Charm physics with physical light and strange quarks using domain wall fermions

CERN Document Server

Boyle, Peter A; Garron, Nicolas; Khamseh, Ava; Marinkovic, Marina; Sanfilippo, Francesco; Tsang, Justus Tobias; Boyle, Peter A.

2015-01-01

We present a study of charm physics using RBC/UKQCD 2+1 flavour physical point domain wall fermion ensembles for the light quarks as well as for the valence charm quark. After a brief motivation of domain wall fermions as a suitable heavy quark discretisation we will show first results for masses and matrix elements.

Top-quark pair production in a running mass scheme

International Nuclear Information System (INIS)

Dowling, M.; Moch, S.; Hamburg Univ.

2013-11-01

Between the Tevatron and LHC, top-quark physics is now becoming an area for precision physics. This has lead to an increase in theoretical activity to match the experimental accuracy of top anti-top production. We discuss the difficulty in properly defining the top-quark mass as measured by experiments and present results for differential distributions of top-quark pair production in a running mass scheme. The use of such a scheme shows better convergence in the perturbative expansion and improves the scale dependence as opposed to the typical on-shell scheme.

Top-quark pair production in a running mass scheme

Energy Technology Data Exchange (ETDEWEB)

Dowling, M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik

2013-11-15

Between the Tevatron and LHC, top-quark physics is now becoming an area for precision physics. This has lead to an increase in theoretical activity to match the experimental accuracy of top anti-top production. We discuss the difficulty in properly defining the top-quark mass as measured by experiments and present results for differential distributions of top-quark pair production in a running mass scheme. The use of such a scheme shows better convergence in the perturbative expansion and improves the scale dependence as opposed to the typical on-shell scheme.

Heavy quark effective theory computation of the mass of the bottom quark

International Nuclear Information System (INIS)

Della Morte, M.; Papinutto, M.

2006-10-01

We present a fully non-perturbative computation of the mass of the b-quark in the quenched approximation. Our strategy starts from the matching of HQET to QCD in a finite volume and finally relates the quark mass to the spin averaged mass of the B s meson in HQET. All steps include the terms of order Λ 2 /m b . We discuss the computation and renormalization of correlation functions at order 1/m b . With the strange quark mass fixed from the Kaon mass and the QCD scale set through r 0 =0.5 fm, we obtain a renormalization group invariant mass M b =6.758(86) GeV or anti m b (anti m b )=4.347(48) GeV in the MS scheme. The uncertainty in the computed Λ 2 /m b terms contributes little to the total error and Λ 3 /m 2 b terms are negligible. The strategy is promising for full QCD as well as for other B-physics observables. (orig.)

Top quark mass measurement in dilepton channel

International Nuclear Information System (INIS)

Lysak, R.

2007-01-01

In this work, we measured the top quark mass in tt'-' events produced in pp'-' interactions at the center-of-mass energy 1.96 TeV using CDF detector. We used dilepton in tt'-' events where both W bosons from top quarks are decaying into leptons. The data sample corresponds to 340 pb -1 . We found there 33 tt'-' candidates while expecting 10.5 ± 1.9 background events. In the measurement, we reconstruct one, representative mass for each event using the assumption about longitudinal momentum of in tt'-' system, in order to be able to kinematically solve the under-constrained system. The mass distributions (templates) are created for simulated signal and background events. Templates are parametrized in order to obtain smooth probability density functions. Likelihood maximization which includes these parametrized templates is then performed on reconstructed masses obtained from data sample in order to obtain final top quark mass estimate. The result of applying this procedure on data events is top quark mass estimate 169.5 +7. 7 - 7.2 (stat.) ± 4.0(syst.) GeV/c 2 for 30 out of 33 candidates, where the solution for top quark mass was found. This measurement was a part of first top quark mass measurement in dilepton channel at CDF in Run II. The top quark mass measured here is consistent with the CDF measurement in dilepton channel from Run I M top = 167.4 ± 10.3(stat.) ± 4.8(syst.) GeV/c 2 . Moreover, the combined result of four top quark mass measurements in dilepton channel from Run II (one of these four measurements is our measurement) M top = 167.9 ± 5.2(stat.) ± 3.7(syst.) GeV/c 2 significantly (by ∼ 40%) improved the precision of top quark mass determination from Run I. It should be also noted, that this combined result is consistent with measurement obtained in 'lepton+jets' channel at CDF in Run II (M top = 173.5 +3.9 -3.8 GeV/c 2 ). So, we don't have yet any indication about new physics beyond the Standard Model. My main contribution in this analysis was

Top Quark Mass Measurements at ATLAS and CMS

CERN Document Server

McCarthy, Tom; The ATLAS collaboration

2016-01-01

The top quark mass ($m_{top}$) is a fundamental parameter of the Standard Model of Particle Physics (SM). As the heaviest of all known SM particles with a mass close to the EW symmetry breaking scale, the top quark plays a pivotal role in the theory of elementary particles. The exact value of the top quark mass has implications on a number of theoretical predictions, which motivates the need for precision measurements of $m_{top}$. This presentation highlights a number of such precision measurements carried out by the ATLAS and CMS collaborations at centre-of-mass energies of $\\sqrt{s}=7$ and $8$ TeV from the combined LHC Run I datasets. A wide range of analysis strategies are employed in a number of channels. Measurements of both the top quark pole mass and $m_{top}$ as defined by the Monte Carlo generator in simulated signal samples are shown. Finally, a summary of combinations of the LHC measurements is presented, together with a look toward top quark mass measurements at $\\sqrt{s}=13$ TeV.

Quark mass effects in quark number susceptibilities

International Nuclear Information System (INIS)

Graf, Thorben; Petreczky, Peter

2017-01-01

The quark degrees of freedom of the QGP with special focus on mass effects are investigated. A next-to-leading-order perturbation theory approach with quark mass dependence is applied and compared to lattice QCD results. (paper)

Heavy quark hadron mass scale

International Nuclear Information System (INIS)

Anderson, J.T.

1994-01-01

Without the spin interactions the hardron masses within a multiplet are degenerate. The light quark hadron degenerate mulitplet mass spectrum is extended from the 3 quark ground state multiplets at J P =0 - , 1/2 + , 1 - to include the excited states which follow the spinorial decomposition of SU(2)xSU(2). The mass scales for the 4, 5, 6, .. quark hadrons are obtained from the degenerate multiplet mass m 0 /M=n 2 /α with n=4, 5, 6, .. The 4, 5, 6, .. quark hadron degenerate multiplet masses follow by splitting of the heavy quark mass scales according to the spinorial decomposition of SU(2)xSU(2). (orig.)

Heavy quark effective theory computation of the mass of the bottom quark

Energy Technology Data Exchange (ETDEWEB)

Della Morte, M. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Garron, N.; Sommer, R. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Papinutto, M. [INFN Sezione di Roma Tre, Rome (Italy)

2006-10-15

We present a fully non-perturbative computation of the mass of the b-quark in the quenched approximation. Our strategy starts from the matching of HQET to QCD in a finite volume and finally relates the quark mass to the spin averaged mass of the B{sub s} meson in HQET. All steps include the terms of order {lambda}{sup 2}/m{sub b}. We discuss the computation and renormalization of correlation functions at order 1/m{sub b}. With the strange quark mass fixed from the Kaon mass and the QCD scale set through r{sub 0}=0.5 fm, we obtain a renormalization group invariant mass M{sub b}=6.758(86) GeV or anti m{sub b}(anti m{sub b})=4.347(48) GeV in the MS scheme. The uncertainty in the computed {lambda}{sup 2}/m{sub b} terms contributes little to the total error and {lambda}{sup 3}/m{sup 2}{sub b} terms are negligible. The strategy is promising for full QCD as well as for other B-physics observables. (orig.)

Mass of the b quark and B -meson decay constants from Nf=2+1+1 twisted-mass lattice QCD

DEFF Research Database (Denmark)

Bussone, A.; Carrasco, N.; Dimopoulos, P

2016-01-01

We present precise lattice computations for the b-quark mass, the quark mass ratios mb/mc and mb/ms as well as the leptonic B-decay constants. We employ gauge configurations with four dynamical quark flavors, up-down, strange and charm, at three values of the lattice spacing (a∼0.06-0.09 fm......) and for pion masses as low as 210 MeV. Interpolation in the heavy quark mass to the bottom quark point is performed using ratios of physical quantities computed at nearby quark masses exploiting the fact that these ratios are exactly known in the static quark mass limit. Our results are also extrapolated...... to the physical pion mass and to the continuum limit and read mb(MS,mb)=4.26(10) GeV, mb/mc=4.42(8), mb/ms=51.4(1.4), fBs=229(5) MeV, fB=193(6) MeV, fBs/fB=1.184(25) and (fBs/fB)/(fK/fπ)=0.997(17)....

Hierarchy plus anarchy in quark masses and mixings

International Nuclear Information System (INIS)

Aguilar-Saavedra, J.A.

2003-01-01

We introduce a parametrization of the effect of unknown corrections from new physics on quark and lepton mass matrices. This parametrization is used in order to study how the hierarchies of quark masses and mixing angles are modified by random perturbations of the Yukawa matrices. We discuss several examples of flavor relations predicted by different textures, analyzing how these relations are influenced by the random perturbations. We also comment on the unlikely possibility that unknown corrections contribute significantly to the hierarchy of masses and mixings

Pseudoscaler meson masses in the quark model

International Nuclear Information System (INIS)

Karl, G.

1976-10-01

Pseudoscaler meson masses and sum rules are compared in two different limits of a quark model with 4 quarks. The conventional limit corresponds to a heavy c anti c state and generalizes ideal mixing in a nonet. The second limit corresponds to a missing SU 4 unitary singlet and appears more relevant to the masses of π, K, eta, eta'. If SU 3 is broken only by the mass difference between the strange and nonstrange quarks, the physical masses imply that the u anti u, d anti d and s anti s pairs account only for 33% of the composition of the eta'(960), while for the eta(548) this fraction is 86%. If some of the remaining matter is in the form of the constituents of J/psi, the relative proportion of the relative decays J/psi → eta γ vs J/psi → etaγ is accounted for in satisfactory agreement with experiment. (author)

Top-quark mass and top-quark pole mass measurements with the ATLAS detector

CERN Document Server

Barillari, Teresa; The ATLAS collaboration

2017-01-01

Results of top-quark mass measurements in the di-lepton and in the all-jets top-antitop decay channels with the ATLAS detector are presented. The measurements are obtained using proton--proton collisions at a centre-of-mass energy \\sqrt{s} = 8 TeV at the CERN Large Hadron Collider. The data set used corresponds to an integrated luminosity of 20.2 fb-1. The top-quark mass in the di-lepton channel is measured to be 172.99 +/-0.41 (stat.) +/- 0.74 (syst.) GeV. In the all-jets analysis the top-quark mass is measured to be 173.72 +/- 0.55 (stat.)+/- 1.01 (syst.) GeV. In addition, the top-quark pole mass is determined from inclusive cross-section measurements in the top-antitop di-lepton decay channel with the ATLAS detector. The measurements are obtained using data at \\sqrt{s} = 7 TeV and \\sqrt{s} =8 TeV corresponding to an integrated luminosity of 4.6 fb-1 and 20.2 fb-1 respectively. The top-quark pole mass is measured to be 172.9^{+2.5}_{-2.6} GeV.

Octet baryon mass splittings from up-down quark mass differences

Energy Technology Data Exchange (ETDEWEB)

Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Najjar, J. [Regensburg Univ. (Germany). Institut fuer Theoretische Physik; Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Kobe, Hyogo (Japan); Pleiter, D. [Regensburg Univ. (Germany). Institut fuer Theoretische Physik; Juelich Research Centre, Juelich (Germany); Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Div.; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Zanotti, J.M. [Adelaide Univ., SA (Australia). CSSM, School of Chemistry and Physics; Collaboration: QCDSF-UKQCD Collaboration

2012-12-15

Using an SU(3) flavour symmetry breaking expansion in the quark mass, we determine the QCD component of the neutron-proton, Sigma and Xi mass splittings of the baryon octet due to updown (and strange) quark mass differences. Provided the average quark mass is kept constant, the expansion coefficients in our procedure can be determined from computationally cheaper simulations with mass degenerate sea quarks and partially quenched valence quarks.

arXiv Top Quark Mass Measurements at the LHC

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00220136

2016-01-01

The top quark mass ($m_{top}$) is a fundamental parameter of the Standard Model of Particle Physics (SM). As the heaviest of all SM particles with a mass close to the electroweak symmetry-breaking scale, the top quark plays a pivotal role in the theory of elementary particles. The exact value of the top quark mass has implications on a number of theoretical predictions, which motivates the need for precision measurements of $m_{top}$. This document highlights a number of such measurements carried out by the ATLAS and CMS collaborations based on the combined LHC Run 1 datasets at centre-of-mass energies of $\\sqrt{s}=7$ and $8$ TeV. A wide range of analysis strategies are employed for a number of final-state signatures. Measurements of both the top quark pole mass as well as the value of $m_{top}$ as defined by the Monte Carlo generator in simulated signal samples are discussed.

