ferrero, M.I.; Lamberti, L.; Maselli, S.; Monaco, V.; Peroni, C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Galea, R.; Koop, T.; Levman, G.M.; Martin, J.F.; Mirea, A.; Sabetfakhri, A.; Butterworth, J.M.; Gwenlan, C.; Hall-Wilton, R.; Jones, T.W.; Lightwood, M.S.; Ciborowski, J.; Ciesielski, R.; Nowak, R.J.; Pawlak, J.M.; Smalska, B.; Sztuk, J.; Tymieniecka, T.; Ukleja, A.; Ukleja, J.; Zarnecki, A.F.; Adamus, M.; Plucinski, P.; Eisenberg, Y.; Gladilin, L.K.; Hochman, D.; Karshon, U.; Kcira, D.; Lammers, S.; Li, L.; Reeder, D.D.; Savin, A.A.; Smith, W.H.; Deshpande, A.; Dhawan, S.; Hughes, V.W.; Straub, P.B.; Bhadra, S.; Catterall, C.D.; Fourletov, S.; Menary, S.; Soares, M.; Standage, J.

2003-01-01

Events with a final-state proton carrying a large fraction of the proton beam momentum, x L >0.6, and the square of the transverse momentum p T 2 2 , have been studied in e + p collisions with the ZEUS detector at HERA. Data with different photon virtualities were used: Q 2 2 , 0.1 2 2 and 3 2 2 , corresponding to integrated luminosities of 0.9, 1.85 and 3.38 pb -1 . The cross sections are given as a function of x L , p T 2 , Q 2 and the Bjorken scaling variable, x. The ratio of the cross section for leading proton production to the inclusive e + p cross section shows only a mild dependence on Q 2 and on x. In the region 0.6 L L

Dijet production in diffractive deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2007-08-01

The production of dijets in diffractive deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 61 pb -1 . The dijet cross section has been measured for virtualities of the exchanged virtual photon, 5 2 2 , and γ * p centre-of-mass energies, 100 T algorithm in the γ * p frame, were required to have a transverse energy E * T,jet >4 GeV and the jet with the highest transverse energy was required to have E * T,jet >5 GeV. All jets were required to be in the pseudorapidity range -3.5 * jet <0. The differential cross sections are compared to leading-order predictions and next-to-leading- order QCD calculations based on recent diffractive parton densities extracted from inclusive diffractive deep inelastic scattering data. (orig.)

ZEUS hardware control system

Science.gov (United States)

Loveless, R.; Erhard, P.; Ficenec, J.; Gather, K.; Heath, G.; Iacovacci, M.; Kehres, J.; Mobayyen, M.; Notz, D.; Orr, R.; Orr, R.; Sephton, A.; Stroili, R.; Tokushuku, K.; Vogel, W.; Whitmore, J.; Wiggers, L.

1989-12-01

The ZEUS collaboration is building a system to monitor, control and document the hardware of the ZEUS detector. This system is based on a network of VAX computers and microprocessors connected via ethernet. The database for the hardware values will be ADAMO tables; the ethernet connection will be DECNET, TCP/IP, or RPC. Most of the documentation will also be kept in ADAMO tables for easy access by users.

ZEUS hardware control system

International Nuclear Information System (INIS)

Loveless, R.; Erhard, P.; Ficenec, J.; Gather, K.; Heath, G.; Iacovacci, M.; Kehres, J.; Mobayyen, M.; Notz, D.; Orr, R.; Sephton, A.; Stroili, R.; Tokushuku, K.; Vogel, W.; Whitmore, J.; Wiggers, L.

1989-01-01

The ZEUS collaboration is building a system to monitor, control and document the hardware of the ZEUS detector. This system is based on a network of VAX computers and microprocessors connected via ethernet. The database for the hardware values will be ADAMO tables; the ethernet connection will be DECNET, TCP/IP, or RPC. Most of the documentation will also be kept in ADAMO tables for easy access by users. (orig.)

Measurement of D{sup {+-}} and D{sup 0} production in deep inelastic scattering using a lifetime tag at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Lab., IL (US)] (and others)

2008-12-15

The production of D{sup {+-}} and D{sup 0} mesons has been measured with the ZEUS detector at HERA using an integrated luminosity of 133.6 pb{sup -1}. The measurements cover the kinematic range 5ZEUS microvertex detector to reconstruct displaced secondary vertices. Production cross sections are compared with the predictions of next-to-leading-order QCD which is found to describe the data well. Measurements are extrapolated to the full kinematic phase space in order to obtain the open-charm contribution, F{sup c} {sup anti} {sup c}{sub 2}, to the proton structure function, F{sub 2}. (orig.)

Search for a narrow baryonic state decaying to pKS0 and p‾KS0 in deep inelastic scattering at HERA

Directory of Open Access Journals (Sweden)

H. Abramowicz

2016-08-01

Full Text Available A search for a narrow baryonic state in the pKS0 and p‾KS0 system has been performed in ep collisions at HERA with the ZEUS detector using an integrated luminosity of 358pb−1 taken in 2003–2007. The search was performed with deep inelastic scattering events at an ep centre-of-mass energy of 318GeV for exchanged photon virtuality, Q2, between 20 and 100GeV2. Contrary to evidence presented for such a state around 1.52 GeV in a previous ZEUS analysis using a sample of 121 pb−1 taken in 1996–2000, no resonance peak was found in the p(p‾KS0 invariant-mass distribution in the range 1.45–1.7 GeV. Upper limits on the production cross section are set.

Diffractive dijet production in deep inelastic scattering at ZEUS

International Nuclear Information System (INIS)

Bonato, A.

2008-03-01

This thesis presents a measurement of dijet production of diffractive deep inelastic scattering ep collisions. This type of process is specially relevant for the experimental validity of the perturbative QCD approach to diffractive physics. The measurement was based on an integrated luminosity of 61 pb -1 collected at the HERA collider with the ZEUS experiment. The events were selected for virtualities of the photon, γ*, 5 2 2 , and energies of the γ*p centre-of-mass, 100 T algorithm in the γ*p frame. The jets were required to have a transverse energy in the γ*p frame E T jet *>4 GeV. The jet with the highest transverse energy was required to have E T jet *>5 GeV. All jets were required to be in the pseudorapidity range -3.5 jet * P , was required to be x P TOT D (ep→ep jet 1 jet 2 X')=9.15±1.2 (stat.) 5.4 3.3 (syst.) -5.3 +6.4 (corr.)pb. Single and double differential cross sections were extracted and compared to leading-order predictions and next-to-leading-order QCD calculations. The latter used several diffractive parton densities extracted from inclusive diffractive deep inelastic scattering data. The agreement with the leading and next-to-leading order predictions is good and no hints of factorisation breaking are observed. The double differential measurement can be a previous input for the extraction of more accurate diffractive parton densities. (orig.)

Energy dependence of the charged multiplicity in deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2008-03-15

The charged multiplicity distributions and the mean charged multiplicity have been investigated in inclusive neutral current deep inelastic ep scattering with the ZEUS detector at HERA, using an integrated luminosity of 38.6 pb{sup -1}. The measurements were performed in the current region of the Breit frame, as well as in the current fragmentation region of the hadronic centre-of-mass frame. The KNO-scaling properties of the data were investigated and the energy dependence was studied using different energy scales. The data are compared to results obtained in e{sup +}e{sup -} collisions and to previous DIS measurements as well as to leading-logarithm parton-shower Monte Carlo predictions. (orig.)

Measurement of the {upsilon} meson productin cross section in ep scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Rubinskiy, Igor

2009-04-15

This thesis presents a measurement of {upsilon} meson production in ep collisions with the ZEUS detector at HERA using an integrated luminosity of 468 pb{sup -1}. The {upsilon} mesons were identified using the decay channel {upsilon}{yields}{mu}{sup +}{mu}{sup -}. The measurements were performed for exclusive diffractive production in the kinematic range Q{sup 2}<1 GeV{sup 2}, 60Zeus Event Visualisation (ZEVIS) software package are presented. STT developments include: the STT DSP (Digital Signal Processor) quality monitor was developed, the pattern recognition algorithm was optimised for speed, and used in the Third Level Trigger (TLT) in order to reduce the accepted event rate by rejecting non-physics background. The TLT Charge Current(CC) slot rate was reduced by an order of magnitude, offering a rate reduction for the total accepted TLT rate by {approx}2%. ZEVIS developments include: the STT hit visualisation scheme in 2D, 3D and tan({theta})-{phi} view, and a user-friendly interface called ''EasyTool'' for global ZEUS track and hit visualisation for all ZEUS components. (orig.)

Measurement of open beauty production at HERA in the D{sup *}{mu} final state

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, IL (US)] (and others)

2006-09-15

The production of beauty quarks with a D{sup *{+-}} and a muon in the final state has been measured with the ZEUS detector at HERA using an integrated luminosity of 114 pb{sup -1}. Low transverse-momentum thresholds for the muon and D{sup *} meson allow a measurement of beauty production closer to the production threshold than previous measurements. The beauty signal was extracted using the charge correlations and angular distributions of the muon with respect to the D{sup *} meson. Cross sections for photoproduction and deep inelastic scattering are somewhat higher than, but compatible with, next-to-leading-order QCD predictions, and compatible with other measurements. (orig.)

Bose-Einstein correlations of charged and neutral kaons in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2007-05-01

Bose-Einstein correlations of charged and neutral kaons have been measured in e ± p deep inelastic scattering with an integrated luminosity of 121 pb -1 using the ZEUS detector at HERA. The two-particle correlation function was studied as a function of the four-momentum difference of the kaon pairs, Q 12 =√(-(p 1 -p 2 ) 2 ), assuming a Gaussian shape for the particle source. The values of the radius of the production volume, r, and of the correlation strength, λ, were obtained for both neutral and charged kaons. The radii for charged and neutral kaons are similar and are consistent with those obtained at LEP. (orig.)

Results from the H1 experiment at HERA

International Nuclear Information System (INIS)

Krasny, M.W.

1993-01-01

Results obtained by the H1 collaboration at HERA from the analysis of the data collected in 1992 - the first year of HERA operation are presented. Measurements of the total photoproduction cross-section and the inclusive jet cross-section in γp scattering, the structure function F 2 (x,Q 2 ) and the jet rates in deep inelastic ep scattering, and results of direct searches for leptoquarks are discussed. (author) 37 refs., 6 figs

Exclusive J/ψ production in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Voss, K.C.

2004-10-01

The exclusive electroproduction of J/ψ mesons, ep→ep J/ψ, is studied with the ZEUS detector at HERA for virtualities of the exchanged photon in the range 2 2 2 , using an integrated luminosity of 83 pb -1 . The photon-proton centre-of-mass energy is in the range 30 2 . The cross-sections and the decay angular distributions are presented as functions of Q 2 , W and t. The effective parameters of the Pomeron trajectory are determined. The spin-density matrix elements, calculated from the decay angular distributions, are used to test the hypothesis of s-channel helicity conservation. The ratio of the longitudinal and transverse cross-sections σ L /σ T is measured as a function Q 2 , W and t. The results are compared to QCD inspired models. (orig.)

Combination of the H1 and ZEUS inclusive cross-section measurements at proton beam energies of 460 GeV and 575 GeV and tests of low Bjorken-x phenomenological models

International Nuclear Information System (INIS)

Belov, Pavel

2013-06-01

A combination is presented of the inclusive neutral current e ± p scattering cross section data collected by the H1 and ZEUS collaborations during the last months of the HERA II operation period with proton beam energies E p of 460 and 575 GeV. The kinematic range of the cross section data covers low absolute four-momentum transfers squared, 1.5 GeV 2 ≤ Q 2 ≤ 110 GeV 2 , small values of Bjorken-x, 2.8.10 -5 ≤ x ≤ 1.5.10 -2 , and high inelasticity y ≤ 0.85. The combination algorithm is based on the method of least squares and takes into account correlations of the systematic uncertainties. The combined data are used in the QCD fits to extract the parton distribution functions. The phenomenological low-x dipole models are tested and parameters of the models are obtained. A good description of the data by the dipole model taking into account the evolution of the gluon distribution is observed. The longitudinal structure function F L is extracted from the combination of the currently used H1 and ZEUS reduced proton beam energy data with previously published H1 nominal proton beam energy data of 920 GeV. A precision of the obtained values of F L is improved at medium Q 2 compared to the published results of the H1 collaboration.

Measurement of the charm fragmentation function in D{sup *} photoproduction at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Lab., IL (US)] (and others)

2008-12-15

The charm fragmentation function has been measured in D{sup *} photoproduction with the ZEUS detector at HERA using an integrated luminosity of 120 pb{sup -1}. The fragmentation function is measured versus z=(E+p {sub parallel}){sup D{sup *}}/2E{sup jet}, where E is the energy of the D{sup *} meson and p {sub parallel} is the longitudinal momentum of the D{sup *} meson relative to the axis of the associated jet of energy E{sup jet}. Jets were reconstructed using the k{sub T} clustering algorithm and required to have transverse energy larger than 9 GeV. The D{sup *} meson associated with the jet was required to have a transverse momentum larger than 2 GeV. The measured function is compared to different fragmentation models incorporated in leading-logarithm Monte Carlo simulations and in a next-to-leading-order QCD calculation. The free parameters in each fragmentation model are fitted to the data. The extracted parameters and the function itself are compared to measurements from e{sup +}e{sup -} experiments. (orig.)

High energy physics at the University of Iowa

International Nuclear Information System (INIS)

McCliment, E.R.; Mallik, U.; Newsom, C.R.; Onel, Y.

1993-01-01

Efforts were devoted to three tasks: a study of electron proton physics with ZEUS at HERA (the ZEUS detector, the J/ψ search, future upgrades), fixed-target experiments at Fermilab (Coulomb-nuclear interference measurement, inclusive Λ measurements, hyperon radiative decay, charmed baryon studies at CERN and at Fermilab--detector status), and R ampersand D related to Superconducting Supercollider (SSC) detector development with the GEM collaboration

Measurement of D+ and Λc+ production in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2010-06-01

Charm production in deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 120 pb -1 . The hadronic decay channels D + → K S 0 π + , Λ c + → pK S 0 and Λ c + →Λπ + , and their charge conjugates, were reconstructed. The presence of a neutral strange hadron in the final state reduces the combinatorial background and extends the measured sensitivity into the low transverse momentum region. The kinematic range is 0 T (D + , Λ c + ) + , Λ c + ) vertical stroke 2 2 and 0.02 + mesons are compared to next-to-leading-order QCD predictions. The fraction of c quarks hadronizing into Λ c + baryons is extracted. (orig.)

Measurement of beauty photoproduction using decays into muons in dijet events at HERA

International Nuclear Information System (INIS)

2009-01-01

Beauty photoproduction in dijet events has been measured at HERA with the ZEUS detector using an integrated luminosity of 126 pb -1 . Beauty was identified in events with a muon in the final state by using the transverse momentum of the muon relative to the closest jet. Lifetime information from the silicon vertex detector was also used; the impact parameter of the muon with respect to the primary vertex was exploited to discriminate between signal and background. Cross sections for beauty production as a function of the muon and the jet variables as well as dijet correlations are compared to QCD predictions and to previous measurements. The data are well described by predictions from next-to-leading-order QCD.

Event shapes in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2006-04-01

Mean values and differential distributions of event-shape variables have been studied in neutral current deep inelastic scattering using an integrated luminosity of 82.2 pb -1 collected with the ZEUS detector at HERA. The kinematic range was 80 2 2 and 0.0024 2 is the virtuality of the exchanged boson and x is the Bjorken variable. The data are compared with a model based on a combination of next-to-leading-order QCD calculations with next-to-leading-logarithm corrections and the Dokshitzer-Webber non-perturbative power corrections. The power-correction method provides a reasonable description of the data for all event-shape variables studied. Nevertheless, the lack of consistency of the determination of α s and of the non-perturbative parameter of the model, anti α 0 , suggests the importance of higher-order processes that are not yet included in the model. (orig.)

Diffractive photoproduction of D*±(2010) at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2007-03-01

Diffractive photoproduction of D *± (2010) mesons was measured with the ZEUS detector at the ep collider HERA, using an integrated luminosity of 78.6 pb -1 . The D * mesons were reconstructed in the kinematic range: transverse momentum p T (D * )>1.9 GeV and pseudorapidity vertical stroke η(D * ) vertical stroke *+ → D 0 π + s followed by D 0 → K - π + (+c.c.). Diffractive events were identified by a large gap in pseudorapidity between the produced hadronic state and the outgoing proton. Cross sections are reported for photon-proton centre-of-mass energies in the range 130 2 2 , in two ranges of the Pomeron fractional momentum x P P *± (2010) photoproduction cross section is about 6%. The data are in agree- ment with perturbative QCD calculations based on various parameterisations of diffractive parton distribution functions. The results are consistent with diffractive QCD factorisation. (orig.)

A measurement of the Q2, W and t dependences of deeply virtual Compton scattering at HERA

International Nuclear Information System (INIS)

2009-01-01

Deeply virtual Compton scattering, γ*p → γp, has been measured in e + p collisions at HERA with the ZEUS detector using an integrated luminosity of 61.1 pb -1 . Cross sections are presented as a function of the photon virtuality, Q 2 , and photon-proton centre-of-mass energy, W, for a wide region of the phase space, Q 2 > 1.5 GeV 2 and 40 -1 , is used for the first direct measurement of the differential cross section as a function of t, where t is the square of the four-momentum transfer at the proton vertex.

A measurement of the Q2, W and t dependences of deeply virtual Compton scattering at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-12-01

Deeply virtual Compton scattering, γ * p→γp, has been measured in e + p collisions at HERA with the ZEUS detector using an integrated luminosity of 61.1 pb -1 . Cross sections are presented as a function of the photon virtuality, Q 2 , and photon-proton centre-of-mass energy, W, for a wide region of the phase space, Q 2 >1.5 GeV 2 and 40 -1 , is used for the first direct measurement of the differential cross section as a function of t, where t is the square of the four-momentum transfer at the proton vertex. (orig.)

Measurement of K0S, Λ and anti Λ production at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2006-12-01

The production of the neutral strange hadrons K 0 S , Λ and anti Λ has been measured in ep collisions at HERA using the ZEUS detector. Cross sections, baryon-to-meson ratios, relative yields of strange and charged light hadrons, Λ (anti Λ) asymmetry and polarization have been measured in three kinematic regions: Q 2 >25 GeV 2 ; 5 2 2 ; and in photoproduction (Q 2 ≅0), in which the presence of two hadronic jets, each with at least 5 GeV transverse energy, was required. The measurements agree in general with Monte Carlo models and are consistent with measurements made at e + e - colliders, except for an enhancement of baryon relative to meson production in photoproduction. (orig.)

External meeting: GENEVA UNIVERSITY

CERN Multimedia

2006-01-01

ECOLE DE PHYSIQUE Département de physique nucléaire et corspusculaire 24, Quai Ernest-Ansermet1211 GENEVE 4 - Tél : 022 379 62 73 - Fax: 022 379 69 92 Wednesday 10 May 2006 PARTICLE PHYSICS SEMINARat 17:00 - Stückelberg Auditorium ZEUS: A detector for HERA by Andrée Robichaud-Véronneau / DPNC, Université de Genè ve HERA is the first lepton-proton collider in the world where a center of mass energy of 318 GeV is reached. Since 1992, the ZEUS detector is gating luminosity from it to probe QCD and look for exotic phenomena of fundamental particle physics. A history and overview of the detector and collider will be presented as well as important physics contributions made by the ZEUS experiment to the understanding of our world. Information: http://dpnc.unige.ch/seminaire/annonce.html Organizer : J.-S. Graulich

Measurement of the longitudinal polarization of the HERA electron beam using crystals and the ZEUS luminosity monitor

International Nuclear Information System (INIS)

Piotrzkowski, K.

1995-12-01

A measurement of the longitudinal polarization of the electron beam at HERA utilizing coherent interactions of high energy photons in crystals is described. Modification of existing facilities would allow an independent polarization measurement and a verification of birefringence phenomena in crystals for 20-30 GeV photons. Relevant experimental issues and systematic uncertainties are also presented. (orig.)

Search for a narrow baryonic state decaying to ${pK^0_S}$ and ${\\overline{p}K^0_S}$ in deep inelastic scattering at HERA

CERN Document Server

Abramowicz, H.; Adamczyk, L.; Adamus, M.; Antonelli, S.; Aushev, V.; Behnke, O.; Behrens, U.; Bertolin, A.; Bhadra, S.; Bloch, I.; Boos, E.G.; Brock, I.; Brook, N.H.; Brugnera, R.; Bruni, A.; Bussey, P.J.; Caldwell, A.; Capua, M.; Catterall, C.D.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Cooper-Sarkar, A.M.; Corradi, M.; Dementiev, R.K.; Devenish, RCE; Dusini, S.; Foster, B.; Gach, G; Gallo, E.; Garfagnini, A.; Geiser, A.; Gizhko, A.; Gladilin, L.K.; Golubkov, Yu.A.; Grzelak, G.; Guzik, M.; Gwenlan, C.; Hain, W.; Hlushchenko, O.; Hochman, D.; Hori, R.; Ibrahim, Z.A.; Iga, Y.; Ishitsuka, M.; Januschek, F.; Jomhari, N.Z.; Kadenko, I.; Kananov, S.; Karshon, U.; Kaur, P.; Kisielewska, D.; Klanner, R.; Klein, U.; Korzhavina, I.A.; Kotański, A.; Kötz, U.; Kovalchuk, N.; Kowalski, H.; Krupa, B.; Kuprash, O.; Kuze, M; Levchenko, B.B.; Levy, A.; Limentani, S.; Lisovyi, M.; Lobodzinska, E.; Löhr, B.; Lohrmann, E.; Longhin, A.; Lontkovskyi, D.; Lukina, O.Yu.; Makarenko, I.; Malka, J.; Mastroberardino, A.; Mohamad Idris, F.; Mohammad Nasir, N; Myronenko, V.; Nagano, K.; Nobe, T.; Nowak, R.J.; Onishchuk, Yu.; Paul, E.; Perlański, W.; Pokrovskiy, N.S.; Polini, A.; Przybycien, M.; Roloff, P.; Ruspa, M.; Saxon, D.H.; Schioppa, M.; Schneekloth, U.; Schörner-Sadenius, T.; Shcheglova, L.M.; Shevchenko, R.; Shkola, O.; Shyrma, Yu.; Singh, I.; Skillicorn, I.O.; Słomiński, W.; Solano, A.; Stanco, L.; Stefaniuk, N.; Stern, A.; Stopa, P.; Sztuk-Dambietz, J.; Tassi, E.; Tokushuku, K.; Tomaszewska, J.; Tsurugai, T.; Turcato, M.; Turkot, O.; Tymieniecka, T.; Verbytskyi, A.; Wan Abdullah, W.A.T.; Wichmann, K.; Wing, M.; Yamada, S.; Yamazaki, Y.; Zakharchuk, N.; Żarnecki, A.F.; Zawiejski, L.; Zenaiev, O.; Zhautykov, B.O.; Zotkin, D.S.; Mastroberardino, A

2016-08-10

A search for a narrow baryonic state in the $pK^0_S$ and $\\overline{p}K^0_S$ system has been performed in $ep$ collisions at HERA with the ZEUS detector using an integrated luminosity of 358 pb$^{-1}$ taken in 2003-2007. The search was performed with deep inelastic scattering events at an $ep$ centre-of-mass energy of 318 GeV for exchanged photon virtuality, $Q^2$, between 20 and 100 $\\rm{} GeV^{2}$. Contrary to evidence presented for such a state around 1.52 GeV in a previous ZEUS analysis using a sample of 121 pb$^{-1}$ taken in 1996-2000, no resonance peak was found in the $p(\\overline{p})K^0_S$ invariant-mass distribution in the range 1.45-1.7 GeV. Upper limits on the production cross section are set.

Search for a narrow baryonic state decaying to pK0S and anti pK0S in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2016-06-01

A search for a narrow baryonic state in the pK 0 S and anti pK 0 S system has been performed in ep collisions at HERA with the ZEUS detector using an integrated luminosity of 358 pb -1 taken in 2003-2007. The search was performed with deep inelastic scattering events at an ep centre-of-mass energy of 318 GeV for exchanged photon virtuality, Q 2 , between 20 and 100 GeV 2 . Contrary to evidence presented for such a state around 1.52 GeV in a previous ZEUS analysis using a sample of 121 pb -1 taken in 1996-2000, no resonance peak was found in the p(anti p)K 0 S invariant-mass distribution in the range 1.45-1.7 GeV. Upper limits on the production cross section are set.

Measurement of beauty production in deep inelastic scattering at HERA using decays into electrons

Energy Technology Data Exchange (ETDEWEB)

Shehzadi, Ramoona

2011-01-15

The production of beauty quarks in ep interactions has been studied with the ZEUS detector at HERA for exchanged four-momentum squared Q{sup 2}>10 GeV{sup 2}, using an integrated luminosity of 363 pb{sup -1}. The beauty events were identified using electrons from semileptonic b decays with a transverse momentum 0.9

Bose-Einstein correlations of charged and neutral kaons in deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2007-05-15

Bose-Einstein correlations of charged and neutral kaons have been measured in e{sup {+-}}p deep inelastic scattering with an integrated luminosity of 121 pb{sup -1} using the ZEUS detector at HERA. The two-particle correlation function was studied as a function of the four-momentum difference of the kaon pairs, Q{sub 12}={radical}(-(p{sub 1}-p{sub 2}){sup 2}), assuming a Gaussian shape for the particle source. The values of the radius of the production volume, r, and of the correlation strength, {lambda}, were obtained for both neutral and charged kaons. The radii for charged and neutral kaons are similar and are consistent with those obtained at LEP. (orig.)

Combined Measurement and QCD Analysis of the Inclusive ep Scattering Cross Sections at HERA

CERN Document Server

Aaron, F.D.; Abt, I.; Adamczyk, L.; Adamus, M.; Aldaya Martin, M.; Alexa, C.; Andreev, V.; Antonelli, S.; Antonioli, P.; Antonov, A.; Antunovic, B.; Arneodo, M.; Aushev, V.; Bachynska, O.; Backovic, S.; Baghdasaryan, A.; Bamberger, A.; Barakbaev, A.N.; Barbagli, G.; Bari, G.; Barreiro, F.; Barrelet, E.; Bartel, W.; Bartsch, D.; Basile, M.; Begzsuren, K.; Behnke, O.; Behr, J.; Behrens, U.; Bellagamba, L.; Belousov, A.; Bertolin, A.; Bhadra, S.; Bindi, M.; Bizot, J.C.; Blohm, C.; Bold, T.; Boos, E.G.; Borodin, M.; Borras, K.; Boscherini, D.; Bot, D.; Boudry, V.; Boutle, S.K.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Brock, I.; Brownson, E.; Brugnera, R.; Brummer, N.; Bruncko, D.; Bruni, A.; Bruni, G.; Brzozowska, B.; Bunyatyan, A.; Buschhorn, G.; Bussey, P.J.; Butterworth, J.M.; Bylsma, B.; Bystritskaya, L.; Caldwell, A.; Campbell, A.J.; Cantun Avila, K.B.; Capua, M.; Carlin, R.; Catterall, C.D.; Cerny, K.; Cerny, V.; Chekanov, S.; Chekelian, V.; Cholewa, A.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Cifarelli, L.; Cindolo, F.; Contin, A.; Contreras, J.G.; Cooper-Sarkar, A.M.; Coppola, N.; Corradi, M.; Corriveau, F.; Costa, M.; Coughlan, J.A.; Cozzika, G.; Cvach, J.; D'Agostini, G.; Dainton, J.B.; Dal Corso, F.; Daum, K.; Deak, M.; de Favereau, J.; Delcourt, B.; del Peso, J.; Delvax, J.; Dementiev, R.K.; De Pasquale, S.; Derrick, M.; Devenish, R.C.E.; De Wolf, E.A.; Diaconu, C.; Dobur, D.; Dodonov, V.; Dolgoshein, B.A.; Dossanov, A.; Doyle, A.T.; Drugakov, V.; Dubak, A.; Durkin, L.S.; Dusini, S.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eisenberg, Y.; Eliseev, A.; Elsen, E.; Ermolov, P.F.; Eskreys, A.; Falkiewicz, A.; Fang, S.; Favart, L.; Fazio, S.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrando, J.; Ferrero, M.I.; Figiel, J.; Fischer, D.J.; Fleischer, M.; Fomenko, A.; Forrest, M.; Foster, B.; Fourletov, S.; Gabathuler, E.; Galas, A.; Gallo, E.; Garfagnini, A.; Gayler, J.; Geiser, A.; Ghazaryan, S.; Gialas, I.; Gladilin, L.K.; Gladkov, D.; Glasman, C.; Glazov, A.; Glushkov, I.; Goerlich, L.; Gogitidze, N.; Golubkov, Yu.A.; Gottlicher, P.; Gouzevitch, M.; Grab, C.; Grabowska-Bold, I.; Grebenyuk, J.; Greenshaw, T.; Gregor, I.; Grell, B.R.; Grigorescu, G.; Grindhammer, G.; Grzelak, G.; Gwenlan, C.; Haas, T.; Habib, S.; Haidt, D.; Hain, W.; Hamatsu, R.; Hart, J.C.; Hartmann, H.; Hartner, G.; Helebrant, C.; Henderson, R.C.W.; Hennekemper, E.; Henschel, H.; Herbst, M.; Herrera, G.; Hildebrandt, M.; Hilger, E.; Hiller, K.H.; Hochman, D.; Hoffmann, D.; Holm, U.; Hori, R.; Horisberger, R.; Horton, K.; Hreus, T.; Huttmann, A.; Iacobucci, G.; Ibrahim, Z.A.; Iga, Y.; Ingbir, R.; Ishitsuka, M.; Jacquet, M.; Jakob, H.P.; Janssen, X.; Januschek, F.; Jimenez, M.; Jones, T.W.; Jonsson, L.; Jung, A.W.; Jung, H.; Jungst, M.; Kadenko, I.; Kahle, B.; Kamaluddin, B.; Kananov, S.; Kanno, T.; Kapichine, M.; Karshon, U.; Karstens, F.; Katkov, I.I.; Katzy, J.; Kaur, M.; Kaur, P.; Kenyon, I.R.; Keramidas, A.; Khein, L.A.; Kiesling, C.; Kim, J.Y.; Kisielewska, D.; Kitamura, S.; Klanner, R.; Klein, M.; Klein, U.; Kleinwort, C.; Kluge, T.; Knutsson, A.; Koffeman, E.; Kogler, R.; Kollar, D.; Kooijman, P.; Korol, Ie.; Korzhavina, I.A.; Kostka, P.; Kotanski, A.; Kotz, U.; Kowalski, H.; Kraemer, M.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Kulinski, P.; Kuprash, O.; Kutak, K.; Kuze, M.; Kuzmin, V.A.; Landon, M.P.J.; Lange, W.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Lee, A.; Lendermann, V.; Levchenko, B.B.; Levonian, S.; Levy, A.; Li, G.; Libov, V.; Limentani, S.; Ling, T.Y.; Lipka, K.; Liptaj, A.; Lisovyi, M.; List, B.; List, J.; Lobodzinska, E.; Lohmann, W.; Lohr, B.; Lohrmann, E.; Loizides, J.H.; Loktionova, N.; Long, K.R.; Longhin, A.; Lontkovskyi, D.; Lopez-Fernandez, R.; Lubimov, V.; Lukasik, J.; Lukina, O.Yu.; Luzniak, P.; Maeda, J.; Magill, S.; Makankine, A.; Makarenko, I.; Malinovski, E.; Malka, J.; Mankel, R.; Marage, P.; Margotti, A.; Marini, G.; Marti, Ll.; Martin, J.F.; Martyn, H.U.; Mastroberardino, A.; Matsumoto, T.; Mattingly, M.C.K.; Maxfield, S.J.; Mehta, A.; Melzer-Pellmann, I.A.; Meyer, A.B.; Meyer, H.; Meyer, H.; Meyer, J.; Miglioranzi, S.; Mikocki, S.; Milcewicz-Mika, I.; Mohamad Idris, F.; Monaco, V.; Montanari, A.; Moreau, F.; Morozov, A.; Morris, J.D.; Morris, J.V.; Mozer, M.U.; Mudrinic, M.; Muller, K.; Murin, P.; Musgrave, B.; Nagano, K.; Namsoo, T.; Nania, R.; Naumann, Th.; Newman, P.R.; Nicholass, D.; Niebuhr, C.; Nigro, A.; Nikiforov, A.; Nikitin, D.; Ning, Y.; Noor, U.; Notz, D.; Nowak, G.; Nowak, K.; Nowak, R.J.; Nuncio-Quiroz, A.E.; Oh, B.Y.; Okazaki, N.; Oliver, K.; Olkiewicz, K.; Olsson, J.E.; Onishchuk, Yu.; Osman, S.; Ota, O.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, Th.; Papageorgiu, K.; Parenti, A.; Pascaud, C.; Patel, G.D.; Paul, E.; Pawlak, J.M.; Pawlik, B.; Pejchal, O.; Pelfer, P.G.; Pellegrino, A.; Perez, E.; Perlanski, W.; Perrey, H.; Petrukhin, A.; Picuric, I.; Piec, S.; Piotrzkowski, K.; Pitzl, D.; Placakyte, R.; Plucinski, P.; Pokorny, B.; Pokrovskiy, N.S.; Polifka, R.; Polini, A.; Povh, B.; Proskuryakov, A.S.; Przybycien, M.; Radescu, V.; Rahmat, A.J.; Raicevic, N.; Raspiareza, A.; Raval, A.; Ravdandorj, T.; Reeder, D.D.; Reimer, P.; Reisert, B.; Ren, Z.; Repond, J.; Ri, Y.D.; Rizvi, E.; Robertson, A.; Robmann, P.; Roland, B.; Roloff, P.; Ron, E.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Rubinsky, I.; Ruiz Tabasco, J.E.; Rusakov, S.; Ruspa, M.; Sacchi, R.; Salek, D.; Salii, A.; Samson, U.; Sankey, D.P.C.; Sartorelli, G.; Sauter, M.; Sauvan, E.; Savin, A.A.; Saxon, D.H.; Schioppa, M.; Schlenstedt, S.; Schleper, P.; Schmidke, W.B.; Schmitt, S.; Schneekloth, U.; Schoeffel, L.; Schonberg, V.; Schoning, A.; Schorner-Sadenius, T.; Schultz-Coulon, H.C.; Schwartz, J.; Sciulli, F.; Sefkow, F.; Shaw-West, R.N.; Shcheglova, L.M.; Shehzadi, R.; Shimizu, S.; Shtarkov, L.N.; Shushkevich, S.; Singh, I.; Skillicorn, I.O.; Sloan, T.; Slominski, W.; Smiljanic, I.; Smith, W.H.; Sola, V.; Solano, A.; Soloviev, Y.; Son, D.; Sopicki, P.; Sorokin, Iu.; Sosnovtsev, V.; South, D.; Spaskov, V.; Specka, A.; Spiridonov, A.; Stadie, H.; Stanco, L.; Staykova, Z.; Steder, M.; Stella, B.; Stern, A.; Stewart, T.P.; Stifutkin, A.; Stoicea, G.; Stopa, P.; Straumann, U.; Suchkov, S.; Sunar, D.; Susinno, G.; Suszycki, L.; Sykora, T.; Sztuk, J.; Szuba, D.; Szuba, J.; Tapper, A.D.; Tassi, E.; Tchoulakov, V.; Terron, J.; Theedt, T.; Thompson, G.; Thompson, P.D.; Tiecke, H.; Tokushuku, K.; Toll, T.; Tomasz, F.; Tomaszewska, J.; Tran, T.H.; Traynor, D.; Trinh, T.N.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Tsurugai, T.; Turcato, M.; Turnau, J.; Tymieniecka, T.; Urban, K.; Uribe-Estrada, C.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Vazquez, M.; Verbytskyi, A.; Viazlo, V.; Vinokurova, S.; Vlasov, N.N.; Volchinski, V.; Volynets, O.; von den Driesch, M.; Walczak, R.; Wan Abdullah, W.A.T.; Wegener, D.; Whitmore, J.J.; Whyte, J.; Wiggers, L.; Wing, M.; Wissing, Ch.; Wlasenko, M.; Wolf, G.; Wolfe, H.; Wrona, K.; Wunsch, E.; Yagues-Molina, A.G.; Yamada, S.; Yamazaki, Y.; Yoshida, R.; Youngman, C.; Zacek, J.; Zalesak, J.; Zarnecki, A.F.; Zawiejski, L.; Zeniaev, O.; Zeuner, W.; Zhang, Z.; Zhautykov, B.O.; Zhokin, A.; Zhou, C.; Zichichi, A.; Zimmermann, T.; Zohrabyan, H.; Zolko, M.; Zomer, F.; Zotkin, D.S.

2010-01-01

A combination is presented of the inclusive deep inelastic cross sections measured by the H1 and ZEUS Collaborations in neutral and charged current unpolarised ep scattering at HERA during the period 1994-2000. The data span six orders of magnitude in negative four-momentum-transfer squared, Q^2, and in Bjorken x. The combination method used takes the correlations of systematic uncertainties into account, resulting in an improved accuracy. The combined data are the sole input in a NLO QCD analysis which determines a new set of parton distributions HERAPDF1.0 with small experimental uncertainties. This set includes an estimate of the model and parametrisation uncertainties of the fit result.

Observation of hard scattering in photoproduction events with a large rapidity gap at HERA

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magill, S.

1994-11-01

Events with a large rapidity gap and total transverse energy greater than 5 GeV have been observed in quasi-real photoproduction at HERA with the ZEUS detector. The distribution of these events as a function of the γp centre of mass energy is consistent with diffractive scattering. For total transverse energies above 12 GeV, the hadronic final states show predominantly a two-jet structure with each jet having a transverse energy greater than 4 GeV. For the two-jet events, little energy flow is found outside the jets. This observation is consistent with the hard scattering of a quasi-real photon with a colourless object in the proton. (orig.)