Interquark potential with finite quark mass from lattice QCD.

Science.gov (United States)

Kawanai, Taichi; Sasaki, Shoichi

2011-08-26

We present an investigation of the interquark potential determined from the q ̄q Bethe-Salpeter (BS) amplitude for heavy quarkonia in lattice QCD. The q ̄q potential at finite quark mass m(q) can be calculated from the equal-time and Coulomb gauge BS amplitude through the effective Schrödinger equation. The definition of the potential itself requires information about a kinetic mass of the quark. We then propose a self-consistent determination of the quark kinetic mass on the same footing. To verify the proposed method, we perform quenched lattice QCD simulations with a relativistic heavy-quark action at a lattice cutoff of 1/a≈2.1  GeV in a range 1.0≤m(q)≤3.6 GeV. Our numerical results show that the q ̄q potential in the m(q)→∞ limit is fairly consistent with the conventional one obtained from Wilson loops. The quark-mass dependence of the q ̄q potential and the spin-spin potential are also examined. © 2011 American Physical Society

Probing quark mass effects in low-energy hadron physics

International Nuclear Information System (INIS)

Ditsche, Christoph

2012-01-01

Since quarks are confined inside hadrons, their properties as well as their contributions to hadronic observables can be assessed by indirect methods only. As the strength of the strong interaction increases with the spatial distance, the treatment of quantum chromodynamics at low energies in general requires non-perturbative methods like dispersion relations or lattice gauge theory. Based on the fact that the light quark masses are very small with respect to the typical hadronic mass scales for mesons and baryons, furthermore effective field theories can be constructed to describe low-energy properties and dynamics of hadrons perturbatively. The present work is concerned with two particularly interesting hadronic processes that are closely related to the light quark masses. Although distinct theoretical frameworks utilizing different calculational techniques are applied, in both cases the investigations at hand are prerequisites for high-precision analyses of the respective quark-mass effects. In the first part of this thesis, we investigate higher-order isospin-breaking effects in η→3π decays, namely η→π 0 π + π - and η→3π 0 , in chiral perturbation theory. By evaluating the second-order mixed strong and electromagnetic isospin-breaking corrections, we confirm the picture that the electromagnetic contributions are small. Therefore, η→3π is perfectly suited to extract isospin-breaking ratios of light quark masses via comparing theoretical predictions with experimental results. Since for an accurate determination a detailed description of the Dalitz plot distributions is necessary, we study the different effects of higher-order isospin breaking in η→3π on a more general basis. In particular, we investigate corrections to isospin relations between both decay channels at the level of Dalitz plot parameters, showing that the branching ratio of the two partial decay widths entails sizeable uncertainties. In the second part, we develop a dispersive

Up, down, strange and charm quark masses with Nf=2+1+1 twisted mass lattice QCD

Directory of Open Access Journals (Sweden)

N. Carrasco

2014-10-01

Full Text Available We present a lattice QCD calculation of the up, down, strange and charm quark masses performed using the gauge configurations produced by the European Twisted Mass Collaboration with Nf=2+1+1 dynamical quarks, which include in the sea, besides two light mass degenerate quarks, also the strange and charm quarks with masses close to their physical values. The simulations are based on a unitary setup for the two light quarks and on a mixed action approach for the strange and charm quarks. The analysis uses data at three values of the lattice spacing and pion masses in the range 210–450 MeV, allowing for accurate continuum limit and controlled chiral extrapolation. The quark mass renormalization is carried out non-perturbatively using the RI′-MOM method. The results for the quark masses converted to the MS¯ scheme are: mud(2 GeV=3.70(17 MeV, ms(2 GeV=99.6(4.3 MeV and mc(mc=1.348(46 GeV. We obtain also the quark mass ratios ms/mud=26.66(32 and mc/ms=11.62(16. By studying the mass splitting between the neutral and charged kaons and using available lattice results for the electromagnetic contributions, we evaluate mu/md=0.470(56, leading to mu=2.36(24 MeV and md=5.03(26 MeV.

Quark mass variation constraints from Big Bang nucleosynthesis

International Nuclear Information System (INIS)

Bedaque, Paulo F.; Luu, Thomas; Platter, Lucas

2011-01-01

We study the impact on the primordial abundances of light elements created by a variation of the quark masses at the time of Big Bang nucleosynthesis (BBN). In order to navigate through the particle and nuclear physics required to connect quark masses to binding energies and reaction rates in a model-independent way, we use lattice QCD data and a hierarchy of effective field theories. We find that the measured 4 He abundances put a bound of -1% q /m q q /m q .

Top quark and Higgs boson masses from wormhole physics

International Nuclear Information System (INIS)

Harris, B.A.; Joshi, G.C.

1994-01-01

We bring together quantum field theory on S 4 with the Coleman wormhole hypothesis, which imposes constraints on terms in the gravitational Lagrangian. In particular, we investigate the effect of matter fields on the trace anomaly, which is related to the (curvature) 2 terms, by the use of the renormalization group equations. We consider a toy model of a nonconformally coupled Higgs boson to a single ''top'' quark. By numerically solving the renormalization group equations for the couplings of the model, we can find preferred values of the particle masses for various values of the bare nonconformal coupling. By making the ad hoc assumption that the tree-level, Higgs boson treace anomaly vanishes on shell, a unique prediction can be made within this model for the masses of both the Higgs boson and the top quark

Measurements of the top quark mass and decay width with the D0 detector

International Nuclear Information System (INIS)

Ilchenko, Yuriy

2011-01-01

The top quark discovery in 1995 at Fermilab is one of the major proofs of the standard model (SM). Due to its unique place in SM, the top quark is an important particle for testing the theory and probing for new physics. This article presents most recent measurements of top quark properties from the D0 detector. In particular, the measurement of the top quark mass, the top antitop mass difference and the top quark decay width. The discovery of the top quark in 1995 confirmed the existence of a third generation of quarks predicted in the standard model (SM). Being the heaviest elementary particle known, the top quark appears to become an important particle in our understanding of the standard model and physics beyond it. Because of its large mass the top quark has a very short lifetime, much shorter than the hadronization time. The predicted lifetime is only 3.3 · 10 -25 s. Top quark is the only quark whose properties can be studied in isolation. A Lorentz-invariant local Quantum Field Theory, the standard model is expected to conserve CP. Due to its unique properties, the top quark provides a perfect test of CPT invariance in the standard model. An ability to look at the quark before being hadronized allows to measure directly mass of the top quark and its antiquark. An observation of a mass difference between particle and antiparticle would indicate violation of CPT invariance. Top quark through its radiative loop correction to the W mass constrains the mass of the Higgs boson. A precise measurement of the top quark mass provides useful information to the search of Higgs boson by constraining its region of possible masses. Another interesting aspect is that the top quark's Yukawa coupling to the Higgs boson is very close to unity (0.996 ± 0.006). That implies it may play a special role in the electroweak symmetry breaking mechanism.

Quark masses: An environmental impact statement

International Nuclear Information System (INIS)

Jaffe, Robert L.; Jenkins, Alejandro; Kimchi, Itamar

2009-01-01

We investigate worlds that lie on a slice through the parameter space of the standard model over which quark masses vary. We allow as many as three quarks to participate in nuclei, while fixing the mass of the electron and the average mass of the lightest baryon flavor multiplet. We classify as congenial worlds that satisfy the environmental constraint that the quark masses allow for stable nuclei with charge one, six, and eight, making organic chemistry possible. Whether a congenial world actually produces observers capable of measuring those quark masses depends on a multitude of historical contingencies, beginning with primordial nucleosynthesis and including other astrophysical processes, which we do not explore. Such constraints may be independently superimposed on our results. Environmental constraints such as the ones we study may be combined with information about the a priori distribution of quark masses over the landscape of possible universes to determine whether the measured values of the quark masses are determined environmentally, but our analysis is independent of such an anthropic approach. We estimate baryon masses as functions of quark masses via first-order perturbation theory in flavor SU(3) breaking. We estimate nuclear masses as functions of the baryon masses using two separate tools: for a nucleus made of two baryon species, when possible we consider its analog in our world, a nucleus with a similar binding energy, up to Coulomb contributions. For heavy nuclei or nuclei made of more than two baryons, we develop a generalized Weizsaecker semiempirical mass formula, in which strong kinematic flavor symmetry violation is modeled by a degenerate Fermi gas . We check for the stability of nuclei against fission, strong particle emission (analogous to α decay), and weak nucleon emission. For two light quarks with charges 2/3 and -1/3 , we find a band of congeniality roughly 29 MeV wide in their mass difference, with our own world lying comfortably

Italian Physical Society Beyond the Standard Model physics to be observed in precisely measured top quark properties

CERN Document Server

Franceschini, R

2017-01-01

In this contribution I will highlight the new challenges for top quark physics at LHC Run II, focusing in particular on the interplay between precision studies on the top quark and searches for new physics. A new strategy to search for subtle scenarios of new physics is envisaged. The ability to very accurately compute and measure top quark properties such as its production rate, decay rates and distributions, and specific features in the distribution of variables sensitive to the top quark mass is put at the center of this strategy to probe new physics.

Measurement of the top quark mass

International Nuclear Information System (INIS)

Blusk, Steven R.

1998-01-01

The first evidence and subsequent discovery of the top quark was reported nearly 4 years ago. Since then, CDF and D0 have analyzed their full Run 1 data samples, and analysis techniques have been refined to make optimal use of the information. In this paper, we report on the most recent measurements of the top quark mass, performed by the CDF and D0 collaborations at the Fermilab Tevatron. The CDF collaboration has performed measurements of the top quark mass in three decay channels from which the top quark mass is measured to be 175.5 ± 6.9 GeV=c 2 . The D0 collaboration combines measurements from two decay channels to obtain a top quark mass of 172.1 ± 7.1 GeV/c 2 . Combining the measurements from the two experiments, assuming a 2 GeV GeV/c 2 correlated systematic uncertainty, the measurement of the top quark mass at the Tevatron is 173.9 ± 5.2 GeV/c 2 . This report presents the measurements of the top quark mass from each of the decay channels which contribute to this measurement

Quark mass variation constraints from Big Bang nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Bedaque, P; Luu, T; Platter, L

2010-12-13

We study the impact on the primordial abundances of light elements created of a variation of the quark masses at the time of Big Bang nucleosynthesis (BBN). In order to navigate through the particle and nuclear physics required to connect quark masses to binding energies and reaction rates in a model-independent way we use lattice QCD data and an hierarchy of effective field theories. We find that the measured {sup 4}He abundances put a bound of {delta}-1% {approx}< m{sub q}/m{sub 1} {approx}< 0.7%. The effect of quark mass variations on the deuterium abundances can be largely compensated by changes of the baryon-to-photon ratio {eta}. Including the bounds on the variation of {eta} coming from WMAP results and some additional assumptions narrows the range of allowed values of {delta}m{sub q}/m{sub q} somewhat.

Bethe-Salpeter dynamics and the constituent mass concept for heavy quark mesons

International Nuclear Information System (INIS)

Souchlas, N.; Stratakis, D.

2010-01-01

The definition of a quark as heavy requires a comparison of its mass with the nonperturbative chiral symmetry breaking scale which is about 1 GeV (Λ χ ∼1 GeV) or with the scale Λ QCD ∼0.2 GeV that characterizes the distinction between perturbative and nonperturbative QCD. For quark masses significantly larger than these scales, nonperturbative dressing effects, or equivalently nonperturbative self-energy contributions, and relativistic effects are believed to be less important for physical observables. We explore the concept of a constituent mass for heavy quarks in the Dyson-Schwinger equations formalism, for light-heavy and heavy-heavy quark mesons by studying their masses and electroweak decay constants.

Mass-shell properties of the dynamical quark mass

International Nuclear Information System (INIS)

Reinders, L.J.; Stam, K.

1986-07-01

We discuss the running dynamical quark mass in the framework of the operator product expansion. It is shown that for vertical strokep 2 vertical stroke>m 2 the quark-condensate part of the quark self energy has no contributions of order m 2 or higher, and is frozen to its mass-shell value for smaller vertical strokep 2 vertical stroke. (orig.)

Up-down quark mass difference effect in nuclear many-body systems

International Nuclear Information System (INIS)

Nakamura, S.; Muto, K.; Oka, M.; Takeuchi, S.; Oda, T.

1996-01-01

A charge-symmetry-breaking nucleon-nucleon force due to the up-down quark mass difference is evaluated in the quark cluster model. It is applied to the shell-model calculation for the isovector mass shifts of isospin multiplets in 1s0d-shell nuclei. We find that the contribution of the quark mass difference effect explains the systematic behavior of experiment. This contribution is large and may explain the Okamoto-Nolen-Schiffer anomaly, alternatively to the meson-mixing contribution, which is recently predicted to be reduced by the large off-shell correction. copyright 1996 The American Physical Society

Top quark mass measurements with CMS

CERN Document Server

Kovalchuk, Nataliia

2017-01-01

Measurements of the top quark mass are presented, obtained from CMS data collected in proton-proton collisions at the LHC at centre-of-mass energies of 7 TeV and 8 TeV. The mass of the top quark is measured using several methods and channels, including the reconstructed invariant mass distribution of the top quark, an analysis of endpoint spectra as well as measurements from shapes of top quark decay distributions. The dependence of the mass measurement on the kinematic phase space is investigated. The results of the various channels are combined and compared to the world average. The top mass and also $\\alpha_{\\textnormal S}$ are extracted from the top pair cross section measured at CMS.