Photoproduction of isolated photons, inclusively and with a jet, at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max-Planck-Institute for Physics, Munich (Germany); Abt, I. [Max-Planck-Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science; Collaboration: ZEUS Collaboration; and others

2013-12-15

The photoproduction of isolated photons, both inclusive and together with a jet, has been measured with the ZEUS detector at HERA using an integrated luminosity of 374 pb{sup -1}. Differential cross sections are presented in the isolated-photon transverse-energy and pseudorapidity ranges 6

The design of the ZEUS tracking trigger and studies of b quark fragmentation

Energy Technology Data Exchange (ETDEWEB)

Silvester, I M

1989-01-01

This thesis consists of two parts, describing two very different aspects of experimental elementary particle physics. The first part describes, in detail, the design and estimated performance of a hardware track finding trigger processor. This processor is being built as part of the trigger for the ZEUS experiment, one of the two experiments being built to take data at the HERA electron-proton collider, currently under construction at the DESY laboratories in Hamburg. By using information from the main tracking chamber, the CTD, to reject data from events taking place outside the interaction region, this processor should be able to reduce the event rate from a beam crossing rate of 10{sup 6} s{sup -1} to approximately 9500 s{sup -1}. Used in conjunction with a trigger processor processing calorimeter data it should be able to achieve the desired first level trigger rate of 1 kHz. The second part describes two measurements of the fragmentation variable z for b quarks, made using a b enriched sample of 381 jets taken from the 31000 hadronic events with a centre of mass energy of 35 GeV observed with the TASSO detector during 1986. These measurements, obtained from the mean charged multiplicity and the rapidity distribution, have largely independent systematic uncertainties. The values obtained for (z{sub b}) were combined to give a value of 0.87{+-}0.02{+-}0.04. (author).

On the determination of track parameters with the forward drift chambers of the ZEUS detector. Zur Bestimmung von Spurparametern mit den Vorwaertsdriftkammern des ZEUS-Detektors

Energy Technology Data Exchange (ETDEWEB)

Guenzel, T F

1989-01-01

The ep-collider HERA at DESY in Hamburg will probe unexplored kinematical regions of the deep-inelastic electron-proton-scattering. The ZEUS-Collaboration develops a detector to study the physical interactions of the incoming particles. Among the requirements of the ZEUS-detector a good momentum resolution of the particle tracks in the inner detector resp. forward tracking detector (FTD) is necessary. The behaviour of the tracks in the forward tracking detector is determined by the lorentzboost ({beta}=0.93) in forward direction and by the inhomogeneous magnetic field in the FTD, which is mainly parallel to the beampipe-axis. In this thesis all studies regard only the FTD (not including VXD or CTD) for the momentum determination. Two scenarios are considered to determine the limits of momentum measurability in the FTD. The results show that the determination of the momentum in the FTD is only possible with the (exact) knowledge of the vertex position, where the tracks come from. The functional dependence of the track parameters at the vertex on the track parameters at the first FTD-module was intensively studied. Disconnected ambiguities are not found. A track model for tracks in the FTD is developed without regarding multiple scattering. The momentum determination of a track is mainly based on the track part between the first FTD-module and the vertex. A momentum resolution of {sigma}p/P=0.008 P-0.0025 P can be achieved depending on the polar angle (relative to the beampipe-axis) of the track at the vertex. Finally the influence of the multiple scattering between the first FTD-module and the vertex on the momentum resolution is estimated. The increase of the dead material for small polar angles restricts the area of acceptable momentum resolution to polar angles of {lambda}>180 mrad. (orig.).

Measurement of neutral current e±p cross sections at high Bjorken x with the ZEUS detector

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2013-12-01

The neutral current e ± p cross section has been measured up to values of Bjorken x≅1 with the ZEUS detector at HERA using an integrated luminosity of 187 pb -1 of e - p and 142 pb -1 of e + p collisions at √(s)=318 GeV. Differential cross sections in x and Q 2 , the exchanged boson virtuality, are presented for Q 2 ≥725 GeV 2 . An improved reconstruction method and greatly increased amount of data allows a finer binning in the high-x region of the neutral current cross section and leads to a measurement with much improved precision compared to a similar earlier analysis. The measurements are compared to Standard Model expectations based on a variety of recent parton distribution functions.

Research in elementary particle physics. Progress report, March 1, 1994--February 28, 1995

International Nuclear Information System (INIS)

Chan, Lai-Him; Haymaker, R.; Imlay, R.; McNeil, R.; Metcalf, W.; Svoboda, R.

1994-01-01

This report discusses the following topics: Low-energy particle dynamics; QCD dynamics on the lattice; lattice QCD Vacuum; phenomenology ampersand cosmology; the ZEUS Experiment at HERA; neutrino physics at LAMPF; non-accelerator physics; and SSC activity

First level trigger processor for the ZEUS calorimeter

International Nuclear Information System (INIS)

Dawson, J.W.; Talaga, R.L.; Burr, G.W.; Laird, R.J.; Smith, W.; Lackey, J.

1990-01-01

This paper discusses the design of the first level trigger processor for the ZEUS calorimeter. This processor accepts data from the 13,000 photomultipliers of the calorimeter which is topologically divided into 16 regions, and after regional preprocessing, performs logical and numerical operations which cross regional boundaries. Because the crossing period at the HERA collider is 96 ns, it is necessary that first-level trigger decisions be made in pipelined hardware. One microsecond is allowed for the processor to perform the required logical and numerical operations, during which time the data from ten crossings would be resident in the processor while being clocked through the pipelined hardware. The circuitry is implemented in 100K ECL, Advanced CMOS discrete devices, and programmable gate arrays, and operates in a VME environment. All tables and registers are written/read from VME, and all diagnostic codes are executed from VME. Preprocessed data flows into the processor at a rate of 5.2GB/s, and processed data flows from the processor to the Global First-Level Trigger at a rate of 700MB/s. The system allows for subsets of the logic to be configured by software and for various important variables to be histogrammed as they flow through the processor. 2 refs., 3 figs

First-level trigger processor for the ZEUS calorimeter

International Nuclear Information System (INIS)

Dawson, J.W.; Talaga, R.L.; Burr, G.W.; Laird, R.J.; Smith, W.; Lackey, J.

1990-01-01

The design of the first-level trigger processor for the Zeus calorimeter is discussed. This processor accepts data from the 13,000 photomultipliers of the calorimeter, which is topologically divided into 16 regions, and after regional preprocessing performs logical and numerical operations that cross regional boundaries. Because the crossing period at the HERA collider is 96 ns, it is necessary that first-level trigger decisions be made in pipelined hardware. One microsecond is allowed for the processor to perform the required logical and numerical operations, during which time the data from ten crossings would be resident in the processor while being clocked through the pipelined hardware. The circuitry is implemented in 100K emitter-coupled logic (ECL), advanced CMOS discrete devices and programmable gate arrays, and operates in a VME environment. All tables and registers are written/read from VME, and all diagnostic codes are executed from VME. Preprocessed data flows into the processor at a rate of 5.2 Gbyte/s, and processed data flows from the processor to the global first-level trigger at a rate of 70 Mbyte/s. The system allows for subsets of the logic to be configured by software and for various important variables to be histogrammed as they flow through the processor

Diffractive photoproduction of dijets in ep collisions at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2007-09-15

Diffractive photoproduction of dijets was measured with the ZEUS detector at the ep collider HERA using an integrated luminosity of 77.2 pb{sup -1}. The measurements were made in the kinematic range Q{sup 2}<1 GeV{sup 2}, 0.207.5 and 6.5 GeV, respectively, and to lie in the pseudorapidity range -1.5<{eta}{sup jet}<1.5. Differential cross sections were compared to perturbative QCD calculations using available parameterisations of diffractive parton distributions of the proton. (orig.)

Scaled momentum spectra in deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). Raymond and Beverly Sackler Faculty of Exact Sciences; University College London (United Kingdom); Max Planck Inst., Munich (Germany); Abt, I. [Max-Planck-Inst. fuer Physik, Muenchen (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Cracow (PL). Faculty of Physics and Applied Computer Science] (and others)

2009-12-15

Charged particle production has been studied in neutral current deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 0.44 fb{sup -1}. Distributions of scaled momenta in the Breit frame are presented for particles in the current fragmentation region. The evolution of these spectra with the photon virtuality, Q{sup 2}, is described in the kinematic region 10

Hard diffraction at HERA and Tevatron

International Nuclear Information System (INIS)

Kaidalov, A.B.

2001-01-01

A relation between hard diffraction at HERA and Tevatron is discussed. A model, which takes into account unitarity effects is developed for interaction of high-energy virtual photons with nucleons. It is shown that this model gives a good description of HERA data on both total γ* p total cross section and diffractive dissociation of virtual photons in a broad region of Q 2 . It is shown how to describe the CDF data on diffractive jet production at Tevatron using an information on distribution of partons in the Pomeron from HERA experiments

Rapidity gaps between jets in Photoproduction at HERA

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magill, S.

1995-10-01

Photoproduction events which have two or more jets have been studied in the W γp range 135 GeV γp <280 GeV with the ZEUS detector at HERA. A class of events is observed with little hadronic activity between the jets. The jets are separated by pseudorapidity intervals (Δη) of up to four units and have transverse energies greater than 6 GeV. A gap is defined as the absence between the jets of particles with transverse energy greater than 300 MeV. The fraction of events containing a gap is measured as a function of Δη. It decreases exponentially as expected for processes in which colour is exchanged between the jets, up to a value of Δη∼3, then reaches a constant value of about 0.1. The excess above the exponential fall-off can be interpreted as evidence for hard diffractive scattering via a strongly interacting colour singlet object. (orig.)

Event shapes in deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2006-04-15

Mean values and differential distributions of event-shape variables have been studied in neutral current deep inelastic scattering using an integrated luminosity of 82.2 pb{sup -1} collected with the ZEUS detector at HERA. The kinematic range was 80

Results From PAPER/HERA

Science.gov (United States)

Pober, Jonathan C.

2018-05-01

The Precision Array for Probing the Epoch of Reionization (PAPER) was a first-generation 21 cm cosmology experiment with the specific goal of detecting the power spectrum of the 21 cm emission from the Epoch of Reionization. Analysis of PAPER data is still ongoing, but lessons learned from PAPER to date have played a critical role in designing the next-generation Hydrogen Epoch of Reionization Array (HERA) experiment. This article reviews five key design choices made by PAPER: use of a non-imaging configuration, redundancy, short baselines, small antenna elements, and a large instantaneous bandwidth. We describe the impact of these choices and the role they played in designing HERA.

Measurement of beauty photoproduction using decays into muons in dijet events at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Lab., Argonne, IL (US)] (and others)

2008-12-15

Beauty photoproduction in dijet events has been measured at HERA with the ZEUS detector using an integrated luminosity of 126 pb{sup -1}. Beauty was identified in events with a muon in the final state by using the transverse momentum of the muon relative to the closest jet. Lifetime information from the silicon vertex detector was also used; the impact parameter of the muon with respect to the primary vertex was exploited to discriminate between signal and background. Cross sections for beauty production as a function of the muon and the jet variables as well as dijet correlations are compared to QCD predictions and to previous measurements. The data are well described by predictions from next-to-leading-order QCD. (orig.)

Measurement of D* photoproduction at three different centre-of-mass energies at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2014-05-01

The cross sections for the photoproduction of D *± mesons have been measured with the ZEUS detector at HERA at three different ep centre-of-mass energies, √(s), of 318, 251 and 225 GeV. For each data set, D *± mesons were required to have transverse momentum, p D* T , and pseudorapidity, η D * , in the ranges 1.9 D* T D* vertical stroke 2 , of less than 1 GeV 2 . The dependence on √(s) was studied by normalising to the high-statistics measurement at √(s)=318 GeV. This led to the cancellation of a number of systematic effects both in data and theory. Predictions from next-to-leading-order QCD describe the √(s) dependence of the data well.

Measurement of beauty photoproduction using decays into muons in dijet events at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-12-01

Beauty photoproduction in dijet events has been measured at HERA with the ZEUS detector using an integrated luminosity of 126 pb -1 . Beauty was identified in events with a muon in the final state by using the transverse momentum of the muon relative to the closest jet. Lifetime information from the silicon vertex detector was also used; the impact parameter of the muon with respect to the primary vertex was exploited to discriminate between signal and background. Cross sections for beauty production as a function of the muon and the jet variables as well as dijet correlations are compared to QCD predictions and to previous measurements. The data are well described by predictions from next-to-leading-order QCD. (orig.)

A global analysis of inclusive diffractive cross sections at HERA

International Nuclear Information System (INIS)

Royon, C.; Schoeffel, L.; Sapeta, S.; Peschanski, R.; Sauvan, E.

2006-10-01

We describe the most recent data on the diffractive structure functions from the H1 and ZEUS Collaborations at HERA using four models. First, a Pomeron Structure Function (PSF) model, in which the Pomeron is considered as an object with parton distribution functions. Then, the Bartels Ellis Kowalski Wuesthoff (BEKW) approach is discussed, assuming the simplest perturbative description of the Pomeron using a two-gluon ladder. A third approach, the Bialas Peschanski (BP) model, based on the dipole formalism is then described. Finally, we discuss the Golec-Biernat-Wuesthoff (GBW) saturation model which takes into account saturation effects. The best description of all available measurements can be achieved with either the PSF based model or the BEKW approach. In particular, the BEKW prediction allows to include the highest β measurements, which are dominated by higher twists effects and provide an efficient and compact parametrisation of the diffractive cross section. The two other models also give a good description of cross section measurements at small x with a small number of parameters. The comparison of all predictions allows us to identify interesting differences in the behaviour of the effective pomeron intercept and in the shape of the longitudinal component of the diffractive structure functions. In this last part, we present some features that can be discriminated by new experimental measurements, completing the HERA program. (authors)

A global analysis of inclusive diffractive cross sections at HERA

Energy Technology Data Exchange (ETDEWEB)

Royon, C.; Schoeffel, L. [Service de Physique des Particules, CE-Saclay, F-91191 Gif-sur-Yvette Cedex (France); Sapeta, S. [M. Smoluchowski Institue of Physics Jagellonian University Reymonta 4, 30-059 Krakow (Poland); Peschanski, R. [Service de Physique Theorique, CE-Saclay, F-91191 Gif-sur-Yvette Cedex (France); Sauvan, E. [CPPM, IN2P3-CNRS et Universitie de la Mediterranee, F-13288 Marseille Cedex 09 (France)

2006-10-15

We describe the most recent data on the diffractive structure functions from the H1 and ZEUS Collaborations at HERA using four models. First, a Pomeron Structure Function (PSF) model, in which the Pomeron is considered as an object with parton distribution functions. Then, the Bartels Ellis Kowalski Wuesthoff (BEKW) approach is discussed, assuming the simplest perturbative description of the Pomeron using a two-gluon ladder. A third approach, the Bialas Peschanski (BP) model, based on the dipole formalism is then described. Finally, we discuss the Golec-Biernat-Wuesthoff (GBW) saturation model which takes into account saturation effects. The best description of all available measurements can be achieved with either the PSF based model or the BEKW approach. In particular, the BEKW prediction allows to include the highest {beta} measurements, which are dominated by higher twists effects and provide an efficient and compact parametrisation of the diffractive cross section. The two other models also give a good description of cross section measurements at small x with a small number of parameters. The comparison of all predictions allows us to identify interesting differences in the behaviour of the effective pomeron intercept and in the shape of the longitudinal component of the diffractive structure functions. In this last part, we present some features that can be discriminated by new experimental measurements, completing the HERA program. (authors)

Scaled momentum distributions for K0S and Λ/ anti Λ in DIS at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2011-11-01

Scaled momentum distributions for the strange hadrons K S 0 and Λ/ anti Λ were measured in deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 330 pb -1 . The evolution of these distributions with the photon virtuality, Q 2 , was studied in the kinematic region 10 2 2 and 0.001 + e - data alone, fail to describe the measurements. The calculations based on FFs extracted from a global analysis including e + e - , ep and pp data give an improved description. The measurements presented in this paper have the potential to further constrain the FFs of quarks, anti-quarks and gluons yielding K S 0 and Λ/ anti Λ strange hadrons. (orig.)

Measurement of dijet cross sections for events with a leading neutron in photoproduction at HERA

International Nuclear Information System (INIS)

Breitweg, J.; Chekanov, S.; Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Pellegrino, A.; Repond, J.; Stanek, R.; Yoshida, R.; Mattingly, M.C.K.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Sartorelli, G.; Zichichi, A.; Amelung, C.; Bornheim, A.; Brock, I.; Coboeken, K.; Crittenden, J.; Deffner, R.; Hartmann, H.; Heinloth, K.; Hilger, E.; Irrgang, P.; Jakob, H.-P.; Kappes, A.; Katz, U.F.; Kerger, R.; Paul, E.; Rautenberg, J.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K.C.; Weber, A.; Wieber, H.; Bailey, D.S.; Barret, O.; Brook, N.H.; Foster, B.; Heath, G.P.; Heath, H.F.; Rodrigues, E.; Scott, J.; Tapper, R.J.; Capua, M.; Schioppa, M.; Susinno, G.; Jeoung, H.Y.; Kim, J.Y.; Lee, J.H.; Lim, I.T.; Ma, K.J.; Pac, M.Y.; Caldwell, A.; Liu, W.; Liu, X.; Mellado, B.; Paganis, S.; Sampson, S.; Schmidke, W.B.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Klimek, K.; Olkiewicz, K.; Piotrzkowski, K.; Przybycien, M.B.; Stopa, P.; Zawiejski, L.; Bednarek, B.; Jelen, K.; Kisielewska, D.; Kowal, A.M.; Kowalski, T.; Przybycien, M.; Rulikowska-Zarebska, E.; Suszycki, L.; Szuba, D.; Kotanski, A.; Bauerdick, L.A.T.; Behrens, U.; Bienlein, J.K.; Borras, K.; Chiochia, V.; Dannheim, D.; Desler, K.; Drews, G.; Fox-Murphy, A.; Fricke, U.; Goebel, F.; Goers, S.; Goettlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G.F.; Hebbel, K.; Hillert, S.; Koch, W.; Koetz, U.; Kowalski, H.; Labes, H.; Loehr, B.; Mankel, R.; Martens, J.; Martinez, M.; Milite, M.; Moritz, M.; Notz, D.; Petrucci, M.C.; Polini, A.; Rohde, M.; Savin, A.A.; Schneekloth, U.; Selonke, F.; Sievers, M.; Stonjek, S.; Wolf, G.; Wollmer, U.; Youngman, C.; Zeuner, W.; Coldewey, C.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.; Straub, P.B.; Barbagli, G.; Gallo, E.; Parenti, A.; Pelfer, P.G.; Bamberger, A.; Benen, A.; Coppola, N.; Eisenhardt, S.; Markun, P.; Raach, H.; Woelfle, S.; Bussey, P.J.; Bell, M.; Doyle, A.T.; Glasman, C.; Lee, S.W.; Lupi, A.; Macdonald, N.; McCance, G.J.; Saxon, D.H.; Sinclair, L.E.; Skillicorn, I.O.; Waugh, R.; Bohnet, I.; Gendner, N.; Holm, U.; Meyer-Larsen, A.; Salehi, H.; Wick, K.; Carli, T.; Garfagnini, A.; Gialas, I.; Gladilin, L.K.; Kcira, D.; Klanner, R.; Lohrmann, E.; Goncalo, R.; Long, K.R.; Miller, D.B.; Tapper, A.D.; Walker, R.; Cloth, P.; Filges, D.; Ishii, T.; Kuze, M.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Ahn, S.H.; Lee, S.B.; Park, S.K.; Lim, H.; Son, D.; Barreiro, F.; Garcia, G.; Gonzalez, O.; Labarga, L.; del Peso, J.; Redondo, I.; Terron, J.; Vazquez, M.; Barbi, M.; Corriveau, F.; Hanna, D.S.; Ochs, A.; Padhi, S.; Stairs, D.G.; Wing, M.; Tsurugai, T.; Antonov, A.; Bashkirov, V.; Danilov, M.; Dolgoshein, B.A.; Gladkov, D.; Sosnovtsev, V.; Suchkov, S.; Dementiev, R.K.; Ermolov, P.F.; Golubkov, Yu.A.; Katkov, I.I.; Khein, L.A.; Korotkova, N.A.; Korzhavina, I.A.; Kuzmin, V.A.; Lukina, O.Yu.; Proskuryakov, A.S.; Shcheglova, L.M.; Solomin, A.N.; Vlasov, N.N.; Zotkin, S.A.; Bokel, C.; Botje, M.; Bruemmer, N.; Engelen, J.; Grijpink, S.; Koffeman, E.; Kooijman, P.; Schagen, S.; van Sighem, A.; Tassi, E.; Tiecke, H.; Tuning, N.; Velthuis, J.J.; Vossebeld, J.; Wiggers, L.; de Wolf, E.; Bylsma, B.; Durkin, L.S.; Gilmore, J.; Ginsburg, C.M.; Kim, C.L.; Ling, T.Y.; Boogert, S.; Cooper-Sarkar, A.M.; Devenish, R.C.E.; Grosse-Knetter, J.; Matsushita, T.; Ruske, O.; Sutton, M.R.; Walczak, R.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; Dusini, S.; Limentani, S.; Longhin, A.; Posocco, M.; Stanco, L.; Turcato, M.; Adamczyk, L.; Iannotti, L.; Oh, B.Y.; Okrasinski, J.R.; Saull, P.R.B.; Toothacker, W.S.; Whitmore, J.J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cormack, C.; Hart, J.C.; McCubbin, N.A.; Shah, T.P.; Epperson, D.; Heusch, C.; Sadrozinski, H.F.-W.; Seiden, A.; Wichmann, R.; Williams, D.C.; Park, I.H.; Pavel, N.; Abramowicz , H.; Dagan, S.; Kananov, S.; Kreisel, A.; Levy, A.; Abe, T.; Fusayasu, T.; Kohno, T.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Inuzuka, M.; Kitamura, S.; Matsuzawa, K.; Nishimura, T.; Arneodo, M.; Cartiglia, N.; Cirio, R.; Costa, M.; Ferrero, M.I.; Maselli, S.; Monaco, V.; Peroni, C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Bailey, D.C.; Fagerstroem, C.-P.; Galea, R.; Koop, T.; Levman, G.M.; Martin, J.F.; Mirea, A.; Sabetfakhri, A.; Butterworth, J.M.; Hayes, M.E.; Heaphy, E.A.; Jones, T.W.; Lane, J.B.; West, B.J.; Ciborowski, J.; Ciesielski, R.; Grzelak, G.; Nowak, R.J.; Pawlak, J.M.; Pawlak, R.; Smalska, B.; Tymieniecka, T.; Wroblewski, A.K.; Zakrzewski, J.A.; Zarnecki, A.F.; Adamus, M.; Gadaj, T.; Deppe, O.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Badgett, W.F.; Chapin, D.; Cross, R.; Foudas, C.; Mattingly, S.; Reeder, D.D.; Smith, W.H.; Vaiciulis, A.; Wildschek, T.; Wodarczyk, M.; Deshpande, A.; Dhawan, S.; Hughes, V.W.; Bhadra, S.; Catterall, C.; Cole, J.E.; Frisken, W.R.; Hall-Wilton, R.; Khakzad, M.; Menary, S.

2001-01-01

Differential cross sections for dijet photoproduction in association with a leading neutron using the reaction e + +p→e + +n+jet+jet+X r have been measured with the ZEUS detector at HERA using an integrated luminosity of 6.4 pb -1 . The fraction of dijet events with a leading neutron in the final state was studied as a function of the jet kinematic variables. The cross sections were measured for jet transverse energies E T jet >6 GeV, neutron energy E n >400 GeV, and neutron production angle θ n <0.8 mrad. The data are broadly consistent with factorization of the lepton and hadron vertices and with a simple one-pion-exchange model

Inclusive diffractive cross sections in deep inelastic ep scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Sola, Valentina

2012-04-15

Diffractive deep-inelastic scattering events in ep collisions at HERA are the subject of this thesis. The cross sections for inclusive diffraction, ep {yields} eXp, measured by the H1 and ZEUS Collaborations were combined, providing a model-independent check of the data consistency and a cross calibration between the two experiments, and resulting in single data sets with improved accuracy and precision. Two sets of combined results were obtained. The cross sections measured using the proton-spectrometer data were combined, both in the range of t, the squared four-momentum transfer at the proton vertex, common to the two experiments (0.09< vertical stroke t vertical stroke <0.55 GeV{sup 2}) and in the extended t-range vertical stroke t vertical stroke <1 GeV{sup 2}. The resulting cross sections cover the region 2.5{<=} Q{sup 2} {<=}200 GeV{sup 2} in photon virtualities, 0.0003{<=}x{sub P}{<=}0.09 in the proton fractional momentum losses and 0.0018{<=} {beta} {<=}0.816 in {beta}=x/x{sub P}, where x is the Bjorken scaling variable. The cross sections obtained from data with the large rapidity gap signature were also combined in the kinematic range 2.5{<=} Q{sup 2} {<=}1600 GeV{sup 2}, 0.0003{<=}x{sub P}{<=}0.03 and 0.0017{<=} {beta} {<=}0.8, for masses of the hadronic final state M{sub X}>4 GeV. The inclusive diffractive reduced cross section {sigma}{sub r}{sup D(3)} was measured with data collected by the ZEUS detector, at two different centre-of-mass energies, 318 and 225 GeV. The diffractive data were selected with the large rapidity gap method in the kinematic region 20< Q{sup 2} <130 GeV{sup 2}, 0.05< {beta} <0.85 and 0.00063or similar 0.55), the inelasticity of the interaction.

Inclusive-jet and dijet cross sections in deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2006-08-15

Inclusive-jet and dijet differential cross sections have been measured in neutral current deep inelastic ep scattering for exchanged boson virtualities Q{sup 2}>125 GeV{sup 2} with the ZEUS detector at HERA using an integrated luminosity of 82 pb{sup -1}. Jets were identified in the Breit frame using the k{sub T} cluster algorithm. Jet cross sections are presented as functions of several kinematic and jet variables. The results are also presented in different regions of Q{sup 2}. Next-to-leading-order QCD calculations describe the measurements well. Regions of phase space where the theoretical uncertainties are small have been identified. Measurements in these regions have the potential to constrain the gluon density in the proton when used as inputs to global fits of the proton parton distribution functions. (orig.)

Inclusive-jet and dijet cross sections in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2006-08-01

Inclusive-jet and dijet differential cross sections have been measured in neutral current deep inelastic ep scattering for exchanged boson virtualities Q 2 >125 GeV 2 with the ZEUS detector at HERA using an integrated luminosity of 82 pb -1 . Jets were identified in the Breit frame using the k T cluster algorithm. Jet cross sections are presented as functions of several kinematic and jet variables. The results are also presented in different regions of Q 2 . Next-to-leading-order QCD calculations describe the measurements well. Regions of phase space where the theoretical uncertainties are small have been identified. Measurements in these regions have the potential to constrain the gluon density in the proton when used as inputs to global fits of the proton parton distribution functions. (orig.)

Charm production in charged current deep inelastic e+p scattering at HERA

International Nuclear Information System (INIS)

Wang, M.

2006-03-01

The measurement of charm production in charged current deep inelastic positron-proton scattering is investigated with the ZEUS detector at the HERA collider. The data used has been collected from 1995 to 2000, corresponding to an integrated luminosity of 110 pb -1 . Charged D * mesons decaying in the channel D *+ →D 0 π + s with D 0 →K - π + and the charge conjugated channel are reconstructed to tag charm quarks. The visible cross section for D * , σ D* vis =12.8±4.0(stat) +4.7 -1.5 (sys) pb, is measured in the kinematic range of Q 2 >200 GeV 2 and y D * T >1.5 GeV and vertical stroke η D * vertical stroke e + p→ anti ν e cX < 109 pb at 90% confidence level. (orig.)

Combination of the H1 and ZEUS inclusive cross-section measurements at proton beam energies of 460 GeV and 575 GeV and tests of low Bjorken-x phenomenological models

Energy Technology Data Exchange (ETDEWEB)

Belov, Pavel

2013-06-15

A combination is presented of the inclusive neutral current e{sup {+-}}p scattering cross section data collected by the H1 and ZEUS collaborations during the last months of the HERA II operation period with proton beam energies E{sub p} of 460 and 575 GeV. The kinematic range of the cross section data covers low absolute four-momentum transfers squared, 1.5 GeV{sup 2} {<=} Q{sup 2} {<=} 110 GeV{sup 2}, small values of Bjorken-x, 2.8.10{sup -5} {<=} x {<=} 1.5.10{sup -2}, and high inelasticity y {<=} 0.85. The combination algorithm is based on the method of least squares and takes into account correlations of the systematic uncertainties. The combined data are used in the QCD fits to extract the parton distribution functions. The phenomenological low-x dipole models are tested and parameters of the models are obtained. A good description of the data by the dipole model taking into account the evolution of the gluon distribution is observed. The longitudinal structure function F{sub L} is extracted from the combination of the currently used H1 and ZEUS reduced proton beam energy data with previously published H1 nominal proton beam energy data of 920 GeV. A precision of the obtained values of F{sub L} is improved at medium Q{sup 2} compared to the published results of the H1 collaboration.

Combination and QCD analysis of charm production cross section measurements in deep-inelastic ep scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science] [and others; Collaboration: H1 and ZEUS Collaboration

2012-10-15

Measurements of open charm production cross sections in deep-inelastic ep scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections {sigma}{sup c} {sup anti} {sup c}{sub red} for charm production are obtained in the kinematic range of photon virtuality 2.5 {<=} Q{sup 2} {<=} 2000 GeV{sup 2} and Bjorken scaling variable 3.10{sup -5}{<=}x{<=}5.10{sup -2}. The combination method accounts for the correlations of the systematic uncertainties among the different data sets. The combined charm data together with the combined inclusive deepinelastic scattering cross sections from HERA are used as input for a detailed NLO QCD analysis to study the influence of different heavy flavour schemes on the parton distribution functions. The optimal values of the charm mass as a parameter in these different schemes are obtained. The implications on the NLO predictions for W{sup {+-}} and Z production cross sections at the LHC are investigated. Using the fixed flavour number scheme, the running mass of the charm quark is determined.

Structure function measurements from HERA

Indian Academy of Sciences (India)

ZEUS Collaboration: abstract 630, paper submitted to EPS Conference on HEP 2001, Budapest. ZEUS Collaboration: abstract 631, paper submitted to EPS Conference on HEP 2001, Budapest. [8] ZEUS Collaboration: abstract 765, paper submitted to ICHEP02 Conference, Amsterdam. 826. Pramana – J. Phys., Vol. 61, No.

Measurement of the photon-proton total cross section at a center-of-mass energy of 209 GeV at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Pellegrino, A.; Repond, J.; Yoshida, R.; Mattingly, M.C.K.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Sartorelli, G.; Zichichi, A.; Aghuzumtsyan, G.; Bartsch, D.; Brock, I.; Crittenden, J.; Goers, S.; Hartmann, H.; Hilger, E.; Irrgang, P.; Jakob, H.-P.; Kappes, A.; Katz, U.F.; Kerger, R.; Kind, O.; Paul, E.; Rautenberg, J.; Renner, R.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K.C.; Weber, A.; Wessoleck, H.; Bailey, D.S.; Brook, N.H.; Cole, J.E.; Foster, B.; Heath, G.P.; Heath, H.F.; Robins, S.; Rodrigues, E.; Scott, J.; Tapper, R.J.; Wing, M.; Capua, M.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Jeoung, H.Y.; Kim, J.Y.; Lee, J.H.; Lim, I.T.; Ma, K.J.; Pac, M.Y.; Caldwell, A.; Helbich, M.; Liu, X.; Mellado, B.; Paganis, S.; Schmidke, W.B.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Olkiewicz, K.; Przybycien, M.B.; Stopa, P.; Zawiejski, L.; Bednarek, B.; Grabowska-Bold, I.; Jelen, K.; Kisielewska, D.; Kowal, A.M.; Kowal, M.; Kowalski, T.; Mindur, B.; Przybycien, M.; Rulikowska-Zarebska, E.; Suszycki, L.; Szuba, D.; Szuba, J.; Kotanski, A.; Slominski, W.; Bauerdick, L.A.T.; Behrens, U.; Borras, K.; Chiochia, V.; Dannheim, D.; Desler, K.; Drews, G.; Fourletova, J.; Fox-Murphy, A.; Fricke, U.; Geiser, A.; Goebel, F.; Goettlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G.F.; Hillert, S.; Koetz, U.; Kowalski, H.; Labes, H.; Lelas, D.; Loehr, B.; Mankel, R.; Martens, J.; Martinez, M.; Moritz, M.; Notz, D.; Petrucci, M.C.; Polini, A.; Schneekloth, U.; Selonke, F.; Stonjek, S.; Surrow, B.; Whitmore, J.J.; Wichmann, R.; Wolf, G.; Youngman, C.; Zeuner, W.; Coldewey, C.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Genta, C.; Pelfer, P.G.; Bamberger, A.; Benen, A.; Coppola, N.; Markun, P.; Raach, H.; Woelfle, S.; Bell, M.; Bussey, P.J.; Doyle, A.T.; Glasman, C.; Hanlon, S.; Lee, S.W.; Lupi, A.; McCance, G.J.; Saxon, D.H.; Skillicorn, I.O.; Bodmann, B.; Holm, U.; Salehi, H.; Wick, K.; Ziegler, A.; Ziegler, Ar.; Carli, T.; Gialas, I.; Klimek, K.; Lohrmann, E.; Milite, M.; Collins-Tooth, C.; Foudas, C.; Goncalo, R.; Long, K.R.; Metlica, F.; Miller, D.B.; Tapper, A.D.; Walker, R.; Cloth, P.; Filges, D.; Kuze, M.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Barakbaev, A.N.; Boos, E.G.; Pokrovskiy, N.S.; Zhautykov, B.O.; Ahn, S.H.; Lee, S.B.; Park, S.K.; Lim, H.; Son, D.; Barreiro, F.; Garcia, G.; Gonzalez, O.; Labarga, L.; del Peso, J.; Redondo, I.; Terron, J.; Vazquez, M.; Barbi, M.; Bertolin, A.; Corriveau, F.; Ochs, A.; Padhi, S.; Stairs, D.G.; St-Laurent, M.; Tsurugai, T.; Antonov, A.; Bashkirov, V.; Danilov, P.; Dolgoshein, B.A.; Gladkov, D.; Sosnovtsev, V.; Suchkov, S.; Dementiev, R.K.; Ermolov, P.F.; Golubkov, Yu.A.; Katkov, I.I.; Khein, L.A.; Korotkova, N.A.; Korzhavina, I.A.; Kuzmin, V.A.; Levchenko, B.B.; Lukina, O.Yu.; Proskuryakov, A.S.; Shcheglova, L.M.; Solomin, A.N.; Vlasov, N.N.; Zotkin, S.A.; Bokel, C.; Engelen, J.; Grijpink, S.; Koffeman, E.; Kooijman, P.; Maddox, E.; Schagen, S.; Tassi, E.; Tiecke, H.; Tuning, N.; Velthuis, J.J.; Wiggers, L.; de Wolf, E.; Bruemmer, N.; Bylsma, B.; Durkin, L.S.; Gilmore, J.; Ginsburg, C.M.; Kim, C.L.; Ling, T.Y.; Boogert, S.; Cooper-Sarkar, A.M.; Devenish, R.C.E.; Ferrando, J.; Matsushita, T.; Rigby, M.; Ruske, O.; Sutton, M.R.; Walczak, R.; Brugnera, R.; Carlin, R.; Dal Corso, F.; Dusini, S.; Garfagnini, A.; Limentani, S.; Longhin, A.; Parenti, A.; Posocco, M.; Stanco, L.; Turcato, M.; Adamczyk, L.; Oh, B.Y.; Saull, P.R.B.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cormack, C.; Hart, J.C.; McCubbin, N.A.; Heusch, C.; Park, I.H.; Pavel, N.; Abramowicz, H.; Dagan, S.; Gabareen, A.; Kananov, S.; Kreisel, A.; Levy, A.; Abe, T.; Fusayasu, T.; Kohno, T.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Inuzuka, M.; Kitamura, S.; Matsuzawa, K.; Nishimura, T.; Arneodo, M.; Cartiglia, N.; Cirio, R.; Costa, M.; Ferrero, M.I.; Maselli, S.; Monaco, V.; Peroni, C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Galea, R.; Koop, T.; Levman, G.M.; Martin, J.F.; Mirea, A.; Sabetfakhri, A.; Butterworth, J.M.; Gwenlan, C.; Hall-Wilton, R.; Hayes, M.E.; Heaphy, E.A.; Jones, T.W.; Lane, J.B.; Lightwood, M.S.; West, B.J.; Ciborowski, J.; Ciesielski, R.; Grzelak, G.; Nowak, R.J.; Pawlak, J.M.; Smalska, B.; Sztuk, J.; Tymieniecka, T.; Ukleja, A.; Ukleja, J.; Zakrzewski, J.A.; Zarnecki, A.F.; Adamus, M.; Plucinski, P.; Eisenberg, Y.; Gladilin, L.K.; Hochman, D.; Karshon, U.; Breitweg, J.; Chapin, D.; Cross, R.; Kcira, D.; Lammers, S.; Reeder, D.D.; Savin, A.A.; Smith, W.H.; Deshpande, A.; Dhawan, S.; Hughes, V.W.; Straub, P.B.; Bhadra, S.; Catterall, C.D.; Fourletov, S.; Menary, S.; Soares, M.; Standage, J.