Top quark physics: from a few to a few millions

International Nuclear Information System (INIS)

Gallinaro, M.

2014-01-01

As the heaviest known fundamental particle, the top quark has taken a central role in the study of fundamental interactions. The top quark mass is a fundamental parameter of the standard model which places constraints on the Higgs boson mass and electroweak symmetry breaking. Observations of the relative rates and kinematics of top quark final states may provide constraints for new physics processes. Past and current experimental measurements are presented with a critical view, and a look at the future prospects. (author)

Systematics of quark mass

International Nuclear Information System (INIS)

Frampton, P.H.; Jarlskog, C.

1985-01-01

It is shown that the quark mass matrices in the Standard Electroweak Model satisfy the empirical relation M = M 1 + Ψ(Λ 2 ), where M(M sp (')) refers to the mass matrix of the charge 2/3(-1/3) quarks normalized to the largest eigenvalue, m sub (t)(m sub (b)), and Λ = V sub (us) = 0.22

Nucleon spin and quark content at the physical point

International Nuclear Information System (INIS)

Alexandrou, Constantia

2016-12-01

We present results on the spin and quark content of the nucleon using N_f=2 twisted mass clover-improved fermion simulations with a pion mass close to its physical value. We use recently developed methods to obtain accurate results for both connected and disconnected contributions. We provide results for the axial charge, quark and gluon momentum fraction as well as the light, strange and charm σ-terms.

Nucleon spin and quark content at the physical point

Energy Technology Data Exchange (ETDEWEB)

Alexandrou, Constantia [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center; Constantinou, Martha; Hadjiyiannakou, Kyriakos; Kallidonis, Christos; Koutsou, Giannis [The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center; Jansen, Karl; Wiese, Christian [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Vaquero Aviles-Casco, Alejandro [INFN Sezione di Milano-Bicocca, Milano (Italy)

2016-12-15

We present results on the spin and quark content of the nucleon using N{sub f}=2 twisted mass clover-improved fermion simulations with a pion mass close to its physical value. We use recently developed methods to obtain accurate results for both connected and disconnected contributions. We provide results for the axial charge, quark and gluon momentum fraction as well as the light, strange and charm σ-terms.

Top quark physics in ATLAS (CORFU 2014)

CERN Document Server

Moreno Llácer, M; The ATLAS collaboration

2014-01-01

The top quark is the heaviest elementary particle observed to date. Being heavier than a W boson, it is the only quark that decays weakly, i.e. into a real W boson and a b quark, before hadronization can occur. In addition, it is the only quark whose Yukawa coupling to the Higgs boson is order of unity. For these reasons the top quark plays a special role in the Standard Model of Particle Physics and in many of its extensions. An accurate knowledge of its properties (mass, couplings, production cross section, decay branching ratios, etc.) can bring key information on fundamental interactions at the electroweak breaking scale and beyond. In this talk the latest measurements of the characteristics of the top quark carried out in the ATLAS experiment at the Large Hadron Collider are presented.

Quark and gluon tagging in dijet mass resonance search

CERN Document Server

Kellermann, Edgar

2013-01-01

Several models beyond the Standard Model predict new phenomena in particle physics, which would appear as resonant signals in dijet mass distributions. An example for such a resonance is the excited quark q, which is a consequence of Compositeness Models postulating that quarks and leptons are build by more fundamental particles. The main signature of an excited quark would be a dijet event, originated from the radiation of a gluon from the original excited quark when going back to its non-excited state, leading to a quark and a gluon in the final state (with a branching ratio of 83%) . Other examples are the heavy vector bosonsW0 decaying to two quarks and colour octet scalar S8 decaying to two gluons.

Top quark physics at the D0 experiment

International Nuclear Information System (INIS)

Heinson, A.P.

1996-01-01

In this paper I present the latest results on top quark physics from the D0 collaboration since the discovery of the top quark in March 1995. I summarize the discovery results, discuss progress since the discovery, and show how we can measure the top quark mass using three separate techniques. The measurements were made at the Fermilab Tevatron, a p bar p collider with √s = TeV, using ∼50 pb -1 data collected from 1992 to early 1995

Top quark and Higgs boson masses: Interplay between infared and ultraviolet physics

International Nuclear Information System (INIS)

Schrempp, B.; Wimmer, M.

1996-05-01

We review recent efforts to explore the information on masses of heavy matter particles, notable of the top quark and the Higgs boson, as encoded at the quantum level in the renormalization group equations. The standard model (SM) and the minimal supersymmetric standard model (MSSM) are considered in parallel throughout. First, the question is addressed to which extent the infrared physics of the ''top-down'' renormalization group flow is independent of the ultraviolet physics. The central issues are (i) infrared attractive fixed point values for the top and the Higgs mass, the most outstanding one being m t =O (190 GeV) sin β in the MSSM, (ii) infrared attractive relations between parameters, the most prominent ones being an infrared fixed top-Higgs mass relation in the SM, leading to m H =O (156 GeV) for the experimental top mass, and an infrared fixed relation between the top mass and the parameter tan β in the MSSM, and (iii) a systematical analytical assessment of their respective strengths of attraction. The triviality and vacuum stability bounds on the Higgs and top masses in the SM as well as the upper bound on the mass of the lightest Higgs boson in the MSSM are reviewed. The mathematical backbone for all these features, the rich structure of infrared attractive fixed points, lines, surfaces,.. in the corresponding multiparameter space, is made transparent

Nucleon Mass from a Covariant Three-Quark Faddeev Equation

International Nuclear Information System (INIS)

Eichmann, G.; Alkofer, R.; Krassnigg, A.; Nicmorus, D.

2010-01-01

We report the first study of the nucleon where the full Poincare-covariant structure of the three-quark amplitude is implemented in the Faddeev equation. We employ an interaction kernel which is consistent with contemporary studies of meson properties and aspects of chiral symmetry and its dynamical breaking, thus yielding a comprehensive approach to hadron physics. The resulting current-mass evolution of the nucleon mass compares well with lattice data and deviates only by ∼5% from the quark-diquark result obtained in previous studies.

Precision determination of the top-quark mass

International Nuclear Information System (INIS)

Moch, Sven-Olaf

2014-08-01

Precision determinations of the top-quark mass require theory predictions with a well-defined mass parameter in a given renormalization scheme. The top-quark's running mass in the MS scheme can be extracted with good precision from the total cross section at next-to-next-to-leading order in QCD. The Monte Carlo top-quark mass parameter measured from comparison to events with top-quark decay products is not identical with the pole mass. Its translation to the pole mass scheme introduces an additional uncertainty of the order of 1 GeV.

Simulating at realistic quark masses. Light quark masses

International Nuclear Information System (INIS)

Goeckeler, M.; Streuer, T.

2006-11-01

We present new results for light quark masses. The calculations are performed using two flavours of O(a) improved Wilson fermions. We have reached lattice spacings as small as a ∝0.07 fm and pion masses down to m π ∝340 MeV in our simulations. This gives us significantly better control on the chiral and continuum extrapolations. (orig.)

Minkowski space pion model inspired by lattice QCD running quark mass

Energy Technology Data Exchange (ETDEWEB)

Mello, Clayton S. [Instituto Tecnológico de Aeronáutica, DCTA, 12.228-900 São José dos Campos, SP (Brazil); Melo, J.P.B.C. de [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo, SP (Brazil); Frederico, T., E-mail: tobias@ita.br [Instituto Tecnológico de Aeronáutica, DCTA, 12.228-900 São José dos Campos, SP (Brazil)

2017-03-10

The pion structure in Minkowski space is described in terms of an analytic model of the Bethe–Salpeter amplitude combined with Euclidean Lattice QCD results. The model is physically motivated to take into account the running quark mass, which is fitted to Lattice QCD data. The pion pseudoscalar vertex is associated to the quark mass function, as dictated by dynamical chiral symmetry breaking requirements in the limit of vanishing current quark mass. The quark propagator is analyzed in terms of a spectral representation, and it shows a violation of the positivity constraints. The integral representation of the pion Bethe–Salpeter amplitude is also built. The pion space-like electromagnetic form factor is calculated with a quark electromagnetic current, which satisfies the Ward–Takahashi identity to ensure current conservation. The results for the form factor and weak decay constant are found to be consistent with the experimental data.

Minkowski space pion model inspired by lattice QCD running quark mass

Directory of Open Access Journals (Sweden)

Clayton S. Mello

2017-03-01

Full Text Available The pion structure in Minkowski space is described in terms of an analytic model of the Bethe–Salpeter amplitude combined with Euclidean Lattice QCD results. The model is physically motivated to take into account the running quark mass, which is fitted to Lattice QCD data. The pion pseudoscalar vertex is associated to the quark mass function, as dictated by dynamical chiral symmetry breaking requirements in the limit of vanishing current quark mass. The quark propagator is analyzed in terms of a spectral representation, and it shows a violation of the positivity constraints. The integral representation of the pion Bethe–Salpeter amplitude is also built. The pion space-like electromagnetic form factor is calculated with a quark electromagnetic current, which satisfies the Ward–Takahashi identity to ensure current conservation. The results for the form factor and weak decay constant are found to be consistent with the experimental data.

Maximally twisted mass lattice QCD at the physical pion mass

International Nuclear Information System (INIS)

Kostrzewa, Bartosz

2016-01-01

In computer simulations of Lattice Quantum Chromodynamics, the usage of unphysically large quark masses and the subsequent extrapolation of results to the physical value of the quark masses are major sources of systematic uncertainty. In this thesis, the feasibility and practicality of numerical simulations of Quantum Chromodynamics with physically light up and down quarks using the Wilson twisted mass quark discretisation are explored. Working in this regime is complicated firstly by the numerical expense of these simulations and secondly by the presence of potentially large lattice artefacts. The twisted mass discretisation is affected by an unphysical mass difference between the charged and neutral pions, rendering simulations at the physical charged pion mass infeasible if this mass splitting is too large. With the aim of reducing it, the Sheikholeslami-Wohlert term is added to the twisted mass fermion action and simulations with mass degenerate up and down quarks are then performed as a proof of concept. It is demonstrated that these simulations are stable and that the parameters of the lattice theory can be successfully tuned to correspond to the physical charged pion mass. Subsequently, the parameter tuning for simulations with mass degenerate up and down quarks as well as strange and charm quarks is explored and it is shown that it can be carried out in steps. As benchmark observables, the masses and decay constants of pseudoscalar mesons with light, strange and charm valence quarks are calculated and seen to largely reproduce their phenomenological values, even though continuum and infinite volume extrapolations are not performed. Light, strange and charm quark mass estimates are determined based on this data and also seen to coincide with phenomenological and other lattice determinations. In this analysis, a particular emphasis is placed on the systematic error due to the choice of fit range for pseudoscalar correlation functions and a weighting method is

Measurement of the top quark mass in the dilepton channel

International Nuclear Information System (INIS)

Grinstein, S.; Mostafa, M.; Piegaia, R.; Alves, G.A.; Carvalho, W.; Maciel, A.K.; Motta, H. da; Oliveira, E.; Santoro, A.; Lima, J.G.; Oguri, V.; Gomez, B.; Hoeneisen, B.; Mooney, P.; Negret, J.P.; Ducros, Y.; Beri, S.B.; Bhatnagar, V.; Kohli, J.M.; Singh, J.B.; Shivpuri, R.K.; Acharya, B.S.; Banerjee, S.; Dugad, S.R.; Gupta, A.; Krishnaswamy, M.R.; Mondal, N.K.; Narasimham, V.S.; Parua, N.; Shankar, H.C.; Park, Y.M.; Choi, S.; Kim, S.K.; Castilla-Valdez, H.; Gonzalez Solis, J.L.; Hernandez-Montoya, R.; Magana-Mendoza, L.; Sanchez-Hernandez, A.; Pawlik, B.; Gavrilov, V.; Gershtein, Y.; Kuleshov, S.; Belyaev, A.; Dudko, L.V.; Ermolov, P.; Karmanov, D.; Leflat, A.; Manankov, V.; Merkin, M.; Shabalina, E.; Abramov, V.; Babintsev, V.V.; Bezzubov, V.A.; Bojko, N.I.; Burtovoi, V.S.; Chekulaev, S.V.; Denisov, S.P.; Dyshkant, A.; Eroshin, O.V.; Evdokimov, V.N.; Galyaev, A.N.; Goncharov, P.I.; Gurzhiev, S.N.; Kostritskiy, A.V.; Kozelov, A.V.; Kozlovsky, E.A.; Mayorov, A.A.; Babukhadia, L.; Davis, K.; Fein, D.; Forden, G.E.; Guida, J.A.; James, E.; Johns, K.; Nang, F.; Narayanan, A.; Rutherfoord, J.; Shupe, M.; Aihara, H.; Barberis, E.; Chen, L.