2002-01-01

The photon-proton total cross section has been measured in the process e + p→e + γp→e + X with the ZEUS detector at HERA. Events were collected with photon virtuality Q 2 2 and average γp center-of-mass energy W γp =209 GeV in a dedicated run, designed to control systematic effects, with an integrated luminosity of 49 nb -1 . The measured total cross section is σ tot γp =174±1 (stat.)±13 (syst.) μb. The energy dependence of the cross section is compatible with parameterizations of high-energy pp and pp-bar data

Photoproduction of isolated photons, inclusively and with a jet, at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Raymond and Beverly Sackler Faculty of Exact Sciences, School of Physics, Tel Aviv University, Tel Aviv (Israel); Abt, I. [Max-Planck-Institut für Physik, München (Germany); Adamczyk, L. [AGH—University of Science and Technology, Faculty of Physics and Applied Computer Science, Krakow (Poland); Adamus, M. [National Centre for Nuclear Research, Warsaw (Poland); Aggarwal, R. [Panjab University, Department of Physics, Chandigarh (India); Antonelli, S. [University and INFN Bologna, Bologna (Italy); Arslan, O. [Physikalisches Institut der Universität Bonn, Bonn (Germany); Aushev, V. [Institute for Nuclear Research, National Academy of Sciences, Kyiv (Ukraine); Department of Nuclear Physics, National Taras Shevchenko University of Kyiv, Kyiv (Ukraine); Aushev, Y. [Department of Nuclear Physics, National Taras Shevchenko University of Kyiv, Kyiv (Ukraine); Bachynska, O. [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Barakbaev, A.N. [Institute of Physics and Technology of Ministry of Education and Science of Kazakhstan, Almaty (Kazakhstan); Bartosik, N.; Behnke, O.; Behr, J.; Behrens, U. [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Bertolin, A. [INFN Padova, Padova (Italy); Bhadra, S. [Department of Physics, York University, Ontario, M3J 1P3 (Canada); Bloch, I. [Deutsches Elektronen-Synchrotron DESY, Zeuthen (Germany); Bokhonov, V. [Institute for Nuclear Research, National Academy of Sciences, Kyiv (Ukraine); Boos, E.G. [Institute of Physics and Technology of Ministry of Education and Science of Kazakhstan, Almaty (Kazakhstan); and others

2014-03-07

The photoproduction of isolated photons, both inclusive and together with a jet, has been measured with the ZEUS detector at HERA using an integrated luminosity of 374 pb{sup −1}. Differential cross sections are presented in the isolated-photon transverse-energy and pseudorapidity ranges 6

Exclusive electroproduction of two pions at HERA

CERN Document Server

Abramowicz, H.

2012-01-25

The exclusive electroproduction of two pions in the mass range 0.4 < M{\\pi}{\\pi} < 2.5 GeV has been studied with the ZEUS detector at HERA using an integrated luminosity of 82 pb-1. The analysis was carried out in the kinematic range of 2 < Q2 < 80 GeV2, 32 < W < 180 GeV and |t| < 0.6 GeV2, where Q2 is the photon virtuality, W is the photon-proton centre-of-mass energy and t is the squared four-momentum transfer at the proton vertex. The two-pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, |F(M{\\pi}{\\pi})|, assuming that the studied mass range includes the contributions of the {\\rho}, {\\rho}' and {\\rho}" vector-meson states. The masses and widths of the resonances were obtained and the Q2 dependence of the cross-section ratios {\\sigma}({\\rho}' \\rightarrow {\\pi}{\\pi})/{\\sigma}({\\rho}) and {\\sigma}({\\rho}" \\rightarrow {\\pi}{\\pi})/{\\sigma}({\\rho}) was extracted. The pion form factor obtained in the present analysis is compared to that obtained...

Measurement of beauty production in deep inelastic scattering at HERA using decays into electrons

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max-Planck-Institut fuer Physik, Muenchen (Germany); Abt, I. [Max-Planck-Institut fuer Physik, Muenchen (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Cracow (PL). Faculty of Physics and Applied Computer Science] (and others)

2011-01-15

The production of beauty quarks in ep interactions has been studied with the ZEUS detector at HERA for exchanged four-momentum squared Q{sup 2}>10 GeV{sup 2}, using an integrated luminosity of 363 pb{sup -1}. The beauty events were identified using electrons from semileptonic b decays with a transverse momentum 0.9

Measurement of neutral current e{sup {+-}}p cross sections at high Bjorken x with the ZEUS detector

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max-Planck-Institute for Physics, Munich (Germany); Abt, I. [Max-Planck-Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science; Collaboration: ZEUS Collaboration; and others

2013-12-15

The neutral current e{sup {+-}}p cross section has been measured up to values of Bjorken x{approx_equal}1 with the ZEUS detector at HERA using an integrated luminosity of 187 pb{sup -1} of e{sup -}p and 142 pb{sup -1} of e{sup +}p collisions at {radical}(s)=318 GeV. Differential cross sections in x and Q{sup 2}, the exchanged boson virtuality, are presented for Q{sup 2}{>=}725 GeV{sup 2}. An improved reconstruction method and greatly increased amount of data allows a finer binning in the high-x region of the neutral current cross section and leads to a measurement with much improved precision compared to a similar earlier analysis. The measurements are compared to Standard Model expectations based on a variety of recent parton distribution functions.

Studies of the diffractive photoproduction of isolated photons at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2017-01-01

The photoproduction of isolated photons has been measured in diffractive events recorded by the ZEUS detector at HERA. Cross sections are evaluated in the photon transverse-energy and pseudorapidity ranges 50.9, where z meas P is the fraction of the longitudinal momentum of the colourless ''Pomeron'' exchange that is transferred to the photon-jet final state, giving evidence for direct Pomeron interactions.

Inclusive K{sup 0}{sub S}K{sup 0}{sub S} resonance production in ep collisions at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2008-06-15

Inclusive K{sup 0}{sub S}K{sup 0}{sub S} production in ep collisions at HERA was studied with the ZEUS detector using an integrated luminosity of 0.5 fb{sup -1}. Enhancements in the mass spectrum were observed and are attributed to the production of f{sub 2}(1270)/a{sup 0}{sub 2}(1320), f'{sub 2}(1525) and f{sub 0}(1710). The f{sub 0}(1710) state was observed with a statistical significance of 5 standard deviations. Masses and widths were obtained using a fit which takes into account theoretical predictions based on SU(3) symmetry arguments. (orig.)

Combined measurement and QCD analysis of the inclusive e{sup {+-}}p scattering cross sections at HERA

Energy Technology Data Exchange (ETDEWEB)

Aaron, F.D. [National Inst. for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Bucharest Univ. (Romania). Faculty of Physics; Abramowicz, H. [Tel Aviv Univ. (Israel). Raymond and Beverly Sackler Faculty of Exact Sciences, School of Physics; Max-Planck-Institute, Muenchen (Germany); Abt, I. [Max-Planck-Institut fuer Physik, Muenchen (DE)] (and others)

2009-10-15

A combination is presented of the inclusive deep inelastic cross sections measured by the H1 and ZEUS Collaborations in neutral and charged current unpolarised e{sup {+-}}p scattering at HERA during the period 1994-2000. The data span six orders of magnitude in negative four-momentum-transfer squared, Q{sup 2}, and in Bjorken x. The combination method used takes the correlations of systematic uncertainties into account, resulting in an improved accuracy. The combined data are the sole input in a NLO QCD analysis which determines a new set of parton distributions HERAPDF1.0 with small experimental uncertainties. This set includes an estimate of the model and parametrisation uncertainties of the fit result. (orig.)

News from the proton - recent DIS results from HERA

Energy Technology Data Exchange (ETDEWEB)

Meier, K. [Heidelberg Univ. (Germany)

1997-01-01

Recent results from the two large general-purpose detectors H1 and ZEUS at HERA (DESY, Hamburg, Germany) are presented. Emphasis is given to the analysis of deep inelastic scattering defined by the observation of the scattered electron or positron in the main calorimeters. Results on purely inclusive cross sections lead to a determination of the charged (quarks) parton distribution F{sub 2}(x, Q{sup 2}). Access to the electrically neutral parton content (gluons) is obtained indirectly by an analysis of the expected scaling violation behavior of F{sub 2} or directly from multijet rates originating from well-defined initial parton configurations. Finally, the recently uncovered subclass of large rapidity gap (LRG) events has been analyzed in terms of F{sub 2}. The result supports the concept of a color neutral object (Pomeron IP) being probed by a hard scattering electron. Evidence for factorization of the Pomeron radiation process as well as for scaling in the inclusive IP structure functions has been found.

Dijet production in diffractive deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2007-08-15

The production of dijets in diffractive deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 61 pb{sup -1}. The dijet cross section has been measured for virtualities of the exchanged virtual photon, 54 GeV and the jet with the highest transverse energy was required to have E{sup *}{sub T,jet}>5 GeV. All jets were required to be in the pseudorapidity range -3.5<{eta}{sup *}{sub jet}<0. The differential cross sections are compared to leading-order predictions and next-to-leading- order QCD calculations based on recent diffractive parton densities extracted from inclusive diffractive deep inelastic scattering data. (orig.)

Searches for excited fermions in ep collisions at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Krakauer, D.

2002-01-01

Searches in ep collisions for heavy excited fermions have been performed with the ZEUS detector at HERA. Excited states of electrons and quarks have been searched for in e + p collisions at a centre-of-mass energy of 300 GeV using an integrated luminosity of 47.7 pb -1 . Excited electrons have been sought via the decays e*→eγ, e*→eZ and e*→νW. Excited quarks have been sought via the decays q*→qγ and q*→qW. A search for excited neutrinos decaying via ν*→νγ, ν*→νZ and ν*→eW is presented using e - p collisions at 318 GeV centre-of-mass energy, corresponding to an integrated luminosity of 16.7 pb -1 . No evidence for any excited fermion is found, and limits on the characteristic couplings are derived for masses ≤250 GeV

Development of the calorimeter trigger for the ZEUS detector

International Nuclear Information System (INIS)

Smith, W.H.

1988-01-01

The purpose of this research was to begin development of the trigger for the calorimeter of the ZEUS detector at HERA, a new storage ring that will provide collisions between 820 GeV protons and 30 GeV electrons by 1990. The calorimeter will be made of depleted uranium plates and plastic scintillator read out by wavelength shifter bars into 12,000 photomultiplier tubes. These signals will be combined into 1000 towers with separate electromagnetic and hadronic sums. The calorimeter first level trigger will be pipelined with a decision provided 5 μsec after each beam crossing, occurring every 96 nsec. The trigger will need to determine the total energy, the total transverse energy, the missing energy, and the energy and number of jets and isolated electrons. The trigger rate needs to be held to 1 kHz against a rate of proton-beam gas interactions of 200 kHz. The summed pulseheights will be digitized by 8-bit flash ADC's. They will be linearized, stored and manipulated digitally. The various pipelined sums will be made using ECL and CMOS technology.This grant was used to investigate these technologies, model the trigger performance, and begin the design. This research will be continued by this principal investigator under another DOE grant at the University of Wisconsin

Measurement of D*± meson production in deep-inelastic scattering at HERA

International Nuclear Information System (INIS)

Bachynska, Olena

2012-12-01

Measurements of charm production in deep-inelastic scattering at HERA at a centre-of-mass energy of 318 GeV are reported in this thesis. The analysis was performed using the data collected with the ZEUS detector during the years 2004 to 2007, corresponding to an integrated luminosity of 363 pb -1 . The production of charm quarks was studied through the full kinematic reconstruction of D* ± mesons in the decay channel D* ± → D 0 / anti D 0 π ± . The studies have been performed for virtualities of the exchanged photon of 5 2 2 and inelasticities of 0.02 ± kinematic phase space is defined by the transverse momentum range, 1.5 T D* ± D* ± vertical stroke ± mesons. The total visible cross section for D* ± production as well as single-and double-differential cross sections were measured and compared to the corresponding D* ± measurements performed by the H1 collaboration in the same phase-space region. The measurements are well described by NLO QCD predictions. The double-differential cross sections were exploited to extract the charm contribution to the proton structure function, F 2 c anti c , expressed in terms of the reduced charm-production cross sections, σ red c anti c , and compared to the predictions from HERAPDF1.5 and to the recent measurements from the H1 and ZEUS collaborations.

Measruement of beauty production in DIS and F{sub 2}{sup b} {sup anti} {sup b} extraction at ZEUS

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Univ. College London (United Kingdom); Max Planck Institute, Munich (Germany); Abt, I. [Max-Planck-Institut fuer Physik, Muenchen (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Cracow (PL). Faculty of Physics and Applied Computer Science] (and others)

2010-04-15

Beauty production in deep inelastic scattering with events in which a muon and a jet are observed in the final state has been measured with the ZEUS detector at HERA using an integrated luminosity of 114 pb{sup -1}. The fraction of events with beauty quarks in the data was determined using the distribution of the transverse momentum of the muon relative to the jet. The cross section for beauty production was measured in the kinematic range of photon virtuality, Q{sup 2}>2 GeV{sup 2}, and inelasticity, 0.05

Experimentation at HERA

International Nuclear Information System (INIS)

1983-10-01

These proceedings contain three articles concerning the physics which can be studied by HERA, which were presented at the named workshop, together with convenor reports on working groups which concern technologies, the intersecting regions, photoproduction at HERA, currents and structure functions, exotic phenomena at HERA, and the use of existing detectors. Finally the experimental halls at HERA are described. Separated abstracts were prepared for the articles in these proceedings. (HSI)

Preservation of the HERA-B Collaboration heritage

International Nuclear Information System (INIS)

Ozerov, Dmitry; Rostovtseva, Irina; Goloubkov, Dmitri

2011-01-01

We present the concept of the data preservation developed for the HERA-B experiment which studied proton-nucleus interactions of the 920 GeV/c beam at HERA/DESY. The full analysis chain (starting from raw data) is to be preserved based on the rolling DPHEP model with open access to the data. We have frozen the full working analysis software environment using chroot-jail virtualization and report first experience of porting the software to a newer OS/compiler.

Measurement of dijet cross sections for events with a leading neutron in photoproduction at HERA

Energy Technology Data Exchange (ETDEWEB)

Breitweg, J.; Chekanov, S.; Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Pellegrino, A.; Repond, J.; Stanek, R.; Yoshida, R.; Mattingly, M.C.K.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Sartorelli, G.; Zichichi, A.; Amelung, C.; Bornheim, A.; Brock, I.; Coboeken, K.; Crittenden, J.; Deffner, R.; Hartmann, H.; Heinloth, K.; Hilger, E.; Irrgang, P.; Jakob, H.-P.; Kappes, A.; Katz, U.F.; Kerger, R.; Paul, E.; Rautenberg, J.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K.C.; Weber, A.; Wieber, H.; Bailey, D.S.; Barret, O.; Brook, N.H.; Foster, B. E-mail: b.foster@bristol.ac.uk; Heath, G.P.; Heath, H.F.; Rodrigues, E.; Scott, J.; Tapper, R.J.; Capua, M.; Schioppa, M.; Susinno, G.; Jeoung, H.Y.; Kim, J.Y.; Lee, J.H.; Lim, I.T.; Ma, K.J.; Pac, M.Y.; Caldwell, A.; Liu, W.; Liu, X.; Mellado, B.; Paganis, S.; Sampson, S.; Schmidke, W.B.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Klimek, K.; Olkiewicz, K.; Piotrzkowski, K.; Przybycien, M.B.; Stopa, P.; Zawiejski, L.; Bednarek, B.; Jelen, K.; Kisielewska, D.; Kowal, A.M.; Kowalski, T.; Przybycien, M.; Rulikowska-Zarebska, E.; Suszycki, L.; Szuba, D.; Kotanski, A.; Bauerdick, L.A.T.; Behrens, U.; Bienlein, J.K.; Borras, K.; Chiochia, V.; Dannheim, D.; Desler, K.; Drews, G.; Fox-Murphy, A.; Fricke, U.; Goebel, F.; Goers, S.; Goettlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G.F.; Hebbel, K.; Hillert, S.; Koch, W.; Koetz, U.; Kowalski, H.; Labes, H.; Loehr, B.; Mankel, R.; Martens, J.; Martinez, M.; Milite, M.; Moritz, M.; Notz, D.; Petrucci, M.C.; Polini, A.; Rohde, M.; Savin, A.A.; Schneekloth, U.; Selonke, F.; Sievers, M.; Stonjek, S.; Wolf, G.; Wollmer, U.; Youngman, C.; Zeuner, W.; Coldewey, C.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.[and others

2001-02-26

Differential cross sections for dijet photoproduction in association with a leading neutron using the reaction e{sup +}+p{yields}e{sup +}+n+jet+jet+X{sub r} have been measured with the ZEUS detector at HERA using an integrated luminosity of 6.4 pb{sup -1}. The fraction of dijet events with a leading neutron in the final state was studied as a function of the jet kinematic variables. The cross sections were measured for jet transverse energies E{sub T}{sup jet}>6 GeV, neutron energy E{sub n}>400 GeV, and neutron production angle {theta}{sub n}<0.8 mrad. The data are broadly consistent with factorization of the lepton and hadron vertices and with a simple one-pion-exchange model.

Measurement of the t dependence in exclusive photoproduction of Υ(1S) mesons at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2011-10-01

The exclusive photoproduction reaction γp→Υ(1S)p has been studied with the ZEUS detector in ep collisions at HERA using an integrated luminosity of 468 pb -1 . The measurement covers the kinematic range 60 2 2 , where W is the photon-proton centre-of-mass energy and Q 2 is the photon virtuality. The exponential slope, b, of the t dependence of the cross section, where t is the squared four-momentum transfer at the proton vertex, has been measured, yielding b=4.3 +2.0 -1.3 (stat.) +0.5 -0.6 (syst.) GeV -2 . This constitutes the first measurement of the t dependence of the γp→Υ(1S)p cross section. (orig.)

Measurement of charm and beauty production in deep inelastic ep scattering from decays into muons at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S

2009-04-01

The production of charm and beauty quarks in ep interactions has been measured with the ZEUS detector at HERA for squared four-momentum exchange Q 2 > 20GeV 2 , using an integrated luminosity of 126 pb -1 . Charm and beauty quarks were identified through their decays into muons. Differential cross sections were measured for muon transverse momenta p T μ >1.5 GeV and pseudorapidities -1.6 μ T μ , η μ , Q 2 and Bjorken x. The charm and beauty contributions to the proton structure function F 2 were also extracted. The results agree with previous measurements based on independent techniques and are well described by QCD predictions. (orig.)

Measurement of beauty and charm production in deep inelastic scattering at HERA and measurement of the beauty-quark mass

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2014-05-01

The production of beauty and charm quarks in ep interactions has been studied with the ZEUS detector at HERA for exchanged four-momentum squared 5 2 2 using an integrated luminosity of 354 pb -1 . The beauty and charm content in events with at least one jet have been extracted using the invariant mass of charged tracks associated with secondary vertices and the decay-length significance of these vertices. Differential cross sections as a function of Q 2 , Bjorken x, jet transverse energy and pseudorapidity were measured and compared with next-to-leading-order QCD calculations. The beauty and charm contributions to the proton structure functions were extracted from the double-differential cross section as a function of x and Q 2 . The running beauty-quark mass, m b at the scale m b , was determined from a QCD fit at next-to-leading order to HERA data for the first time and found to be m b (m b )=4.07±0.14(fit) +0.01 -0.07 (mod.) +0.05 -0.00 (param.) +0.08 -0.05 (theo) GeV.

Measurement of the proton structure from high-Q2 neutral current events in e+p deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Schnurbusch, H.

2002-09-01

Inclusive Neutral Current cross sections in e + p deep inelastic scattering yielding the generalised structure function F 2 have been measured in the regime of Q 2 > 185 GeV 2 . The data sample of 63.2 pb -1 was collected in the 1999/2000 data-taking period of the ZEUS experiment at the HERA collider. The centre-of-mass energy was √(s) = 318 GeV. Statistical and systematic uncertainties have been calculated throughout the kinematical range of the data. Systematic uncertainties were studied including photoproduction background, first-level trigger efficiency and the hadronic final state in the Forward Tracking Devices of the detector. The structure function F 2 was measured more precisely than in earlier measurements due to the larger data set and due to increased knowledge about systematic effects. The results are in good agreement with the Standard Model evaluated with the CTEQ5D parton distribution functions. (orig.)

Angular correlations in three-jet events in ep collisions at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, B.

2008-07-01

Three-jet production in deep inelastic ep scattering and photoproduction was investigated with the ZEUS detector at HERA using an integrated luminosity of 127 pb -1 . Measurements of differential cross sections are presented as functions of angular correlations between the three jets in the final state and the proton-beam direction. These correlations provide a stringent test of perturbative QCD and show sensitivity to the contributions from different colour configurations. Fixed-order perturbative QCD calculations assuming the values of the colour factors C F , C A and T F as derived from a variety of gauge groups were compared to the measurements to study the underlying gauge group symmetry. The measured angular correlations in the deep inelastic ep scattering and photoproduction regimes are consistent with the admixture of colour configurations as predicted by SU(3) and disfavour other symmetry groups, such as SU(N) in the limit of large N

Exclusive {rho}{sup 0} production in deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2007-08-15

Exclusive {rho}{sup 0} electroproduction at HERA has been studied with the ZEUS detector using 120 pb{sup -1} of integrated luminosity collected during 1996-2000. The analysis was carried out in the kinematic range of photon virtuality 2

High-E{sub T} dijet photoproduction at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2007-06-15

The cross section for high-E{sub T} dijet production in photoproduction has been measured with the ZEUS detector at HERA using an integrated luminosity of 81.8 pb{sup -1}. The events were required to have a virtuality of the incoming pho- ton, Q{sup 2}, of less than 1 GeV{sup 2} and a photon-proton centre-of-mass energy in the range 14220 GeV and E{sub T}{sup jet2}>15 GeV and pseudorapidity requirements of -1<{eta}{sup jet1,2}<3, with at least one of the jets satisfying -1<{eta}{sup jet}<2.5. The measurements show sensitivity to the parton distributions in the photon and proton and effects beyond next-to-leading order in QCD. Hence these data can be used to constrain further the parton densities in the proton and photon. (orig.)

Studies of the diffractive photoproduction of isolated photons at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institut fuer Physik, Muenchen (Germany); Adamczyk, L. [AGH Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science; Collaboration: ZEUS Collaboration; and others

2017-07-20

The photoproduction of isolated photons has been measured in diffractive events recorded by the ZEUS detector at HERA. Cross sections are evaluated in the photon transverse-energy and pseudorapidity ranges 50.9, where z{sup meas}{sub P} is the fraction of the longitudinal momentum of the colourless ''Pomeron'' exchange that is transferred to the photon-jet final state, giving evidence for direct Pomeron interactions.

Measurement of K{sup 0}{sub S}, {lambda} and anti {lambda} production at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2006-12-15

The production of the neutral strange hadrons K{sup 0}{sub S}, {lambda} and anti {lambda} has been measured in ep collisions at HERA using the ZEUS detector. Cross sections, baryon-to-meson ratios, relative yields of strange and charged light hadrons, {lambda} (anti {lambda}) asymmetry and polarization have been measured in three kinematic regions: Q{sup 2}>25 GeV{sup 2}; 5

Search for a narrow baryonic state decaying to pK{sup 0}{sub S} and anti pK{sup 0}{sub S} in deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max-Planck-Institute for Physics, Munich (Germany); Abt, I. [Max-Planck-Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science; Collaboration: ZEUS Collaboration; and others

2016-06-15

A search for a narrow baryonic state in the pK{sup 0}{sub S} and anti pK{sup 0}{sub S} system has been performed in ep collisions at HERA with the ZEUS detector using an integrated luminosity of 358 pb{sup -1} taken in 2003-2007. The search was performed with deep inelastic scattering events at an ep centre-of-mass energy of 318 GeV for exchanged photon virtuality, Q{sup 2}, between 20 and 100 GeV{sup 2}. Contrary to evidence presented for such a state around 1.52 GeV in a previous ZEUS analysis using a sample of 121 pb{sup -1} taken in 1996-2000, no resonance peak was found in the p(anti p)K{sup 0}{sub S} invariant-mass distribution in the range 1.45-1.7 GeV. Upper limits on the production cross section are set.

DESY. Scientific annual report 2006; DESY. Wissenschaftlicher Jahresbericht 2006

Energy Technology Data Exchange (ETDEWEB)

NONE

2007-06-15

The following topics are dealt with: The H1 experiment, the ZEUS experiment, the HERMES experiment, the HERA-B experiment, the ATLAS experiment, the CMS experiment, astroparticle physics, theoretical work on the standard model and its possible extensions, particle cosmology, string theory, and lattice gauge theory, the International Linear Collider, linear-accelerator technologies, the storage rings HERA and DORIS III, the preaccelerators, the free electron laser FLASH, the future synchrotron radiation source PETRA III, the XFEL, accelerator technologies concerning injection and ejection, RF techniques, accelerator control, personnel safety system, beam diagnostics and instrumentation, beam control, vacuum techniques, cryogenics and superconductivity, power supplies, as well as vacuum techniques. (HSI)

DESY. Scientific annual report 2006

International Nuclear Information System (INIS)

2007-06-01

The following topics are dealt with: The H1 experiment, the ZEUS experiment, the HERMES experiment, the HERA-B experiment, the ATLAS experiment, the CMS experiment, astroparticle physics, theoretical work on the standard model and its possible extensions, particle cosmology, string theory, and lattice gauge theory, the International Linear Collider, linear-accelerator technologies, the storage rings HERA and DORIS III, the preaccelerators, the free electron laser FLASH, the future synchrotron radiation source PETRA III, the XFEL, accelerator technologies concerning injection and ejection, RF techniques, accelerator control, personnel safety system, beam diagnostics and instrumentation, beam control, vacuum techniques, cryogenics and superconductivity, power supplies, as well as vacuum techniques. (HSI)

ZEXP - expert system for ZEUS

International Nuclear Information System (INIS)

Behrens, U.; Flasinski, M.; Hagge, L.

1992-10-01

The proper and timely reactions to errors occurring in the online data-acquisition (DAQ) system are necessary conditions of smooth data taking during the experiment runs. Since the Eventbuilder (EVB) is a central part of the ZEUS DAQ system, it is the best place for monitoring, detecting, and recognizing erroneous behaviour. ZEXP is a software tool for upgrading the DAQ system performance. The pattern recognition methodology used for designing one of its two main modules is discussed. The general design ideas of the system and some preliminary results from the summarizing run module are presented, as well. (orig.)

A first measurement of the charged current DIS cross sections with longitudinally polarised electrons in the H1 experiment at HERA

Energy Technology Data Exchange (ETDEWEB)

Antunovic, B.

2007-07-01

The analysis presented in this thesis is based on data from electron-proton collisions with longitudinally polarised electron beams at a centre-of-mass energy of {radical}(s)=319 GeV. The data were taken with the H1 detector at the HERA collider in the year 2005 corresponding to two polarisation states: a left-handed electron polarisation of -27% and a right-handed electron polarisation of +37%, corresponding to integrated luminosities of 68.6 pb{sup -1} and 29.6 pb{sup -1}, respectively. The inclusive total deep inelastic charged current cross section and the differential cross sections are measured for both helicities in the kinematic domain Q{sup 2}>400 GeV{sup 2} and y<0.9. The entire analysis chain necessary for the determination of the cross sections is described with emphasis on the understanding of the performance of the Liquid Argon trigger system. The experimental results obtained are consistent with the predictions of the Standard Model. In particular, the measurement of the total polarised charged current cross section confirms the Standard Model expectation that there are no weak charged current interactions mediated by a hypothetical right-handed W boson. In addition, a measurement of the charged current structure function F{sup cc}{sub 2} has been performed at the H1 experiment for the first time. The measurements are well described by the theoretical expectations based on parton distributions derived from inclusive neutral current measurements in H1, and are in agreement with published data from the ZEUS (e{sup {+-}}p) and CCFR (anti {nu}{sub {mu}}Fe) experiments. (orig.)

Measurement of αs from jet rates in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magill, S.

1995-10-01

Jet production in deep inelastic scattering for 120 2 2 has been studied using data from an integrated luminosity of 3.2 pb -1 collected with the ZEUS detector at HERA. Jets are identified with the JADE algorithm. A cut on the angular distribution of parton emission in the γ-parton centre-of-mass system minimises the experimental and theoretical uncertainties in the determination of the jet rates. The jet rates, when compared to OMIKRON (α s 2 ) perturbative QCD calculations, allow a precise determination of α s (Q) in three Q 2 -intervals. The values are consistent with a running of α s (Q), as expected from QCD. Extrapolating to Q=M (Z 0 ) yields α s (M Z 0 )=0.117±0.005(stat) -0.005 +0.004 (syst exp )±0. 007(syst theory ). (orig.)

Results from the H1 experiment at HERA

International Nuclear Information System (INIS)

Roeck, A. de

1994-01-01

New results from the H1 experiment at HERA on photoproduction, deep inelastic scattering and search for exotic particles are presented. Clear evidence is found for hard scattering in photoproduction interactions. Jets have been observed and used to examine the x γ distribution, indicating the need for a gluonic component in the photon. Hadronic final states and jet cross sections have been measured in deep inelastic scattering. A class of deep inelastic events with diffractive characteristics has been observed. The proton structure function F 2 (x, Q 2 ) has been measured in the new Bjorken-x region 10 -4 -2 and is found to rise with decreasing x. New limits for leptoquarks, squarks and excited electrons have been deduced. (orig.)

Measurement of azimuthal asymmetries in neutral current deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2006-08-15

The distribution of the azimuthal angle of charged and neutral hadrons relative to the lepton plane has been studied for neutral current deep inelastic ep scattering using an integrated luminosity of 45 pb{sup -1} taken with the ZEUS detector at HERA. The measurements were made in the hadronic centre-of-mass system. The analysis exploits the energy-flow method, which allows the measurement to be made over a larger range of pseudorapidity compared to previous results. The dependence of the moments of the azimuthal distributions on the pseudorapidity and minimum transverse energy of the final-state hadrons are presented. Although the predictions from next-to-leading-order QCD describe the data better than do the Monte Carlo models incorporating leading-logarithm parton showers, they still fail to describe the magnitude of the asymmetries. This suggests that higher-order calculations may be necessary to describe these data. (Orig.)

Measurement of azimuthal asymmetries in neutral current deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2006-08-01

The distribution of the azimuthal angle of charged and neutral hadrons relative to the lepton plane has been studied for neutral current deep inelastic ep scattering using an integrated luminosity of 45 pb -1 taken with the ZEUS detector at HERA. The measurements were made in the hadronic centre-of-mass system. The analysis exploits the energy-flow method, which allows the measurement to be made over a larger range of pseudorapidity compared to previous results. The dependence of the moments of the azimuthal distributions on the pseudorapidity and minimum transverse energy of the final-state hadrons are presented. Although the predictions from next-to-leading-order QCD describe the data better than do the Monte Carlo models incorporating leading-logarithm parton showers, they still fail to describe the magnitude of the asymmetries. This suggests that higher-order calculations may be necessary to describe these data. (Orig.)

Applications of the leading-order Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations to the combined HERA data on deep inelastic scattering

International Nuclear Information System (INIS)

Block, Martin M.; Durand, Loyal; Ha, Phuoc; McKay, Douglas W.

2011-01-01

We recently derived explicit solutions of the leading-order Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations for the Q 2 evolution of the singlet structure function F s (x,Q 2 ) and the gluon distribution G(x,Q 2 ) using very efficient Laplace transform techniques. We apply our results here to a study of the HERA data on deep inelastic ep scattering as recently combined by the H1 and ZEUS groups. We use initial distributions F 2 γp (x,Q 0 2 ) and G(x,Q 0 2 ) determined for x s (x,Q 0 2 ) from F 2 γp (x,Q 0 2 ) using small nonsinglet quark distributions taken from either the CTEQ6L or the MSTW2008LO analyses, evolve F s and G to arbitrary Q 2 , and then convert the results to individual quark distributions. Finally, we show directly from a study of systematic trends in a comparison of the evolved F 2 γp (x,Q 2 ) with the HERA data that the assumption of leading-order DGLAP evolution is inconsistent with those data.

[CII] At 1 Universe with Zeus (1 and 2)

Science.gov (United States)

Ferkinhoff, Carl; Hailey-Dunsheath, S.; Nikola, T.; Oberst, T.; Parshley, S.; Stacey, G.; Benford, D.; staguhn, J.

2010-01-01

We report the detection of the [CII] 158 micron fine structure line from six submillimeter galaxies with redshifts between 1.12 and 1.73. This more than doubles the total number of [CII] 158 micron detections reported from high redshift sources. These observations were made with the Redshift(z) and Early Universe Spectrometer(ZEUS) at the Caltech Submillimeter Observatory on Mauna Kea, Hawaii between December 2006 and March 2009. ZEUS is a background limited submm echelle grating spectrometer (Hailey-Dunsheath 2009). Currently we are constructing ZEUS-2. This new instrument will utilize the same grating but will feature a two dimensional transition-edge sensed bolometer array with SQUID multiplexing readout system enabling simultaneous background limited observations in the 200, 340,450 and 650 micron telluric windows. ZEUS-2 will allow for long slit imaging spectroscopy in nearby galaxies and a [CII] survey from z 0.25 to 2.5.

Production of exclusive dijets in diffractive deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2015-05-01

Production of exclusive dijets in diffractive deep inelastic e ± p scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 372 pb -1 . The measurement was performed for γ * -p centre-of-mass energies in the range 9025 GeV 2 . Energy and transverse-energy flows around the jet axis are presented. The cross section is presented as a function of β and φ, where β=x/x P , x is the Bjorken variable and x P is the proton fractional longitudinal momentum loss. The angle φ is defined by the γ * -dijet plane and the γ * -e ± plane in the rest frame of the diffractive final state. The φ cross section is measured in bins of β. The results are compared to predictions from models based on different assumptions about the nature of the diffractive exchange.

Inclusive charm production at HERA and charm content of the proton

Energy Technology Data Exchange (ETDEWEB)

Drees, M [Wisconsin Univ., Madison, WI (United States). Dept. of Physics; Godbole, R M [Istituto Nazionale di Fisica Nucleare, Frascati (Italy)

1995-05-01

The authors calculate the contribution to inclusive high transverse momentum (p{sub T}) charm production at HERA (hadron electron ring at large) from the excitation of charm in the photon. At large values of p{sub T} the results of such a calculation, in the structure function language, will be more reliable as it sums the large logs log(p{sub T}{sup 2}/m{sub C}{sup 2}), as opposed to calculating the contribution of the 2{yields}3 subprocesses in fixed order of perturbation theory. They find that this contribution is large and comparable to the contribution from {gamma}g fusion production of charm. Suitable cuts on the rapidity of the `away-side` large p{sub T} jet allow a very neat separation between the contributions from the excitation process and from pair-production. Including this excitation contribution the authors can reproduce the measured inclusive D{sup *} and {mu} cross-section measured by the ZEUS and H1 collaborations respectively, in a LO calculation.

Angular correlations in three-jet events in ep collisions at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, B. [Argonne National Laboratory, Illinois (US)] (and others)

2008-07-15

Three-jet production in deep inelastic ep scattering and photoproduction was investigated with the ZEUS detector at HERA using an integrated luminosity of 127 pb{sup -1}. Measurements of differential cross sections are presented as functions of angular correlations between the three jets in the final state and the proton-beam direction. These correlations provide a stringent test of perturbative QCD and show sensitivity to the contributions from different colour configurations. Fixed-order perturbative QCD calculations assuming the values of the colour factors C{sub F}, C{sub A} and T{sub F} as derived from a variety of gauge groups were compared to the measurements to study the underlying gauge group symmetry. The measured angular correlations in the deep inelastic ep scattering and photoproduction regimes are consistent with the admixture of colour configurations as predicted by SU(3) and disfavour other symmetry groups, such as SU(N) in the limit of large N.

Measurement of neutral current deep inelastic e+p scattering cross sections with longitudinally polarized positrons with ZEUS at HERA

International Nuclear Information System (INIS)

Wlasenko, Michal

2009-05-01

Measurements of neutral current deep inelastic scattering of protons colliding with longitudinally polarized positrons, performed with data recorded in years 2006 and 2007 with the ZEUS detector, corresponding to an integrated luminosity of L=113.3 pb -1 , are presented. The single-differential cross sections dσ/dQ 2 , dσ/dx, dσ/dy and the double-differential reduced cross section σ were measured in the kinematic region of 185 2 2 and y + and the generalized structure function x F 3 were extracted. All measurements agree well with the predictions of the Standard Model. (orig.)

Development, construction and test of the planar forward drift chambers of the ZEUS inner detector and analyses of chamber properties

International Nuclear Information System (INIS)

Kramarczyk, S.

1993-08-01

The three planar drift chambers FTD1-3 are part of the inner tracking system of the ZEUS detector at the ep facility HERA, DESY. Together with 2x2 transition radiation modules they form the Forward Detector which covers the range of forward (proton) angles. Development, construction and tests of the drift chambers are described, emphasizing design features and details of the manufacture. Two compensation methods were tested to annihilate the cross talk which emerges from the influence of one signal wire on the others in the same drift cell. A prototyp system of the final digital readout electronics was used together with a test cell. The single wire resolution was studied with optimized drift time algorithms. For the first time it was possible to measure the influence of the track angle on the single wire resolution of the FTDs. (orig.)

Hera presentation generator (Poster)

NARCIS (Netherlands)

Frasincar, F.; Houben, G.J.P.M.; Barna, P.; Ellis, A.; Hagino, T.

2005-01-01

Semantic Web Information Systems (SWIS) are Web Information Systems that use Semantic Web technologies. Hera is a model-driven design methodology for SWIS. In Hera, models are represented in RDFS and model instances in RDF. The Hera Presentation Generator (HPG) is an integrated development

Measurement of D{sup {+-}} production in deep inelastic ep scattering with the ZEUS detector at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science] [and others; Collaboration: ZEUS Collaboration

2013-02-15

Charm production in deep inelastic ep scattering was measured with the ZEUS detector using an integrated luminosity of 354 pb{sup -1}. Charm quarks were identified by reconstructing D{sup {+-}} mesons in the D{sup {+-}}{yields}K{sup -+}{pi}{sup {+-}}{pi}{sup {+-}} decay channel. Lifetime information was used to reduce combinatorial background substantially. Differential cross sections were measured in the kinematic region 5

Spin-orbit maps and electron spin dynamics for the luminosity upgrade project at HERA

International Nuclear Information System (INIS)

Berglund, G.Z.M.