1999-01-01

We report a measurement of the top quark mass using six candidate events for the process p bar p→t bar t+X→l + νbl - bar ν bar b+X, observed in the D0 experiment at the Fermilab p bar p collider. Using maximum likelihood fits to the dynamics of the decays, we measure a mass for the top quark of m t =168.4±12.3(stat)±3.6(syst) Gev. We combine this result with our previous measurement in the t bar t→l+jets channel to obtain m t =172.1±7.1 GeV as the best value of the mass of the top quark measured by D0. copyright 1999 The American Physical Society

The effect of dynamical quark mass on the calculation of a strange quark star's structure

Institute of Scientific and Technical Information of China (English)

Gholam Hossein Bordbar; Babak Ziaei

2012-01-01

We discuss the dynamical behavior of strange quark matter components,in particular the effects of density dependent quark mass on the equation of state of strange quark matter.The dynamical masses of quarks are computed within the Nambu-Jona-Lasinio model,then we perform strange quark matter calculations employing the MIT bag model with these dynamical masses.For the sake of comparing dynamical mass interaction with QCD quark-quark interaction,we consider the one-gluon-exchange term as the effective interaction between quarks for the MIT bag model.Our dynamical approach illustrates an improvement in the obtained equation of state values.We also investigate the structure of the strange quark star using TolmanOppenheimer-Volkoff equations for all applied models.Our results show that dynamical mass interaction leads to lower values for gravitational mass.

Quark ACM with topologically generated gluon mass

Science.gov (United States)

Choudhury, Ishita Dutta; Lahiri, Amitabha

2016-03-01

We investigate the effect of a small, gauge-invariant mass of the gluon on the anomalous chromomagnetic moment (ACM) of quarks by perturbative calculations at one-loop level. The mass of the gluon is taken to have been generated via a topological mass generation mechanism, in which the gluon acquires a mass through its interaction with an antisymmetric tensor field Bμν. For a small gluon mass ( ACM at momentum transfer q2 = -M Z2. We compare those with the ACM calculated for the gluon mass arising from a Proca mass term. We find that the ACM of up, down, strange and charm quarks vary significantly with the gluon mass, while the ACM of top and bottom quarks show negligible gluon mass dependence. The mechanism of gluon mass generation is most important for the strange quarks ACM, but not so much for the other quarks. We also show the results at q2 = -m t2. We find that the dependence on gluon mass at q2 = -m t2 is much less than at q2 = -M Z2 for all quarks.

Chiral symmetry-breaking and the quark mass

International Nuclear Information System (INIS)

Gautam, V.P.; Kar, S.C.

1988-01-01

The generation of mass for light and heavy-quark sectors in the case of chiral symmetry-breaking is studied and an attempt is made to find the origin of quark mass and renormalization point corresponding to current-quark mass. (M.G.B.). 12 refs

Simulating at realistic quark masses. Light quark masses

Energy Technology Data Exchange (ETDEWEB)

Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Physik 1 - Theoretische Physik; Horsley, R.; Zanotti, J.M. [Edinburgh Univ. (United Kingdom). School of Physics; Nakamura, Y.; Pleiter, D. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC]|[Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Streuer, T. [Kentucky Univ., Lexington, KY (United States). Dept. of Physics and Astronomy; Stueben, H. [Konrad-Zuse-Zentrum fuer Informationstechnik Berlin (ZIB) (Germany)

2006-11-15

We present new results for light quark masses. The calculations are performed using two flavours of O(a) improved Wilson fermions. We have reached lattice spacings as small as a {proportional_to}0.07 fm and pion masses down to m{sub {pi}} {proportional_to}340 MeV in our simulations. This gives us significantly better control on the chiral and continuum extrapolations. (orig.)

Recent results on top quark physics and B physics at CDF

International Nuclear Information System (INIS)

Kim, S.

1998-01-01

We present the recent results on top quark physics and B physics with the Collider Detector at Fermilab (CDF). These results come from analyses using a full data sample at an integrated luminosity of 109 pb -1 cross section in 1.8-TeV p anti p collisions. We measure the top quark mass to be 175.8±6.5 GeV/c 2 and the t anti t production cross section to be 7.6 +1.8 -1.5 pb. We also present measurements of the lifetimes of B-hadrons and the time- dependent B 0 -anti B 0 mixing which results in the mass difference between heavy and light B 0 d mesons (Δm d ) of 0.464±0.030(stat)±0.026(syst) ps -1

Light hadron spectrum and quark masses from quenched lattice QCD

International Nuclear Information System (INIS)

Aoki, S.; Boyd, G.; Ejiri, S.; Kaneko, T.; Nagai, K.; Shanahan, H.P.; Burkhalter, R.; Iwasaki, Y.; Kanaya, K.; Ukawa, A.; Yoshie, T.; Fukugita, M.; Hashimoto, S.; Kuramashi, Y.; Okawa, M.

2003-01-01

We present the details of simulations for the light hadron spectrum in quenched QCD carried out on the CP-PACS parallel computer. Simulations are made with the Wilson quark action and the plaquette gauge action on lattices of size 32 3 x56-64 3 x112 at four values of lattice spacings in the range a≅0.1-0.05 fm and spatial extent L s a≅3 fm. Hadronic observables are calculated at five quark masses corresponding to m PS /m V ≅0.75-0.4, assuming the u and d quarks are degenerate, but treating the s quark separately. We find that the presence of quenched chiral singularities is supported from an analysis of the pseudoscalar meson data. The physical values of hadron masses are determined using m π , m ρ , and m K (or m φ ) as input to fix the physical scale of lattice spacing and the u, d, and s quark masses. After chiral and continuum extrapolations, the agreement of the calculated mass spectrum with experiment is at a 10% level. In comparison with the statistical accuracy of 1%-3% and systematic errors of at most 1.7% we have achieved, this demonstrates a failure of the quenched approximation for the hadron spectrum: the hyperfine splitting in the meson sector is too small, and in the baryon sector the octet masses and mass splitting of the decuplet are both smaller than experiment. Light quark masses are calculated using two definitions: the conventional one and the one based on the axial-vector Ward identity. The two results converge toward the continuum limit, yielding m ud =4.29(14) -0.79 +0.51 MeV where the first error is statistical and the second one is systematic due to chiral extrapolation. The s quark mass depends on the strange hadron mass chosen for input: m s =113.8(2.3) -2.9 +5.8 MeV from m K and m s =142.3(5.8) -0 +22.0 MeV from m φ , indicating again a failure of the quenched approximation. We obtain the scale of QCD, Λ MS (0) =219.5(5.4) MeV with m ρ used as input. An O(10%) deviation from experiment is observed in the pseudoscalar meson

Top Quark Mass Measurement in Dilepton Channel

Energy Technology Data Exchange (ETDEWEB)

Lysak, Roman [Inst. of Experimental Physics, Kosice (Slovak Republic)

2007-06-01

We present a measurement of the top quark mass from events produced in p$\\bar{p}$ collisions at a center-of-mass energy of 1.96 TeV, using the Collider Detector at Fermilab. We identify t$\\bar{t}$ candidates where both W bosons from the top quarks decay into leptons (eν, µν, τν) from a data sample of 340 pb^-1. The top quark mass is reconstructed in each event separately by the method which draw upon simulated distribution of t$\\bar{t}$ longitudinal momentum in order to extract probability distribution for the top quark mass. Representative distributions, or templates, are constructed from simulated samples of signal and background events, and parametrized to form continuous probability density functions. A likelihood fit incorporating these parametrized templates is then performed on the data sample masses in order to derive a final top quark mass. Measured top quark mass is M_top = 169.5$+7.7\\atop{-7.2}$(stat.) ± 4.0(syst.) GeV/c².

Infrared fixed point solution for the top quark mass and unification of couplings in the MSSM

International Nuclear Information System (INIS)

Bardeen, W.A.; Carena, M.; Pokorski, S.; Wagner, C.E.M.

1993-08-01

We analyze the implications of the infrared quasi fixed point solution for the top quark mass in the Minimal Supersymmetric Standard Model. This solution could explain in a natural way the relatively large value of the top quark mass and, if confirmed experimentally, may be suggestive of the onset of nonperturbative physics at very high energy scales. In the framework of grand unification, the expected bottom quark -- tau lepton Yukawa coupling unification is very sensitive to the fixed point structure of the top quark mass. For the presently allowed values of the electroweak parameters and the bottom quark mass, the Yukawa coupling unification implies that the top quark mass must be within ten percent of its fixed point values

Inverted radiative hierarchy of quark masses

International Nuclear Information System (INIS)

Berezhiani, Z.G.; Rattazzi, R.

1992-01-01

Inverted radiative hierarchy of quark masses is investigated. The authors suggest that the mass hierarchy is first generated in a sector of heavy isosinglet fermions due to radiative effects and then projected in the inverted way to the usual quarks by means of a universal seesaw. The simple left-right symmetric gauge model is presented with the P- and CP-parities and the exact isotopical symmetry which are softly (or spontaneously) broken in the Higgs potential. This approach naturally explains the observed pattern of quark masses and mixing, providing the quantitatively correct formula for the Cabibbo angle. Top quark is predicted to be in the 90-150 GeV range

Quark mass anomalous dimension from the twisted mass Dirac operator spectrum

Energy Technology Data Exchange (ETDEWEB)

Cichy, Krzysztof [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics

2013-12-15

We investigate whether it is possible to extract the quark mass anomalous dimension and its scale dependence from the spectrum of the twisted mass Dirac operator in Lattice QCD. The answer to this question appears to be positive, provided that one goes to large enough eigenvalues, sufficiently above the non-perturbative regime. The obtained results are compared to continuum perturbation theory. By analyzing possible sources of systematic effects, we find the domain of applicability of the approach, extending from an energy scale of around 1.5 to 4 GeV. The lower limit is dictated by physics (non-perturbative effects at low energies), while the upper bound is set by the ultraviolet cut-off of present-day lattice simulations. We use gauge field configuration ensembles generated by the European Twisted Mass Collaboration (ETMC) with 2 flavours of dynamical twisted mass quarks, at 4 lattice spacings in the range between around 0.04 and 0.08 fm.

Quark mass anomalous dimension from the twisted mass Dirac operator spectrum

International Nuclear Information System (INIS)

Cichy, Krzysztof; Poznan Univ.

2013-12-01

We investigate whether it is possible to extract the quark mass anomalous dimension and its scale dependence from the spectrum of the twisted mass Dirac operator in Lattice QCD. The answer to this question appears to be positive, provided that one goes to large enough eigenvalues, sufficiently above the non-perturbative regime. The obtained results are compared to continuum perturbation theory. By analyzing possible sources of systematic effects, we find the domain of applicability of the approach, extending from an energy scale of around 1.5 to 4 GeV. The lower limit is dictated by physics (non-perturbative effects at low energies), while the upper bound is set by the ultraviolet cut-off of present-day lattice simulations. We use gauge field configuration ensembles generated by the European Twisted Mass Collaboration (ETMC) with 2 flavours of dynamical twisted mass quarks, at 4 lattice spacings in the range between around 0.04 and 0.08 fm.

Quark effects in nuclear physics

International Nuclear Information System (INIS)

Miller, G.A.

1983-01-01

A phenomenological approach which enables the size of quark effects in various nuclear processes is discussed. The principle of conservation of probability provides significant constraints on six quark wave functions. Using this approach, it is found that the low-energy proton-proton weak interaction can be explained in terms of W and Z boson exchanges between quarks. That the value of the asymptotic ratio of D to S state wave functions is influenced (at the 5% level) by quark effects, is another result of our approach. We have not discovered a nuclear effect that can be uniquely explained by quark-quark interactions. However it does seem that quark physics is very relevant for nuclear physics. 52 references

Perturbative current quark masses in QCD

International Nuclear Information System (INIS)

Scadron, M.D.

1982-01-01

Neutral PCAC current quark masses follow from the covariant light plane of QCD requirement that α-m-circumflex(M), which is not inconsistent with the spontaneous breakdown of chiral symmetry. The resulting current quark mass ratio (m sub(s)/m-circumflex) sub(curr)=5 and scale m-circumflex sub(curr)=62 MeV at M=2 Gev are compatible with the observed πNσ - term, the Goldberger-Treiman discrepancy, the low-lying 0 - , 1/2 + , 1 - , 3/2 + hadron mass spectrum, the flavor independence of the dynamically generated quark mass and the perturbative weak binding limit. (author)

Strange Quark Magnetic Moment of the Nucleon at the Physical Point.