2001-09-01

HERA is the high energy electron(positron)-proton collider at deutsches elektronen-synchrotron (DESY) in Hamburg. Following eight years of successful running, five of which were with a longitudinally spin polarized electron(positron) beam for the HERMES experiment, the rings have now been modified to increase the luminosity by a factor of about five and spin rotators have been installed for the H1 and ZEUS experiments. The modifications involve nonstandard configurations of overlapping magnetic fields and other aspects which have profound implications for the polarization. This thesis addresses the problem of calculating the polarization in the upgraded machine and the measures needed to maintain the polarization. A central topic is the construction of realistic spin-orbit transport maps for the regions of overlapping fields and their implementation in existing software. This is the first time that calculations with such fields have been possible. Using the upgraded software, calculations are presented for the polarization that can be expected in the upgraded machine and an analysis is made of the contributions to depolarization from the various parts of the machine. It is concluded that about 50% polarization should be possible. The key issues for tuning the machine are discussed. The last chapter deals with a separate topic, namely how to exploit a simple unitary model of spin motion to describe electron depolarization and thereby expose a misconception appearing in the literature. (orig.)

Measurement of beauty and charm cross sections in photoproduction using decays into electrons with ZEUS at HERA

Energy Technology Data Exchange (ETDEWEB)

Juengst, Markus

2010-02-15

Photoproduction of heavy quarks in events with two jets and an electron associated with one of the jets has been studied with the ZEUS detector using the data recorded in the years 1996-2000 and 2006-2007, corresponding to an integrated luminosity of L=120 pb{sup -1} and L=190 pb{sup -1}, respectively. The fractions of events containing b quarks, and also of events containing c quarks, were extracted from a likelihood fit using variables sensitive to electron identification as well as to semileptonic decays. For the second data-set the list of variables sensitive to the flavour could be extended using the additional information from the microvertexdetector. Total and differential cross sections for beauty and charm production were measured for both data-sets and compared with next-to-leading-order QCD calculations and Monte Carlo models. (orig.)

Measurement of beauty and charm cross sections in photoproduction using decays into electrons with ZEUS at HERA

International Nuclear Information System (INIS)

Juengst, Markus

2010-02-01

Photoproduction of heavy quarks in events with two jets and an electron associated with one of the jets has been studied with the ZEUS detector using the data recorded in the years 1996-2000 and 2006-2007, corresponding to an integrated luminosity of L=120 pb -1 and L=190 pb -1 , respectively. The fractions of events containing b quarks, and also of events containing c quarks, were extracted from a likelihood fit using variables sensitive to electron identification as well as to semileptonic decays. For the second data-set the list of variables sensitive to the flavour could be extended using the additional information from the microvertexdetector. Total and differential cross sections for beauty and charm production were measured for both data-sets and compared with next-to-leading-order QCD calculations and Monte Carlo models. (orig.)

Automatic test system of the photomultipliers

International Nuclear Information System (INIS)

Shiino, Kazuo; Kono, Koji; Ishii, Takanobu; Kasai, Seiji; Yamada, Sakue; Kitamura, Shoichi.

1990-03-01

A test system of R580 photomultipliers (PMTs) was constructed for the ZEUS experiment HERA. In this report, we will describe the general feature of the test system, each component of the setup, the procedure of the measurements, the data analyses and the results of the first 800 PMT measurements. (author)

Calibration of the forward and rear ZEUS calorimeter using cosmic ray muons

International Nuclear Information System (INIS)

Behrens, U.; Freidhof, A.; Fuertjes, A.; Mitchell, J.; Molthagen, K.; Tsurugai, T.; Yoshida, R.

1993-08-01

The forward and rear calorimeter of the ZEUS experiment consists of 48 modules. Before their installation into the ZEUS detector they were calibrated at DESY using cosmic ray muons in order to check their performance and to compare the response to cosmic muons to the response, obtained for some modules, to 100 GeV beam muons. The set-up, the test procedure and the analysis of the data are described in this paper. The relative calibration of the different modules, as well as of the different cells within a module can be obtained with cosmic ray muons with an accuracy of about one percent for a measurement time of 3-5 days/module. (orig.)

Multijet production at low xBj in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2007-05-01

Inclusive dijet and trijet production in deep inelastic ep scattering has been measured for 10 2 2 and low Bjorken x, 10 -4 Bj -2 . The data were taken at the HERA ep collider with centre-of-mass energy √(s)=318 GeV using the ZEUS detector and correspond to an integrated luminosity of 82 pb -1 . Jets were identified in the hadronic centre-of-mass (HCM) frame using the k T cluster algorithm in the longitudinally invariant inclusive mode. Measurements of dijet and trijet differential cross sections are presented as functions of Q 2 , x Bj , jet transverse energy, and jet pseudorapidity. As a further examination of low-x Bj dynamics, multi-differential cross sections as functions of the jet correlations in transverse momenta, azimuthal angles, and pseudorapidity are also presented. Calculations at O(α 3 s ) generally describe the trijet data well and improve the description of the dijet data compared to the calculation at O(α 2 s ). (orig.)

Measurement of dijet photoproduction for events with a leading neutron at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, B.

2009-09-01

Differential cross sections for dijet photoproduction and this process in association with a leading neutron, e + +p→e + +jet+jet+X(+n), have been measured with the ZEUS detector at HERA using an integrated luminosity of 40 pb -1 . The fraction of dijet events with a leading neutron was studied as a function of different jet and event variables. Single- and double-differential cross sections are presented as a function of the longitudinal fraction of the proton momentum carried by the leading neutron, x L , and of its transverse momentum squared, p T 2 . The dijet data are compared to inclusive DIS and photoproduction results; they are all consistent with a simple pion-exchange model. The neutron yield as a function of x L was found to depend only on the fraction of the proton beam energy going into the forward region, independent of the hard process. No firm conclusion can be drawn on the presence of rescattering effects. (orig)

A first study of the structure of the virtual photon at HERA

International Nuclear Information System (INIS)

Utley, M.L.

1996-01-01

The production of two or more jets of hadrons in photoproduction events at the HERA e + p collider has been studied using the ZEUS detector. By tagging the final state positron, two samples of event have been isolated where the photon exchanged between proton and positron is quasi-real (of virtuality P 2 2 ) and virtual (0.1 2 2 ) respectively. It is shown that photons in both P 2 ranges show resolved structure. The P 2 evolution of the structure of the photon is studied by measuring the relative contribution of direct and resolved photon processes to the cross-section for the production of two or more jets. Events have been classified as direct or resolved based upon the value of the final state observable X γ obs . The data suggest that the contribution from resolved photon processes is suppressed relative to that from direct photon processes as P 2 rises and are in general agreement with leading order calculations. (author)

Fast simulation of electromagnetic showers in the ZEUS calorimeter

International Nuclear Information System (INIS)

Peso, J. del; Ros, E.

1991-02-01

We present a fast Monte Carlo algorithm for the generation of electromagnetic showers in the uranium-scintillator sampling calorimeter of the ZEUS experiment. This algorithm includes a simulation of longitudinal and transverse profiles, their fluctuations and the correlation between these fluctuations as well. The tuning of this fast Monte Carlo with data generated with EGS is described and its performance together with some applications is discussed. (orig.)

Measurement of the t dependence in exclusive photoproduction of {upsilon}(1S) mesons at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (PL). Faculty of Physics and Applied Computer Science] (and others)

2011-10-15

The exclusive photoproduction reaction {gamma}p{yields}{upsilon}(1S)p has been studied with the ZEUS detector in ep collisions at HERA using an integrated luminosity of 468 pb{sup -1}. The measurement covers the kinematic range 60

Combination of differential D*± cross-section measurements in deep-inelastc ep scattering at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2015-03-01

H1 and ZEUS have published single-differential cross sections for inclusive D *± -meson production in deep-inelastic ep scattering at HERA from their respective final data sets. These cross sections are combined in the common visible phase-space region of photon virtuality Q 2 >5 GeV 2 , electron inelasticity 0.021.5 GeV and pseudorapidity vertical stroke η(D * ) vertical stroke <1.5. The combination procedure takes into account all correlations, yielding significantly reduced experimental uncertainties. Double-differential cross sections d 2 σ/dQ 2 dy are combined with earlier D *± data, extending the kinematic range down to Q 2 >1.5 GeV 2 . Perturbative next-to-leadingorder QCD predictions are compared to the results.

Exclusive J/{psi} production in deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Voss, K.C.

2004-10-15

The exclusive electroproduction of J/{psi} mesons, ep{yields}ep J/{psi}, is studied with the ZEUS detector at HERA for virtualities of the exchanged photon in the range 2 < Q{sup 2} < 100 GeV{sup 2}, using an integrated luminosity of 83 pb{sup -1}. The photon-proton centre-of-mass energy is in the range 30 < W < 220 GeV and the squared four-momentum transfer at the proton vertex vertical stroke t vertical stroke <1 GeV{sup 2}. The cross-sections and the decay angular distributions are presented as functions of Q{sup 2}, W and t. The effective parameters of the Pomeron trajectory are determined. The spin-density matrix elements, calculated from the decay angular distributions, are used to test the hypothesis of s-channel helicity conservation. The ratio of the longitudinal and transverse cross-sections {sigma}{sub L}/{sigma}{sub T} is measured as a function Q{sup 2}, W and t. The results are compared to QCD inspired models. (orig.)

Measurement of charm and beauty production in deep inelastic ep scattering from decays into muons at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S [Argonne National Lab., Argonne, IL (US)] (and others)

2009-04-15

The production of charm and beauty quarks in ep interactions has been measured with the ZEUS detector at HERA for squared four-momentum exchange Q{sup 2} > 20GeV{sup 2}, using an integrated luminosity of 126 pb{sup -1}. Charm and beauty quarks were identified through their decays into muons. Differential cross sections were measured for muon transverse momenta p{sub T}{sup {mu}}>1.5 GeV and pseudorapidities -1.6<{eta}{sup {mu}}<2.3, as a function of p{sub T}{sup {mu}}, {eta}{sup {mu}}, Q{sup 2} and Bjorken x. The charm and beauty contributions to the proton structure function F{sub 2} were also extracted. The results agree with previous measurements based on independent techniques and are well described by QCD predictions. (orig.)

Measurement of charged current deep inelastic scattering cross sections with a longitudinally polarised electron beam at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-12-01

Measurements of the cross sections for charged current deep inelastic scattering in e - p collisions with longitudinally polarised electron beams are presented. The measurements are based on a data sample with an integrated luminosity of 175 pb -1 collected with the ZEUS detector at HERA at a centre-of-mass energy of 318 GeV. The total cross section is given for positively and negatively polarised electron beams. The differential cross-sections dσ/dQ 2 , dσ/dx and dσ/dy are presented for Q 2 >200 GeV 2 . The double-differential cross-section d 2 σ/dxdQ 2 is presented in the kinematic range 280 2 and 0.015< x<0.65. The measured cross sections are compared with the predictions of the Standard Model. (orig.)

Development of the HERA-Β-target-control system and study of target operation at the HERA storage ring

International Nuclear Information System (INIS)

Issever, S.

2001-03-01

The HERA-B experiment investigates the physics of heavy quarks, which are produced in pN reactions of the 920 GeV protons of HERA with the HERA-B internal fixed target. It consists out of eight wires, which surround the proton beam from four sides and is a high luminosity particle source. As being the closest mechanical device to the proton beam, it has to be operated very carefully and thus needs a secure and automatic control system, which additionally must be efficient and reliable to guarantee an efficient HERA-B data taking. The implementation of the target control system and its performance as well as dedicated studies of target-beam physics are presented. These include the measurement of the aperture limitation, usual target operational position, target efficiency, target independent proton loss in HERA and the scrape velocity of the target. The source of rate fluctuations is investigated in detail; among many dependencies environmental noise has a major impact on the rate fluctuations. Further studies include the analysis of beam position fluctuations and its correlation to the rate fluctuations; the rate changes about a factor of 2, if the beam is changing its position by 10 μm. This rate sensitivity is also verified directly by means of step function measurements. Furthermore the step function measurements can be used to study target-beam dynamics on time scales as short as a second. Experiments to reduce the rate sensitivity - the so called beam tail shaping measurements - are presented as well. During target operation a current, which is proportional to the interaction rate, is measured and used to determine the rate of each single wire. It is shown, that the source of this current is delta electron production. Finally the multiwire performance of the target control system is presented. (orig.)

Photoproduction of J/{psi} mesons at medium and low elasticities at HERA

Energy Technology Data Exchange (ETDEWEB)

Salvaire, F.

2007-09-15

The first analysis of inelastic J/{psi} meson production in photoproduction (Q{sup 2}<2.5 GeV{sup 2}) of the H1 experiment for the second phase of HERA (HERA II) is presented. The analysis is carried out at low and medium elasticities. The production of heavy quarks (charm, or bottom) is of special interest since the mass of the quarks provides a hard scale for the application of perturbative QCD. The muonic decay channel is used to select the J/{psi} mesons. The data was collected by the H1 detector during the period 2003-2005, and corresponds to an integrated luminosity of 133 pb{sup -1}. However only a subset of this data could be analysed. At the start of HERA II the trigger system was affected by a sizeable background. Then a fault was introduced in the trigger software during the summer 2004 and was only discovered and solved in April 2006. This means that approximately 80 % of the triggered events at medium elasticities and 65 % at low elasticities was lost during this period. Moreover during the first half of 2005 the muon trigger was affected by faulty power supplies. Consequently two good data taking periods are analysed: a first period with an integrated luminosity of 23 pb{sup -1} collected in 2004, and a second period of 60 pb{sup -1} collected during the second half of 2005, which is however strongly affected by the malfunction of the trigger software. In the medium elasticity region the total photoproduction cross section as a function of the photon-proton centre-of-mass energy W and the single differential cross sections as functions of the transverse momentum squared of the J/{psi} meson Pt{sup 2}{sub t,{psi}} and the elasticity z are extracted. The analysis covers the kinematic range 0.3{<=}z{<=}0.9, 60{<=}W{sub {gamma}}{sub p}{<=}240 GeV, and Pt{sup 2}{sub t,{psi}}>1 GeV{sup 2}. The same analysis is performed at low elasticity for the kinematic region 0.05{<=}z{<=}0.45, 120{<=}W{sub {gamma}}{sub p}{<=}260 GeV, and Pt{sup 2}{sub t,{psi}}>1 Ge

Comparison of HuRAM+ and HERA for Development of Data Worksheet for Simulator based HERA Databank

International Nuclear Information System (INIS)

Choi, Sunyoung; Jung, Wondea

2013-01-01

We also compared the existing HERA methods and HERA database to select essential data fields. We performed a preliminary study to see the possibility to induce the operator's emergency operating procedure (EOP) noncompliance behaviors under a simulated emergency. The purpose of this paper is to compare the HuRAM + and HERA to obtain an insight into the construction of a data worksheet for a qualitative HERA. In this paper, we performed a case study for applying simulator training data to HuRAM + and HERA. With this insight, as well as the results of the researches mentioned above, we have a plan to develop a systematic and qualitative HERA and a data worksheet for the work. In this paper, we compared HuRAM + and HERA to obtain an insight into the construction of a data worksheet for a qualitative HERA and performed a case study. HERA requires a burden to analyze and input an event data due to too many data fields even though it is well designed to estimate Heaps. It is somewhat more convenient to input data into the HuRAM + ; however, it is difficult to analyze the organization and safety culture factors. We are now trying to develop the framework of a data worksheet for a qualitative HERA based on simulator training data. The purpose of our data worksheet is to provide key information for HEP estimation and to enhance the understanding of an operators' behavior under an off-normal plant status. We aim less encumbered means of obtaining the needed data for HERA by changing the existing data worksheet framework of HuRAM + and HERA and by reducing data fields that require reading the between the lines

Department of Hadron Structure - Overview

International Nuclear Information System (INIS)

Eskreys, A.

2000-01-01

Full Text: The XII Department of the Institute of Nuclear Physics has been involved in 1999 in the following experiments and projects: -ZEUS experiment at HERA (DESY), which covered the main activity of the department. The group from department participating in this experiment consisted of physicists: J. Chwastowski, A. Eskreys, J. Figiel, K. Klimek, K. Olkiewicz, M.B. Przybycien, P. Stopa, M. Zachara, and L. Zawiejski and engineers and technicians: J. Andruszkow, W. Daniluk, B. Dabrowski, P. Jurkiewicz, A. Kotarba, K. Oliwa, W. Wierba, and A. Wlodarczyk; -D0 experiment at TEVATRON (FNAL), USA - one physicist: B. Pawlik from the department was involved in this experiment; -TESLA project at DESY - two engineers: J. Andruszkow and P. Jurkiewicz were participating in this project; -ATLAS project at LHC (CERN) - one physicist: K. Piotrzkowski from the department was participating in this project. 11 physicists and 8 engineers and technicians have been involved in carrying above programs. ZEUS experiment is the continuation of the investigation of e ± p interactions at HERA collider which has started over 10 years ago and has a perspective of another 5 years of activity. The upgrade of HERA and the expected 5-7 fold increase of luminosity makes the physics program very attractive. Cracow group is responsible for upgrade of the luminosity monitor to meet the new working conditions after HERA upgrade. An extended proposal for luminosity measurement after HERA upgrade, including the measurements of the Bremsstrahlung events rates by additional detectors apart from the photon calorimeter (i.e. 6m and 40m electron taggers and luminosity spectrometer), has been prepared and was accepted for realization by the ZEUS collaboration and the DESY Physics Research Committee (PRC). D0 is the (anti)pp experiment carried out at FNAL (Batavia), USA, and is now designed to deliver 100 times higher luminosity than has been achieved so far. In ATLAS project the preparation of the physics

Experiences at HERA with the H1 data acquisition system

International Nuclear Information System (INIS)

Haynes, W.J.

1992-09-01

The recently commissioned HERA collider provides a significant pointer to the problems that have to be surmounted in data acquisition systems at the next generation of hadron machines. With bunch crossings, between 30 GeV electrons and 820 GeV protons, 96 nanoseconds apart, the H1 experiment illustrates the application of sophisticated pipelining solutions in the readout of several hundred thousand electronic channels. A modular, multiprocessor design structure emphasis the architectural concepts necessary to cope with large data throughput and yet remain flexible enough to exploit ongoing technological advances in both hardware and software. The range of techniques implemented will be surveyed, covering various digitisation solutions at the front-end through to embedded microprocessor arrays in standard busses controlled by graphics-based stations executing object- orientated code. The experiences gained in developing such a system are also discussed. (orig.)

Production of the excited charm mesons D1 and D*2 at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2012-08-01

The production of the excited charm mesons D 1 (2420) and D * 2 (2460) in ep collisions has been measured with the ZEUS detector at HERA using an integrated luminosity of 373 pb -1 . The masses of the neutral and charged states, the widths of the neutral states, and the helicity parameter of D 1 (2420) 0 were determined and compared with other measurements and with theoretical expectations. The measured helicity parameter of the D 0 1 allows for some mixing of S- and D-waves in its decay to D *± π -+ . The result is also consistent with a pure D-wave decay. Ratios of branching fractions of the two decay modes of the D * 2 (2460) 0 and D * 2 (2460) ± states were measured and compared with previous measurements. The fractions of charm quarks hadronising into D 1 and D * 2 were measured and are consistent with those obtained in e + e - annihilations.

Measurement of charm and beauty production in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Roloff, Philipp

2011-12-01

In this thesis two measurements of heavy quark production in deep inelastic scattering at HERA are presented. Cross sections for the production of heavy quarks can be calculated in quantum chromodynamics (QCD). The heavy quark masses represent hard scales, which allow to apply perturbative methods. Charm production has been measured with the ZEUS detector using an integrated luminosity of 120 pb -1 . The hadronic decay channels D + → K 0 S π + , Λ + c → pK 0 S and Λ + c → Λπ + were reconstructed. The presence of a neutral strange hadron in the final state reduces the combinatorial background and extends the measured sensitivity into the region p T (D + , Λ + c ) T 2 (D + ), η(D + ), Q 2 and x for the production of D + mesons are in reasonable agreement with predictions from perturbative QCD. The fraction of c quarks hadronising into Λ + c baryons was extracted from a combination of both investigated Λ + c decay channels. The result is consistent with a previous measurement in the photoproduction regime and with the average e + e - value. The production of charm and beauty quarks has been measured with the ZEUS detector using the data collected between 2004 and 2007. This data sample corresponds to an integrated luminosity of 354 pb -1 . The charm and beauty contents in events with a jet were determined using the decay-length significance and invariant mass of the reconstructed secondary decay vertices. Differential cross sections in E jet T , η jet , Q 2 and x are in reasonable agreement with predictions for perturbative QCD. The open charm and beauty contributions to the inclusive proton structure function F 2 were extracted from double differential cross sections in x and Q 2 . The obtained F c anti c 2 and F b anti b 2 values are in good agreement with previous measurements and theoretical predictions. This measurement represents the most precise determination of F b anti b 2 at the HERA collider in a large part of the accessible phase space

Events with an isolated lepton and missing transverse momentum and measurement of W production at HERA

Energy Technology Data Exchange (ETDEWEB)

Aaron, F.D. [National Inst. for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Bucharest Univ. (Romania). Faculty of Physics; Abramowicz, H. [Tel Aviv Univ. (Israel). Raymond and Beverly Sackler Faculty of Exact Sciences, School of Physics; Max-Planck-Institute, Muenchen (Germany).; Abt, I. [Max-Planck-Institut fuer Physik, Muenchen (DE)] (and others)

2009-09-15

A search for events containing an isolated electron or muon and missing transverse momentum produced in e{sup {+-}}p collisions is performed with the H1 and ZEUS detectors at HERA. The data were taken in the period 1994-2007 and correspond to an integrated luminosity of 0.98 fb{sup -1}. The observed event yields are in good overall agreement with the Standard Model prediction, which is dominated by single W production. In the e{sup +}p data, at large hadronic transverse momentum P{sub T}{sup X}>25 GeV, a total of 23 events are observed compared to a prediction of 14.0{+-}1.9. The total single W boson production cross section is measured as 1.06{+-}0.16(stat.){+-}0.07(sys.) pb, in agreement with an SM expectation of 1.26{+-}0.19 pb. (orig.)

DESY: HERA polarization

International Nuclear Information System (INIS)

Anon.

1992-01-01

The new HERA electron-proton collider at DESY in Hamburg achieved the first luminosity for electron-proton collisions on 19 October last year. Only one month later, on 20 November, HERA passed another important milestone with the observation of transverse electron polarization

DESY: HERA polarization

Energy Technology Data Exchange (ETDEWEB)

Anon.

1992-03-15

The new HERA electron-proton collider at DESY in Hamburg achieved the first luminosity for electron-proton collisions on 19 October last year. Only one month later, on 20 November, HERA passed another important milestone with the observation of transverse electron polarization.

Measurement of the reaction γ*p →φp in deep inelastic e+p scattering at HERA

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magill, S.

1996-04-01

The production of φ mesons in the reaction e + p→e + φp (φ→K + K - ), for 7 2 2 and for virtual photon-proton centre of mass energies (W) in the range 42-134 GeV, has been studied with the ZEUS detector at HERA. When compared to lower energy data at similar Q 2 , the results show that the γ*p→φp cross section rises strongly with W. This behaviour is similar to that previously found for the γ*p→ρ 0 p cross section. This strong dependence cannot be explained by production through soft pomeron exchange. It is, however, consistent with perturbative QCD expectations, where it reflects the rise of the gluon momentum density in the proton at small x. The ratio of σ(φ)/σ(ρ 0 ), which has previously been determined by ZEUS to be 0.065±0.013(stat.) in photoproduction at a mean W of 70 GeV, is measured to be 0.18±0.05(stat.)±0.03(syst.) at a mean Q 2 of 12.3 GeV 2 and mean W of ∼100 GeV and is thus approaching at large Q 2 the value of 2/9 predicted from the quark charges of the vector mesons and a flavour independent production mechanism. (orig.)

Selectron and squark production in ep collisions at HERA

International Nuclear Information System (INIS)

Bartels, J.; Hollik, W.

1988-01-01

For the SUSY Standard Model we give a detailed discussion how HERA can be used for disentangling the mixing structure in the neutralino sector. We present 3-dimensional plots for the total cross section and for the polarization asymmetry for selectron-squark production, varying both the sfermion masses and a mixing parameter. The main results are: (I) production rates at HERA are reasonably large for a wide range of mixing parameters; (II) the polarization asymmetry depends only weakly upon the sfermion masses and thus is a very useful tool in determining mixing parameters or mass splittings between left and right handed selectron masses. (orig.)

Measurement of inelastic J/{psi} and {psi}' photoproduction at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science] [and others; Collaboration: ZEUS Collaboration

2012-11-15

The cross sections for inelastic photoproduction of J/{psi} and {psi}' mesons have been measured in ep collisions with the ZEUS detector at HERA, using an integrated luminosity of 468 pb{sup -1} collected in the period 1996-2007. The {psi}' to J/{psi} cross section ratio was measured in the range 0.551 GeV. Theoretical predictions within the non-relativistic QCD framework including NLO colour-singlet and colour-octet contributions were compared to the data, as were predictions based on the k{sub T}-factorisation approach.

QED radiative corrections in exclusive ρ0 leptoproduction

International Nuclear Information System (INIS)

Kurek, K.

1996-09-01

A semi-analytical approach to the model independent calculation of radiative corrections for exclusive ρ 0 meson leptoproduction (i.e. electron and muon scattering experiments) is presented. The corrections to ρ 0 production at large Q 2 as well as to ρ 0 photoproduction are studied in detail. The numerical results are calculated for two different experimental analyses: NMC (muoproduction at large Q 2 ) and ZEUS at HERA (quasi-real photoproduction). It is shown that the corrections are 2-5% for NMC and below 2% for the ZEUS measurement. The application of the presented approach to other vector meson production is straightforward. (orig.)

Spin structure function measurements with polarized protons and electrons at HERA

International Nuclear Information System (INIS)

Ball, R.D.; Deshpande, A.; Forte, S.; Hughes, V.W.; Lichtenstadt, J.; Ridolfi, G.

1995-01-01

Useful insights into the spin structure functions of the nucleon can be achieved by measurements of spin-dependent asymmetries in inclusive scattering of high energy polarized electrons by high energy polarized protons at HERA. Such an experiment would be a natural extension of the polarized lepton-nucleon scattering experiments presently carried out at CERN and SLAC. We present here estimates of possible data in the extended kinematic range of HERA and associated statistical errors. (orig.)

Measurement of high-Q2 charged current cross sections in e+p deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Rautenberg, J.

2004-06-01

Cross sections for charged current deep inelastic scattering have been measured in e + p collisions at a center-of-mass energy of 318 GeV. The data collected with the ZEUS detector at HERA in the running periods 1999 and 2000 correspond to an integrated luminosity of 61 pb -1 . Single differential cross sections dσ/dQ 2 , dσ/dx and dσ/dy have been measured for Q 2 >200 GeV 2 , as well as the double differential reduced cross section d 2 σ/dxdQ 2 in the kinematic range 280 GeV 2 2 2 and 0.008 - p charged current deep inelastic scattering cross sections. The helicity structure is investigated in particular. The mass of the space-like W boson propagator has been determined from a fit to dσ/dQ 2 . (orig.)

Events with an Isolated Lepton and Missing Transverse Momentum and Measurement of {\\boldmath $W$} Production at HERA

CERN Document Server

Aaron, F.D.; H1 and ZEUS Collaborations; Abt, I.; Adamczyk, L.; Adamus, M.; Aldaya Martin, M.; Alexa, C.; Andreev, V.; Antonelli, S.; Antonioli, P.; Antonov, A.; Antunovic, B.; Arneodo, M.; Aushev, V.; Bachynska, O.; Backovic, S.; Baghdasaryan, A.; Bamberger, A.; Barakbaev, A.N.; Barbagli, G.; Bari, G.; Barreiro, F.; Barrelet, E.; Bartel, W.; Bartsch, D.; Basile, M.; Begzsuren, K.; Behnke, O.; Behr, J.; Behrens, U.; Bellagamba, L.; Belousov, A.; Bertolin, A.; Bhadra, S.; Bindi, M.; Bizot, J.C.; Blohm, C.; Bold, T.; Boos, E.G.; Borodin, M.; Borras, K.; Boscherini, D.; Bot, D.; Boudry, V.; Boutle, S.K.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Brock, I.; Brownson, E.; Brugnera, R.; Brummer, N.; Bruncko, D.; Bruni, A.; Bruni, G.; Brzozowska, B.; Bunyatyan, A.; Buschhorn, G.; Bussey, P.J.; Butterworth, J.M.; Bylsma, B.; Bystritskaya, L.; Caldwell, A.; Campbell, A.J.; Cantun Avila, K.B.; Capua, M.; Carlin, R.; Catterall, C.D.; Cerny, K.; Cerny, V.; Chekanov, S.; Chekelian, V.; Cholewa, A.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Cifarelli, L.; Cindolo, F.; Contin, A.; Contreras, J.G.; Cooper-Sarkar, A.M.; Coppola, N.; Corradi, M.; Corriveau, F.; Costa, M.; Coughlan, J.A.; Cozzika, G.; Cvach, J.; D'Agostini, G.; Dainton, J.B.; Dal Corso, F.; Daum, K.; Deak, M.; de Favereau, J.; Delcourt, B.; Del Degan, M.; del Peso, J.; Delvax, J.; Dementiev, R.K.; De Pasquale, S.; Derrick, M.; Devenish, R.C.E.; De Wolf, E.A.; Diaconu, C.; Dobur, D.; Dodonov, V.; Dolgoshein, B.A.; Dossanov, A.; Doyle, A.T.; Drugakov, V.; Dubak, A.; Durkin, L.S.; Dusini, S.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eisenberg, Y.; Eliseev, A.; Elsen, E.; Ermolov, P.F.; Eskreys, A.; Falkiewicz, A.; Fang, S.; Favart, L.; Fazio, S.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrando, J.; Ferrero, M.I.; Figiel, J.; Fischer, D.J.; Fleischer, M.; Fomenko, A.; Forrest, M.; Foster, B.; Fourletov, S.; Gabathuler, E.; Galas, A.; Gallo, E.; Garfagnini, A.; Gayler, J.; Geiser, A.; Ghazaryan, S.; Gialas, I.; Gladilin, L.K.; Gladkov, D.; Glasman, C.; Glazov, A.; Glushkov, I.; Goerlich, L.; Gogitidze, N.; Golubkov, Yu.A.; Gottlicher, P.; Gouzevitch, M.; Grab, C.; Grabowska-Bold, I.; Grebenyuk, J.; Greenshaw, T.; Gregor, I.; Grell, B.R.; Grigorescu, G.; Grindhammer, G.; Grzelak, G.; Gwenlan, C.; Haas, T.; Habib, S.; Haidt, D.; Hain, W.; Hamatsu, R.; Hart, J.C.; Hartmann, H.; Hartner, G.; Helebrant, C.; Henderson, R.C.W.; Hennekemper, E.; Henschel, H.; Herbst, M.; Herrera, G.; Hildebrandt, M.; Hilger, E.; Hiller, K.H.; Hochman, D.; Hoffmann, D.; Holm, U.; Hori, R.; Horisberger, R.; Horton, K.; Hreus, T.; Huttmann, A.; Iacobucci, G.; Ibrahim, Z.A.; Iga, Y.; Ingbir, R.; Ishitsuka, M.; Jacquet, M.; Jakob, H.P.; Janssen, X.; Januschek, F.; Jimenez, M.; Jones, T.W.; Jonsson, L.; Jung, A.W.; Jung, H.; Jungst, M.; Kadenko, I.; Kahle, B.; Kamaluddin, B.; Kananov, S.; Kanno, T.; Kapichine, M.; Karshon, U.; Karstens, F.; Katkov, I.I.; Katzy, J.; Kaur, M.; Kaur, P.; Kenyon, I.R.; Keramidas, A.; Khein, L.A.; Kiesling, C.; Kim, J.Y.; Kisielewska, D.; Kitamura, S.; Klanner, R.; Klein, M.; Klein, U.; Kleinwort, C.; Kluge, T.; Knutsson, A.; Koffeman, E.; Kogler, R.; Kollar, D.; Kooijman, P.; Korol, Ie.; Korzhavina, I.A.; Kostka, P.; Kotanski, A.; Kotz, U.; Kowalski, H.; Kraemer, M.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Kulinski, P.; Kuprash, O.; Kutak, K.; Kuze, M.; Kuzmin, V.A.; Landon, M.P.J.; Lange, W.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Lee, A.; Leibenguth, G.; Lendermann, V.; Levchenko, B.B.; Levonian, S.; Levy, A.; Li, G.; Libov, V.; Limentani, S.; Ling, T.Y.; Lipka, K.; Liptaj, A.; Lisovyi, M.; List, B.; List, J.; Lobodzinska, E.; Lohmann, W.; Lohr, B.; Lohrmann, E.; Loizides, J.H.; Loktionova, N.; Long, K.R.; Longhin, A.; Lontkovskyi, D.; Lopez-Fernandez, R.; Lubimov, V.; Lukasik, J.; Lukina, O.Yu.; Luzniak, P.; Maeda, J.; Magill, S.; Makankine, A.; Makarenko, I.; Malinovski, E.; Malka, J.; Mankel, R.; Marage, P.; Margotti, A.; Marini, G.; Marti, Ll.; Martin, J.F.; Martyn, H.U.; Mastroberardino, A.; Matsumoto, T.; Mattingly, M.C.K.; Maxfield, S.J.; Mehta, A.; Melzer-Pellmann, I.A.; Meyer, A.B.; Meyer, H.; Meyer, H.; Meyer, J.; Miglioranzi, S.; Mikocki, S.; Milcewicz-Mika, I.; Mohamad Idris, F.; Monaco, V.; Montanari, A.; Moreau, F.; Morozov, A.; Morris, J.D.; Morris, J.V.; Mozer, M.U.; Mudrinic, M.; Muller, K.; Murin, P.; Musgrave, B.; Nagano, K.; Namsoo, T.; Nania, R.; Naumann, Th.; Newman, P.R.; Nicholass, D.; Niebuhr, C.; Nigro, A.; Nikiforov, A.; Nikitin, D.; Ning, Y.; Noor, U.; Notz, D.; Nowak, G.; Nowak, K.; Nowak, R.J.; Nozicka, M.; Nuncio-Quiroz, A.E.; Oh, B.Y.; Okazaki, N.; Oliver, K.; Olivier, B.; Olkiewicz, K.; Olsson, J.E.; Onishchuk, Yu.; Osman, S.; Ota, O.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, Th.; Papageorgiu, K.; Parenti, A.; Pascaud, C.; Patel, G.D.; Paul, E.; Pawlak, J.M.; Pawlik, B.; Pejchal, O.; Pelfer, P.G.; Pellegrino, A.; Perez, E.; Perlanski, W.; Perrey, H.; Petrukhin, A.; Picuric, I.; Piec, S.; Piotrzkowski, K.; Pitzl, D.; Placakyte, R.; Plucinski, P.; Pokorny, B.; Pokrovskiy, N.S.; Polifka, R.; Polini, A.; Povh, B.; Proskuryakov, A.S.; Przybycien, M.; Radescu, V.; Rahmat, A.J.; Raicevic, N.; Raspiareza, A.; Raval, A.; Ravdandorj, T.; Reeder, D.D.; Reimer, P.; Reisert, B.; Ren, Z.; Repond, J.; Ri, Y.D.; Rizvi, E.; Robertson, A.; Robmann, P.; Roland, B.; Roloff, P.; Ron, E.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Rubinsky, I.; Ruiz Tabasco, J.E.; Rurikova, Z.; Rusakov, S.; Ruspa, M.; Sacchi, R.; Salek, D.; Salii, A.; Samson, U.; Sankey, D.P.C.; Sartorelli, G.; Sauter, M.; Sauvan, E.; Savin, A.A.; Saxon, D.H.; Schioppa, M.; Schlenstedt, S.; Schleper, P.; Schmidke, W.B.; Schmitt, S.; Schneekloth, U.; Schoeffel, L.; Schonberg, V.; Schoning, A.; Schorner-Sadenius, T.; Schultz-Coulon, H.C.; Schwartz, J.; Sciulli, F.; Sefkow, F.; Shaw-West, R.N.; Shcheglova, L.M.; Shehzadi, R.; Shimizu, S.; Shtarkov, L.N.; Shushkevich, S.; Singh, I.; Skillicorn, I.O.; Sloan, T.; Slominski, W.; Smiljanic, I.; Smith, W.H.; Sola, V.; Solano, A.; Soloviev, Y.; Son, D.; Sopicki, P.; Sorokin, Iu.; Sosnovtsev, V.; South, D.; Spaskov, V.; Specka, A.; Spiridonov, A.; Stadie, H.; Stanco, L.; Staykova, Z.; Steder, M.; Stella, B.; Stern, A.; Stewart, T.P.; Stifutkin, A.; Stoicea, G.; Stopa, P.; Straumann, U.; Suchkov, S.; Sunar, D.; Susinno, G.; Suszycki, L.; Sykora, T.; Sztuk, J.; Szuba, D.; Szuba, J.; Tapper, A.D.; Tassi, E.; Tchoulakov, V.; Terron, J.; Theedt, T.; Thompson, G.; Thompson, P.D.; Tiecke, H.; Tokushuku, K.; Toll, T.; Tomasz, F.; Tomaszewska, J.; Tran, T.H.; Traynor, D.; Trinh, T.N.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Tsurugai, T.; Turcato, M.; Turnau, J.; Tymieniecka, T.; Urban, K.; Uribe-Estrada, C.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Vazquez, M.; Verbytskyi, A.; Viazlo, V.; Vinokurova, S.; Vlasov, N.N.; Volchinski, V.; Volynets, O.; von den Driesch, M.; Walczak, R.; Wan Abdullah, W.A.T.; Wegener, D.; Whitmore, J.J.; Whyte, J.; Wiggers, L.; Wing, M.; Wissing, Ch.; Wlasenko, M.; Wolf, G.; Wolfe, H.; Wrona, K.; Wunsch, E.; Yagues-Molina, A.G.; Yamada, S.; Yamazaki, Y.; Yoshida, R.; Youngman, C.; Zacek, J.; Zalesak, J.; Zarnecki, A.F.; Zawiejski, L.; Zenaiev, O.; Zeuner, W.; Zhang, Z.; Zhautykov, B.O.; Zhokin, A.; Zhou, C.; Zichichi, A.; Zimmermann, T.; Zohrabyan, H.; Zolko, M.; Zomer, F.; Zotkin, D.S.; Zus, R.; 10.1007/JHEP03(2010)035

2010-01-01

A search for events containing an isolated electron or muon and missing transverse momentum produced in $e^{\\pm}p$ collisions is performed with the H1 and ZEUS detectors at HERA. The data were taken in the period 1994--2007 and correspond to an integrated luminosity of 0.98 fb$^{-1}$. The observed event yields are in good overall agreement with the Standard Model prediction, which is dominated by single $W$ production.In the $e^{+}p$ data, at large hadronic transverse momentum $P_{T}^{X}>25$ GeV, a total of 23 events are observed compared to a prediction of $14.0 \\pm 1.9$. % The total single $W$ boson production cross section is measured as $1.06 \\pm 0.16 ({\\rm stat.}) \\pm 0.07 ({\\rm sys.})$ pb, in agreement with an SM expectation of $1.26 \\pm 0.19$ pb.