Science.gov (United States)

Sufian, Raza Sabbir; Yang, Yi-Bo; Alexandru, Andrei; Draper, Terrence; Liang, Jian; Liu, Keh-Fei

2017-01-27

We report a lattice QCD calculation of the strange quark contribution to the nucleon's magnetic moment and charge radius. This analysis presents the first direct determination of strange electromagnetic form factors including at the physical pion mass. We perform a model-independent extraction of the strange magnetic moment and the strange charge radius from the electromagnetic form factors in the momentum transfer range of 0.051  GeV^{2}≲Q^{2}≲1.31  GeV^{2}. The finite lattice spacing and finite volume corrections are included in a global fit with 24 valence quark masses on four lattices with different lattice spacings, different volumes, and four sea quark masses including one at the physical pion mass. We obtain the strange magnetic moment G_{M}^{s}(0)=-0.064(14)(09)μ_{N}. The four-sigma precision in statistics is achieved partly due to low-mode averaging of the quark loop and low-mode substitution to improve the statistics of the nucleon propagator. We also obtain the strange charge radius ⟨r_{s}^{2}⟩_{E}=-0.0043(16)(14)  fm^{2}.

Baryon interactions from lattice QCD with physical quark masses - Nuclear forces and ΞΞ forces -

Science.gov (United States)

Doi, Takumi; Iritani, Takumi; Aoki, Sinya; Gongyo, Shinya; Hatsuda, Tetsuo; Ikeda, Yoichi; Inoue, Takashi; Ishii, Noriyoshi; Miyamoto, Takaya; Nemura, Hidekatsu; Sasaki, Kenji

2018-03-01

We present the latest lattice QCD results for baryon interactions obtained at nearly physical quark masses. Nf = 2 + 1 nonperturbatively O(a)-improved Wilson quark action with stout smearing and Iwasaki gauge action are employed on the lattice of (96a)4 ≃(8.1fm)4 with a-1 ≃2.3 GeV, where mπ ≃146 MeV and mK ≃525 MeV. In this report, we study the two-nucleon systems and two-Ξ systems in 1S0 channel and 3S1-3D1 coupled channel, and extract central and tensor interactions by the HAL QCD method. We also present the results for the NΩ interaction in 5S2 channel which is relevant to the NΩ pair-momentum correlation in heavy-ion collision experiments.

New Physics with Energetic Top Quarks

CERN Document Server

Andeen, Timothy; The ATLAS collaboration

2018-01-01

Many theories beyond the Standard Model predict new phenomena which decay to energetic top quarks. Searches for such new physics models are performed using the ATLAS experiment at the LHC using proton-proton collision data collected in 2015 and 2016 with a center-of-mass energy of 13 TeV. Selected recent results will be discussed.

Twisted mass lattice QCD with non-degenerate quark masses

International Nuclear Information System (INIS)

Muenster, Gernot; Sudmann, Tobias

2006-01-01

Quantum Chromodynamics on a lattice with Wilson fermions and a chirally twisted mass term is considered in the framework of chiral perturbation theory. For two and three numbers of quark flavours, respectively, with non-degenerate quark masses the pseudoscalar meson masses and decay constants are calculated in next-to-leading order including lattice effects quadratic in the lattice spacing a

Lattice QCD studies on baryon interactions in the strangeness -2 sector with physical quark masses

Science.gov (United States)

Sasaki, Kenji; Aoki, Sinya; Doi, Takumi; Gongyo, Shinya; Hatsuda, Tetsuo; Ikeda, Yoichi; Inoue, Takashi; Iritani, Takumi; Ishii, Noriyoshi; Miyamoto, Takaya

2018-03-01

We investigate baryon-baryon (BB) interactions in the strangeness S = -2 sector via the coupled-channel HAL QCD method which enables us to extract the scattering observables from Nambu-Bethe-Salpeter (NBS) wave function on the lattice. The simulations are performed with (almost) physical quark masses (mπ = 146MeV) and a huge lattice volume of La = 8.1fm. We discuss the fate of H-dibaryon state through the ΛΛ and NΞ coupled-channel scatterings

Pole masses of quarks in dimensional reduction

International Nuclear Information System (INIS)

Avdeev, L.V.; Kalmykov, M.Yu.

1997-01-01

Pole masses of quarks in quantum chromodynamics are calculated to the two-loop order in the framework of the regularization by dimensional reduction. For the diagram with a light quark loop, the non-Euclidean asymptotic expansion is constructed with the external momentum on the mass shell of a heavy quark

Quark mass relations to four-loop order

International Nuclear Information System (INIS)

Marquard, Peter; Smirnov, Alexander V.; Smirnov, Vladimir A.; Steinhauser, Matthias

2015-02-01

We present results for the relation between a heavy quark mass defined in the on-shell and MS scheme to four-loop order. The method to compute the four-loop on-shell integral is briefly described and the new results are used to establish relations between various short-distance masses and the MS quark mass to next-to-next-to-next-to-leading order accuracy. These relations play an important role in the accurate determination of the MS heavy quark masses.

Non-perturbative quark mass renormalization

CERN Document Server

Capitani, S.; Luescher, M.; Sint, S.; Sommer, R.; Weisz, P.; Wittig, H.

1998-01-01

We show that the renormalization factor relating the renormalization group invariant quark masses to the bare quark masses computed in lattice QCD can be determined non-perturbatively. The calculation is based on an extension of a finite-size technique previously employed to compute the running coupling in quenched QCD. As a by-product we obtain the $\\Lambda$--parameter in this theory with completely controlled errors.

Top-quark mass measurements: Alternative techniques (LHC + Tevatron)

CERN Document Server

Adomeit, Stefanie; The ATLAS collaboration

2014-01-01

Measurements of the top-quark mass employing alternative techniques are presented, performed by the D0 and CDF collaborations at the Tevatron as well as the ATLAS and CMS experiments at the LHC. The alternative methods presented include measurements using the lifetime of $B$-hadrons, the transverse momentum of charged leptons and the endpoints of kinematic distributions in top quark anti-quark pair ($t\\bar{t}$) final states. The extraction of the top-quark pole mass from the $t\\bar{t}$ production cross-section and the normalized differential $t\\bar{t}$ + 1-jet cross-section are discussed as well as the top-quark mass extraction using fixed-order QCD predictions at detector level. Finally, a measurement of the top-quark mass using events enhanced in single top t-channel production is presented.

Lattice QCD studies on baryon interactions in the strangeness -2 sector with physical quark masses

Directory of Open Access Journals (Sweden)

Sasaki Kenji

2018-01-01

Full Text Available We investigate baryon-baryon (BB interactions in the strangeness S = −2 sector via the coupled-channel HAL QCD method which enables us to extract the scattering observables from Nambu-Bethe-Salpeter (NBS wave function on the lattice. The simulations are performed with (almost physical quark masses (mπ = 146MeV and a huge lattice volume of La = 8.1fm. We discuss the fate of H-dibaryon state through the ΛΛ and NΞ coupled-channel scatterings

Searches for New Physics with Top Quarks in CMS

CERN Multimedia

CERN. Geneva

2013-01-01

We will present a review of non-MSSM inspired searches for new physics beyond the Standard Model in final states containing top quarks or bottom quarks performed by the CMS experiment. These include searches for heavy gauge bosons, excited quarks, sequential and vector-like top quark partners. The analyses span a range of final states, from multi-leptonic to entirely hadronic, and many use modern reconstruction and analysis techniques to reconstruct the highly boosted final states that are created in these topologies. The talk will focus on the most recent results from CMS, using the full dataset collected in proton-proton collisions at the LHC at a centre-of-mass energy of 8 TeV.

Top quark mass measurements: how precise does it get?

CERN Multimedia

CERN. Geneva

2014-01-01

The mass of the top quark is a fundamental parameter of the Standard Model and has to be determined experimentally. Its precise knowledge can be used to constrain new physics models or to check the internal consistency of the Standard Model. Dramatic improvements in experimental techniques over the last years allowed to achieve an unprecedented uncertainty of below 0.5%. In this talk, I present a legacy measurement of the top quark mass performed in lepton+jets final states using the full dataset of proton-antiproton collisions recorded by the DZero detector in Run II at the Tevatron collider, which achieves a relative precision of 0.43%, and outline the perspectives for future improvements at the LHC.

Recent results on top quark physics with the CMS detector

CERN Multimedia

CERN. Geneva

2015-01-01

Top quarks are produced abundantly at the LHC due to the large cross section, high luminosity and outstanding performance of the accelerator chain. These unique conditions have opened the door to precise measurements of the top quark cross section, the top quark's peculiar properties and to searches for new physics in the top quark sector. In this seminar, recent top quark measurements performed by the CMS experiment will be reviewed. The measurements are based on the data collected at center-of-mass energies of 7, 8 and 13 TeV. Special emphasis will be given to the latest inclusive cross section measurements including those that analyse the data taken after the restart of the LHC.

Top quark mass measurement and color effects at the LHC

International Nuclear Information System (INIS)

Kovalchuk, Nataliia

2018-04-01

The top quark, the heaviest fundamental particle discovered to date, is one of the most peculiar particles that were discovered so far. It plays a crucial role in consistency checks of the Standard Model and in searches for new physics, e.g., supersymmetry, composite Higgs, and many other exotic models. In this thesis, an important property of the top quark is measured: the mass. This analysis is based on the data recorded at a center-of-mass energy of 13 TeV in 2016 with the CMS detector at the CERN LHC, and corresponds to an integrated luminosity of 35.9 fb -1 . The mass of the top quark is measured using the top quark pair event candidate, which corresponds to events with one muon or electron and at least four jets. The corresponding decay products are used in a kinematic fit to perform the jet quark assignment, increase the fraction of correctly reconstructed top quarks and to improve the mass resolution. Using the ideogram method the top quark mass is measured simultaneously with the jet scale factor (JSF), constrained by the jets arising from the W boson decay. The estimated result is calibrated with samples simulated with a next-to-leading order matrix element generator matched to the parton shower. The top quark mass is measured to be m t =172.25±0.08 (stat+JSF)±0.62 (syst) GeV. The results are tested for possible kinematic dependence by performing measurements of the top quark mass in different phase space regions. The residual data-to-simulation calibration of the energy of the jets is also estimated from dijet events with data collected at center-of-mass energy of 13 TeV in 2015 with the CMS detector corresponding to an integrated luminosity of 2.1 fb -1 . The corrections are performed using selected back-to-back dijet events by the MPF and dijet balance methods and are found to differ from unity by less then 3% in the barrel region and up to 17% in the endcap and forward regions of the detector. This result was used in the top mass measurement

Precision top-quark mass measurement at CDF.

Science.gov (United States)