Combined inclusive diffractive cross sections measured with forward proton spectrometers in deep inelastic ep scattering at HERA

CERN Document Server

Aaron, F.D.; Abt, I.; Adamczyk, L.; Adamus, M.; Aggarwal, R.; Alexa, C.; Andreev, V.; Antonelli, S.; Antonioli, P.; Antonov, A.; Arneodo, M.; Arslan, O.; Aushev, V.; Aushev, Y.; Bachynska, O.; Backovic, S.; Baghdasaryan, A.; Baghdasaryan, S.; Bamberger, A.; Barakbaev, A.N.; Barbagli, G.; Bari, G.; Barreiro, F.; Barrelet, E.; Bartel, W.; Bartosik, N.; Bartsch, D.; Basile, M.; Begzsuren, K.; Behnke, O.; Behr, J.; Behrens, U.; Bellagamba, L.; Belousov, A.; Belov, P.; Bertolin, A.; Bhadra, S.; Bindi, M.; Bizot, J.C.; Blohm, C.; Bokhonov, V.; Bondarenko, K.; Boos, E.G.; Borras, K.; Boscherini, D.; Bot, D.; Boudry, V.; Bozovic-Jelisavcic, I.; Bold, T.; Brummer, N.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Britzger, D.; Brock, I.; Brownson, E.; Brugnera, R.; Bruncko, D.; Bruni, A.; Bruni, G.; Brzozowska, B.; Bunyatyan, A.; Bussey, P.J.; Bylinkin, A.; Bylsma, B.; Bystritskaya, L.; Caldwell, A.; Campbell, A.J.; Cantun Avila, K.B.; Capua, M.; Carlin, R.; Catterall, C.D.; Ceccopieri, F.; Cerny, K.; Cerny, V.; Chekanov, S.; Chekelian, V.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Cifarelli, L.; Cindolo, F.; Contin, A.; Contreras, J.G.; Cooper-Sarkar, A.M.; Coppola, N.; Corradi, M.; Corriveau, F.; Costa, M.; Coughlan, J.A.; Cvach, J.; D'Agostini, G.; Dainton, J.B.; Dal Corso, F.; Daum, K.; Delcourt, B.; Delvax, J.; Dementiev, R.K.; Derrick, M.; Devenish, R.C.E.; De Pasquale, S.; De Wolf, E.A.; del Peso, J.; Diaconu, C.; Dobre, M.; Dobur, D.; Dodonov, V.; Dolgoshein, B.A.; Dolinska, G.; Dossanov, A.; Doyle, A.T.; Drugakov, V.; Dubak, A.; Durkin, L.S.; Dusini, S.; Eckerlin, G.; Egli, S.; Eisenberg, Y.; Eliseev, A.; Elsen, E.; Ermolov, P.F.; Eskreys, A.; Fang, S.; Favart, L.; Fazio, S.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrando, J.; Ferrero, M.I.; Figiel, J.; Fischer, D.J.; Fleischer, M.; Fomenko, A.; Forrest, M.; Foster, B.; Gabathuler, E.; Gach, G.; Galas, A.; Gallo, E.; Garfagnini, A.; Gayler, J.; Geiser, A.; Ghazaryan, S.; Gialas, I.; Gizhko, A.; Gladilin, L.K.; Gladkov, D.; Glasman, C.; Glazov, A.; Goerlich, L.; Gogitidze, N.; Gogota, O.; Golubkov, Yu.A.; Gottlicher, P.; Gouzevitch, M.; Grab, C.; Grabowska-Bold, I.; Grebenyuk, A.; Grebenyuk, J.; Greenshaw, T.; Gregor, I.; Grigorescu, G.; Grindhammer, G.; Grzelak, G.; Gueta, O.; Guzik, M.; Gwenlan, C.; Huttmann, A.; Haas, T.; Habib, S.; Haidt, D.; Hain, W.; Hamatsu, R.; Hart, J.C.; Hartmann, H.; Hartner, G.; Henderson, R.C.W.; Hennekemper, E.; Henschel, H.; Herbst, M.; Herrera, G.; Hildebrandt, M.; Hilger, E.; Hiller, K.H.; Hladky, J.; Hochman, D.; Hoffmann, D.; Hori, R.; Horisberger, R.; Hreus, T.; Huber, F.; Ibrahim, Z.A.; Iga, Y.; Ingbir, R.; Ishitsuka, M.; Jacquet, M.; Jakob, H.P.; Janssen, X.; Januschek, F.; Jones, T.W.; Jonsson, L.; Jungst, M.; Jung, H.; Kadenko, I.; Kahle, B.; Kananov, S.; Kanno, T.; Kapichine, M.; Karshon, U.; Karstens, F.; Katkov, I.I.; Kaur, P.; Kaur, M.; Kenyon, I.R.; Keramidas, A.; Khein, L.A.; Kiesling, C.; Kim, J.Y.; Kisielewska, D.; Kitamura, S.; Klanner, R.; Klein, M.; Klein, U.; Kleinwort, C.; Koffeman, E.; Kogler, R.; Kondrashova, N.; Kononenko, O.; Kooijman, P.; Korol, Ie.; Korzhavina, I.A.; Kostka, P.; Kotanski, A.; Kotz, U.; Kowalski, H.; Kramer, M.; Kretzschmar, J.; Kruger, K.; Kuprash, O.; Kuze, M.; Landon, M.P.J.; Lange, W.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Lee, A.; Lendermann, V.; Levchenko, B.B.; Levonian, S.; Levy, A.; Libov, V.; Limentani, S.; Ling, T.Y.; Lipka, K.; Lisovyi, M.; List, B.; List, J.; Lobodzinska, E.; Lobodzinski, B.; Lohmann, W.; Lohr, B.; Lohrmann, E.; Long, K.R.; Longhin, A.; Lontkovskyi, D.; Lopez-Fernandez, R.; Lubimov, V.; Lukina, O.Yu.; Maeda, J.; Magill, S.; Makarenko, I.; Malinovski, E.; Malka, J.; Mankel, R.; Margotti, A.; Marini, G.; Martin, J.F.; Martyn, H.U.; Mastroberardino, A.; Mattingly, M.C.K.; Maxfield, S.J.; Mehta, A.; Melzer-Pellmann, I.A.; Mergelmeyer, S.; Meyer, A.B.; Meyer, H.; Meyer, J.; Miglioranzi, S.; Mikocki, S.; Milcewicz-Mika, I.; Idris, F.Mohamad; Monaco, V.; Montanari, A.; Moreau, F.; Morozov, A.; Morris, J.V.; Morris, J.D.; Mujkic, K.; Muller, K.; Musgrave, B.; Nagano, K.; Namsoo, T.; Nania, R.; Naumann, Th.; Newman, P.R.; Niebuhr, C.; Nigro, A.; Nikitin, D.; Ning, Y.; Nobe, T.; Notz, D.; Nowak, G.; Nowak, K.; Nowak, R.J.; Nuncio-Quiroz, A.E.; Oh, B.Y.; Okazaki, N.; Olkiewicz, K.; Olsson, J.E.; Onishchuk, Yu.; Ozerov, D.; Pahl, P.; Palichik, V.; Pandurovic, M.; Papageorgiu, K.; Parenti, A.; Pascaud, C.; Patel, G.D.; Paul, E.; Pawlak, J.M.; Pawlik, B.; Pelfer, P.G.; Pellegrino, A.; Perez, E.; Perlanski, W.; Perrey, H.; Petrukhin, A.; Picuric, I.; Piotrzkowski, K.; Pirumov, H.; Pitzl, D.; Placakyte, R.; Plucinski, P.; Pokorny, B.; Pokrovskiy, N.S.; Polifka, R.; Polini, A.; Povh, B.; Proskuryakov, A.S.; Przybycien, M.; Radescu, V.; Raicevic, N.; Raval, A.; Ravdandorj, T.; Reeder, D.D.; Reimer, P.; Reisert, B.; Ren, Z.; Repond, J.; Ri, Y.D.; Rizvi, E.; Robertson, A.; Robmann, P.; Roloff, P.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Rubinsky, I.; Ruiz Tabasco, J.E.; Rusakov, S.; Ruspa, M.; Sacchi, R.; Salek, D.; Samson, U.; Sankey, D.P.C.; Sartorelli, G.; Sauter, M.; Sauvan, E.; Savin, A.A.; Saxon, D.H.; Schioppa, M.; Schlenstedt, S.; Schleper, P.; Schmidke, W.B.; Schmitt, S.; Schneekloth, U.; Schoeffel, L.; Schonberg, V.; Schoning, A.; Schorner-Sadenius, T.; Schultz-Coulon, H.C.; Schwartz, J.; Sciulli, F.; Sefkow, F.; Shcheglova, L.M.; Shehzadi, R.; Shimizu, S.; Shtarkov, L.N.; Shushkevich, S.; Singh, I.; Skillicorn, I.O.; Slominski, W.; Sloan, T.; Smith, W.H.; Sola, V.; Solano, A.; Soloviev, Y.; Son, D.; Sopicki, P.; Sosnovtsev, V.; South, D.; Spaskov, V.; Specka, A.; Spiridonov, A.; Stadie, H.; Stanco, L.; Staykova, Z.; Steder, M.; Stefaniuk, N.; Stella, B.; Stern, A.; Stewart, T.P.; Stifutkin, A.; Stoicea, G.; Stopa, P.; Straumann, U.; Suchkov, S.; Susinno, G.; Suszycki, L.; Sykora, T.; Sztuk-Dambietz, J.; Szuba, J.; Szuba, D.; Tapper, A.D.; Tassi, E.; Terron, J.; Theedt, T.; Thompson, P.D.; Tiecke, H.; Tokushuku, K.; Tomaszewska, J.; Tran, T.H.; Traynor, D.; Truol, P.; Trusov, V.; Tsakov, I.; Tseepeldorj, B.; Tsurugai, T.; Turcato, M.; Turkot, O.; Turnau, J.; Tymieniecka, T.; Vazquez, M.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vazdik, Y.; Verbytskyi, A.; Viazlo, O.; Vlasov, N.N.; Walczak, R.; Wan Abdullah, W.A.T.; Wegener, D.; Whitmore, J.J.; Wichmann, K.; Wiggers, L.; Wing, M.; Wlasenko, M.; Wolf, G.; Wolfe, H.; Wrona, K.; Wunsch, E.; Yagues-Molina, A.G.; Yamada, S.; Yamazaki, Y.; Yoshida, R.; Youngman, C.; Zabiegalov, O.; Zacek, J.; Zalesak, J.; Zawiejski, L.; Zenaiev, O.; Zeuner, W.; Zhang, Z.; Zhautykov, B.O.; Zhmak, N.; Zhokin, A.; Zichichi, A.; Zlebcik, R.; Zohrabyan, H.; Zolkapli, Z.; Zomer, F.; Zotkin, D.S.; Zarnecki, A.F.

2012-10-10

A combination of the inclusive diffractive cross section measurements made by the H1 and ZEUS Collaborations at HERA is presented. The analysis uses samples of diffractive deep inelastic ep scattering data at a centre-of-mass energy sqrt(s) = 318 GeV where leading protons are detected by dedicated spectrometers. Correlations of systematic uncertainties are taken into account, resulting in an improved precision of the cross section measurement which reaches 6% for the most precise points. The combined data cover the range 2.5 < Q2 < 200 GeV2 in photon virtuality, 0.00035 < xIP < 0.09 in proton fractional momentum loss, 0.09 < |t| < 0.55 GeV2 in squared four-momentum transfer at the proton vertex and 0.0018 < beta < 0.816 in beta = x/xIP, where x is the Bjorken scaling variable.

The magnetic field for the ZEUS central detector - analysis and correction of the field measurement

International Nuclear Information System (INIS)

Mengel, S.

1992-06-01

The magnetic field in the central tracking region of the ZEUS-detector - a facility to investigate highly energetic electron-proton-collisions at the HERA-collider at DESY Hamburg - is generated by a superconducting coil and reaches 18 kG (1.8 T). Some of the tracking devices particularly the drift chambers in the proton forward and rear direction (FTD1-3 and RTD) are not fully contained within the coil and therefore situated in a highly inhomogeneous magnetic field: The radial component B r is up to 6.6 kG, maximum gradients are found to be 300 G/cm for δB r /δr. Evaluating the space drifttime relation necessitates a detailed knowledge of the magnetic field. To reach this goal we analysed the field measurements and corrected them for systematic errors. The corrected data were compared with the field calculations (TOSCA-maps). Measurements and calculations are confirmed by studying consistency with Maxwell's equations. The accuracy reached is better than 100 G throughout the forward and central drift chambers (FTD1-3, CTD) and better than 150 G in the RTD. (orig.) [de

Properties of hadronic final states in diffractive deep inelastic ep scattering at DESY HERA

International Nuclear Information System (INIS)

2002-01-01

Characteristics of the hadronic final state of diffractive deep inelastic scattering events ep→eXp were studied in the kinematic range 4 X 2 2 , 70 P <0.03 with the ZEUS detector at the DESY ep collider HERA using an integrated luminosity of 13.8 pb-1. The events were tagged by identifying the diffractively scattered proton using the leading proton spectrometer. The properties of the hadronic final state X were studied in its center-of-mass frame using thrust, thrust angle, sphericity, energy flow, transverse energy flow, and 'seagull' distributions. As the invariant mass of the system increases, the final state becomes more collimated, more aligned, and more asymmetric in the average transverse momentum with respect to the direction of the virtual photon. Comparisons of the properties of the hadronic final state with predictions from various Monte Carlo model generators suggest that the final state is dominated by qq-barg states at the parton level

Measurement of D*{sup {+-}} meson production in deep-inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Bachynska, Olena

2012-12-15

Measurements of charm production in deep-inelastic scattering at HERA at a centre-of-mass energy of 318 GeV are reported in this thesis. The analysis was performed using the data collected with the ZEUS detector during the years 2004 to 2007, corresponding to an integrated luminosity of 363 pb{sup -1}. The production of charm quarks was studied through the full kinematic reconstruction of D*{sup {+-}} mesons in the decay channel D*{sup {+-}} {yields} D{sup 0}/ anti D{sup 0}{pi}{sup {+-}}. The studies have been performed for virtualities of the exchanged photon of 5 < Q{sup 2} < 1000 GeV{sup 2} and inelasticities of 0.02 < y < 0.7. The visible D*{sup {+-}} kinematic phase space is defined by the transverse momentum range, 1.5 < p{sub T}{sup D*{sup {+-}}} < 20 GeV, and by the pseudorapidity region, vertical stroke {eta}{sup D*{sup {+-}}} vertical stroke < 1.5, of the produced D*{sup {+-}} mesons. The total visible cross section for D*{sup {+-}} production as well as single-and double-differential cross sections were measured and compared to the corresponding D*{sup {+-}} measurements performed by the H1 collaboration in the same phase-space region. The measurements are well described by NLO QCD predictions. The double-differential cross sections were exploited to extract the charm contribution to the proton structure function, F{sub 2}{sup c} {sup anti} {sup c}, expressed in terms of the reduced charm-production cross sections, {sigma}{sub red}{sup c} {sup anti} {sup c}, and compared to the predictions from HERAPDF1.5 and to the recent measurements from the H1 and ZEUS collaborations.

Test of internal halo targets in the HERA proton ring

International Nuclear Information System (INIS)

Hast, C.; Hofmann, W.; Khan, S.; Knoepfle, K.T.; Reber, M.; Rieling, J.; Spahn, M.; Spengler, J.; Lohse, T.; Pugatch, V.

1994-07-01

Internal wire targets in the halo of stored proton beams provide a line source of proton-nucleus interactions for highest-rate fixed target experiments. We have studied such internal halo targets at the 820 GeV proton ring of the HERA ep collider. The tests showed that most of the protons in the beam halo - which would otherwise hit the collimators - can be brought to interaction in a relatively thin target wire at distances of 7 to 8 beam widths from the center of the beam. At less than 10% of the HERA total design current, and less than 20% of the current per bunch, interaction rates up to 8 MHz were observed, corresponding to more than 2 interactions per bunch crossing. The halo targets were used in parallel to the HERA luminosity operation; no significant disturbances of the HERA ep experiments, of the machine stability or beam quality were observed. We present data on the steady-state and transient behaviour of interaction rates and discuss the interpretation in terms of a simple beam dynamics model. Issues of short-, medium- and long-term rate fluctuations and of rate stabilization by feedback are addressed. (orig.)

Test of internal halo targets in the HERA proton ring

International Nuclear Information System (INIS)

Hast, C.; Hofmann, W.; Khan, S.; Knoepfle, K.T.; Reber, M.; Rieling, J.; Spahn, M.; Spengler, J.; Lohse, T.; Pugatch, V.

1995-01-01

Internal wire targets in the halo of stored proton beams provide a line source of proton-nucleus interactions for highest-rate fixed target experiments. We have studied such internal halo targets at the 820 GeV proton ring of the HERA ep collider. The tests showed that most of the protons in the beam halo - which would otherwise hit the collimators - can be brought to interaction in a relatively thin target wire at distances of 7 to 8 beam widths from the center of the beam. At less than 10% of the HERA total design current, and less than 20% of the current per bunch, interaction rates up to 8 MHz were observed, corresponding to more than 2 interactions per bunch crossing. The halo targets were used in parallel to the HERA luminosity operation; no significant disturbances of the HERA ep experiments, of the machine stability or beam quality were observed. We present data on the steady-state and transient behaviour of interaction rates and discuss the interpretation in terms of a simple beam dynamics model. Issues of short-, medium- and long-term rate fluctuations and of rate stabilization by feedback are addressed. ((orig.))

Combination of differential D{sup *±} cross-section measurements in deep-inelastc ep scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science; Collaboration: The H1 and ZEUS Collaborations; and others

2015-03-15

H1 and ZEUS have published single-differential cross sections for inclusive D{sup *±}-meson production in deep-inelastic ep scattering at HERA from their respective final data sets. These cross sections are combined in the common visible phase-space region of photon virtuality Q{sup 2}>5 GeV{sup 2}, electron inelasticity 0.021.5 GeV and pseudorapidity vertical stroke η(D{sup *}) vertical stroke <1.5. The combination procedure takes into account all correlations, yielding significantly reduced experimental uncertainties. Double-differential cross sections d{sup 2}σ/dQ{sup 2}dy are combined with earlier D{sup *±} data, extending the kinematic range down to Q{sup 2}>1.5 GeV{sup 2}. Perturbative next-to-leadingorder QCD predictions are compared to the results.

Measurement of dijet photoproduction for events with a leading neutron at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, B. [Argonne National Lab., Argonne, IL (US)] (and others)

2009-09-15

Differential cross sections for dijet photoproduction and this process in association with a leading neutron, e{sup +}+p{yields}e{sup +}+jet+jet+X(+n), have been measured with the ZEUS detector at HERA using an integrated luminosity of 40 pb{sup -1}. The fraction of dijet events with a leading neutron was studied as a function of different jet and event variables. Single- and double-differential cross sections are presented as a function of the longitudinal fraction of the proton momentum carried by the leading neutron, x{sub L}, and of its transverse momentum squared, p{sub T}{sup 2}. The dijet data are compared to inclusive DIS and photoproduction results; they are all consistent with a simple pion-exchange model. The neutron yield as a function of x{sub L} was found to depend only on the fraction of the proton beam energy going into the forward region, independent of the hard process. No firm conclusion can be drawn on the presence of rescattering effects. (orig)

Possible future HERA analyses

International Nuclear Information System (INIS)

Geiser, Achim

2015-12-01

A variety of possible future analyses of HERA data in the context of the HERA data preservation programme is collected, motivated, and commented. The focus is placed on possible future analyses of the existing ep collider data and their physics scope. Comparisons to the original scope of the HERA pro- gramme are made, and cross references to topics also covered by other participants of the workshop are given. This includes topics on QCD, proton structure, diffraction, jets, hadronic final states, heavy flavours, electroweak physics, and the application of related theory and phenomenology topics like NNLO QCD calculations, low-x related models, nonperturbative QCD aspects, and electroweak radiative corrections. Synergies with other collider programmes are also addressed. In summary, the range of physics topics which can still be uniquely covered using the existing data is very broad and of considerable physics interest, often matching the interest of results from colliders currently in operation. Due to well-established data and MC sets, calibrations, and analysis procedures the manpower and expertise needed for a particular analysis is often very much smaller than that needed for an ongoing experiment. Since centrally funded manpower to carry out such analyses is not available any longer, this contribution not only targets experienced self-funded experimentalists, but also theorists and master-level students who might wish to carry out such an analysis.

A measurement of the Q{sup 2}, W and t dependences of deeply virtual Compton scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Lab., Argonne, IL (US)] (and others)

2008-12-15

Deeply virtual Compton scattering, {gamma}{sup *}p{yields}{gamma}p, has been measured in e{sup +}p collisions at HERA with the ZEUS detector using an integrated luminosity of 61.1 pb{sup -1}. Cross sections are presented as a function of the photon virtuality, Q{sup 2}, and photon-proton centre-of-mass energy, W, for a wide region of the phase space, Q{sup 2}>1.5 GeV{sup 2} and 40

Exclusive electroproduction of two pions at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (PL). Faculty of Physics and Applied Computer Science] (and others)

2011-11-15

The exclusive electroproduction of two pions in the mass range 0.4< M{sub {pi}}{sub {pi}} <2.5 GeV has been studied with the ZEUS detector at HERA using an integrated luminosity of 82 pb{sup -1}. The analysis was carried out in the kinematic range of 2< Q{sup 2}<80 GeV{sup 2}, 32

Scaled momentum distributions for K0s and Lambda/bar Lambda in DIS at HERA

CERN Document Server

Abramowicz, H.

2012-01-01

Scaled momentum distributions for the strange hadrons K0s and Lambda/bar Lambda were measured in deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 330 pb-1. The evolution of these distributions with the photon virtuality, Q2, was studied in the kinematic region 10 < Q2 < 40000 GeV2 and 0.001 < x < 0.75, where x is the Bjorken scaling variable. Clear scaling violations are observed. Predictions based on different approaches to fragmentation were compared to the measurements. Tuned leading-logarithm parton-shower Monte Carlo calculations interfaced to the Lund string fragmentation model describe the data reasonably well in the whole range measured. Next-to-leading-order QCD calculations based on fragmentation functions, FFs, extracted from e+e- data alone, fail to describe the measurements. The calculations based on FFs extracted from a global analysis including e+e-, ep and pp data give an improved description. The measurements presented in this paper hav...

Measurement of neutral current deep inelastic e{sup +}p scattering cross sections with longitudinally polarized positrons with ZEUS at HERA

Energy Technology Data Exchange (ETDEWEB)

Wlasenko, Michal

2009-05-15

Measurements of neutral current deep inelastic scattering of protons colliding with longitudinally polarized positrons, performed with data recorded in years 2006 and 2007 with the ZEUS detector, corresponding to an integrated luminosity of L=113.3 pb{sup -1}, are presented. The single-differential cross sections d{sigma}/dQ{sup 2}, d{sigma}/dx, d{sigma}/dy and the double-differential reduced cross section {sigma} were measured in the kinematic region of 185

Dijets in photoproduction and soft multiparton interactions at HERA

Energy Technology Data Exchange (ETDEWEB)

Naumann, S.

2007-07-15

Dijet events in photoproduction at HERA have been studied using data collected with the ZEUS detector in the period 1998-2000 that correspond to an integrated luminosity of 81.7 pb{sup -1}. The events have been selected in a kinematic region defined by restricting the virtuality of the incoming photon, Q{sup 2}, to Q{sup 2}<1 GeV{sup 2} and its inelasticity, y, to 0.214 GeV and E{sub T,2}>11 GeV in each event. Cross sections measured for this inclusive dijet sample have been compared to results obtained in data from the 1996-1997 period. Another sample of dijet events has been obtained using the transverse-energy requirements E{sub T,1}>10 GeV and E{sub T,2}>8 GeV, demanding additionally that the two jets are roughly back-to-back in the azimuthal plane and have almost equal transverse energies and that no third hard jet is found in the event. All results have been compared to leading-order Monte Carlo predictions. The transverse energy in the region between the jets shows a large sensitivity to multiparton interactions, allowing parameters of the corresponding models to be tested. The measurement suggests that multiparton interactions are needed to describe the data. The analysis presented here contains the most comprehensive study of soft multiparton interactions at ZEUS to date. (orig.)

Combination of differential D{sup ∗±} cross-section measurements in deep-inelastic ep scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Raymond and Beverly Sackler Faculty of Exact Sciences, School of Physics, Tel Aviv University, Tel Aviv (Israel); Abt, I. [Max-Planck-Institut für Physik, München (Germany); Adamczyk, L. [AGH-University of Science and Technology, Faculty of Physics and Applied Computer Science, Krakow (Poland); Adamus, M. [National Centre for Nuclear Research, Warsaw (Poland); Collaboration: The H1 and ZEUS collaboration; and others

2015-09-22

H1 and ZEUS have published single-differential cross sections for inclusive D{sup ∗±}-meson production in deep-inelastic ep scattering at HERA from their respective final data sets. These cross sections are combined in the common visible phase-space region of photon virtuality Q{sup 2}>5 GeV{sup 2}, electron inelasticity 0.021.5 GeV and pseudorapidity |η(D{sup ∗})|<1.5. The combination procedure takes into account all correlations, yielding significantly reduced experimental uncertainties. Double-differential cross sections d{sup 2}σ/dQ{sup 2}dy are combined with earlier D{sup ∗±} data, extending the kinematic range down to Q{sup 2}>1.5 GeV{sup 2}. Perturbative next-to-leading-order QCD predictions are compared to the results.

Measurement of charged current deep inelastic scattering cross sections with a longitudinally polarised electron beam at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, IL (US)] (and others)

2008-12-15

Measurements of the cross sections for charged current deep inelastic scattering in e{sup -}p collisions with longitudinally polarised electron beams are presented. The measurements are based on a data sample with an integrated luminosity of 175 pb{sup -1} collected with the ZEUS detector at HERA at a centre-of-mass energy of 318 GeV. The total cross section is given for positively and negatively polarised electron beams. The differential cross-sections d{sigma}/dQ{sup 2}, d{sigma}/dx and d{sigma}/dy are presented for Q{sup 2}>200 GeV{sup 2}. The double-differential cross-section d{sup 2}{sigma}/dxdQ{sup 2} is presented in the kinematic range 280

Combined inclusive diffractive cross sections measured with foreward proton spectrometers in deep inelastic ep scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Aaron, F.D. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Bucharest Univ. (Romania). Faculty of Physics; Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (DE)] (and others)

2012-07-15

A combination of the inclusive diffractive cross section measurements made by the H1 and ZEUS Collaborations at HERA is presented. The analysis uses samples of diffractive deep inelastic ep scattering data at a centre-of-mass energy {radical}(s)=318 GeV where leading protons are detected by dedicated spectrometers. Correlations of systematic uncertainties are taken into account, resulting in an improved precision of the cross section measurement which reaches 6% for the most precise points. The combined data cover the range 2.5

Production of heavy flavours with associated jets at HERA

Energy Technology Data Exchange (ETDEWEB)

Kind, O M

2006-12-15

Inclusive cross-sections for the production of open beauty and charm in ep collisions at HERA recorded with the ZEUS detector in the years 1996-2000 are measured. The data is restricted to photoproduction processes, i. e. collision events with small four-momentum transfers squared, Q{sup 2} {approx}0. Two associated jets with transverse energies E{sub t}>7(6)GeV and pseudo-rapidities vertical stroke {eta} vertical stroke <2.5 are required. The flavour is tagged by the identification of electrons and positrons from semi-leptonic decays of the heavy quark. For this a likelihood method is developed, mainly consisting of energy loss measurements in the central drift chamber of the detector and some other discriminant variables. The fractions of beauty and charm production are determined by a fit of Monte Carlo templates to the data. The total measured production cross-section for b anti b production is 820{+-}150{sup +20}{sub -30} pb for centre-of-mass energies {radical}(S{sub ep})=300 GeV and 1170{+-}130{sup +30}{sub -100} pb for {radical}(S{sub ep})=318 GeV. The total cross-section for charm production is given as well as differential cross-sections for b anti b and c anti c production. (orig.)

Multijet production at low x{sub Bj} in deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2007-05-15

Inclusive dijet and trijet production in deep inelastic ep scattering has been measured for 10HERA ep collider with centre-of-mass energy {radical}(s)=318 GeV using the ZEUS detector and correspond to an integrated luminosity of 82 pb{sup -1}. Jets were identified in the hadronic centre-of-mass (HCM) frame using the k{sub T} cluster algorithm in the longitudinally invariant inclusive mode. Measurements of dijet and trijet differential cross sections are presented as functions of Q{sup 2}, x{sub Bj}, jet transverse energy, and jet pseudorapidity. As a further examination of low-x{sub Bj} dynamics, multi-differential cross sections as functions of the jet correlations in transverse momenta, azimuthal angles, and pseudorapidity are also presented. Calculations at O({alpha}{sup 3}{sub s}) generally describe the trijet data well and improve the description of the dijet data compared to the calculation at O({alpha}{sup 2}{sub s}). (orig.)

Searches for New Phenomena at the Tevatron and at HERA

Energy Technology Data Exchange (ETDEWEB)

Meyer, Arnd

2006-10-01

Recent results on searches for new physics at Run II of the Tevatron and highlights from HERA are reported. The searches cover many different final states and a wide range of models. All analyses have at this point led to negative results, but some interesting anomalies have been found.

A Preliminary ZEUS Lightning Location Error Analysis Using a Modified Retrieval Theory

Science.gov (United States)

Elander, Valjean; Koshak, William; Phanord, Dieudonne

2004-01-01

The ZEUS long-range VLF arrival time difference lightning detection network now covers both Europe and Africa, and there are plans for further expansion into the western hemisphere. In order to fully optimize and assess ZEUS lightning location retrieval errors and to determine the best placement of future receivers expected to be added to the network, a software package is being developed jointly between the NASA Marshall Space Flight Center (MSFC) and the University of Nevada Las Vegas (UNLV). The software package, called the ZEUS Error Analysis for Lightning (ZEAL), will be used to obtain global scale lightning location retrieval error maps using both a Monte Carlo approach and chi-squared curvature matrix theory. At the core of ZEAL will be an implementation of an Iterative Oblate (IO) lightning location retrieval method recently developed at MSFC. The IO method will be appropriately modified to account for variable wave propagation speed, and the new retrieval results will be compared with the current ZEUS retrieval algorithm to assess potential improvements. In this preliminary ZEAL work effort, we defined 5000 source locations evenly distributed across the Earth. We then used the existing (as well as potential future ZEUS sites) to simulate arrival time data between source and ZEUS site. A total of 100 sources were considered at each of the 5000 locations, and timing errors were selected from a normal distribution having a mean of 0 seconds and a standard deviation of 20 microseconds. This simulated "noisy" dataset was analyzed using the IO algorithm to estimate source locations. The exact locations were compared with the retrieved locations, and the results are summarized via several color-coded "error maps."

Measurement of D mesons production in deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Chakanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2007-04-15

Charm production in deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 82 pb{sup -1}. Charm has been tagged by reconstructing D{sup *+}, D{sup 0}, D{sup +} and D{sup +}{sub s} (+c.c.) charm mesons. The charm hadrons were measured in the kinematic range p{sub T}(D{sup *+},D{sup 0},D{sup +})>3 GeV, p{sub T}(D{sup +}{sub s})>2 GeV and vertical stroke {eta}(D) vertical stroke <1.6 for 1.5

J/ψ-production mechanisms and determination of the gluon density at HERA

International Nuclear Information System (INIS)

Jung, H.; Schuler, G.A.; Terron, J.

1992-02-01

We discuss photo- and leptoproduction of J/ψ-mesons at energies ranging from fixed-target experiments up to HERA. Elastic and diffractive production as well as various inelastic processes are studied. We investigate the range in which J/ψ-production is described by photon-gluon fusion in the colour-singlet model. We show how inelastic J/ψ production at HERA can be used to extract the gluon density. We estimate an accessible range of 3 x 10 -4 < x < 0.1 and discuss sources of errors in the reconstruction of the gluon density at HERA. (orig.)

Measurement of elastic ρ0 photoproduction at HERA

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magill, S.

1995-01-01

Elastic ρ 0 photoproduction has been measured using the ZEUS detector at HERA. Untagged photoproduction events from ep interactions were used to measure the reaction γp→ρ 0 p (ρ 0 →π + π - )at photon-proton centre-of-mass energies between 60 and 80 GeV and vertical stroke t vertical stroke 2 , where t is the square of the four-momentum transferred at the proton vertex. The differential cross section dσ/dM ππ , where M ππ is the invariant mass of the two pions, and the integrated cross section, σ γp →ρ 0 p , are presented; the latter was measured to be 14.7 ±0.4(stat.)±2.4(syst.) μb. The differential cross section dσ/dt has an approximately exponential shape; a fit of the type A' t exp(-b' t vertical stroke t vertical stroke +c' t t 2 ) yields a t-slope b' t =9.9±1.2(stat.)±1.4(syst.) GeV -2 . The results, when compared to low energy data, show a weak energy dependence of both σ γp→ρ 0 p and of the t-slope. The ρ 0 is produced predominantly with transverse polarisation, demostrating that s-channel helicity conservation holds at these energies. (orig.)

Measurement of elastic ρ0 photoproduction at HERA

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magill, S.

1995-07-01

Elastic ρ 0 photoproduction has been measured using the ZEUS detector at HERA. Untagged photoproduction events from ep interactions were used to measure the reaction γp→ρ 0 p (ρ 0 →π + π - ) at photon-proton centre-of-mass energies between 60 and 80 GeV and vertical stroke tvertical stroke 2 , where t is the square of the four-momentum transferred at the proton vertex. The differential cross section dσ/dM ππ , where M ππ is the invariant mass of the two pions, and the integrated cross section, σsub(γp→ρ 0 p), are presented; the latter was measured to be 14.7±0.4(stat.)±2.4(syst.) μb. The differential cross section dσ/dt has an approximately exponential shape; a fit of the type A' t exp(-b' t vertical stroke tvertical stroke +c' t t 2 ) yields a t-slope b' t =9.9±1.2(stat.)±1.4(syst.) μb. The results, when compared to low energy data, show a weak energy dependence of both σsub(γp→ρ 0 p) and of the t-slope. The ρ 0 is produced predominantly with transverse polarisation, demonstrating that s-channel helicity conservation holds at these energies. (orig.)

Charm quark pair correlations with D*-muon tag at HERA

International Nuclear Information System (INIS)

Gladkov, D.

2007-07-01

This thesis presents a measurement of double-tagged charm quark pair production via the process ep→e' ccX→e' D*μX' in lepton-proton collisions at HERA, using an integrated luminosity of 114 pb -1 gated by the ZEUS detector in the years 1996-2000. Since the charm quark mass provides a large enough energy scale, the perturbative Quantum Chromo-Dynamics approach can be used to calculate the cross section for charm D*-muon pairs. Using the D*-muon pair to tag the charm quark pair, the measurement is sensitive not only to properties of the leading order hard scattering process but also to the hadronisation and the parton density in the proton as well as higher order effects. Employing the angular and charge correlations between the D* meson and the muon, the fraction of charm events is extracted from the data. Cross sections for charm D*-muon pair production in the visible range of the D* transverse momentum p T D* >1.5 GeV, the D* pseudorapidity vertical stroke η D* vertical stroke T μ >1.0 GeV and the muon pseudorapidity vertical stroke η μ vertical stroke 2 2 ) and deep inelastic scattering (y 2 >2 GeV 2 ) regimes. For the inclusive and photoproduction regimes differential cross sections in various kinematic variables of the D*-muon pair are measured as well. The differential cross sections for the inclusive regime are compared to the leading order plus parton shower MC approach, while the differential cross sections for the photoproduction regime are compared to next-to leading order calculations. The momentum fraction carried by the gluon in the proton is also measured. The possibility of extending the Global Track Trigger of the ZEUS DAQ/trigger system with a forward trigger algorithm is the technical task of this thesis. A forward trigger algorithm has been written which finds the event vertex position using STT and FMVD detector data. (orig.)

Intercalibration of the ZEUS high resolution and backing calorimeters

International Nuclear Information System (INIS)

Abramowicz, H.; Czyrkowski, H.; Derlicki, A.; Krzyzanowski, M.; Kudla, I.; Kusmierz, W.; Nowak, R.J.; Pawlak, J.M.; Rajca, A.; Stopczynski, A.; Walczak, R.; Zarnecki, A.F.; Kowalski, T.Z.