Aaltonen, T; Alvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, J A; Arisawa, T; Artikov, A; Asaadi, J; Ashmanskas, W; Auerbach, B; Aurisano, A; Azfar, F; Badgett, W; Bae, T; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Barria, P; Bartos, P; Bauce, M; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Bhatti, A; Bisello, D; Bizjak, I; Bland, K R; Blumenfeld, B; Bocci, A; Bodek, A; Bortoletto, D; Boudreau, J; Boveia, A; Brigliadori, L; Bromberg, C; Brucken, E; Budagov, J; Budd, H S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Calamba, A; Calancha, C; Camarda, S; Campanelli, M; Campbell, M; Canelli, F; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chung, W H; Chung, Y S; Ciocci, M A; Clark, A; Clarke, C; Compostella, G; Convery, M E; Conway, J; Corbo, M; Cordelli, M; Cox, C A; Cox, D J; Crescioli, F; Cuevas, J; Culbertson, R; Dagenhart, D; d'Ascenzo, N; Datta, M; de Barbaro, P; Dell'Orso, M; Demortier, L; Deninno, M; Devoto, F; d'Errico, M; Di Canto, A; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Dorigo, M; Dorigo, T; Ebina, K; Elagin, A; Eppig, A; Erbacher, R; Errede, S; Ershaidat, N; Eusebi, R; Farrington, S; Feindt, M; Fernandez, J P; Field, R; Flanagan, G; Forrest, R; Frank, M J; Franklin, M; Freeman, J C; Funakoshi, Y; Furic, I; Gallinaro, M; Garcia, J E; Garfinkel, A F; Garosi, P; Gerberich, H; Gerchtein, E; Giagu, S; Giakoumopoulou, V; Giannetti, P; Gibson, K; Ginsburg, C M; Giokaris, N; Giromini, P; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldin, D; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Grinstein, S; Grosso-Pilcher, C; Group, R C; Guimaraes da Costa, J; Hahn, S R; Halkiadakis, E; Hamaguchi, A; Han, J Y; Happacher, F; Hara, K; Hare, D; Hare, M; Harr, R F; Hatakeyama, K; Hays, C; Heck, M; Heinrich, J; Herndon, M; Hewamanage, S; Hocker, A; Hopkins, W; Horn, D; Hou, S; Hughes, R E; Hurwitz, M; Husemann, U; Hussain, N; Hussein, M; Huston, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jang, D; Jayatilaka, B; Jeon, E J; Jindariani, S; Jones, M; Joo, K K; Jun, S Y; Junk, T R; Kamon, T; Karchin, P E; Kasmi, A; Kato, Y; Ketchum, W; Keung, J; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kim, Y J; Kimura, N; Kirby, M; Klimenko, S; Knoepfel, K; Kondo, K; Kong, D J; Konigsberg, J; Kotwal, A V; Kreps, M; Kroll, J; Krop, D; Kruse, M; Krutelyov, V; Kuhr, T; Kurata, M; Kwang, S; Laasanen, A T; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; LeCompte, T; Lee, E; Lee, H S; Lee, J S; Lee, S W; Leo, S; Leone, S; Lewis, J D; Limosani, A; Lin, C-J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, C; Liu, H; Liu, Q; Liu, T; Lockwitz, S; Loginov, A; Lucchesi, D; Lueck, J; Lujan, P; Lukens, P; Lungu, G; Lys, J; Lysak, R; Madrak, R; Maeshima, K; Maestro, P; Malik, S; Manca, G; Manousakis-Katsikakis, A; Margaroli, F; Marino, C; Martínez, M; Mastrandrea, P; Matera, K; Mattson, M E; Mazzacane, A; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Mesropian, C; Miao, T; Mietlicki, D; Mitra, A; Miyake, H; Moed, S; Moggi, N; Mondragon, M N; Moon, C S; Moore, R; Morello, M J; Morlock, J; Movilla Fernandez, P; Mukherjee, A; Muller, Th; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Naganoma, J; Nakano, I; Napier, A; Nett, J; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Noh, S Y; Norniella, O; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Ortolan, L; Pagan Griso, S; Pagliarone, C; Palencia, E; Papadimitriou, V; Paramonov, A A; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Pianori, E; Pilot, J; Pitts, K; Plager, C; Pondrom, L; Poprocki, S; Potamianos, K; Prokoshin, F; Pranko, A; Ptohos, F; Punzi, G; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Renton, P; Rescigno, M; Riddick, T; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rodriguez, T; Rogers, E; Rolli, S; Roser, R; Ruffini, F; Ruiz, A; Russ, J; Rusu, V; Safonov, A; Sakumoto, W K; Sakurai, Y; Santi, L; Sato, K; Saveliev, V; Savoy-Navarro, A; Schlabach, P; Schmidt, A; Schmidt, E E; Schwarz, T; Scodellaro, L; Scribano, A; Scuri, F; Seidel, S; Seiya, Y; Semenov, A; Sforza, F; Shalhout, S Z; Shears, T; Shepard, P F; Shimojima, M; Shochet, M; Shreyber-Tecker, I; Simonenko, A; Sinervo, P; Sliwa, K; Smith, J R; Snider, F D; Soha, A; Sorin, V; Song, H; Squillacioti, P; Stancari, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Strycker, G L; Sudo, Y; Sukhanov, A; Suslov, I; Takemasa, K; Takeuchi, Y; Tang, J; Tecchio, M; Teng, P K; Thom, J; Thome, J; Thompson, G A; Thomson, E; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Totaro, P; Trovato, M; Ukegawa, F; Uozumi, S; Varganov, A; Vázquez, F; Velev, G; Vellidis, C; Vidal, M; Vila, I; Vilar, R; Vizán, J; Vogel, M; Volpi, G; Wagner, P; Wagner, R L; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Wester, W C; Whiteson, D; Wicklund, A B; Wicklund, E; Wilbur, S; Wick, F; Williams, H H; Wilson, J S; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, H; Wright, T; Wu, X; Wu, Z; Yamamoto, K; Yamato, D; Yang, T; Yang, U K; Yang, Y C; Yao, W-M; Yeh, G P; Yi, K; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanetti, A; Zeng, Y; Zhou, C; Zucchelli, S

2012-10-12

We present a precision measurement of the top-quark mass using the full sample of Tevatron √s = 1.96 TeV proton-antiproton collisions collected by the CDF II detector, corresponding to an integrated luminosity of 8.7 fb(-1). Using a sample of tt¯ candidate events decaying into the lepton+jets channel, we obtain distributions of the top-quark masses and the invariant mass of two jets from the W boson decays from data. We then compare these distributions to templates derived from signal and background samples to extract the top-quark mass and the energy scale of the calorimeter jets with in situ calibration. The likelihood fit of the templates from signal and background events to the data yields the single most-precise measurement of the top-quark mass, M(top)=172.85±0.71(stat)±0.85(syst) GeV/c(2).

The Top Quark as a Window to Beyond the Standard Model Physics

Energy Technology Data Exchange (ETDEWEB)

Yu, Chiu-Tien [Univ. of Wisconsin, Madison, WI (United States)

2013-01-01

The top quark was the last of the Standard Model quarks to be discovered, and is of considerable interest. The closeness of the top quark mass to the electroweak scale is suggestive that the top quark could be closely related to the mechanisms for electroweak symmetry breaking. Any new physics in electroweak symmetry breaking models could then preferentially couple to the top quark, making the top quark a promising probe for new physics. In this thesis, we will explore two aspects of the top quark as a harbinger to new physics: the top forward-backward asymmetry as seen at the Tevatron and the search for stops. In this thesis, we will discuss the Asymmetric Left-Right Model (ALRM), a model that is based on the gauge group $U'(1)\\times SU(2)\\times SU'(2)$ with couplings $g_1^\\prime, g_2^\\prime,$ and $g'$ associated with the fields $B',W,W'$, respectively, and show how this model can explain the top forward-backward asymmetry. We will then explore the scalar sector of the ALRM, and provide a specific Higgs mechanism that provides the masses for the $W'$ and $Z'$ bosons. The top forward-backward asymmetry is a test of invariance of charge-conjugation. Thus, we look at the $X$-gluon model, a model that was motivated by the top forward-backward asymmetry, and show that one can look at the longitudinal polarization of the top-quark to test parity conservation. Finally, we investigate searches for stop squarks, the supersymmetric partner of the top quark, at the Large Hadron Collider (LHC) using shape-based analyses.

Top quark mass spectrum from flavor-changing processes

Energy Technology Data Exchange (ETDEWEB)

Albright, C.H. (Northern Illinois Univ., Dekalb, IL (USA). Dept. of Physics Fermi National Accelerator Lab., Batavia, IL (USA))

1990-09-01

The input from flavor-changing processes is reviewed and results of several analyses are presented on the top quark mass spectrum without recourse to the neutral-current data. A top quark mass in the range 135 {plus minus} 25 GeV is much preferred, but a very massive top quark above 300 GeV can not be ruled out. Comments are made about the future use of the inclusive decay B {yields} {gamma} + X{sub S=1} for constraining the top quark mass. 24 refs., 2 figs.

Additivity of quark masses in gauge theories

International Nuclear Information System (INIS)

Scadron, M.D.

1987-01-01

It is shown that, in spite of the confinement of quarks in (color-singlet) hadrons, effective quark masses of all types (dynamically generated, constituent and current masses), naturally form hadron masses in an additivity fashion. For the purposes of brevity, the discussion is limited primarily to the nonstrange flavor sector

Top Quark Physics

International Nuclear Information System (INIS)

Larios, F.

2006-01-01

We give an overview of the physics of the Top quark, from the experimental discovery to the studies of its properties. We review some of the work done on the Electroweak and Flavor Changing couplings associated with the Top quark in the Standard Model and beyond. We will focus on the specific contribution of phycisits working in Mexico and Mexican physicists working abroad

Up-, down-, strange-, charm-, and bottom-quark masses from four-flavor lattice QCD

Energy Technology Data Exchange (ETDEWEB)

Bazavov, A.; Bernard, C.; Brambilla, N.; Brown, N.; DeTar, C.; El-Khadra, A. X.; Gámiz, E.; Gottlieb, Steven; Heller, U. M.; Komijani, J.; Kronfeld, A. S.; Laiho, J.; Mackenzie, P. B.; Neil, E. T.; Simone, J. N.; Sugar, R. L.; Toussaint, D.; Vairo, A.; Van de Water, R. S.

2018-02-12

We calculate the up-, down-, strange-, charm-, and bottom-quark masses using the MILC highly improved staggered-quark ensembles with four flavors of dynamical quarks. We use ensembles at six lattice spacings ranging from $a\\approx0.15~$fm to $0.03~$fm and with both physical and unphysical values of the two light and the strange sea-quark masses. We use a new method based on heavy-quark effective theory (HQET) to extract quark masses from heavy-light pseudoscalar meson masses. Combining our analysis with our separate determination of ratios of light-quark masses we present masses of the up, down, strange, charm, and bottom quarks. Our results for the $\\overline{\\text{MS}}$-renormalized masses are $m_u(2~\\text{GeV}) = 2.118(38)~$MeV, $m_d(2~\\text{GeV}) = 4.690(54)~$MeV, $m_s(2~\\text{GeV}) = 92.52(69)~$MeV, $m_c(3~\\text{GeV}) = 984.3(5.6)~$MeV, and $m_c(m_c) = 1273(10)~$MeV, with four active flavors; and $m_b(m_b) = 4197(14)~$MeV with five active flavors. We also obtain ratios of quark masses $m_c/m_s = 11.784(22)$, $m_b/m_s = 53.93(12)$, and $m_b/m_c = 4.577(8)$. The result for $m_c$ matches the precision of the most precise calculation to date, and the other masses and all quoted ratios are the most precise to date. Moreover, these results are the first with a perturbative accuracy of $\\alpha_s^4$. As byproducts of our method, we obtain the matrix elements of HQET operators with dimension 4 and 5: $\\overline{\\Lambda}_\\text{MRS}=552(30)~$MeV in the minimal renormalon-subtracted (MRS) scheme, $\\mu_\\pi^2 = 0.06(22)~\\text{GeV}^2$, and $\\mu_G^2(m_b)=0.38(2)~\\text{GeV}^2$. The MRS scheme [Phys. Rev. D97, 034503 (2018), arXiv:1712.04983 [hep-ph

Flavor Physics in the Quark Sector

CERN Document Server

Antonelli, Mario; Bauer, Daniel Adams; Becher, Thomas G.; Beneke, M.; Bevan, Adrian John; Blanke, Monika; Bloise, C.; Bona, Marcella; Bondar, Alexander E.; Bozzi, Concezio; Brod, Joachim; Buras, Andrzej J.; Cabibbo, N.; Carbone, A.; Cavoto, Gianluca; Cirigliano, Vincenzo; Ciuchini, Marco; Coleman, Jonathon P.; Cronin-Hennessy, Daniel P.; Dalseno, J.P.; Davies, C.H.; Di Lodovico, Francesca; Dingfelder, Jochen C.; Dolezal, Zdenek; Donati, Simone; Dungel, W.; Egede, Ulrik; Eigen, Gerald; Faccini, Riccardo; Feldmann, Thorsten; Ferroni, Fernando; Flynn, Jonathan M.; Franco, Enrico; Fujikawa, M.; Furic, Ivan K.; Gambino, Paolo; Gardi, E.; Gershon, Timothy John; Giagu, Stefano; Golowich, Eugene; Goto, Toru; Greub, C.; Grojean, Christophe; Guadagnoli, Diego; Haisch, U.A.; Harr, Robert Francis; Hoang, Andre H.; Hurth, Tobias; Isidori, Gino; Jaffe, D.E.; Juttner, Andreas; Jager, Sebastian; Khodjamirian, Alexander; Koppenburg, Patrick Stefan; Kowalewski, Robert V.; Krokovny, P.; Kronfeld, Andreas Samuel; Laiho, J.; Lanfranchi, G.; Latham, Thomas Edward; Libby, James F.; Limosani, A.; Lopes Pegna, David; Lu, Cai-Dian; Lubicz, Vittorio; Lunghi, Enrico; Luth, Vera G.; Maltman, K.; Marciano, William Joseph; Martin, Emilie Claire Mutsumi; Martinelli, Guido; Martinez-Vidal, Fernando; Masiero, A.; Mateu, V.; Mescia, Federico; Mohanty, Gagan Bihari; Moulson, Matthew; Neubert, Matthias; Neufeld, Helmut; Nishida, Shohei; Offen, Nils; Palutan, M.; Paradisi, Paride; Parsa, Z.; Passemar, Emilie; Patel, M.; Pecjak, B.D.; Petrov, Alexey A.; Pich, Antonio; Pierini, Maurizio; Plaster, Brad; Powell, Brian Alfred; Prell, Soeren Andre; Rademaker, J.; Rescigno, Marco; Ricciardi, Stefania; Robbe, Patrick; Rodrigues, E.; Rotondo, Marcello; Sacco, Roberto; Schilling, Christopher James; Schneider, Olivier; Scholz, Enno E.; Schumm, Bruce Andrew; Schwanda, C.; Schwartz, Alan Jay; Sciascia, Barbara; Serrano, Justine; Shigemitsu, J.; Shipsey, Ian P.J.; Sibidanov, A.L.; Silvestrini, Luca; Simonetto, Franco; Simula, Silvano; Smith, Christopher; Soni, A.; Sonnenschein, Lars; Sordini, Viola; Sozzi, Marco S.; Spadaro, Tommaso; Spradlin, Patrick Michael; Stocchi, Achille; Tantalo, Nazario; Tarantino, Cecilia; Telnov, Alexandre V.; Tonelli, Diego; Towner, I.S.; Trabelsi, K.; Urquijo, Phillip; Van de Water, R.S.; Van Kooten, Richard J.; Virto, Javier; Volpi, Guido; Wanke, R.; Westhoff, Susanne; Wilkinson, G.; Wingate, Matthew Bowen; Xie, Y.; Zupan, Jure

2010-01-01

One of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor and measurements and theoretical interpretations of their results have advanced tremendously: apart from masses and quantum numbers of flavor particles, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. Till early 1990s observations of CP violation were confined to neutral $K$ mesons, but since then a large number of CP-violating processes have been studied in detail in neutral $B$ mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of $K, D$, and $B$ mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near...