1991-07-01

We have studied the combined performance of two calorimeters, the high resolution uranium-scintillator prototype of the ZEUS forward calorimeter (FCAL), followed by a prototype of the coarser ZEUS backing calorimeter (BAC), made out of thick iron plates interleaved with planes of aluminium proportional chambers. The test results, obtained in an exposure of the calorimeter system to a hadron test beam at the CERN-SPS, show that the backing calorimeter does fulfil its role of recognizing the energy leaking out of the FCAL calorimeter. The measurement of this energy is feasible, if an appropriate calibration of the BAC calorimeter is performed. (orig.)

Intercalibration of the ZEUS high resolution and backing calorimeters

International Nuclear Information System (INIS)

Abramowicz, H.; Czyrkowski, H.; Derlicki, A.; Krzyzanowski, M.; Kudla, I.; Kusmierz, W.; Nowak, R.J.; Pawlak, J.M.; Rajca, A.; Stopczynski, A.; Walczak, R.; Zarnecki, A.F.; Kowalski, T.Z.

1992-01-01

We have studied the combined performance of two calorimeters, the high resolution uranium-scintillator prototype of the ZEUS forward calorimeter (FCAL), followed by a prototype of the coarser ZEUS backing calorimeter (BAC), made out of thick iron plates interleaved with planes of aluminium proportional chambers. The test results, obtained in an exposure of the calorimeter system to a hadron test beam at the CERN SPS, show that the backing calorimeter does fulfil its role of recognizing the energy leaking out of the FCAL calorimeter. The measurement of this energy is feasible, if an appropriate calibration of the BAC calorimeter is performed. (orig.)

The outer tracker detector of the HERA-B experiment. Pt. 3. Operation and performance

International Nuclear Information System (INIS)

Albrecht, H.; Bauer, T.S.; Utrecht Univ.; Beck, M.

2006-12-01

In this paper we describe the operation and performance of the HERA-B Outer Tracker, a 112674 channel system of planar drift tube layers. The performance of the HERA-B Outer Tracker system fullfilled all requirements for stable and efficient operation in a hadronic environment, thus confirming the adequacy of the honeycomb drift tube technology and of the front-end readout system. The detector was stably operated with a gas gain of 3 . 10 4 in an Ar/CF 4 /CO 2 (65:35:5) gas mixture, yielding a good efficiency for triggering and track reconstruction, larger than 95 % for tracks with momenta above 5 GeV/c. The hit resolution of the drift cells was 300 to 320 μm and the relative momentum resolution can be described as: σ(p)/p(%) = (1.61 ± 0.02) + (0.0051 ± 0.0006) . p. At the end of the HERA-B running no aging effects in the Outer Tracker cells were observed. (orig.)

Development of the ZEUS central tracking detector

Science.gov (United States)

Brooks, C. B.; Bullock, F. W.; Cashmore, R. J.; Devenish, R. C.; Foster, B.; Fraser, T. J.; Gibson, M. D.; Gilmore, R. S.; Gingrich, D.; Harnew, N.; Hart, J. C.; Heath, G. P.; Hiddleston, J.; Holmes, A. R.; Jamdagni, A. K.; Jones, T. W.; Llewellyn, T. J.; Long, K. R.; Lush, G. J.; Malos, J.; Martin, N. C.; McArthur, I.; McCubbin, N. A.; McQuillan, D.; Miller, D. B.; Mobayyen, M. M.; Morgado, C.; Nash, J.; Nixon, G.; Parham, A. G.; Payne, B. T.; Roberts, J. H. C.; Salmon, G.; Saxon, D. H.; Sephton, A. J.; Shaw, D.; Shaw, T. B.; Shield, P. D.; Shulman, J.; Silvester, I.; Smith, S.; Strachan, D. E.; Tapper, R. J.; Tkaczyk, S. M.; Toudup, L. W.; Wallis, E. W.; Wastie, R.; Wells, J.; White, D. J.; Wilson, F. F.; Yeo, K. L.; ZEUS-UK Collaboration

1989-11-01

The design concept and development of the ZEUS central tracking detector is described. This is a cylindrical drift chamber designed for track reconstruction, electron identification and event triggering in a high-crossing-rate, high-magnetic-field environment.

Production of Z0 bosons in elastic and quasi-elastic ep collisions at HERA

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2012-10-01

The production of Z 0 bosons in the reaction ep → eZ 0 p (*) , where p (*) stands for a proton or a low-mass nucleon resonance, has been studied in ep collisions at HERA using the ZEUS detector. The analysis is based on a data sample collected between 1996 and 2007, amounting to 496 pb -1 of integrated luminosity. The Z 0 was measured in the hadronic decay mode. The elasticity of the events was ensured by a cut on η max max is the maximum pseudorapidity of energy deposits in the calorimeter defined with respect to the proton beam direction. A signal was observed at the Z 0 mass. The cross section of the reaction ep → eZ 0 p (*) was measured to be σ (ep → eZ 0 p (*) ) = 0.13 ± 0.06 (stat.) ± 0.01 (syst.) pb, in agreement with the Standard Model prediction of 0.16 pb. This is the first measurement of Z 0 production in ep collisions.

Study of beauty quark production and next-to-leading order at HERA

Energy Technology Data Exchange (ETDEWEB)

Nuncio Quiroz, Adriana Elizabeth

2008-08-15

In this thesis a study on the production and evolution of beauty quarks in ep collisions at HERA is presented. The emphasis is put on the corresponding Quantum Chromodynamics predictions including next-to-leading order corrections. In the context of this work the FMNR x Pythia interface was developed, which calculates next-to-leading order Quantum Chromodynamics predictions at visible level for heavy-flavour processes in the photoproduction regime. This is achieved using the RedStat routines which transform the FMNR program into a Monte Carlo-like event generator. The parton-level events obtained are interfaced to Pythia using the Le Houches accord routines. All branching ratios and decay channels of the heavy quarks implemented in the Pythia framework are used, and therefore complex cuts on the nal state can be applied. The FMNR x Pythia interface is applied in this thesis to obtain next-to-leading order predictions for the recently finished heavy flavour ZEUS analyses: the ep {yields} b anti bX {yields} D{sup *}{mu}X' and ep {yields} b anti bX {yields} {mu}{sup +}{mu}{sup -}X' channels. A comparison with the H1 D{sup *}{mu} measurement is also performed. Since the use of such double tagging techniques to identify events where heavy flavours are present proved to be very convenient when the nal state is a pair of leptons, another part of this thesis work deals with the implementation of an electron finder, the {sup G}Elec finder. This finder is tested on the reconstruction of the J/{psi} {yields} e{sup +}e{sup -} signal. Finally, a heavy-flavour analysis has been started, namely the ep {yields} b anti bX {yields} e{mu}X' dilepton channel, using an integrated luminosity of 114 pb{sup -1} gated by the ZEUS detector in the years 1996-2000. Compared to previous analyses the study of beauty quark production in this channel extends the phase space of the measurement closer to the kinematic threshold, since electrons provide access to lower p{sub T} values

Measurement of the cross section for the reaction γp →J/ψp with the ZEUS detector at HERA

International Nuclear Information System (INIS)

Derrick, M.; Krakauer, D.; Magill, S.

1995-03-01

This paper reports the cross section measurements for the process ep→eJ/ψ p for Q 2 2 at √s=296 GeV, based on an integrated luminosity of about 0.5 pb -1 , using the ZEUS detector. The J/ψ was detected in its e + e - and μ + μ - decay modes. The photoproduction cross section was measured to be 52 -12 +7 ±10 nb at an average γp centre of mass energy of 67 GeV and 71 -20 +13 ±12 nb at 114 GeV. The significant rise of the cross section compared to lower energy measurements is not in agreement with VDM models, but can be described by QCD inspired models if a rise in the gluon momentum density at low x in the proton is assumed. (orig.)

Diffractive dijet production in deep inelastic scattering at ZEUS

Energy Technology Data Exchange (ETDEWEB)

Bonato, A.

2008-03-15

This thesis presents a measurement of dijet production of diffractive deep inelastic scattering ep collisions. This type of process is specially relevant for the experimental validity of the perturbative QCD approach to diffractive physics. The measurement was based on an integrated luminosity of 61 pb{sup -1} collected at the HERA collider with the ZEUS experiment. The events were selected for virtualities of the photon, {gamma}*, 54 GeV. The jet with the highest transverse energy was required to have E{sub T} {sub jet}*>5 GeV. All jets were required to be in the pseudorapidity range -3.5<{eta}{sub jet}*<0 as measured in the {gamma}*p frame. The selection of diffractive events was carried out by requiring a large rapidity gap in the direction of the scattered proton. The value of the fraction of initial proton momentum entering in the hard process, x{sub P}, was required to be x{sub P}<0.03. The total cross section for the process was measured to be {sigma}{sub TOT}{sup D}(ep{yields}ep jet{sub 1}jet{sub 2} X')=9.15{+-}1.2 (stat.){sub 5.4}{sup 3.3} (syst.){sub -5.3}{sup +6.4} (corr.)pb. Single and double differential cross sections were extracted and compared to leading-order predictions and next-to-leading-order QCD calculations. The latter used several diffractive parton densities extracted from inclusive diffractive deep inelastic scattering data. The agreement with the leading and next-to-leading order predictions is good and no hints of factorisation breaking are observed. The double differential measurement can be a previous input for the extraction of more accurate diffractive parton densities. (orig.)

Development of the ZEUS central tracking detector

International Nuclear Information System (INIS)

Brooks, C.B.; Cashmore, R.J.; Gingrich, D.; Harnew, N.; Heath, G.P.; Holmes, A.R.; Martin, N.C.; McArthur, I.; Nash, J.; Salmon, G.; Shield, P.D.; Silvester, I.; Smith, S.; Wastie, R.; Wells, J.; Jamdagni, A.K.; McQuillan, D.; Miller, D.B.; Mobayyen, M.M.; Shulman, J.; Toudup, L.W.

1989-01-01

The design concept and development of the ZEUS central tracking detector is described. This is a cylindrical drift chamber designed for track reconstruction, electron identification and event triggering in a high-crossing-rate, high-magnetic-field environment. (orig.)

Investigation of ADAMO performance in the ZEUS calorimeter reconstruction program

International Nuclear Information System (INIS)

Kowalski, H.; Poser, T.; Stanco, L.; Tscheslog, E.

1989-01-01

The ADAMO package has been investigated for the reconstruction of jets simulated in the ZEUS calorimeter. The feasibility of ADAMO routines was tested under various aspects. The study was based on different versions of a cluster algorithm using ADAMO tools or direct BOS memory management tools. In particular, the amount of CPU time needed by each of the versions was determined. Results are quite promising and support an extensive use of the ADAMO package in the software development of high energy physics experiments. (orig.)

Simulations of Polarization Leakage and Ionospheric Attenuation in Visibility Measurements for the HERA and PAPER Experiments

Science.gov (United States)

Martinot, Zachary; Kohn, Saul; Aguirre, James; Washington, Immanuel; HERA Collaboration, PAPER Collaboration

2018-01-01

The HERA and PAPER experiments that aim to detect the power spectrum of the 21cm brightness temperature during the Epoch of Reionization (EoR) are planned with the expectation that foregrounds will be separated from the cosmological signal by a clearly demarcated boundary in Fourier space. Polarized foregrounds with complex frequency structure present a potential systematic as their mixing into unpolarized signal by the polarized response of an instrument's beam may be confused for the unpolarized EoR signal. There are two factors we believe will mitigate this systematic to the point that it will not impede the detection of the cosmological power spectrum in the foreground avoidance scheme. First, variation in the ionospheric plasma density observed between different days produces attenuation of the effective polarized power on the sky when visibilities are averaged coherently over many days. Second, the absolute level of polarization leakage can be suppressed through careful design of the instrument. We have performed detailed visibility simulations to investigate both effects, and present the results of these simulations for both the HERA and PAPER instruments.

Measurement of the neutral current reaction at high Q{sup 2} in the H1 experiment at HERA II

Energy Technology Data Exchange (ETDEWEB)

Shushkevich, Stanislav

2012-12-15

This thesis presents inclusive e{sup {+-}}p double and single differential cross section measurements for neutral current deep inelastic scattering of longitudinally polarized leptons on protons as a function of the negative four-momentum transfer squared Q{sup 2} and the Bjorken variable x. The data were collected in the years 2003-2007 in the H1 experiment at HERA with positively and negatively longitudinally polarized lepton beams of 27 GeV and a proton beam of 920 GeV corresponding to the centre-of-mass energy of {radical}(s)=319 GeV. The integrated luminosity is about 330 pb{sup -1}. An overview of the phenomenology of the deep inelastic scattering is given and the experimental apparatus is described. The NC cross section measurement procedure is presented and discussed in details. The measured cross sections are used to investigate electroweak effects at high Q{sup 2}. The proton structure function xF{sub 3}, sensitive to the valence quarks in the proton, is measured. The polarization effects sensitive to the chiral structure of neutral currents are investigated. The Standard Model predictions are found to be in a good agreement with the measurement.

HERA the new frontier

International Nuclear Information System (INIS)

Feltesse, J.

1992-01-01

The large storage ring Hardon-Electron-Ring Accelerator (HERA) has been completed at DESY. The first collisions for physics studies are scheduled for spring 1992. HERA is the first electron-proton storage ring ever built. Electrons and protons of nominal energies, E e = 30 GeV and E p = 820 GeV will collide at center of mass energy 314 GeV. The beam energies can be varied, while maintaining luminosity, over the range E e = 10-35 GeV and E p = 300-1000 GeV. The theoretical motivations and questions raised by quantum chromodynamics in this new demain are approached at a phenomenological level. The measurement of x the momentum fraction carried by the struck quark inside the proton, and Q 2 , are reviewed over the accessible domain at HERA energies from the scattered electron and hadron flow laboratory variables. The various experimental methods to extract the gluon distribution are described. Other physics opportunities to test the standard model are briefly given. Finally, a few examples of processes not expected by the standard model, but within the reach of HERA energetics, are outlined

A RISC multiprocessor event trigger for the data acquisition system of the H1 experiment at HERA

International Nuclear Information System (INIS)

Campbell, A.J.

1992-01-01

In late 1991 HERA will collide for the first time stored beams of electrons and protons. This paper describes the multiple RISC processor system for online event filtering and reconstruction installed within the data acquisition system of the H1 experiment. Data is processed at a continuous average rate of ∼6 Mbytes/s in parallel by ∼20 R3000 VMEbus based monoboard computers providing some 400 MIPS computing power

Study of beauty quark production and next-to-leading order effects at HERA

International Nuclear Information System (INIS)

Nuncio Quiroz, Adriana Elizabeth

2008-08-01

In this thesis a study on the production and evolution of beauty quarks in ep collisions at HERA is presented. The emphasis is put on the corresponding Quantum Chromodynamics predictions including next-to-leading order corrections. In the context of this work the FMNR x Pythia interface was developed, which calculates next-to-leading order Quantum Chromodynamics predictions at visible level for heavy-flavour processes in the photoproduction regime. This is achieved using the RedStat routines which transform the FMNR program into a Monte Carlo-like event generator. The parton-level events obtained are interfaced to Pythia using the Le Houches accord routines. All branching ratios and decay channels of the heavy quarks implemented in the Pythia framework are used, and therefore complex cuts on the nal state can be applied. The FMNR x Pythia interface is applied in this thesis to obtain next-to-leading order predictions for the recently finished heavy flavour ZEUS analyses: the ep → b anti bX → D * μX' and ep → b anti bX → μ + μ - X' channels. A comparison with the H1 D * μ measurement is also performed. Since the use of such double tagging techniques to identify events where heavy flavours are present proved to be very convenient when the nal state is a pair of leptons, another part of this thesis work deals with the implementation of an electron finder, the G Elec finder. This finder is tested on the reconstruction of the J/ψ → e + e - signal. Finally, a heavy-flavour analysis has been started, namely the ep → b anti bX → eμX' dilepton channel, using an integrated luminosity of 114 pb -1 gated by the ZEUS detector in the years 1996-2000. Compared to previous analyses the study of beauty quark production in this channel extends the phase space of the measurement closer to the kinematic threshold, since electrons provide access to lower p T values than muons do. The technical part of this thesis consisted in the calibration, maintenance and data

Measurement of charm and beauty production in deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Roloff, Philipp

2011-12-15

In this thesis two measurements of heavy quark production in deep inelastic scattering at HERA are presented. Cross sections for the production of heavy quarks can be calculated in quantum chromodynamics (QCD). The heavy quark masses represent hard scales, which allow to apply perturbative methods. Charm production has been measured with the ZEUS detector using an integrated luminosity of 120 pb{sup -1}. The hadronic decay channels D{sup +} {yields} K{sup 0}{sub S}{pi}{sup +}, {lambda}{sup +}{sub c} {yields} pK{sup 0}{sub S} and {lambda}{sup +}{sub c} {yields} {lambda}{pi}{sup +} were reconstructed. The presence of a neutral strange hadron in the final state reduces the combinatorial background and extends the measured sensitivity into the region p{sub T}(D{sup +}, {lambda}{sup +}{sub c}) < 1.5 GeV. The inclusive cross section and differential cross sections in p{sub T}{sup 2} (D{sup +}), {eta}(D{sup +}), Q{sup 2} and x for the production of D{sup +} mesons are in reasonable agreement with predictions from perturbative QCD. The fraction of c quarks hadronising into {lambda}{sup +}{sub c} baryons was extracted from a combination of both investigated {lambda}{sup +}{sub c} decay channels. The result is consistent with a previous measurement in the photoproduction regime and with the average e{sup +}e{sup -} value. The production of charm and beauty quarks has been measured with the ZEUS detector using the data collected between 2004 and 2007. This data sample corresponds to an integrated luminosity of 354 pb{sup -1}. The charm and beauty contents in events with a jet were determined using the decay-length significance and invariant mass of the reconstructed secondary decay vertices. Differential cross sections in E{sup jet}{sub T}, {eta}{sup jet}, Q{sup 2} and x are in reasonable agreement with predictions for perturbative QCD. The open charm and beauty contributions to the inclusive proton structure function F{sub 2} were extracted from double differential cross

Measurement of inelastic J/ψ production in deep inelastic ep scattering at HERA

International Nuclear Information System (INIS)

Antonov, A.

2007-08-01

This thesis presents a measurement of the inelastic production of J/ψ mesons in ep collisions with the ZEUS detector at HERA using an integrated luminosity of 109 pb -1 . The J/ψ mesons were identified using the decay channel J/ψ → μ + μ - . The measurements were performed in the kinematic range 2 2 2 , 50 lab 2 is the virtuality of the exchanged photon, W is the photon-proton centre-of-mass energy, z is the fraction of the photon energy carried by the J/ψ meson in the proton rest frame and Y lab is the rapidity of the J/ψ in the laboratory frame. The measured cross sections are compared to theoretical predictions within the non-relativistic QCD framework including colour-singlet and colour-octet contributions, as well as to predictions based on the k T -factorisation approach. Calculations of the colour-singlet process generally agree with the data, whereas inclusion of colour-octet terms spoils this agreement. As a technical part of this thesis, the Straw-Tube Tracker (STT) GEANT simulation and track reconstruction software developed. Studies of the STT performance with MC data and real data presented. (orig.)

Charm production in charged current deep inelastic e{sup +}p scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Wang, M.

2006-03-15

The measurement of charm production in charged current deep inelastic positron-proton scattering is investigated with the ZEUS detector at the HERA collider. The data used has been collected from 1995 to 2000, corresponding to an integrated luminosity of 110 pb{sup -1}. Charged D{sup *} mesons decaying in the channel D{sup *+}{yields}D{sup 0}{pi}{sup +}{sub s} with D{sup 0}{yields}K{sup -}{pi}{sup +} and the charge conjugated channel are reconstructed to tag charm quarks. The visible cross section for D{sup *}, {sigma}{sup D*}{sub vis}=12.8{+-}4.0(stat){sup +4.7}{sub -1.5}(sys) pb, is measured in the kinematic range of Q{sup 2}>200 GeV{sup 2} and y<0.9, and of p{sup D{sup *}}{sub T}>1.5 GeV and vertical stroke {eta}{sup D{sup *}} vertical stroke <1.5. The upper-limit for the charm production in the same DIS kinematic range is determined to be {sigma}{sup e{sup +}}{sup p{yields}} {sup anti} {sup {nu}{sub e}}{sup cX} < 109 pb at 90% confidence level. (orig.)

Measurement of the cross-section ratio σψ(2S/σJ/ψ(1S in deep inelastic exclusive ep scattering at HERA

Directory of Open Access Journals (Sweden)

H. Abramowicz

2016-08-01

Full Text Available The exclusive deep inelastic electroproduction of ψ(2S and J/ψ(1S at an ep centre-of-mass energy of 317 GeV has been studied with the ZEUS detector at HERA in the kinematic range 2II periods and correspond to an integrated luminosity of 468 pb−1. The decay modes analysed were μ+μ− and J/ψ(1Sπ+π− for the ψ(2S and μ+μ− for the J/ψ(1S. The cross-section ratio σψ(2S/σJ/ψ(1S has been measured as a function of Q2,W  and t. The results are compared to predictions of QCD-inspired models of exclusive vector-meson production.

Diffractive open charm production at DESY HERA. Experiment versus two-gluon exchange model

Energy Technology Data Exchange (ETDEWEB)

Baranov, S.P. [P.N. Lebedev Inst. of Physics, Moscow (Russian Federation)

2010-03-15

Diffractive production of D{sup *} mesons at HERA conditions is considered in the framework of collinear two-gluon exchange model. Theoretical results are compared with recent experimental data. (orig.)

Measurement of D{sup +} and {lambda}{sub c}{sup +} production in deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ (Israel). Raymond and Beverly Sackler Faculty of Exact Sciences; Max Planck Institute, Munich (Germany); Abt, I. [Max Planck Institut, Muenchen (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Cracow (PL). Faculty of Physics and Applied Computer Science] (and others)

2010-06-15

Charm production in deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 120 pb{sup -1}. The hadronic decay channels D{sup +} {yields} K{sub S}{sup 0}{pi}{sup +}, {lambda}{sub c}{sup +} {yields} pK{sub S}{sup 0} and {lambda}{sub c}{sup +}{yields}{lambda}{pi}{sup +}, and their charge conjugates, were reconstructed. The presence of a neutral strange hadron in the final state reduces the combinatorial background and extends the measured sensitivity into the low transverse momentum region. The kinematic range is 0< p{sub T}(D{sup +}, {lambda}{sub c}{sup +})<10 GeV, vertical stroke {eta}(D{sup +}, {lambda}{sub c}{sup +}) vertical stroke <1.6, 1.5 < Q{sup 2}<1000 GeV{sup 2} and 0.02

Production of the excited charm mesons D{sub 1} and D{sup *}{sub 2} at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science] [and others; Collaboration: ZEUS Collaboration

2012-08-15

The production of the excited charm mesons D{sub 1}(2420) and D{sup *}{sub 2}(2460) in ep collisions has been measured with the ZEUS detector at HERA using an integrated luminosity of 373 pb{sup -1}. The masses of the neutral and charged states, the widths of the neutral states, and the helicity parameter of D{sub 1}(2420){sup 0} were determined and compared with other measurements and with theoretical expectations. The measured helicity parameter of the D{sup 0}{sub 1} allows for some mixing of S- and D-waves in its decay to D{sup *{+-}}{pi}{sup -+}. The result is also consistent with a pure D-wave decay. Ratios of branching fractions of the two decay modes of the D{sup *}{sub 2}(2460){sup 0} and D{sup *}{sub 2}(2460){sup {+-}} states were measured and compared with previous measurements. The fractions of charm quarks hadronising into D{sub 1} and D{sup *}{sub 2} were measured and are consistent with those obtained in e{sup +}e{sup -} annihilations.

A RISC multiprocessor event trigger for the data acquisition system of the H1 experiment at HERA

International Nuclear Information System (INIS)

Campbell, A.J.

1991-09-01

In late 1991 HERA will for the first time collide stored beams of electrons and protons. This paper describes the multiple (RISC) modern reduced instruction set processor system for online event filtering and reconstruction installed within the data acquisition system of the H1 experiment. Data is processed at a continuous average rate of ∼ 6 Mbytes/s in parallel by ∼ 20 R3000 VMEbus based monoboard computers providing some 400 mips computing power. (author)

Hydrogen Epoch of Reionization Array (HERA)

Science.gov (United States)

DeBoer, David R.; HERA

2015-01-01

The Hydrogen Epoch of Reionization Arrays (HERA - reionization.org) roadmap uses the unique properties of the neutral hydrogen (HI) 21cm line to probe our cosmic dawn: from the birth of the first stars and black holes, through the full reionization of the primordial intergalactic medium (IGM). HERA is a collaboration between the Precision Array Probing the Epoch of Reionization (PAPER - eor.berkeley.edu), the US-based Murchison Widefield Array (MWA - mwatelescope.org), and MIT Epoch of Reionization (MITEOR) teams along with the South African SKA-SA, University of KwaZulu Natal and the University of Cambridge Cavendish Laborabory. HERA has recently been awarded a National Science Foundation Mid-Scale Innovation Program grant to begin the next phase.HERA leverages the operation of the PAPER and MWA telescopes to explore techniques and designs required to detect the primordial HI signal in the presence of systematics and radio continuum foreground emission some four orders of magnitude brighter. With this understanding, we are now able to remove foregrounds to the limits of our sensitivity, culminating in the first physically meaningful upper limits. A redundant calibration algorithm from MITEOR improves the sensitivity of the approach.Building on this, the next stage of HERA incorporates a 14m diameter antenna element that is optimized both for sensitivity and for minimizing foreground systematics. Arranging these elements in a compact hexagonal grid yields an array that facilitates calibration, leverages proven foreground removal techniques, and is scalable to large collecting areas. HERA will be located in the radio quiet environment of the SKA site in the Karoo region of South Africa (where PAPER is currently located). It will have a sensitivity close to two orders of magnitude better than PAPER and the MWA to ensure a robust detection. With its sensitivity and broader frequency coverage, HERA can paint an uninterrupted picture through reionization, back to the

What one can learn about QCD from nuclear beams at HERA?

International Nuclear Information System (INIS)

Strikman, M.

1996-01-01

Overview is given of the theoretical issues of the physics which can be addressed with nuclear beams circulating in HERA. It is shown that such experiments widen considerably the horizon for probing QCD compared to that from free nucleon targets. They would allow to study nonlinear QCD phenomena at small x, understand dynamics of nuclear shadowing, as well as the the origin of diffraction in deep inelastic scattering. Interplay between the physics to be studied at HERA and in AA collisions at RHIC and LHC is also discussed. (author)

Working Group I: Parton distributions: Summary report for the HERA LHC Workshop Proceedings

Energy Technology Data Exchange (ETDEWEB)

Dittmar, M.; /Zurich, ETH; Forte, S.; /Milan U. /INFN, Milan; Glazov, A.; /DESY; Moch, S.; /DESY, Zeuthen; Alekhin, S.; Altarelli, G.; Andersen, Jeppe R.; Ball, R.D.; Blumlein, J.; Bottcher, H.; Carli, T.; Ciafaloni, M.; Colferai, D.; Cooper-Sarkar, A.; Corcella, G.; Del Debbio, L.; Dissertori, G.; Feltesse, J.; Guffanti, A.; Gwenlan, C.; Huston, J.; /Zurich, ETH /DESY, Zeuthen /Serpukhov, IHEP /CERN /Rome III U. /INFN, Rome3 /Cambridge U. /Edinburgh U. /Florence U. /INFN, Florence /Oxford U. /DSM, DAPNIA, Saclay

2005-11-01

We provide an assessment of the impact of parton distributions on the determination of LHC processes, and of the accuracy with which parton distributions (PDFs) can be extracted from data, in particular from current and forthcoming HERA experiments. We give an overview of reference LHC processes and their associated PDF uncertainties, and study in detail W and Z production at the LHC.We discuss the precision which may be obtained from the analysis of existing HERA data, tests of consistency of HERA data from different experiments, and the combination of these data. We determine further improvements on PDFs which may be obtained from future HERA data (including measurements of F{sub L}), and from combining present and future HERA data with present and future hadron collider data. We review the current status of knowledge of higher (NNLO) QCD corrections to perturbative evolution and deep-inelastic scattering, and provide reference results for their impact on parton evolution, and we briefly examine non-perturbative models for parton distributions. We discuss the state-of-the art in global parton fits, we assess the impact on them of various kinds of data and of theoretical corrections, by providing benchmarks of Alekhin and MRST parton distributions and a CTEQ analysis of parton fit stability, and we briefly presents proposals for alternative approaches to parton fitting. We summarize the status of large and small x resummation, by providing estimates of the impact of large x resummation on parton fits, and a comparison of different approaches to small x resummation, for which we also discuss numerical techniques.

Search for excited leptons in the data of the H1 experiment at the HERA collider

International Nuclear Information System (INIS)

Delerue, N.

2002-09-01

Composite models are one of the possible extensions of the Standard Model. One of their implications, at the energy in the reach of present particles accelerators, would be the excitation of leptons. This PhD. thesis describes the search for excited leptons with the H1 detector installed on the electron-proton collider HERA in Hamburg (Germany). The data used were accumulated between 1994 and 2000 and amount to an integrated luminosity of 120 pb -1 . The analysis of 6 different topologies were done and cover all the branching ratios of desexcitation of excited electron and neutrino. The numbers of candidates found during those analysis is in agreement with the Standard Model expectations. This means that no evidence of excited leptons production was found at HERA. This result was translated in the form of exclusion limits on the coupling of excited leptons (f/A) depending on the mass of the excited lepton. For the first time at HERA we addressed the case were the natural decay width of the excited neutrino is wider than the experimental resolution. For the first time also, a study of the variation of limit depending on the ratio f' / f was carried out. This study lead to the setting of limits independent of this ratio. The limits obtained extend results previously obtained at HERA and also the results of direct searches at LEP. (orig.)

The HERA Approach To Morally Competent Robots

DEFF Research Database (Denmark)

Lindner, Felix; Bentzen, Martin Mose; Nebel, Bernhard

2017-01-01

for implementation in robots. The novelty is that HERA implements multiple ethical principles like utilitarianism, the principle of double effect, and a Pareto-inspired principle. These principles can be used to automatically assess moral situations represented in a format we call causal agency models. We discuss......To address the requirement for autonomous moral decision making, we introduce a software library for modeling hybrid ethical reasoning agents (short: HERA). The goal of the HERA project is to provide theoretically well-founded and practically usable logic-based machine ethics tools...... how to model moral situations using our approach, and how it can cope with uncertainty about moral values. Finally, we briefly outline the architecture of our robot IMMANUEL, which implements HERA and is able to explain ethical decisions to humans....

An experiment to study CP violation in the B system using an internal target at the HERA proton ring

International Nuclear Information System (INIS)

Hofmann, W.

1993-03-01

A group of physicists centered around the ARGUS collaboration got interested in hadron accelerators as a prolific source of B hadrons. The group is presently studying the option of a major-B-physics experiment to be performed at the HERA proton storage ring in fixed target mode using an internal target. Basic goal of the experiment is the detection of CP violation in the 'gold plated' B 0 → J/Ψ K s decay mode, using a dedicated detector triggered on lepton pairs from J/Ψ decay. (orig./HSI)

Measurement of high-Q{sup 2} charged current deep inelastic scattering cross sections with a longitudinally polarised positron beam at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). Faculty of Exact Sciences, School of Physics; Max-Planck-Inst., Munich (Germany); Abt, I. [Max-Planck-Inst. fuer Physik, Muenchen (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Cracow (PL). Faculty of Physics and Applied Computer Science] (and others)

2010-08-15

Measurements of the cross sections for charged current deep inelastic scattering in e{sup +}p collisions with a longitudinally polarised positron beam are presented. The measurements are based on a data sample with an integrated luminosity of 132 pb{sup -1} collected with the ZEUS detector at HERA at a centre-of-mass energy of 318 GeV. The total cross section is presented at positive and negative values of the longitudinal polarisation of the positron beams. The single-differential cross sections d{sigma}/dQ{sup 2}, d{sigma}/dx and d{sigma}/dy are presented for Q{sup 2}>200 GeV{sup 2}. The reduced cross-section {sigma} is presented in the kinematic range 200

Search for excited leptons in the data of the H1 experiment at the HERA collider; Recherche de leptons excites dans les donnees de l'experience H1 aupres du collisionneur HERA

Energy Technology Data Exchange (ETDEWEB)

Delerue, N

2002-05-01

Composite models are one of the possible extensions of the Standard Model. One of their implications, at the energy in the reach of present particles accelerators, would be the excitation of leptons. This PhD. thesis describes the search for excited leptons with the H1 detector installed on the electron-proton collider HERA in Hamburg (Germany). The data used were accumulated between 1994 and 2000 and amount to an integrated luminosity of 120 pb{sup -1}. The analysis of 6 different topologies were done and cover all the branching ratios of deexcitation of excited electron and neutrino. The numbers of candidates found during those analysis is in agreement with the Standard Model expectations. This means that no evidence of excited leptons production was found at HERA. This result was translated in the form of exclusion limits on the coupling of excited leptons (f/{lambda}) depending on the mass of the excited lepton. For the first time at HERA we addressed the case were the natural decay width of the excited neutrino is wider than the experimental resolution. For the first time also, a study of the variation of limit depending on the ratio f'/f was carried out. This study lead to the setting of limits independent of this ratio. The limits obtained extend results previously obtained at HEA and also the results of direct searches at LEP. (author)

Jet energy measurements with the ZEUS prototype calorimeter

International Nuclear Information System (INIS)

Kroeger, W.

1993-01-01

The uranium scintillator calorimeter of the ZEUS detector is designed to achieve an excellent energy calibration and the best possible energy resolution for jets. Therefore the response of the prototype calorimeter to jets has been measured using an interaction trigger. The mean response and energy resolution was measured for jets of 50 GeV - 100 GeV and compared to the one for pions. Within the ZEUS detector dead material is placed in front of the calorimeter. The influence of 4 cm and 10 cm thick aluminium absorbers in front of the calorimeter was measured. The charged multiplicity was measured in front and behind the aluminium absorber. With these multiplicities the energy loss in the absorber is corrected. The correction has been done so that the mean response with absorber is equal to the mean response without absorber. The improvement of the energy resolution is investigated. The measured results are compared with Monte Carlo simulations. (orig.) [de

Production of Z{sup 0} bosons in elastic and quasi-elastic ep collisions at HERA

Energy Technology Data Exchange (ETDEWEB)

Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science] [and others; Collaboration: ZEUS Collaboration

2012-10-15

The production of Z{sup 0} bosons in the reaction ep {yields} eZ{sup 0}p{sup (*)}, where p{sup (*)} stands for a proton or a low-mass nucleon resonance, has been studied in ep collisions at HERA using the ZEUS detector. The analysis is based on a data sample collected between 1996 and 2007, amounting to 496 pb{sup -1} of integrated luminosity. The Z{sup 0} was measured in the hadronic decay mode. The elasticity of the events was ensured by a cut on {eta}{sub max} < 3.0, where {eta}{sub max} is the maximum pseudorapidity of energy deposits in the calorimeter defined with respect to the proton beam direction. A signal was observed at the Z{sup 0} mass. The cross section of the reaction ep {yields} eZ{sup 0}p{sup (*)} was measured to be {sigma} (ep {yields} eZ{sup 0}p{sup (*)}) = 0.13 {+-} 0.06 (stat.) {+-} 0.01 (syst.) pb, in agreement with the Standard Model prediction of 0.16 pb. This is the first measurement of Z{sup 0} production in ep collisions.

The New Web-Based Hera Data Processing System at the HEASARC

Science.gov (United States)

Pence, W.; Chai, P.

2012-09-01

The HEASARC at NASA/GSFC has hosted an on-line astronomical data processing system called Hera for several years. Hera provides a complete data processing environment, including installed software packages, local data storage, and the CPU resources needed to support astronomical research by external users. The original design of Hera was based on a ‘client/server’ model which required that the user a) download and install a small helper program on their own computer before using Hera, and b) ensure that several non-standard computer ports/sockets be open for communication through any local firewalls on the user's machine. Hera has now been redesigned to eliminate these restrictions by operating within a purely Web-based environment which is accessed via a standard Web browser. Web-Hera is available at http://heasarc.gsfc.nasa.gov/webHera.

Propagation of epithermal neutrons in the empty mesh of the EDF3 reactor. Application of Zeus IV

International Nuclear Information System (INIS)

Brisbois, Jacques; Sonnet, Alain; Rafalovitch, Armand

1969-10-01

The authors report the verification of the Zeus 4 Monte Carlo code by applying it to an actual example of neutron propagation in a large enclosure, the empty mesh of the EDF3 reactor, supplied through the box holes (for the passage of heat transfer fluid ducts). This enclosure is represented by 105 parallelepipedic meshes in which are placed 4 plane and square sources of same cross section as the holes, and emitting inwards in cos θ. Source intensity is determined by flow rate measurements during tests in the air, interpreted by a Zeus-based calculation and channel power measurements during a 387 MW level operation. The presence of ducts is taken into account by applying a global attenuation coefficient to the sources. Calculation and experiment results agree very well in view of geometry complexity [fr

A QCD analysis of ZEUS diffractive data

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

2009-11-15

ZEUS inclusive diffractive cross-section measurements have been used in a DGLAP next-to-leading-order QCD analysis to extract the diffractive parton distribution functions. Data on diffractive dijet production in deep inelastic scattering have also been included to constrain the gluon density. Predictions based on the extracted parton densities are compared to diffractive charm and dijet photoproduction data. (orig.)

A QCD analysis of ZEUS diffractive data

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2009-11-01

ZEUS inclusive diffractive cross-section measurements have been used in a DGLAP next-to-leading-order QCD analysis to extract the diffractive parton distribution functions. Data on diffractive dijet production in deep inelastic scattering have also been included to constrain the gluon density. Predictions based on the extracted parton densities are compared to diffractive charm and dijet photoproduction data. (orig.)