Vector-like quarks at the origin of light quark masses and mixing

Energy Technology Data Exchange (ETDEWEB)

Botella, Francisco J. [Universitat de Valencia-CSIC, Departament de Fisica Teorica and IFIC, Burjassot (Spain); Branco, G.C.; Nebot, Miguel; Rebelo, M.N.; Silva-Marcos, J.I. [Universidade de Lisboa, Departamento de Fisica and Centro de Fisica Teorica de Particulas (CFTP), Instituto Superior Tecnico (IST), Lisbon (Portugal)

2017-06-15

We show how a novel fine-tuning problem present in the Standard Model can be solved through the introduction of a Z{sub 6} flavour symmetry, together with three Q = -1/3 quarks, three Q = 2/3 quarks, as well as a complex singlet scalar. The Z{sub 6} symmetry is extended to the additional fields and it is an exact symmetry of the Lagrangian, only softly broken in the scalar potential, in order to avoid the domain-wall problem. Specific examples are given and a phenomenological analysis of the main features of the model is presented. It is shown that even for vector-like quarks with masses accessible at the LHC, one can have realistic quark masses and mixing, while respecting the strict constraints on processes arising from flavour changing neutral currents. The vector-like quark decay channels are also described. (orig.)

Top quark as a window to new physics: recent ATLAS results

CERN Document Server

Serkin, Leonid; The ATLAS collaboration

2017-01-01

The Large Hadron Collider proton-proton collision centre-of-mass energy was recently increased to 13 TeV, opening a unique window to search for signatures with mass scales higher than ever before and involving several high-mass particles. One attractive possibility is to focus on the heaviest known elementary particle described by the Standard Model, the top quark. With a mass close to the scale of electroweak symmetry breaking, the top quark is predicted to have a very large coupling to the Higgs boson and in many physics models beyond the Standard Model also to other new resonances. Possible new phenomena may enhance the SM cross-sections through the production of heavy objects in association with a top-quark pair. In this talk, I will present recent results from the ATLAS Collaboration which target a variety of scenarios and improve the sensitivity to a wider class of BSM processes.

Sea quark contribution to the dynamical mass and light quark content of a nucleon

International Nuclear Information System (INIS)

Singh, J.P.

1995-01-01

We calculate the flavor mixing in the wave function of a light valence quark. For this, we use the idea of dynamical symmetry breaking. A sea quark of a different flavor may appear through the vacuum polarization of a gluon propagator which appears in the gap equation for the dynamical mass. We have also used the fact that any one of these quark lines may undergo condensation. The dependence of the dynamical mass, generated in this way, on the sea quark mass up to quadratic terms has been retained. The momentum dependence is like 1/p 4 , in contrast with the 1/p 2 kind of dependence which occurs for the leading term of the dynamical mass in the subasymptotic region. The extension of the result to the ''mass shell'' yields σ πN =53--54 MeV for the pion-nucleon σ term and m s left-angle p|bar ss|p right-angle=122--264 meV for the strange quark contribution to the proton mass, for different values of parameters. These are in reasonable agreement with current phenomenological estimates of these quantities

The quark revolution and the ZGS - new quarks physics since the ZGS

International Nuclear Information System (INIS)

Lipkin, H.J.

1994-01-01

Overwhelming experimental evidence for quarks as real physical constituents of hadrons along with the QCD analogs of the Balmer Formula, Bohr Atom and Schroedinger Equation already existed in 1966 but was dismissed as heresy. ZGS experiments played an important role in the quark revolution. This role is briefly reviewed and subsequent progress in quark physics is described

Physics of the quark - gluon plasma

International Nuclear Information System (INIS)

2001-09-01

This document gathers 31 contributions to the workshop on the physics of quark-gluon plasma that took place in Palaiseau in september 2001: 1) gamma production in heavy collisions, 2) BRAHMS, 3) experimental conference summary, 4) modelling relativistic nuclear collisions, 5) microscopic reaction dynamics at SPS and RHIC, 6) direct gamma and hard scattering at SPS, 7) soft physics at RHIC, 8) results from the STAR experiment, 9) quarkonia: experimental possibilities, 10) elliptic flow measurements with PHENIX, 11) charmonium production in p-A collisions, 12) anisotropic flow at the SPS and RHIC, 13) deciphering the space-time evolution of heavy ion collisions with correlation measurements, 14) 2-particle correlation at RHIC, 15) particle spectra at AGS, SPS and RHIC, 16) strangeness production in STAR, 17) strangeness production in Pb-Pb collisions at SPS, 18) heavy ion physics at CERN after 2000 and before LHC, 19) NEXUS guideline and theoretical consistency, 20) introduction to high p T physics at RHIC, 21) a novel quasiparticle description of the quark-gluon plasma, 22) dissociation of excited quarkonia states, 23) high-mass dimuon and B → J/Ψ production in ultrarelativistic heavy ion collisions, 24) strange hyperon production in p + p and p + Pb interactions from NA49, 25) heavy quarkonium hadron cross-section, 26) a new method of flow analysis, 27) low mass dilepton production and chiral symmetry restoration, 28) classical initial conditions for nucleus-nucleus collisions, 29) numerical calculation of quenching weights, 30) strangeness enhancement energy dependence, and 31) heavy quarkonium dissociation

Physics of the quark - gluon plasma

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-09-01

This document gathers 31 contributions to the workshop on the physics of quark-gluon plasma that took place in Palaiseau in september 2001: 1) gamma production in heavy collisions, 2) BRAHMS, 3) experimental conference summary, 4) modelling relativistic nuclear collisions, 5) microscopic reaction dynamics at SPS and RHIC, 6) direct gamma and hard scattering at SPS, 7) soft physics at RHIC, 8) results from the STAR experiment, 9) quarkonia: experimental possibilities, 10) elliptic flow measurements with PHENIX, 11) charmonium production in p-A collisions, 12) anisotropic flow at the SPS and RHIC, 13) deciphering the space-time evolution of heavy ion collisions with correlation measurements, 14) 2-particle correlation at RHIC, 15) particle spectra at AGS, SPS and RHIC, 16) strangeness production in STAR, 17) strangeness production in Pb-Pb collisions at SPS, 18) heavy ion physics at CERN after 2000 and before LHC, 19) NEXUS guideline and theoretical consistency, 20) introduction to high p{sub T} physics at RHIC, 21) a novel quasiparticle description of the quark-gluon plasma, 22) dissociation of excited quarkonia states, 23) high-mass dimuon and B {yields} J/{psi} production in ultrarelativistic heavy ion collisions, 24) strange hyperon production in p + p and p + Pb interactions from NA49, 25) heavy quarkonium hadron cross-section, 26) a new method of flow analysis, 27) low mass dilepton production and chiral symmetry restoration, 28) classical initial conditions for nucleus-nucleus collisions, 29) numerical calculation of quenching weights, 30) strangeness enhancement energy dependence, and 31) heavy quarkonium dissociation.

Quark mass matrices in left-right symmetric gauge theories

International Nuclear Information System (INIS)

Ecker, G.; Grimus, W.; Konetschny, W.

1981-01-01

The most general left-right symmetry for SU(2)sub(L) x SU(2)sub(R) x U(1) gauge theories with any number of flavours and with at most two scalar multiplets transforming as anti qq bilinears is analyzed. In order to get additional constraints on the structure of quark mass matrices all possible horizontal groups (continuous or discrete) are investigated. A complete classification of physically inequivalent quark mass matrices is given for four and six flavours. It is argued that the methods and results are also applicable in the case of dynamical symmetry breaking. Parity invariance and horizontal symmetry are shown to imply CP conservation on the Lagrangian level. For all non-trivial three-generation models there is spontaneous CP violation which in most cases turns out to be naturally small. (Auth.)

Radiative generation of quark masses and mixing angles in the two Higgs doublet model

International Nuclear Information System (INIS)

Ibarra, Alejandro; Solaguren-Beascoa, Ana

2014-01-01

We present a framework to generate the quark mass hierarchies and mixing angles by extending the Standard Model with one extra Higgs doublet. The charm and strange quark masses are generated by small quantum effects, thus explaining the hierarchy between the second and third generation quark masses. All the mixing angles are also generated by small quantum effects: the Cabibbo angle is generated at zeroth order in perturbation theory, while the remaining off-diagonal entries of the Cabibbo–Kobayashi–Maskawa matrix are generated at first order, hence explaining the observed hierarchy |V ub |,|V cb |≪|V us |. The values of the radiatively generated parameters depend only logarithmically on the heavy Higgs mass, therefore this framework can be reconciled with the stringent limits on flavor violation by postulating a sufficiently large new physics scale

Running heavy-quark masses in DIS

International Nuclear Information System (INIS)

Alekhin, S.; Moch, S.

2011-07-01

We report on determinations of the running mass for charm quarks from deep-inelastic scattering reactions. The method provides complementary information on this fundamental parameter from hadronic processes with space-like kinematics. The obtained values are consistent with but systematically lower than the world average as published by the PDG. We also address the consequences of the running mass scheme for heavy-quark parton distributions in global fits to deep-inelastic scattering data. (orig.)

The Top Quark, QCD, And New Physics.

Science.gov (United States)

Dawson, S.

2002-06-01

The role of the top quark in completing the Standard Model quark sector is reviewed, along with a discussion of production, decay, and theoretical restrictions on the top quark properties. Particular attention is paid to the top quark as a laboratory for perturbative QCD. As examples of the relevance of QCD corrections in the top quark sector, the calculation of e{sup+}e{sup -}+ t{bar t} at next-to-leading-order QCD using the phase space slicing algorithm and the implications of a precision measurement of the top quark mass are discussed in detail. The associated production of a t{bar t} pair and a Higgs boson in either e{sup+}e{sup -} or hadronic collisions is presented at next-to-leading-order QCD and its importance for a measurement of the top quark Yulrawa coupling emphasized. Implications of the heavy top quark mass for model builders are briefly examined, with the minimal supersymmetric Standard Model and topcolor discussed as specific examples.

Quark mass correction to chiral separation effect and pseudoscalar condensate

Energy Technology Data Exchange (ETDEWEB)

Guo, Er-dong [State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics,Chinese Academy of Sciences,Beijing 100190 (China); Kavli Institute of Theoretical Physics China, Chinese Academy of Sciences,Beijing 100190 (China); Lin, Shu [School of Physics and Astronomy, Sun Yat-Sen University,No 2 University Road, Zhuhai 519082 (China)

2017-01-25

We derived an analytic structure of the quark mass correction to chiral separation effect (CSE) in small mass regime. We confirmed this structure by a D3/D7 holographic model study in a finite density, finite magnetic field background. The quark mass correction to CSE can be related to correlators of pseudo-scalar condensate, quark number density and quark condensate in static limit. We found scaling relations of these correlators with spatial momentum in the small momentum regime. They characterize medium responses to electric field, inhomogeneous quark mass and chiral shift. Beyond the small momentum regime, we found existence of normalizable mode, which possibly leads to formation of spiral phase. The normalizable mode exists beyond a critical magnetic field, whose magnitude decreases with quark chemical potential.

Top-quark mass from the diphoton mass spectrum

Energy Technology Data Exchange (ETDEWEB)

Kawabata, Sayaka [Seoul National University of Science and Technology, Institute of Convergence Fundamental Studies, Seoul (Korea, Republic of); Yokoya, Hiroshi [Quantum Universe Center, KIAS, Seoul (Korea, Republic of)

2017-05-15

We calculate the gg → γγ amplitude by including the t anti t bound-state effects near their mass threshold. In terms of the non-relativistic expansion of the amplitude, the LO contribution is an energy-independent term in the one-loop amplitude. We include the NLO contribution described by the non-relativistic Green function and part of the NNLO contribution. Despite a missing NLO piece which can be accomplished with the two-loop-level amplitude via massive quarks, the shape of the diphoton mass spectrum is predicted with a good accuracy. Thanks to the simple and clean nature of the observable, its experimental measurement can be a direct method to determine the short-distance mass of the top quark at hadron colliders. (orig.)