Search for Excited Electrons in ep Collisions at HERA

CERN Document Server

Aaron, F.D.; Andreev, V.; Antunovic, B.; Aplin, S.; Asmone, A.; Astvatsatourov, A.; Bacchetta, A.; Backovic, S.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Beckingham, M.; Begzsuren, K.; Behnke, O.; Belousov, A.; Berger, N.; Bizot, J.C.; Boenig, M.-O.; Boudry, V.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Bruncko, D.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Cantun Avila, K.B.; Cassol-Brunner, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Cholewa, A.; Contreras, J.G.; Coughlan, J.A.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Daum, K.; Deak, M.; de Boer, Y.; Delcourt, B.; Del Degan, M.; Delvax, J.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dodonov, V.; Dossanov, A.; Dubak, A.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eliseev, A.; Elsen, E.; Essenov, S.; Falkiewicz, A.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Finke, L.; Fleischer, M.; Fomenko, A.; Gabathuler, E.; Gayler, J.; Ghazaryan, Samvel; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gouzevitch, M.; Grab, C.; Greenshaw, T.; Grell, B.R.; Grindhammer, G.; Habib, S.; Haidt, D.; Hansson, M.; Helebrant, C.; Henderson, R.C.W.; Henschel, H.; Herrera, G.; Hildebrandt, M.; Hiller, K.H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Hreus, T.; Jacquet, M.; Janssen, M.E.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jung, Andreas Werner; Jung, H.; Kapichine, M.; Katzy, J.; Kenyon, I.R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knutsson, A.; Kogler, R.; Korbel, V.; Kostka, P.; Kraemer, M.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Kutak, K.; Landon, M.P.J.; Lange, W.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Leibenguth, G.; Lendermann, V.; Levonian, S.; Li, G.; Lipka, K.; Liptaj, A.; List, B.; List, J.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.-I.; Lytkin, L.; Makankine, A.; Malinovski, E.; Marage, P.; Marti, Ll.; Martyn, H.-U.; Maxfield, S.J.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, H.; Meyer, J.; Michels, V.; Mikocki, S.; Milcewicz-Mika, I.; Moreau, F.; Morozov, A.; Morris, J.V.; Mozer, Matthias Ulrich; Mudrinic, M.; Muller, K.; Murin, P.; Nankov, K.; Naroska, B.; Naumann, Th.; Newman, Paul R.; Niebuhr, C.; Nikiforov, A.; Nowak, G.; Nowak, K.; Nozicka, M.; Olivier, B.; Olsson, J.E.; Osman, S.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, Th.; Pascaud, C.; Patel, G.D.; Pejchal, O.; Peng, H.; Perez, E.; Petrukhin, A.; Picuric, I.; Piec, S.; Pitzl, D.; Placakyte, R.; Polifka, R.; Povh, B.; Preda, T.; Radescu, V.; Rahmat, A.J.; Raicevic, N.; Raspiareza, A.; Ravdandorj, T.; Reimer, P.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Ruiz Tabasco, J.E.; Rurikova, Z.; Rusakov, S.; Salek, D.; Salvaire, F.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schoning, A.; Schultz-Coulon, H.-C.; Sefkow, F.; Shaw-West, R.N.; Sheviakov, I.; Shtarkov, L.N.; Shushkevich, S.; Sloan, T.; Smiljanic, Ivan; Smirnov, P.; Soloviev, Y.; Sopicki, P.; South, D.; Spaskov, V.; Specka, Arnd E.; Staykova, Z.; Steder, M.; Stella, B.; Straumann, U.; Sunar, D.; Sykora, T.; Tchoulakov, V.; Thompson, G.; Thompson, P.D.; Toll, T.; Tomasz, F.; Tran, T.H.; Traynor, D.; Trinh, T.N.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, K.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Vinokurova, S.; Volchinski, V.; Wegener, D.; Wessels, M.; Wissing, Ch.; Wunsch, E.; Yeganov, V.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zhu, Y.C.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.

2008-01-01

A search for excited electrons is performed using the full $e^{\\pm}p$ data sample collected by the H1 experiment at HERA, corresponding to a total luminosity of 475 pb$^{-1}$. The electroweak decays of excited electrons ${e}^{*}\\to{e}{\\gamma}$, ${e}^{*}\\to{e}Z$ and ${e}^{*}{\\to}\

Ground based THz Spectroscopy of Obscured Starbursts in the Early Universe enabled by the 2nd generation Redshift (z) & Early Universe Spectrometer (ZEUS-2)

Science.gov (United States)

Vishwas, Amit; Stacey, Gordon; Nikola, Thomas; Ferkinhoff, Carl; Parshley, Stephen; Schoenwald, Justin; Lamarche, Cody James; Higdon, James; Higdon, Sarah; Brisbin, Drew; Güesten, Rolf; Weiss, Axel; Menten, Karl; Irwin, Kent; Cho, Hsiao-Mei; Niemack, Michael; Hilton, Gene; Hubmayr, Johannes; Amiri, Mandana; Halpern, Mark; Wiebe, Donald; Hasselfield, Matthew; Ade, Peter; Tucker, Carole

2018-01-01

Galaxies were surprisingly dusty in the early Universe, with more than half of the light emitted from stars being absorbed by dust within the system and re-radiated into far infrared (FIR, ~50-150μm) wavelengths. Dusty star forming galaxies (DSFGs) dominate the co-moving star formation rate density of the Universe that peaks around redshift, z~2, making it compelling to study them in rest frame FIR bands. From galaxies at z > 1, the FIR line emission from abundant ions like [O III], [C II] and [N II], are redshifted into the short sub-mm telluric windows. My thesis work is based on building and deploying the 2nd Generation Redshift (z) and Early Universe Spectrometer (ZEUS-2), a long-slit, echelle grating spectrometer optimized to study broad (Δv = 300km/s) spectral lines from galaxies in the 200-650µm telluric windows using TES bolometers. These far-IR lines being extinction free and major coolants of the gas heated by (young) massive stars, are powerful probes of the physical conditions of the gas and the stellar radiation field. I present results from our survey of the [O III] 88µm line in galaxies at redshift, z ~ 2.8 to 4.6, with ZEUS-2 at the Atacama Pathfinder Experiment (APEX) Telescope. To interpret our observations along with ancillary data from optical to radio facilities, we apply photoionization models for HII regions and Photo Dissociation Region (PDR) models and confirm that the galaxies host substantial ongoing obscured star formation. The presence of doubly ionized oxygen suggests hard radiation fields and hence, elevated ionization parameters that can only be accounted for by a large population of massive stars formed during the ongoing starburst, that contribute a large fraction of the infrared luminosity. This study highlights the use of FIR line emission to trace the assembly of current day massive galaxies, conditions of star formation and details of their stellar populations. The construction and operation of ZEUS-2 were funded by NSF ATI

Search for excited leptons in the data of the H1 experiment at the HERA collider; Recherche de leptons excites dans les donnees de l'experience H1 aupres du collisionneur HERA

Energy Technology Data Exchange (ETDEWEB)

Delerue, N

2002-05-01

Composite models are one of the possible extensions of the Standard Model. One of their implications, at the energy in the reach of present particles accelerators, would be the excitation of leptons. This PhD. thesis describes the search for excited leptons with the H1 detector installed on the electron-proton collider HERA in Hamburg (Germany). The data used were accumulated between 1994 and 2000 and amount to an integrated luminosity of 120 pb{sup -1}. The analysis of 6 different topologies were done and cover all the branching ratios of deexcitation of excited electron and neutrino. The numbers of candidates found during those analysis is in agreement with the Standard Model expectations. This means that no evidence of excited leptons production was found at HERA. This result was translated in the form of exclusion limits on the coupling of excited leptons (f/{lambda}) depending on the mass of the excited lepton. For the first time at HERA we addressed the case were the natural decay width of the excited neutrino is wider than the experimental resolution. For the first time also, a study of the variation of limit depending on the ratio f'/f was carried out. This study lead to the setting of limits independent of this ratio. The limits obtained extend results previously obtained at HEA and also the results of direct searches at LEP. (author)

Charm quark pair correlations with D{sup *}-muon tag at HERA

Energy Technology Data Exchange (ETDEWEB)

Gladkov, D.

2007-07-15

This thesis presents a measurement of double-tagged charm quark pair production via the process ep{yields}e' ccX{yields}e' D*{mu}X' in lepton-proton collisions at HERA, using an integrated luminosity of 114 pb{sup -1} gated by the ZEUS detector in the years 1996-2000. Since the charm quark mass provides a large enough energy scale, the perturbative Quantum Chromo-Dynamics approach can be used to calculate the cross section for charm D*-muon pairs. Using the D*-muon pair to tag the charm quark pair, the measurement is sensitive not only to properties of the leading order hard scattering process but also to the hadronisation and the parton density in the proton as well as higher order effects. Employing the angular and charge correlations between the D* meson and the muon, the fraction of charm events is extracted from the data. Cross sections for charm D*-muon pair production in the visible range of the D* transverse momentum p{sub T}{sup D*}>1.5 GeV, the D* pseudorapidity vertical stroke {eta}{sup D*} vertical stroke <1.5, the muon transverse momentum p{sub T}{sup {mu}}>1.0 GeV and the muon pseudorapidity vertical stroke {eta}{sup {mu}} vertical stroke <2.2 are measured for the inclusive, photoproduction (inelasticity 0.052 GeV{sup 2}) regimes. For the inclusive and photoproduction regimes differential cross sections in various kinematic variables of the D*-muon pair are measured as well. The differential cross sections for the inclusive regime are compared to the leading order plus parton shower MC approach, while the differential cross sections for the photoproduction regime are compared to next-to leading order calculations. The momentum fraction carried by the gluon in the proton is also measured. The possibility of extending the Global Track Trigger of the ZEUS DAQ/trigger system with a forward trigger algorithm is the technical task of this thesis. A forward

Photoproduction at collider energies: from RHIC and HERA to the LHC

CERN Document Server

Baltz, A; Brodsky, S J; D'Enterria, D G; Dreyer, U; Engel, R; Frankfurt, L; Gorbunov, Y; Guzey, V; Hamilton, A; Klasen, M; Klein, S R; Kowalski, H; Levonian, S; Lourenço, C; Machado, M V T; Nachtmann, O; Nagy, Z; Nystrand, J; Piotrzkowski, K; Ramalhete, P; Savin, A; Scapparone, E; Schicker, R; Silvermyr, D; Strikman, M I; Valkárová, A; Vogt, R; Yilmaz, M; Enterria, David d'

2007-01-01

We present the mini-proceedings of the workshop on "Photoproduction at collider energies: from RHIC and HERA to the LHC" held at the European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*, Trento) from January 15 to 19, 2007. The workshop gathered both theorists and experimentalists to discuss the current status of investigations of high-energy photon-induced processes at different colliders (HERA, RHIC, and Tevatron) as well as preparations for extension of these studies at the LHC. The main physics topics covered were: (i) small-$x$ QCD in photoproduction studies with protons and in electromagnetic (aka. ultraperipheral) nucleus-nucleus collisions, (ii) hard diffraction physics at hadron colliders, and (iii) photon-photon collisions at very high energies: electroweak and beyond the Standard Model processes. These mini-proceedings consist of an introduction and short summaries of the talks presented at the meeting.

HERA and the LHC: A Workshop on the implications of HERA for LHC physics: Proceedings Part A

CERN Document Server

De Roeck, A.; Startup Meeting; Working Group Meeting; Mid-term Review Meeting; Working Group Meeting; Working Group Meeting; Final Meeting

2005-01-01

The HERA electron--proton collider has collected 100 pb$^{-1}$ of data since its start-up in 1992, and recently moved into a high-luminosity operation mode, with upgraded detectors, aiming to increase the total integrated luminosity per experiment to more than 500 pb$^{-1}$. HERA has been a machine of excellence for the study of QCD and the structure of the proton. The Large Hadron Collider (LHC), which will collide protons with a centre-of-mass energy of 14 TeV, will be completed at CERN in 2007. The main mission of the LHC is to discover and study the mechanisms of electroweak symmetry breaking, possibly via the discovery of the Higgs particle, and search for new physics in the TeV energy scale, such as supersymmetry or extra dimensions. Besides these goals, the LHC will also make a substantial number of precision measurements and will offer a new regime to study the strong force via perturbative QCD processes and diffraction. For the full LHC physics programme a good understanding of QCD phenomena and the ...

The New Web-Based Hera Data Processing System at the HEASARC

Science.gov (United States)

Pence, W.

2011-01-01

The HEASARC at NASA/GSFC has provide an on-line astronomical data processing system called Hera for several years. Hera provides a complete data processing environment, including installed software packages, local data storage, and the CPU resources needed to process the user's data. The original design of Hera, however, has 2 requirements that has limited it's usefulness for some users, namely, that 1) the user must download and install a small helper program on their own computer before using Hera, and 2) Hera requires that several computer ports/sockets be allowed to communicate through any local firewalls on the users machine. Both of these restrictions can be problematic for some users, therefore we are now migrating Hera into a purely Web based environment which only requires a standard Web browser. The first release of Web Hera is now publicly available at http://heasarc.gsfc.nasa.gov/webheara/. It currently provides a standard graphical interface for running hundreds of different data processing programs that are available in the HEASARC's ftools software package. Over the next year we to add more features to Web Hera, including an interactive command line interface, and more display and line capabilities.

Measurement of high-Q{sup 2} charged current cross sections in e{sup +}p deep inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Rautenberg, J

2004-06-01

Cross sections for charged current deep inelastic scattering have been measured in e{sup +}p collisions at a center-of-mass energy of 318 GeV. The data collected with the ZEUS detector at HERA in the running periods 1999 and 2000 correspond to an integrated luminosity of 61 pb{sup -1}. Single differential cross sections d{sigma}/dQ{sup 2}, d{sigma}/dx and d{sigma}/dy have been measured for Q{sup 2}>200 GeV{sup 2}, as well as the double differential reduced cross section d{sup 2}{sigma}/dxdQ{sup 2} in the kinematic range 280 GeV{sup 2}

Combination of Measurements of Inclusive Deep Inelastic $e^{\\pm}p$ Scattering Cross Sections and QCD Analysis of HERA Data

CERN Document Server

Abramowicz, H.; Adamczyk, L.; Adamus, M.; Andreev, V.; Antonelli, S.; Antunovic, B.; Aushev, V.; Aushev, Y.; Baghdasaryan, A.; Begzsuren, K.; Behnke, O.; Behrendt Dubak, A.; Behrens, U.; Belousov, A.; Belov, P.; Bertolin, A.; Bloch, I.; Boos, E.G.; Borras, K.; Boudry, V.; Brandt, G.; Brisson, V.; Britzger, D.; Brock, I.; Brook, N.H.; Brugnera, R.; Bruni, A.; Buniatyan, A.; Bussey, P.J.; Bylinkin, A.; Bystritskaya, L.; Caldwell, A.; Campbell, A.J.; Cantun Avila, K.B.; Capua, M.; Catterall, C.D.; Ceccopieri, F.; Cerny, K.; Chekelian, V.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Contreras, J.G.; Cooper-Sarkar, A.M.; Corradi, M.; Corriveau, F.; Cvach, J.; Dainton, J.B.; Daum, K.; Dementiev, R.K.; Devenish, R.C.E.; Diaconu, C.; Dobre, M.; Dodonov, V.; Dolinska, G.; Dusini, S.; Eckerlin, G.; Egli, S.; Elsen, E.; Favart, L.; Fedotov, A.; Feltesse, J.; Ferencei, J.; Figiel, J.; Fleischer, M.; Fomenko, A.; Foster, B.; Gabathuler, E.; Gach, G.; Gallo, E.; Garfagnini, A.; Gayler, J.; Geiser, A.; Ghazaryan, S.; Gizhko, A.; Gladilin, L.K.; Goerlich, L.; Gogitidze, N.; Golubkov, Yu. A.; Gouzevitch, M.; Grab, C.; Grebenyuk, A.; Grebenyuk, J.; Greenshaw, T.; Gregor, I.; Grindhammer, G.; Grzelak, G.; Gueta, O.; Guzik, M.; Gwenlan, C.; Haidt, D.; Hain, W.; Henderson, R.C.W.; Henkenjohann, P.; Hladky, J.; Hochman, D.; Hoffmann, D.; Hori, R.; Horisberger, R.; Hreus, T.; Huber, F.; Ibrahim, Z.A.; Iga, Y.; Ishitsuka, M.; Iudin, A.; Jacquet, M.; Janssen, X.; Januschek, F.; Jomhari, N.Z.; Jung, H.; Kadenko, I.; Kananov, S.; Kapichine, M.; Karshon, U.; Kaur, M.; Kaur, P.; Kiesling, C.; Kisielewska, D.; Klanner, R.; Klein, M.; Klein, U.; Kleinwort, C.; Kogler, R.; Kondrashova, N.; Kononenko, O.; Korol, Ie.; Korzhavina, I.A.; Kostka, P.; Kotanski, A.; Kotz, U.; Kovalchuk, N.; Kowalski, H.; Kretzschmar, J.; Kruger, K.; Krupa, B.; Kuprash, O.; Kuze, M.; Landon, M.P.J.; Lange, W.; Laycock, P.; Lebedev, A.; Levchenko, B.B.; Levonian, S.; Levy, A.; Libov, V.; Limentani, S.; Lipka, K.; Lisovyi, M.; List, B.; List, J.; Lobodzinska, E.; Lobodzinski, B.; Lohr, B.; Lohrmann, E.; Longhin, A.; Lontkovskyi, D.; Lukina, O.Yu.; Makarenko, I.; Malinovski, E.; Malka, J.; Martyn, H.U.; Maxfield, S.J.; Mehta, A.; Mergelmeyer, S.; Meyer, A.B.; Meyer, H.; Meyer, J.; Mikocki, S.; Idris, F.Mohamad; Morozov, A.; Nasir, N.Muhammad; Muller, K.; Myronenko, V.; Nagano, K.; Naumann, Th.; Newman, P.R.; Niebuhr, C.; Nikiforov, A.; Nobe, T.; Notz, D.; Nowak, G.; Nowak, R.J.; Olsson, J.E.; Onishchuk, Yu.; Ozerov, D.; Pahl, P.; Pascaud, C.; Patel, G.D.; Paul, E.; Perez, E.; Perlanski, W.; Petrukhin, A.; Picuric, I.; Pirumov, H.; Pitzl, D.; Pokorny, B.; Pokrovskiy, N.S.; Polifka, R.; Przybycien, M.; Radescu, V.; Raicevic, N.; Ravdandorj, T.; Reimer, P.; Rizvi, E.; Robmann, P.; Roloff, P.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Rubinsky, I.; Rusakov, S.; Ruspa, M.; Salek, D.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Saxon, D.H.; Schioppa, M.; Schmidke, W.B.; Schmitt, S.; Schneekloth, U.; Schoeffel, L.; Schoning, A.; Schorner-Sadenius, T.; Sefkow, F.; Shcheglova, L.M.; Shevchenko, R.; Shkola, O.; Shushkevich, S.; Shyrma, Yu.; Singh, I.; Skillicorn, I.O.; Slominski, W.; Solano, A.; Soloviev, Y.; Sopicki, P.; South, D.; Spaskov, V.; Specka, A.; Stanco, L.; Steder, M.; Stefaniuk, N.; Stella, B.; Stern, A.; Stopa, P.; Straumann, U.; Sykora, T.; Sztuk-Dambietz, J.; Szuba, D.; Szuba, J.; Tassi, E.; Thompson, P.D.; Tokushuku, K.; Tomaszewska, J.; Traynor, D.; Trofymov, A.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Tsurugai, T.; Turcato, M.; Turkot, O.; Turnau, J.; Tymieniecka, T.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vazdik, Y.; Verbytskyi, A.; Viazlo, O.; Walczak, R.; Wan Abdullah, W.A.T.; Wegener, D.; Wichmann, K.; Wing, M.; Wolf, G.; Wunsch, E.; Yamada, S.; Yamazaki, Y.; Zacek, J.; Zakharchuk, N.; Zarnecki, A.F.; Zawiejski, L.; Zenaiev, O.; Zhang, Z.; Zhautykov, B.O.; Zhmak, N.; Zlebcik, R.; Zohrabyan, H.; Zomer, F.; Zotkin, D.S.

2015-12-08

A combination is presented of all inclusive deep inelastic cross sections previously published by the H1 and ZEUS collaborations at HERA for neutral and charged current $e^{\\pm}p$ scattering for zero beam polarisation. The data were taken at proton beam energies of 920, 820, 575 and 460 GeV and an electron beam energy of 27.5 GeV. The data correspond to an integrated luminosity of about 1 fb$^{-1}$ and span six orders of magnitude in negative four-momentum-transfer squared, $Q^2$, and Bjorken $x$. The correlations of the systematic uncertainties were evaluated and taken into account for the combination. The combined cross sections were input to QCD analyses at leading order, next-to-leading order and at next-to-next-to-leading order, providing a new set of parton distribution functions, called HERAPDF2.0. In addition to the experimental uncertainties, model and parameterisation uncertainties were assessed for these parton distribution functions. Variants of HERAPDF2.0 with an alternative gluon parameterisatio...

Analysis of spin depolarizing effects in electron storage rings

International Nuclear Information System (INIS)

Boege, M.

1994-05-01

In this thesis spin depolarizing effects in electron storage rings are analyzed and the depolarizing effects in the HERA electron storage ring are studied in detail. At high beam energies the equilibrium polarization is limited by nonlinear effects. This will be particularly true in the case of HERA, when the socalled ''spin rotators'' are inserted which are designed to provide longitudinal electron polarization for the HERMES experiment in 1994 and later for the H1 and ZEUS experiment. It is very important to quantify the influence of these effects theoretically by a proper modelling of HERA, so that ways can be found to get a high degree of polarization in the real machine. In this thesis HERA is modelled by the Monte-Carlo tracking program SITROS which was originally written by J. Kewisch in 1982 to study the polarization in PETRA. The first part of the thesis is devoted to a detailed description of the fundamental theoretical concepts on which the program is based. Then the approximations which are needed to overcome computing time limitations are explained and their influence on the simulation result is discussed. The systematic and statistical errors are studied in detail. Extensions of the program which allow a comparison of SITROS with the results given by ''linear'' theory are explained. (orig.)

Inclusive-jet cross sections in NC DIS at HERA and a comparison of the kT, anti-kT and SIScone jet algorithms

International Nuclear Information System (INIS)

Abramowicz, H.; Abt, I.; Adamczyk, L.

2010-03-01

For the first time, differential inclusive-jet cross sections have been measured in neutral current deep inelastic ep scattering using the anti-k T and SIScone algorithms. The measurements were made for boson virtualities Q 2 > 125 GeV 2 with the ZEUS detector at HERA using an integrated luminosity of 82 pb -1 and the jets were identified in the Breit frame. The performance and suitability of the jet algorithms for their use in hadron-like reactions were investigated by comparing the measurements to those performed with the k T algorithm. Next-to-leading-order QCD calculations give a good description of the measurements. Measurements of the ratios of cross sections using different jet algorithms are also presented; the measured ratios are well described by calculations including up to O(α s 3 ) terms. Values of α s (M Z ) were extracted from the data; the results are compatible with and have similar precision to the value extracted from the k T analysis. (orig.)

Deep inelastic inclusive and diffractive scattering at Q2 values from 25 to 320 GeV2 with the ZEUS forward plug calorimeter

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-01-01

Deep inelastic scattering and its diffractive component, ep→e'γ * p→e'XN, have been studied at HERA with the ZEUS detector using an integrated luminosity of 52.4 pb -1 . The M X method has been used to extract the diffractive contribution. A wide range in the centre-of-mass energy W (37-245 GeV), photon virtuality Q 2 (20-450 GeV 2 ) and mass M X (0.28-35 GeV) is covered. The diffractive cross section for 2 X 2 increases. The data are also presented in terms of the diffractive structure function, F D(3) 2 , of the proton. For fixed Q 2 and fixed M X , x P F D(3) 2 shows a strong rise as x P →0, where x P is the fraction of the proton momentum carried by the Pomeron. For Bjorken-x -3 , x P F D(3) 2 shows positive log Q 2 scaling violations, while for x≥5 x 10 -3 negative scaling violations are observed. The diffractive structure function is compatible with being leading twist. The data show that Regge factorisation is broken. (orig.)

Dijet cross sections at O(αα2s) in photon-proton-proton collisions

International Nuclear Information System (INIS)

Klasen, M.; Kramer, G.

1995-08-01

We have calculated inclusive two-jet production in low Q 2 ep collisions at O(αα s 2 ) superimposing direct and resolved contributions. The results are compared with recent experimental data from the ZEUS collaboration at HERA. (orig.)

Proceedings of the 15{sup th} international workshop on deep-inelastic scattering and related subjects - DIS 2007. Vol. 1

Energy Technology Data Exchange (ETDEWEB)

Grindhammer, Guenter; Sachs, Kirsten (eds.)

2007-09-15

The following topics were dealt with: QCD parton dynamics, results form the H1 and ZEUS experiments at HERA, the spin structure of the nucleon, QCD Monte Carlo generators, results from the Jefferson Lab, lattice QCD, results from the Tevatron, heavy flavour production, the fluid nature of the quark-gluon plasma, QCD dynamics in hadrons and nuclei at high energies, QCD and string theory, structure functions, electroweak measurements, physics beyond the Standard Model, diffraction and vector mesons, spin physics. (HSI)

Proceedings of the 15th international workshop on deep-inelastic scattering and related subjects - DIS 2007. Vol. 1

International Nuclear Information System (INIS)

Grindhammer, Guenter; Sachs, Kirsten

2007-09-01

The following topics were dealt with: QCD parton dynamics, results form the H1 and ZEUS experiments at HERA, the spin structure of the nucleon, QCD Monte Carlo generators, results from the Jefferson Lab, lattice QCD, results from the Tevatron, heavy flavour production, the fluid nature of the quark-gluon plasma, QCD dynamics in hadrons and nuclei at high energies, QCD and string theory, structure functions, electroweak measurements, physics beyond the Standard Model, diffraction and vector mesons, spin physics. (HSI)

Jet-radius dependence of inclusive-jet cross sections in deep inelastic scattering at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2006-12-01

Differential inclusive-jet cross sections have been measured for different jet radii in neutral current deep inelastic ep scattering for boson virtualities Q 2 >125 GeV 2 with the ZEUS detector at HERA using an integrated luminosity of 81.7 pb -1 . Jets were identified in the Breit frame using the k T cluster algorithm in the longitudinally inclusive mode for different values of the jet radius R. Differential cross sections are presented as functions of Q 2 and the jet transverse energy, E T,B jet . The dependence on R of the inclusive-jet cross section has been measured for Q 2 > 125 and 500 GeV 2 and found to be linear with R in the range studied. Next-to-leading-order QCD calculations give a good description of the measurements for 0.5 s (M Z ) has been extracted from the measurements of the inclusive-jet cross-section dσ/dQ 2 with R=1 for Q 2 > 500 GeV 2 : α s (M Z )=0.1207±0.0014(stat.) -0.0028 +0.0030 (exp.) -0.0 023 +0.0022 (th.). The variation of α s with E T,B jet is in good agreement with the running of α s as predicted by QCD. (orig.)

Measurement of the diffractive structure function of the proton in deep inelastic ep scattering with the ZEUS detector

International Nuclear Information System (INIS)

Doeker, T.

1995-10-01

The analysis of deep inelastic scattering events at the ep collider HERA at DESY has shown that in about 7% of the recorded events a large rapidity gap of at least 3 units is observed between the proton direction and the observed hadronic system. The observation can be understood in terms of soft photon-hadron reactions, where the hadronic final state is interpreted as arising from the dissociation of a virtual photon in the field of a diffractively scattered proton. The cross section of this process can be expressed in terms of the diffractive structure function of the proton. Here a measurement with the ZEUS detector is presented of the diffractive structure function of the proton as a function of x IP , the momentum fraction lost by the proton, of β, the momentum fraction of the struck constituent with respect to x IP , and of Q 2 , the virtuality of the exchanged photon. The kinematic range of this measurement is 6.3.10 -4 IP -2 , 0.1 2 2 2 . The x IP dependence is consistent with the form (1/x IP ) a where a=1.30±0.08(stat) -0.14 +0.08 (sys) in all bins of β and Q 2 . The diffractive structure function scales with Q 2 at fixed β. The results are compared with theoretical predictions of diffractive dissociation in deep inelastic scattering. (orig.)

Search for a narrow baryonic state decaying to pKS0 and p‾KS0 in deep inelastic scattering at HERA

OpenAIRE

Abramowicz, H.; Abt, I.; Adamczyk, L.; Adamus, M.; Antonelli, S.; Aushev, V.; Behnke, O.; Behrens, U.; Bertolin, A.; Bhadra, S.; Bloch, I.; Boos, E.G.; Brock, I.; Brook, N.H.; Brugnera, R.

2016-01-01

A search for a narrow baryonic state in the $pK^0_S$ and $\\bar{p}K^0_S$ system has been performed in $ep$ collisions at HERA with the ZEUS detector using an integrated luminosity of 358 pb$^{-1}$ taken in 2003-2007. The search was performed with deep inelastic scattering events at an $ep$ centre-of-mass energy of 318 GeV for exchanged photon virtuality, $Q^2$, between 20 and 100 $\\rm{} GeV^{2}$. Contrary to evidence presented for such a state around 1.52 GeV in a previous ZEUS analysis using ...

Measurement of Charm and Beauty Production in Deep Inelastic Scattering at HERA and Test Beam Studies of ATLAS Pixel Sensors

CERN Document Server

Libov, Vladyslav; Klanner, Robert; Haller, Johannes; Geiser, Achim

A measurement of charm and beauty production in Deep Inelastic Scattering at HERA is presented. The analysis is based on the data sample collected by the ZEUS detector in the period from 2003 to 2007 corresponding to an integrated luminosity of 354 pb 1 . The kinematic region of the measurement is given by 5 4 : 2(5) GeV for charm (beauty) and 1 : 6 < jet < 2 : 2 for both charm and beauty, where E jet T and jet are the transverse energy and pseudorapidity of the jet, respectively. The signicance of the decay length and the invariant mass of charged tracks associated with the secondary vertex are used as discriminating variables to distinguish between signal and background. Dierential cross sections of jet production in charm and beauty events as a function of Q 2 , y , E jet T and jet are measured. Results are compared to Next-to-Leading Order (NLO) predictions from Quantum Chromodynamics (QCD) in the xed avour number scheme. Good agreement between data and theory is observed. Contributions of the char...

Mathematical framework for fast and rigorous track fit for the ZEUS detector

Energy Technology Data Exchange (ETDEWEB)

Spiridonov, Alexander

2008-12-15

In this note we present a mathematical framework for a rigorous approach to a common track fit for trackers located in the inner region of the ZEUS detector. The approach makes use of the Kalman filter and offers a rigorous treatment of magnetic field inhomogeneity, multiple scattering and energy loss. We describe mathematical details of the implementation of the Kalman filter technique with a reduced amount of computations for a cylindrical drift chamber, barrel and forward silicon strip detectors and a forward straw drift chamber. Options with homogeneous and inhomogeneous field are discussed. The fitting of tracks in one ZEUS event takes about of 20ms on standard PC. (orig.)

Identification and angle reconstruction of the scattered electron with the ZEUS calorimeter

International Nuclear Information System (INIS)

Doeker, T.

1992-10-01

For the analysis of deep-inelastic electron-proton events with the ZEUS detector, a key ingredient is the reliable and efficient identification of a scattered electron. To this end an essential mean is the information from the uranium-scintillator calorimeter. In this work an algorithm is presented which uses the segmentation properties of the ZEUS calorimeter to identify the scattered electron in neutral current events. For energy deposits in adjacent calorimeter cells the algorithm determines the probability that these deposits result from an electromagnetic shower. Furthermore several methods of measuring the scattering angle of the final state electron are compared. An angular resolution of about 3 mrad is obtained. (orig.) [de

DESY: HERA commissioning

International Nuclear Information System (INIS)

Anon.

1992-01-01

The commissioning of the world's first electron-proton collider - the 6.3 kilometre HERA ring at the DESY Laboratory in Hamburg - last year was the result of more than a decade of careful planning, design and construction

HERA results on QCD and EW physics

International Nuclear Information System (INIS)

Zarnecki, A.F.

1997-01-01

Selected HERA results on QCD and EW interactions are presented. They include the measurement of the proton structure function and its analysis in terms of the QCD evolution, as well as results concerning deep inelastic scattering at very low and very high Q 2 . Selected HERA limits on new physics and parameters which extend the standard model are also presented. (author)

The soft pomeron and HERA

International Nuclear Information System (INIS)

Donnachie, A.; Landshoff, P.V.

1996-01-01

The standard phenomenology of the soft pomeron in hadron-hadron interactions is recalled briefly. The model is confronted with the HERA data for the total photoproduction cross section, deep inelastic scattering, diffractive vector meson photoproduction and diffractive electroproduction of vector mesons. Although much of the data can be explained by the model, there are some aspects of the HERA data which require a more rapid variation with energy than can be incorporated. It is argued that the perturbative (BFKL) pomeron cannot give a sufficiently large contribution to explain these observations. Possible non-perturbative solutions to this problem are indicated. (author)

The soft pomeron and HERA

International Nuclear Information System (INIS)

Donnachie, A.; Landshoff, P.V.

1996-01-01

The standard phenomenology of the soft pomeron in hadron-hadron interactions is recalled briefly. The model is confronted with the HERA data for the total photoproduction cross section, deep inelastic scattering, diffractive vector meson photoproduction and diffractive electroproduction of vector mesons. Although much of the data can be explained by the model, there are some aspects of the HERA data which require a more rapid variation with energy than can be incorporated. It is argued that the perturbative (BFKL) pomeron cannot give a sufficiently large contribution to explain these observations. Possible nonperturbative solutions to this problem are indicated. (author)

Cornell and Marseille

International Nuclear Information System (INIS)

Anon.

1993-01-01

A major theme running through the Cornell meeting, as with most physics meetings these days, was the need to look hard at suppressed or forbidden reactions for signs of an excess or positive signal, suggesting that at last something new might be happening. At Cornell, Jack Ritchie (Texas) covered the kaon front, while Anthony Sanda (Nagoya) gave an overall status report. Rare processes mediated by second order effects (two quarks mechanisms coupled back-to-back) have been seen by the CLEO detector at Cornell (June page 1), and Sanda suggested that other such effects could now begin to show up. Last year's major international meeting at Dallas marked the debut of physics results from the Zeus and H1 experiments at the new and unique HERA electron-proton collider at DESY, Hamburg. This year HERA's collision rate is climbing, and the entire 1992 collision score was matched in just one weekend at the end of July. Cornell's plenary-only programme featured back-to-back presentations from H1 (John Dainton, Liverpool) and Zeus (John Martin, Toronto). Both experiments are beginning to see signs of the tight particle clusters ('jets') indicative of constituent quark/ gluon interactions deep inside the 'target' protons. HERA probes the structure of the proton in an unexplored kinematical region (quark momentum fraction x approaching 10 -4 ), and H1 was the first to see how this structure develops as x decreases. As the proton is probed in increasingly finer detail, it shows a richer quark content as more transient ('virtual') quark/gluon contributions come into play. This structure evolution provides important information for quark field theory, with additional mechanisms opening up

Measurement of inelastic J/{psi} production in deep inelastic ep scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Antonov, A.

2007-08-15

This thesis presents a measurement of the inelastic production of J/{psi} mesons in ep collisions with the ZEUS detector at HERA using an integrated luminosity of 109 pb{sup -1}. The J/{psi} mesons were identified using the decay channel J/{psi} {yields} {mu}{sup +}{mu}{sup -}. The measurements were performed in the kinematic range 2

Initial study of deep inelastic scattering with ZEUS at HERA

Science.gov (United States)

Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Repond, J.; Repond, S.; Stanek, R.; Talaga, R. L.; Thron, J.; Arzarello, F.; Ayad, R.; Barbagli, G.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Bruni, P.; Cara Romeo, G.; Castellini, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Ciralli, F.; Contin, A.; D'Auria, S.; del Papa, C.; Frasconi, F.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Lin, Q.; Lisowski, B.; Maccarrone, G.; Margotti, A.; Massam, T.; Nania, R.; Nemoz, C.; Palmonari, F.; Sartorelli, G.; Timellini, R.; Zamora Garcia, Y.; Zichichi, A.; Bargende, A.; Crittenden, J.; Dabbous, H.; Desch, K.; Diekmann, B.; Doeker, T.; Geerts, M.; Geitz, G.; Gutjahr, B.; Hartmann, H.; Hartmann, J.; Haun, D.; Heinloth, K.; Hilger, E.; Jakob, H.-P.; Kramarczyk, S.; Kückes, M.; Mass, A.; Mengel, S.; Mollen, J.; Monaldi, D.; Müsch, H.; Paul, E.; Schattevoy, R.; Schneider, J.-L.; Wedemeyer, R.; Cassidy, A.; Cussans, D. G.; Dyce, N.; Fawcett, H. F.; Foster, B.; Gilmore, R.; Heath, G. P.; Lancaster, M.; Llewellyn, T. J.; Malos, J.; Morgado, C. J. S.; Tapper, R. J.; Wilson, S. S.; Rau, R. R.; Barillari, T.; Schioppa, M.; Susinno, G.; Bernstein, A.; Caldwell, A.; Gialas, I.; Parsons, J. A.; Ritz, S.; Sciulli, F.; Straub, P. B.; Wai, L.; Yang, S.; Burkot, W.; Eskreys, A.; Piotrzkowski, K.; Zachara, M.; Zawiejski, L.; Borzemski, P.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Rulikowska-Zerȩbska, E.; Suszycki, L.; Zajc, J.; Kȩdzierski, T.; Kotański, A.; Przybycień, M.; Bauerdick, L. A. T.; Behrens, U.; Bienlein, J. K.; Coldewey, C.; Dannemann, A.; Dierks, K.; Dorth, W.; Drews, G.; Erhard, P.; Flasiński, M.; Fleck, I.; Fürtjes, A.; Gläser, R.; Göttlicher, P.; Hass, T.; Hagge, L.; Hain, W.; Hasell, D.; Hultschig, H.; Jahnen, G.; Joos, P.; Kasemann, M.; Klanner, R.; Koch, W.; Kötz, U.; Kowalski, H.; Labs, J.; Ladage, A.; Löhr, B.; Lüke, D.; Mainusch, J.; Manczak, O.; Momayezi, M.; Ng, J. S. T.; Nicel, S.; Notz, D.; Park, I. H.; Pösnecker, K.-U.; Rohde, M.; Ros, E.; Schneekloth, S.; Schroeder, J.; Schulz, W.; Selonke, F.; Stiliaris, E.; Tscheslog, E.; Tsurugai, T.; Turkot, F.; Vogel, W.; Woeniger, T.; Wolf, G.; Youngman, C.; Grabosch, H. J.; Leich, A.; Meyer, A.; Rethfeldt, C.; Schlensthdt, S.; Casalbuoni, R.; de Curtis, S.; Dominici, D.; Francescato, A.; Nuti, M.; Pelfer, P.; Anzivino, G.; Casaccia, R.; de Pasquale, S.; Qian, S.; Votano, L.; Bamberger, A.; Freidhof, A.; Poser, T.; Söldner-Rembold, S.; Theisen, G.; Trefzger, T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Forbes, J. R.; Jamieson, V. A.; Raine, C.; Saxon, D. H.; Brückmann, H.; Gloth, G.; Holm, U.; Kammerdocher, H.; Krebs, B.; Neumann, T.; Wick, K.; Hofmann, A.; Kröger, W.; Krüger, J.; Lohrmann, E.; Milewski, J.; Nakahata, M.; Pavel, N.; Poelz, G.; Salomon, R.; Seidman, A.; Schott, W.; Wiik, B. H.; Zetsche, F.; Bacon, T. C.; Butterworth, I.; Markou, C.; McQuillan, D.; Miller, D. B.; Mobayyen, M. M.; Prinias, A.; Vorvolakos, A.; Bienz, T.; Kreutzmann, H.; Mallik, U.; McCliment, E.; Roco, M.; Wang, M. Z.; Cloth, P.; Filges, D.; Chen, L.; Imlay, R.; Kartik, S.; Kim, H.-J.; McNeil, R. R.; Metcalf, W.; Barreiro, F.; Cases, G.; Hervás, L.; Labarga, L.; del Peso, J.; Roldán, J.; Terrón, J.; de Trocóniz, J. F.; Ikraiam, F.; Mayer, J. K.; Smith, G. R.; Corriveau, F.; Gilkinson, D. J.; Hanna, D. S.; Hung, L. W.; Mitchell, J. W.; Patel, P. M.; Sinclair, L. E.; Stairs, D. G.; Ullmann, R.; Bashindzhagyan, G. L.; Ermolov, P. F.; Golubkov, Y. A.; Kuzmin, V. A.; Kuznetsov, E. N.; Savin, A. A.; Voronin, A. G.; Zotov, N. P.; Bentvelsen, S.; Dake, A.; Engelen, J.; de Jong, P.; de Jong, S.; de Kamps, M.; Kooijman, P.; Kruse, A.; van der Lugt, H.; O'dell, V.; Straver, J.; Tenner, A.; Tiecke, H.; Uijterwaal, H.; Vermeulen, J.; Wiggers, L.; de Wolf, E.; van Woudenberg, R.; Yoshida, R.; Bylsma, B.; Durkin, L. S.; Li, C.; Ling, T. Y.; McLean, K. W.; Murray, W. N.; Park, S. K.; Romanowski, T. A.; Seidlein, R.; Blair, G. A.; Butterworth, J. M.; Byrne, A.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Gingrich, D. M.; Hallam-Baker, P. M.; Harnew, N.; Khatri, T.; Long, K. R.; Luffman, P.; McArthur, I.; Morawitz, P.; Nash, J.; Smith, S. J. P.; Roocroft, N. C.; Wilson, F. F.; Abbiendi, G.; Brugnera, R.; Carlin, R.; dal Corso, F.; de Giorgi, M.; Dosselli, U.; Gasparini, F.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Field, G.; Lim, J. N.; Oh, B. Y.; Whitmore, J.; Contino, U.; D'Agostini, G.; Guida, M.; Iori, M.; Mari, S. M.; Marini, G.; Mattioli, M.; Nigro, A.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Short, T. L.; Barberis, E.; Cartiglia, N.; Heusch, C.; Hubbard, B.; Leslie, J.; O'Shaughnessy, K.; Sadrozinski, H. F.; Seiden, A.; Badura, E.; Biltzinger, J.; Chaves, H.; Rost, M.; Seifert, R. J.; Walenta, A. H.; Weihs, W.; Zech, G.; Dagan, S.; Levy, A.; Zer-Zion, D.; Hasegawa, T.; Hazumi, M.; Ishii, T.; Kasai, S.; Kuze, M.; Nagasawa, Y.; Nakao, M.; Okuno, H.; Tokushuku, K.; Watanabe, T.; Yamada, S.; Chiba, M.; Hamatsu, R.; Hirose, T.; Kitamura, S.; Nagayama, S.; Nakamitsu, Y.; Arneodo, M.; Costa, M.; Ferrero, M. I.; Lamberti, L.; Maselli, S.; Peroni, C.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Bandyopadhyay, D.; Benard, F.; Bhadra, S.; Brkic, M.; Burow, B. D.; Chlebana, F. S.; Crombie, M. B.; Hartner, G. F.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Prentice, J. D.; Sampson, C. R.; Stairs, G. G.; Teuscher, R. J.; Yoon, T.-S.; Bullock, F. W.; Catterall, C. D.; Giddings, J. C.; Jones, T. W.; Khan, A. M.; Lane, J. B.; Makkar, P. L.; Shaw, D.; Shulman, J.; Blankenship, K.; Gibaut, D. B.; Kochocki, J.; Lu, B.; Mo, L. W.; Charchula, K.; Ciborowski, J.; Gajewski, J.; Grzelak, G.; Kasprzak, M.; Krzyżanowski, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Stojda, K.; Stopczyński, A.; Szwed, R.; Tymieniecka, T.; Walczak, R.; Wróblewski, A. K.; Zakrzewski, J. A.; Zarnecki, A. F.; Adamus, M.; Abramowicz, H.; Eisenberg, Y.; Glasman, C.; Karshon, U.; Montag, A.; Revel, D.; Shapira, A.; Ali, I.; Behrens, B.; Camerini, U.; Dasu, S.; Fordham, C.; Foudas, C.; Goussiou, A.; Lomperski, M.; Loveless, R. J.; Nylander, P.; Ptacek, M.; Reeder, D. D.; Smith, W. H.; Silverstein, S.; Frisken, W. R.; Furutani, K. M.; Iga, Y.

1993-04-01

Results are presented on neutral current, deep inelastic scattering measured in collisions of 26.7 GeV electrons and 820 GeV protons. The events typically populate a range in Q2 from 10 to 100 GeV2. The values of x extend down to x ~ 10-4 which is two orders of magnitude lower than previously measured at such Q2 values in fixed target experiments. The measured cross sections are in accord with the extrapolations of current parametrisations of parton distributions.

A Search for Excited Neutrinos in e-p Collisions at HERA

CERN Document Server

Aaron, F.D.; Andreev, V.; Antunovic, B.; Aplin, S.; Asmone, A.; Astvatsatourov, A.; Backovic, S.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Baudrand, S.; Beckingham, M.; Begzsuren, K.; Behnke, O.; Belousov, A.; Berger, N.; Bizot, J.C.; Boenig, M.O.; Boudry, V.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Bruncko, D.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Cantun Avila, K.B.; Cassol-Brunner, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Cholewa, A.; Contreras, J.G.; Coughlan, J.A.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Daum, K.; Deak, M.; de Boer, Y.; Delcourt, B.; Del Degan, M.; Delvax, J.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dodonov, V.; Dossanov, A.; Dubak, A.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eisele, F.; Eliseev, A.; Elsen, E.; Essenov, S.; Falkiewicz, A.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Finke, L.; Fleischer, M.; Fomenko, A.; Franke, G.; Frisson, T.; Gabathuler, E.; Gayler, J.; Ghazaryan, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gouzevitch, M.; Grab, C.; Greenshaw, T.; Grell, B.R.; Grindhammer, G.; Habib, S.; Haidt, D.; Hansson, M.; Helebrant, C.; Henderson, R.C.W.; Henschel, H.; Herrera, G.; Hildebrandt, M.; Hiller, K.H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Hreus, T.; Jacquet, M.; Janssen, M.E.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jung, A.W.; Jung, H.; Kapichine, M.; Katzy, J.; Kenyon, I.R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knutsson, A.; Kogler, R.; Korbel, V.; Kostka, P.; Kraemer, M.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Kutak, K.; Landon, M.P.J.; Lange, W.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Leibenguth, G.; Lendermann, V.; Levonian, S.; Li, G.; Lipka, K.; Liptaj, A.; List, B.; List, J.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.I.; Lytkin, L.; Makankine, A.; Malinovski, E.; Marage, P.; Marti, Ll.; Martyn, H.U.; Maxfield, S.J.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, H.; Meyer, J.; Michels, V.; Mikocki, S.; Milcewicz-Mika, I.; Moreau, F.; Morozov, A.; Morris, J.V.; Mozer, M.U.; Mudrinic, M.; Muller, K.; Murin, P.; Nankov, K.; Naroska, B.; Naumann, Th.; Newman, P.R.; Niebuhr, C.; Nikiforov, A.; Nowak, G.; Nowak, K.; Nozicka, M.; Olivier, B.; Olsson, J.E.; Osman, S.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, Th.; Pascaud, C.; Patel, G.D.; Pejchal, O.; Peng, H.; Perez, E.; Petrukhin, A.; Picuric, I.; Piec, S.; Pitzl, D.; Placakyte, R.; Polifka, R.; Povh, B.; Preda, T.; Radescu, V.; Rahmat, A.J.; Raicevic, N.; Raspiareza, A.; Ravdandorj, T.; Reimer, P.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Ruiz Tabasco, J.E.; Rurikova, Z.; Rusakov, S.; Salek, D.; Salvaire, F.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schoning, A.; Schultz-Coulon, H.C.; Sefkow, F.; Shaw-West, R.N.; Sheviakov, I.; Shtarkov, L.N.; Sloan, T.; Smiljanic, I.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, A.; Staykova, Z.; Steder, M.; Stella, B.; Straumann, U.; Sunar, D.; Sykora, T.; Tchoulakov, V.; Thompson, G.; Thompson, P.D.; Toll, T.; Tomasz, F.; Tran, T.H.; Traynor, D.; Trinh, T.N.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, K.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Vinokurova, S.; Volchinski, V.; Wegener, D.; Wessels, M.; Wissing, Ch.; Wolf, R.; Wunsch, E.; Yeganov, V.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zhu, Y.C.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.

2008-01-01

A search for excited neutrinos is performed using the full $e^{-}p$ data sample collected by the H1 experiment at HERA at a centre-of-mass energy of 319 GeV, corresponding to a total luminosity of 184 pb$^{-1}$.The electroweak decays of excited neutrinos ${\

A Search for Leptoquark Bosons in e^-p Collisions at HERA

CERN Document Server

Adloff, C.; Andrieu, B.; Anthonis, T.; Arkadov, V.; Astvatsatourov, A.; Babaev, A.; Bahr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bate, P.; Becker, J.; Beglarian, A.; Behnke, O.; Beier, C.; Belousov, A.; Benisch, T.; Berger, Christoph; Berndt, T.; Bizot, J.C.; Boehme, J.; Boudry, V.; Braunschweig, W.; Brisson, V.; Broker, H.B.; Brown, D.P.; Bruckner, W.; Bruncko, D.; Burger, J.; Busser, F.W.; Bunyatyan, A.; Burrage, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Cao, Jun; Caron, S.; Cassol-Brunner, F.; Clarke, D.; Clerbaux, B.; Collard, C.; Contreras, J.G.; Coppens, Y.R.; Coughlan, J.A.; Cousinou, M.C.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; Davidsson, M.; Delcourt, B.; Delerue, N.; Demirchyan, R.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dingfelder, J.; Dixon, P.; Dodonov, V.; Dowell, J.D.; Droutskoi, A.; Dubak, A.; Duprel, C.; Eckerlin, Guenter; Eckstein, D.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Ferron, S.; Fleischer, M.; Fleming, Y.H.; Flugge, G.; Fomenko, A.; Foresti, I.; Formanek, J.; Franke, G.; Gabathuler, E.; Gabathuler, K.; Garvey, J.; Gassner, J.; Gayler, Joerg; Gerhards, R.; Gerlich, C.; Ghazaryan, Samvel; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Grab, C.; Grassler, H.; Greenshaw, T.; Grindhammer, Guenter; Hadig, T.; Haidt, D.; Hajduk, L.; Haller, J.; Haynes, W.J.; Heinemann, B.; Heinzelmann, G.; Henderson, R.C.W.; Hengstmann, S.; Henschel, H.; Heremans, R.; Herrera, G.; Herynek, I.; Hildebrandt, M.; Hilgers, M.; Hiller, K.H.; Hladky, J.; Hoting, P.; Hoffmann, D.; Horisberger, R.; Hurling, S.; Ibbotson, M.; Issever, C .; Jacquet, M.; Jaffre, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, C.; Johnson, D.P.; Jones, M.A.S.; Jung, H.; Kant, D.; Kapichine, M.; Karlsson, M.; Karschnick, O.; Keil, F.; Keller, N.; Kennedy, J.; Kenyon, I.R.; Kermiche, S.; Kiesling, Christian M.; Kjellberg, P.; Klein, M.; Kleinwort, C.; Kluge, T.; Knies, G.; Koblitz, B.; Kolya, S.D.; Korbel, V.; Kostka, P.; Kotelnikov, S.K.; Koutouev, R.; Koutov, A.; Krehbiel, H.; Kroseberg, J.; Kruger, K.; Kupper, A.; Kuhr, T.; Kurca, T.; Lahmann, R.; Lamb, D.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Laycock, P.; Lebailly, E.; Lebedev, A.; Leissner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; Lindstroem, M.; List, B.; Lobodzinska, E.; Lobodzinski, B.; Loginov, A.; Loktionova, N.; Lubimov, V.; Luders, S.; Luke, D.; Lytkin, L.; Mahlke-Kruger, H.; Malden, N.; Malinovski, E.; Malinovski, I.; Maracek, R.; Marage, P.; Marks, J.; Marshall, R.; Martyn, H.U.; Martyniak, J.; Maxfield, S.J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, J.; Meyer, P.O.; Mikocki, S.; Milstead, D.; Mkrtchyan, T.; Mohr, R.; Mohrdieck, S.; Mondragon, M.N.; Moreau, F.; Morozov, A.; Morris, J.V.; Muller, K.; Murin, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, T.; Nellen, G.; Newman, Paul R.; Nicholls, T.C.; Niebergall, F.; Niebuhr, C.; Nix, O.; Nowak, G.; Olsson, J.E.; Ozerov, D.; Panassik, V.; Pascaud, C.; Patel, G.D.; Peez, M.; Perez, E.; Phillips, J.P.; Pitzl, D.; Poschl, R.; Potachnikova, I.; Povh, B.; Rabbertz, K.; Radel, G.; Rauschenberger, J.; Reimer, P.; Reisert, B.; Reyna, D.; Risler, C.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rusakov, S.; Rybicki, K.; Sankey, D.P.C.; Scheins, J.; Schilling, F.P.; Schleper, P.; Schmidt, D.; Schmidt, S.; Schmitt, S.; Schneider, M.; Schoeffel, L.; Schoning, A.; Schorner, T.; Schroder, V.; Schultz-Coulon, H.C.; Schwanenberger, C.; Sedlak, K.; Sefkow, F.; Chekelian, V.; Sheviakov, I.; Shtarkov, L.N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, Arnd E.; Spitzer, H.; Stamen, R.; Stella, B.; Stiewe, J.; Straumann, U.; Swart, M.; Tasevsky, M.; Tchernyshov, V.; Tchetchelnitski, S.; Thompson, Graham; Thompson, P.D.; Tobien, N.; Traynor, D.; Truoel, Peter; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Turney, J.E.; Tzamariudaki, E.; Udluft, S.; Urban, Marcel; Usik, A.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vassiliev, S.; Vazdik, Y.; Vichnevski, A.; Wacker, K.; Wallny, R.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Werner, C.; Werner, M.; Werner, N.; White, G.; Wiesand, S.; Wilksen, T.; Winde, M.; Winter, G.G.; Wissing, C.; Wobisch, M.; Woehrling, E.E.; Wunsch, E.; Wyatt, A.C.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zomer, F.; Zsembery, J.; Zur Nedden, M.

2001-01-01

A search for scalar and vector leptoquarks coupling to first generation fermions is performed in the H1 experiment at the ep collider HERA. The analysis uses e^- p data collected in 1998 and 1999 at a centre-of-mass energy of 320 GeV, corresponding to an integrated luminosity of 15 pb^-1. No evidence for the direct production of such particles is found in a data sample with a large transverse momentum final state electron or with large missing transverse momentum, and constraints on leptoquark models are established. For a Yukawa coupling of electromagnetic strength leptoquarks are excluded for masses up to 290 GeV. This analysis complements the leptoquark searches performed previously using data collected whilst HERA was operating with positrons instead of electrons.

Physics results from the first electron-proton collider HERA

Energy Technology Data Exchange (ETDEWEB)

Roeck, A de

1995-03-01

After two years of experimenting at the new ep collider HERA many new results have been obtained. In this report we have presented results on interactions of high energy photons with matter, and showed that similar to hadronic interactions, hard scattering is observed in these collisions. The different photoproduction processes have been isolated, and a first attempt was made to measure the structure of the photon at HERA. A new region has been explored for deep inelastic scattering interactions. The proton structure is probed to very small values of Bjorken-x, showing a large increase of with decreasing x. Events with a large rapidity gap have been observed and are identified as diffractive scattering. The first electroweak results became available by studying the production of charged current events. Searches for new, exotic phenomena were made, but no evidence for the breakdown of the standard model has been found. (orig.)

Measurement of neutral current cross-sections at high Bjorken-x with ...

Indian Academy of Sciences (India)

2012-11-16

Nov 16, 2012 ... theory predictions. Keywords. NC; deep inelastic scattering; ZEUS; HERA; Q2; x; y; Monte Carlo. PACS Nos 12.15.y; 13.85.Qk .... bins with zero measured events, a 68% probability limit is given. 1328. Pramana – J. Phys., Vol ...

Overview of the Human Exploration Research Analog (HERA)

Science.gov (United States)

Neigut, J.

2015-01-01

In 2013, the Human Research Program at NASA began developing a new confinement analog specifically for conducting research to investigate the effects of confinement on the human system. The HERA (Human Exploration Research Analog) habitat has been used for both 7 and 14 day missions to date to examine and mitigate exploration risks to enable safe, reliable and productive human space exploration. This presentation will describe how the Flight Analogs Project developed the HERA facility and the infrastructure to suit investigator requirements for confinement research and in the process developed a new approach to analog utilization and a new state of the art analog facility. Details regarding HERA operations will be discussed including specifics on the mission simulation utilized for the current 14-day campaign, the specifics of the facility (total volume, overall size, hardware), and the capabilities available to researchers. The overall operational philosophy, mission fidelity including timeline, schedule pressures and cadence, and development and implementation of mission stressors will be presented. Research conducted to date in the HERA has addressed risks associated with behavioral health and performance, human physiology, as well as human factors. This presentation will conclude with a discussion of future research plans for the HERA, including infrastructure improvements and additional research capabilities planned for the upcoming 30-day missions in 2016.

The Future is Hera! Analyzing Astronomical Over the Internet

Science.gov (United States)

Valencic, L. A.; Chai, P.; Pence, W.; Shafer, R.; Snowden, S.

2008-01-01

Hera is the data processing facility provided by the High Energy Astrophysics Science Archive Research Center (HEASARC) at the NASA Goddard Space Flight Center for analyzing astronomical data. Hera provides all the pre-installed software packages, local disk space, and computing resources need to do general processing of FITS format data files residing on the users local computer, and to do research using the publicly available data from the High ENergy Astrophysics Division. Qualified students, educators and researchers may freely use the Hera services over the internet of research and educational purposes.

Measurement of high-Q2 neutral current deep inelastic e-p scattering cross sections with a longitudinally polarised electron beam at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-12-01

Measurements of the neutral current cross sections for deep inelastic scattering in e - p collisions at HERA with a longitudinally polarised electron beam are presented. The single-differential cross-sections dσ/dQ 2 , dσ/dx and dσ/dy and the double-differential cross sections in Q 2 and x are measured in the kinematic region y 2 > 185GeV 2 for both positively and negatively polarised electron beams and for each polarisation state separately. The measurements are based on an integrated luminosity of 169.9 pb -1 taken with the ZEUS detector in 2005 and 2006 at a centre-of-mass energy of 318GeV. The structure functions xF 3 and xF 3 γZ are determined by combining the e - p results presented in this paper with previously measured e + p neutral current data. The asymmetry parameter A - is used to demonstrate the parity violating effects of electroweak interactions at large spacelike photon virtuality. The measurements agree well with the predictions of the Standard Model. (orig.)

Measurements of Jets and αs at HERA

International Nuclear Information System (INIS)

Bunyatyan, Armen

2009-01-01

Jet production in electron-proton scattering at HERA provides an important testing ground for Quantum Chromodynamics and allows improved determinations of the strong coupling, α s . A review of recent measurements of jet cross sections in photoproduction and neutral current DIS (NC DIS) at HERA is presented, and the latest determinations of α s are shown.

Construction and beam test of the ZEUS forward and rear calorimeter

International Nuclear Information System (INIS)

Andresen, A.; Kroeger, W.; Krueger, J.; Ros, E.; Tsurugai, T.; Woeniger, T.; Bargende, A.; Crittenden, J.A.; Hartmann, J.; Hilger, E.; Kraemer, M.; Prange, K.; Schneider, H.L.; Barreiro, F.; Cases, G.; Hervas, L.; Behrens, U.; Dannemann, A.; Holm, U.; Kammerlocher, H.; Krebs, B.; Wick, K.; Caldwell, A.; Ritz, S.; Sippach, W.; Dawson, J.; Dierks, K.; Drews, G.; Fuertjes, A.; Hagge, L.; Klanner, R.; Koetz, U.; Rohde, M.; Schulz, W.; Selonke, F.; Vogel, W.; Youngman, C.; Fawcett, H.; Frisken, W.; Hasell, D.; Gilkinson, D.; Hanna, D.; Mitchell, J.; Patel, P.; Hamatsu, R.; Kitamura, S.; Hasegawa, T.; Hazumi, M.; Ishii, T.; Kasai, S.; Kuze, M.; Tokushuku, K.; Yamada, S.; Romanowski, T.

1991-04-01

The forward and rear calorimeters of the ZEUS experiment are made of 48 modules with maximum active dimensions of 4.6 m height, 0.2 m width, 7 λ depth and maximum weigth of 12 t. It consists of 1 X 0 uranium plates interleaved with plastic scintillator tiles read out via wavelength shifters and photomultipliers. The mechanical construction, the achieved tolerances as well as the optical and electronics readout are described. Ten of these modules have been tested with electrons, hadrons and muons in the momentum range 15-100 GeV/c. Results von resolution, uniformity and calibration are presented. Our main result is the achieved calibration accuracy of about 1% obtained by using the signal from the uranium radioactivity. (orig.)

The design and construction of the ZEUS central tracking detector

Energy Technology Data Exchange (ETDEWEB)

Foster, B.; Malos, J.; Saxon, D.H.; Clark, D.E.; Jamdagni, A.K.; Markou, C.; Miller, D.B.; Miller, D.G.; Toudup, L.W.; Auty, C.G.; Blair, G.A.; Brooks, C.B.; Cashmore, R.J.; Hanford, A.T.; Harnew, N.; Holmes, A.R.; Linford, W.; Martin, N.C.; McArthur, I.C.; Nash, J.; Nobbs, K.N.; Wastie, R.L.; Williams, M.T.; Wilson, F.F.; Wilson, R.D.; Hart, J.C.; Hatley, R.W.; Hiddleston, J.W.; Gibson, M.D.; McCubbin, N.A.; Middleton, A.; Morrissey, M.C.; Morrow, D.; O' Brien, P.; Payne, B.T.; Roberts, J.C.H.; Shaw, T.B.; Sinclair, C.K.; Wallis, E.W.G.; White, D.J.; Yeo, K.L.; Bullock, F.W.; Dumper, J.; Fraser, T.J.; Hayes, D.; Jones, T.W.; Strachan, D.E.; Vine, I.A. (H.H. Wills Physics Lab., Univ. of Bristol (United Kingdom) Dept. of Physics and Astronomy, Univ. of Glasgow (United Kingdom) Blackett Lab., Physics Dept., Imperial Coll., London (United Kingdom) Dept. of Physics, Nuclear Physics Lab., Univ. of Oxford (United Kingdom) Rutherford Appleton Lab., Chilton (United Kingdom) Dept. of Physics an

1994-01-15

The mechanical, electrical and electronic design and construction of the ZEUS central tracking detector are described, together with the chamber monitoring and environmental control. This cylindrical drift chamber is designed for track reconstruction, electron identification and fast event triggering in a high beam-crossing rate, high magnetic field application. (orig.)

Search for Excited Neutrinos at HERA

CERN Document Server

Adloff, C.; Andrieu, B.; Anthonis, T.; Arkadov, V.; Astvatsatourov, A.; Babaev, A.; Bahr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bate, P.; Becker, J.; Beglarian, A.; Behnke, O.; Beier, C.; Belousov, A.; Benisch, T.; Berger, C.; Berndt, T.; Bizot, J.C.; Boehme, J.; Boudry, V.; Braunschweig, W.; Brisson, V.; Broker, H.B.; Brown, D.P.; Bruckner, W.; Bruncko, D.; Burger, J.; Busser, F.W.; Bunyatyan, A.; Burrage, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Cao, Jun; Caron, S.; Cassol-Brunner, F.; Clarke, D.; Clerbaux, B.; Collard, C.; Contreras, J.G.; Coppens, Y.R.; Coughlan, J.A.; Cousinou, M.C.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; Davidsson, M.; Delcourt, B.; Delerue, N.; Demirchyan, R.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dingfelder, J.; Dixon, P.; Dodonov, V.; Dowell, J.D.; Droutskoi, A.; Dubak, A.; Duprel, C.; Eckerlin, Guenter; Eckstein, D.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Ferron, S.; Fleischer, M.; Fleming, Y.H.; Flugge, G.; Fomenko, A.; Foresti, I.; Formanek, J.; Franke, G.; Gabathuler, E.; Gabathuler, K.; Garvey, J.; Gassner, J.; Gayler, Joerg; Gerhards, R.; Gerlich, C.; Ghazaryan, Samvel; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Grab, C.; Grassler, H.; Greenshaw, T.; Grindhammer, Guenter; Hadig, T.; Haidt, D.; Hajduk, L.; Haller, J.; Haynes, W.J.; Heinemann, B.; Heinzelmann, G.; Henderson, R.C.W.; Hengstmann, S.; Henschel, H.; Heremans, R.; Herrera, G.; Herynek, I.; Hildebrandt, M.; Hilgers, M.; Hiller, K.H.; Hladky, J.; Hoting, P.; Hoffmann, D.; Horisberger, R.; Hurling, S.; Ibbotson, M.; Issever, C.; Jacquet, M.; Jaffre, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, C.; Johnson, D.P.; Jones, M.A.S.; Jung, H.; Kant, D.; Kapichine, M.; Karlsson, M.; Karschnick, O.; Keil, F.; Keller, N.; Kennedy, J.; Kenyon, I.R.; Kermiche, S.; Kiesling, Christian M.; Kjellberg, P.; Klein, M.; Kleinwort, C.; Kluge, T.; Knies, G.; Koblitz, B.; Kolya, S.D.; Korbel, V.; Kostka, P.; Kotelnikov, S.K.; Koutouev, R.; Koutov, A.; Krehbiel, H.; Kroseberg, J.; Kruger, K.; Kupper, A.; Kuhr, T.; Kurca, T.; Lahmann, R.; Lamb, D.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Laycock, P.; Lebailly, E.; Lebedev, A.; Leissner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; Lindstroem, M.; List, B.; Lobodzinska, E.; Lobodzinski, B.; Loginov, A.; Loktionova, N.; Lubimov, V.; Luders, S.; Luke, D.; Lytkin, L.; Mahlke-Kruger, H.; Malden, N.; Malinovski, E.; Malinovski, I.; Maracek, R.; Marage, P.; Marks, J.; Marshall, R.; Martyn, H.U.; Martyniak, J.; Maxfield, S.J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, J.; Meyer, P.O.; Mikocki, S.; Milstead, D.; Mkrtchyan, T.; Mohr, R.; Mohrdieck, S.; Mondragon, M.N.; Moreau, F.; Morozov, A.; Morris, J.V.; Muller, K.; Murin, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, T.; Nellen, G.; Newman, Paul R.; Nicholls, T.C.; Niebergall, F.; Niebuhr, C.; Nix, O.; Nowak, G.; Olsson, J.E.; Ozerov, D.; Panassik, V.; Pascaud, C.; Patel, G.D.; Peez, M.; Perez, E.; Phillips, J.P.; Pitzl, D.; Poschl, R.; Potachnikova, I.; Povh, B.; Rabbertz, K.; Radel, G.; Rauschenberger, J.; Reimer, P.; Reisert, B.; Reyna, D.; Risler, C.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rusakov, S.; Rybicki, K.; Sankey, D.P.C.; Scheins, J.; Schilling, F.P.; Schleper, P.; Schmidt, D.; Schmidt, S.; Schmitt, S.; Schneider, M.; Schoeffel, L.; Schoning, A.; Schorner, T.; Schroder, V.; Schultz-Coulon, H.C.; Schwanenberger, C.; Sedlak, K.; Sefkow, F.; Chekelian, V.; Sheviakov, I.; Shtarkov, L.N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, Arnd E.; Spitzer, H.; Stamen, R.; Stella, B.; Stiewe, J.; Straumann, U.; Swart, M.; Tasevsky, M.; Chernyshov, V.; Chetchelnitski, S.; Thompson, Graham; Thompson, P.D.; Tobien, N.; Traynor, D.; Truoel, Peter; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Turney, J.E.; Tzamariudaki, E.; Udluft, S.; Urban, Marcel; Usik, A.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vassiliev, S.; Vazdik, Y.; Vichnevski, A.; Wacker, K.; Wallny, R.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Werner, C.; Werner, M.; Werner, N.; White, G.; Wiesand, S.; Wilksen, T.; Winde, M.; Winter, G.G.; Wissing, C.; Wobisch, M.; Woehrling, E.E.; Wunsch, E.; Wyatt, A.C.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zomer, F.; Zsembery, J.; zur Nedden, M.

2002-01-01

We present a search for excited neutrinos using e^-p data taken by the H1 experiment at HERA at a center-of-mass energy of 318 GeV with an integrated luminosity of 15 pb-1. No evidence for excited neutrino production is found. Mass dependent exclusion limits are determined for the ratio of the coupling to the compositeness scale, f/Lambda, independently of the relative couplings to the SU(2) and U(1) gauge bosons. These limits extend the excluded region to higher masses than has been possible in previous searches at other colliders.

Prompt photons in photoproduction at HERA

International Nuclear Information System (INIS)

Aaron, F.D.; Alexa, C.; Rotaru, M.; Stoicea, G.; Zus, R.; Aldaya Martin, M.; Antunovic, B.; Bartel, W.; Brandt, G.; Campbell, A.J.; Cholewa, A.; Deak, M.; Boer, Y. de; Eckerlin, G.; Elsen, E.; Felst, R.; Fischer, D.J.; Fleischer, M.; Gayler, J.; Glazov, A.; Gouzevitch, M.; Grell, B.R.; Haidt, D.; Helebrant, C.; Jung, H.; Katzy, J.; Kleinwort, C.; Knutsson, A.; Kraemer, M.; Krastev, K.; Kutak, K.; Levonian, S.; Lipka, K.; List, J.; Marti, Ll.; Meyer, A.B.; Meyer, H.; Meyer, J.; Michels, V.; Niebuhr, C.; Nikiforov, A.; Nozicka, M.; Olsson, J.E.; Panagoulias, I.; Papadopoulou, T.; Pitzl, D.; Placakyte, R.; Radescu, V.; Rurikova, Z.; Schmitt, S.; Sefkow, F.; Staykova, Z.; Steder, M.; Vargas Trevino, A.; Vinokurova, S.; Driesch, M. von den; Wissing, C.; Wuensch, E.; Andreev, V.; Belousov, A.; Eliseev, A.; Fomenko, A.; Gogitidze, N.; Lebedev, A.; Loktionova, N.; Malinovski, E.; Rusakov, S.; Shtarkov, L.N.; Soloviev, Y.; Vazdik, Y.; Backovic, S.; Dubak, A.; Lastovicka-Medin, G.; Picuric, I.; Raicevic, N.; Baghdasaryan, A.; Ghazaryan, S.; Volchinski, V.; Zohrabyan, H.; Barrelet, E.; Begzsuren, K.; Ravdandorj, T.; Tseepeldorj, B.; Bizot, J.C.; Brisson, V.; Delcourt, B.; Jacquet, M.; Li, G.; Pascaud, C.; Tran, T.H.; Zhang, Z.; Zomer, F.; Boudry, V.; Moreau, F.; Specka, A.; Bozovic-Jelisavcic, I.; Mudrinic, M.; Pandurovic, M.; Smiljanic, I.; Bracinik, J.; Kenyon, I.R.; Newman, P.R.; Shaw-West, R.N.; Thompson, P.D.; Brinkmann, M.; Habib, S.; List, B.; Pokorny, B.; Toll, T.; Bruncko, D.; Cerny, V.; Ferencei, J.; Murin, P.; Tomasz, F.; Bunyatyan, A.; Buschhorn, G.; Chekelian, V.; Dossanov, A.; Grindhammer, G.; Kiesling, C.; Kogler, R.; Liptaj, A.; Olivier, B.; Raspiareza, A.; Shushkevich, S.; Bystritskaya, L.; Efremenko, V.; Fedotov, A.; Kropivnitskaya, A.; Lubimov, V.; Ozerov, D.; Petrukhin, A.; Rostovtsev, A.; Zhokin, A.; Cantun Avila, K.B.; Contreras, J.G.; Ruiz Tabasco, J.E.; Cerny, K.; Pejchal, O.; Polifka, R.; Salek, D.; Valkarova, A.; Zacek, J.; Coughlan, J.A.; Morris, J.V.; Sankey, D.P.C.; Cozzika, G.; Feltesse, J.; Perez, E.; Schoeffel, L.; Cvach, J.; Reimer, P.; Zalesak, J.; Dainton, J.B.; Gabathuler, E.; Greenshaw, T.; Klein, M.; Kluge, T.; Kretzschmar, J.; Laycock, P.; Maxfield, S.J.; Mehta, A.; Patel, G.D.; Rahmat, A.J.; Daum, K.; Meyer, H.; Del Degan, M.; Grab, C.; Leibenguth, G.; Sauter, M.; Zimmermann, T.; Delvax, J.; Wolf, E.A. de; Favart, L.; Hreus, T.; Janssen, X.; Marage, P.; Mozer, M.U.; Roland, B.; Roosen, R.; Sunar, D.; Sykora, T.; Mechelen, P. van; Diaconu, C.; Hoffmann, D.; Sauvan, E.; Trinh, T.N.; Vallee, C.; Dodonov, V.; Povh, B.; Egli, S.; Hildebrandt, M.; Horisberger, R.; Falkiewicz, A.; Goerlich, L.; Mikocki, S.; Milcewicz-Mika, I.; Nowak, G.; Sopicki, P.; Turnau, J.; Glushkov, I.; Henschel, H.; Hiller, K.H.; Kostka, P.; Lange, W.; Naumann, T.; Piec, S.; Henderson, R.C.W.; Sloan, T.; Hennekemper, E.; Herbst, M.; Jung, A.W.; Krueger, K.; Lendermann, V.; Schultz-Coulon, H.C.; Urban, K.; Herrera, G.; Lopez-Fernandez, R.; Joensson, L.; Osman, S.; Kapichine, M.; Makankine, A.; Morozov, A.; Nikitin, D.; Palichik, V.; Spaskov, V.; Tchoulakov, V.; Landon, M.P.J.; Rizvi, E.; Thompson, G.; Traynor, D.; Martyn, H.U.; Mueller, K.; Nowak, K.; Robmann, P.; Straumann, U.; Truoel, P.; Schoening, A.; South, D.; Wegener, D.; Stella, B.; Tsakov, I.

2010-01-01

The production of prompt photons is measured in the photoproduction regime of electron-proton scattering at HERA. The analysis is based on a data sample corresponding to a total integrated luminosity of 340 pb -1 collected by the H1 experiment. Cross sections are measured for photons with transverse momentum and pseudorapidity in the range 6 T γ γ γ and x p carried by the partons entering the hard scattering process. The correlation between the photon and the jet is also studied. The results are compared with QCD predictions based on the collinear and on the k T factorization approaches. (orig.) 7

Nuclei at HERA and heavy ion physics

International Nuclear Information System (INIS)

Gavin, S.; Strikman, M.

1995-01-01

Copies of 16 viewgraph sets from a workshop held at Brookhaven National Laboratory, 17-18 November, 1995. Titles of talks: HERA: The Present; HERA: Potential with Nuclei; Review of Hadron-Lepton Nucleus Data; Fermilab E665: results in muon scattering; Interactions of Quarks and Gluons with Nuclear Matter; Rescattering in Nuclear Targets for Photoproduction and DIS; Structure Functions and Nuclear Effect at PHENIX; Probing Spin-Averaged and Spin-Dependent Parton Distributions Using the Solenoidal Tracker at RHIC (STAR); Jet Quenching in eA, pA, AA; Nuclear Gluon Shadowing via Continuum Lepton Pairs; What can we learn from HERA with a colliding heavy ion beam? The limiting curve of leading particles at infinite A; Coherent Production of Vector Mesons off Light Nuclei in DIS; A Model of High Parton Densities in PQCD; Gluon Production for Weizaecker-Williams Field in Nucleus-Nucleus Collisions; Summary Talk