Mass-radius relation for magnetized strange quark stars

CERN Document Server

Martinez, A Perez; Paret, D Manreza

2010-01-01

We review the stability of magnetized strange quark matter (MSQM) within the phenomenological MIT bag model, taking into account the variation of the relevant input parameters, namely, the strange quark mass, baryon density, magnetic field and bag parameter. A comparison with magnetized asymmetric quark matter in $\\beta$-equilibrium as well as with strange quark matter (SQM) is presented. We obtain that the energy per baryon for MSQM decreases as the magnetic field increases, and its minimum value at vanishing pressure is lower than the value found for SQM, which implies that MSQM is more stable than non-magnetized SQM. The mass-radius relation for magnetized strange quark stars is also obtained in this framework.

Effects of Density-Dependent Quark Mass on Phase Diagram of Color-Flavor-Locked Quark Matter

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

Considering the density dependence of quark mass, we investigate the phase transition between the (unpaired) strange quark matter and the color-flavor-locked matter, which are supposed to be two candidates for the ground state of strongly interacting matter. We find that if the current mass of strange quark ms is small, the strange quark matter remains stable unless the baryon density is very high. If ms is large, the phase transition from the strange quark matter to the color-flavor-locked matter in particular to its gapless phase is found to be different from the results predicted by previous works. A complicated phase diagram of three-flavor quark matter is presented, in which the color-flavor-locked phase region is suppressed for moderate densities.

Measurement of the Top Quark Mass in Dilepton Final States with the Neutrino Weighting Method

Energy Technology Data Exchange (ETDEWEB)

Ilchenko, Yuriy [Southern Methodist Univ., Dallas, TX (United States)

2012-12-15

The top quark is the heaviest fundamental particle observed to date. The mass of the top quark is a free parameter in the Standard Model (SM). A precise measurement of its mass is particularly important as it sets an indirect constraint on the mass of the Higgs boson. It is also a useful constraint on contributions from physics beyond the SM and may play a fundamental role in the electroweak symmetry breaking mechanism. I present a measurement of the top quark mass in the dilepton channel using the Neutrino Weighting Method. The data sample corresponds to an integrated luminosity of 4.3 fb^-1 of p$\\bar{p}$ collisions at Tevatron with √s = 1.96 TeV, collected with the DØ detector. Kinematically under-constrained dilepton events are analyzed by integrating over neutrino rapidity. Weight distributions of t$\\bar{t}$ signal and background are produced as a function of the top quark mass for different top quark mass hypotheses. The measurement is performed by constructing templates from the moments of the weight distributions and input top quark mass, followed by a subsequent likelihood t to data. The dominant systematic uncertainties from jet energy calibration is reduced by using a correction from `+jets channel. To replicate the quark avor dependence of the jet response in data, jets in the simulated events are additionally corrected. The result is combined with our preceding measurement on 1 fb^-1 and yields m_t = 174.0± 2.4 (stat.) ±1.4 (syst.) GeV.

A measurement of the mass of the top quark using the ideogram technique

Energy Technology Data Exchange (ETDEWEB)

Houben, Pieter Willem Huib [Univ. of Amsterdam (Netherlands)

2009-06-03

This thesis describes a measurement of the mass of the top quark on data collected with the D0 detector at the Tevatron collider in the period from 2002 until 2006. The first chapter describes the Standard Model and the prominent role of the top quark mass. The second chapter gives a description of the D0 detector which is used for this measurement. After the p$\\bar{p}$ collisions have been recorded, reconstruction of physics objects is required, which is described in Chapter 3. Chapter 4 describes how the interesting collisions in which top quarks are produced are separated from the `uninteresting' ones with a set of selection criteria. The method to extract the top quark mass from the sample of selected collisions (also called events), which is based on the ideogram technique, is explained in Chapter 5, followed in Chapter 6 by the description of the calibration of the method using simulation of our most precise knowledge of nature. Chapter 7 shows the result of the measurement together with some cross checks and an estimation of the uncertainty on this measurement. This thesis concludes with a constraint on the Higgs boson mass.

A precision measurement of the mass of the top quark

International Nuclear Information System (INIS)

Abazov, V.M.

2004-01-01

The standard model of particle physics contains parameters -- such as particle masses -- whose origins are still unknown and which cannot be predicted, but whose values are constrained through their interactions. In particular, the masses of the top quark (M t ) and W boson (M W ) constrain the mass of the long-hypothesized, but thus far not observed, Higgs boson. A precise measurement of M t can therefore indicate where to look for the Higgs, and indeed whether the hypothesis of a standard model Higgs is consistent with experimental data. As top quarks are produced in pairs and decay in only about 10 -24 s into various final states, reconstructing their masses from their decay products is very challenging. Here we report a technique that extracts more information from each top-quark event and yields a greatly improved precision (of +- 5.3 GeV/c 2 ) when compared to previous measurements. When our new result is combined with our published measurement in a complementary decay mode and with the only other measurements available, the new world average for M t becomes 178.0 +- 4.3 GeV/c 2 . As a result, the most likely Higgs mass increases from the experimentally excluded value of 96 to 117 GeV/c 2 , which is beyond current experimental sensitivity. The upper limit on the Higgs mass at the 95% confidence level is raised from 219 to 251 GeV/c 2

On measuring the top quark mass using the dilepton decay modes

International Nuclear Information System (INIS)

Raja, R.

1996-09-01

We demonstrate a new likelihood method for extracting the top quark mass from events of the type t anti t → bW + (lepton+ν)anti bW - (lepton+ν). This method estimates the top quark mass correctly from an ensemble of dilepton events. The method proposed by Dalitz and Goldstein is shown to result in a systematic underestimation of the top quark mass. Effects due to the spin correlations between the top and anti-top quarks are shown to be unimportant in estimating the mass of the top quark

Influence of light-quark masses in dynamical scale breaking

International Nuclear Information System (INIS)

Barcelos Neto, J.; Chanda, R.

1984-01-01

It is demonstrated that light quark masses may significantly contribute to the logarithmic scale breaking in deep inelastic electromagnetic lepton-nucleon scattering. This is mainly due to the combination of scale variables together with large 'current' masses for u and d quarks, recently reported in the literature. Upper limits for current masses of u and d quarks, using positivity properties of the forward electromagnetic structure function F 2 of the nucleon are also estimated. (Author) [pt

Top Quark and Higgs Boson Physics at LHC-ATLAS

Science.gov (United States)

Tomoto, M.

2013-03-01

One of the main goal of the Large Hadron Collider (LHC) experiments at CERN in Switzerland is to aim to solve the "origin of the mass" by discovering the Higgs boson and understanding the interaction of the Higgs boson with the elementary particles. The ATLAS, which is one of the LHC experiments has taken about 5 fb-1 of physics quality data and published several results with regard to the "origin of the mass" since March 2010. This presentation focuses on the latest results of the heaviest elementary particle, namely, top quark physics and the Higgs boson searches from ATLAS.

Physical and cut-off effects of heavy sea quarks

CERN Document Server

Knechtli, Francesco; Bruno, Mattia; Finkenrath, Jacob; Leder, Björn; Marinkovic, Marina; Sommer, Rainer

2014-01-01

We simulate a theory with two dynamical O($a$) improved Wilson quarks whose mass $M$ ranges from a factor eight up to a factor two below the charm quark mass and at three values of the lattice spacing ranging from 0.066 to 0.034 fm. This theory is a prototype to study the decoupling of heavy quarks. We measure the mass and cut-off dependence of ratios of gluonic observables defined from the Wilson flow or the static potential. The size of the 1/$M$ corrections can be determined and disentangled from the lattice artifacts. The difference with the pure gauge theory is at the percent level when two quarks with a mass of the charm quark are present.

Flavor Physics in the Quark Sector

Energy Technology Data Exchange (ETDEWEB)

Antonelli, Mario; /Frascati; Asner, David Mark; /Carleton U.; Bauer, Daniel Adams; /Imperial Coll., London; Becher, Thomas G.; /Fermilab; Beneke, M.; /Aachen, Tech. Hochsch.; Bevan, Adrian John; /Queen Mary, U. of London; Blanke, Monika; /Munich, Tech. U. /Munich, Max Planck Inst.; Bloise, C.; /Frascati; Bona, Marcella; /CERN; Bondar, Alexander E.; /Novosibirsk, IYF; Bozzi, Concezio; /INFN, Ferrara; Brod, Joachim; /Karlsruhe U.; Buras, Andrzej J.; /Munich, Tech. U.; Cabibbo, N.; /INFN, Rome /Rome U.; Carbone, A.; /INFN, Bologna; Cavoto, Gianluca; /INFN, Rome; Cirigliano, Vincenzo; /Los Alamos; Ciuchini, Marco; /INFN, Rome; Coleman, Jonathon P.; /SLAC; Cronin-Hennessy, Daniel P.; /Minnesota U.; Dalseno, J.P.; /KEK, Tsukuba /Glasgow U. /Queen Mary, U. of London /Freiburg U. /Charles U. /Pisa U. /Vienna, OAW /Imperial Coll., London /Bergen U. /INFN, Rome /Rome U. /Munich, Tech. U. /INFN, Rome /Rome U. /Southampton U. /INFN, Rome /Nara Women' s U. /Florida U. /INFN, Turin /Turin U. /Edinburgh U. /Warwick U. /INFN, Rome /Rome U. /Massachusetts U., Amherst /KEK, Tsukuba /Bern U. /CERN /Munich, Tech. U. /Mainz U., Inst. Phys. /Wayne State U. /Munich, Max Planck Inst. /CERN /Frascati /Brookhaven /Mainz U., Inst. Kernphys. /Munich, Tech. U. /Siegen U. /Imperial Coll., London /Victoria U. /KEK, Tsukuba /Fermilab /Washington U., St. Louis /Frascati /Warwick U. /Indian Inst. Tech., Madras /Melbourne U. /Princeton U. /Beijing, Inst. High Energy Phys. /INFN, Rome /INFN, Rome3 /Fermilab /SLAC /York U., Canada /Brookhaven /UC, Irvine /INFN, Rome /Rome U. /Valencia U., IFIC /INFN, Padua /Padua U. /Munich, Max Planck Inst. /Barcelona U. /Warwick U. /Tata Inst. /Frascati /Mainz U., Inst. Phys. /Vienna U. /KEK, Tsukuba /Orsay, LPT /Frascati /Munich, Tech. U. /Brookhaven /Bern U. /CERN /Mainz U., Inst. Phys. /Wayne State U. /Valencia U., IFIC /CERN /Kentucky U. /Oxford U. /Iowa State U. /Bristol U. /INFN, Rome /Rutherford /CERN /Orsay, LAL /Glasgow U. /INFN, Padua /Queen Mary, U. of London /Texas U. /LPHE, Lausanne /Fermilab /UC, Santa Cruz /Vienna, OAW /Cincinnati U. /Frascati /Orsay, LAL /Ohio State U. /Purdue U. /Novosibirsk, IYF /Frascati /INFN, Rome /Padua U. /INFN, Rome /Bern U. /Karlsruhe U. /Brookhaven /CERN /Paris U., VI-VII /Zurich, ETH /Pisa U. /Frascati /Oxford U. /Orsay, LAL /INFN, Rome2 /INFN, Rome /INFN, Rome3 /Princeton U. /Fermilab /Queen' s U., Kingston /KEK, Tsukuba /Melbourne U. /Brookhaven /Indiana U. /INFN, Rome /Rome U. /Pisa U. /Mainz U., Inst. Phys. /Karlsruhe U. /Oxford U. /Cambridge U., DAMTP /Edinburgh U. /CERN

2010-08-26

In the past decade, one of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor. In this time frame, measurements and the theoretical interpretation of their results have advanced tremendously. A much broader understanding of flavor particles has been achieved, apart from their masses and quantum numbers, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. In the past, observations of CP violation were confined to neutral K mesons, but since the early 1990s, a large number of CP-violating processes have been studied in detail in neutral B mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of K,D, and B mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near future, there will be a transition from the current to a new generation of experiments, thus a review of the status of quark flavor physics is timely. This report is the result of the work of the physicists attending the 5th CKM workshop, hosted by the University of Rome 'La Sapienza', September 9-13, 2008. It summarizes the results of the current generation of experiments that is about to be completed and it confronts these results with the theoretical understanding of the field which has greatly improved in the past decade.

Masses of light quarks in quantum chromodynamics

Energy Technology Data Exchange (ETDEWEB)

Hubschmid, W; Mallik, S [Bern Univ. (Switzerland). Inst. fuer Theoretische Physik

1982-12-28

We try to determine light quark masses by considering sum rules for the vacuum expectation value of the time-ordered correlation function of two divergences of the axial vector current. The evaluation is carried out at momenta high enough for the non-perturbative contributions to be negligible. We find that the average mass of the up and down quark at a momentum of 1 GeV lies between 3.3 and 7.9 MeV while that for the strange quark lies between 84 and 212 MeV. The ranges of values reflect predominantly the uncertainty in the absorptive part in the low energy region (approx. <= 1.7 GeV).

Determination of the top-quark mass from hadro-production of single top-quarks

International Nuclear Information System (INIS)

Alekhin, S.; Moch, S.; Thier, S.

2016-08-01

We present a new determination of the top-quark mass m_t based on the experimental data from the Tevatron and the LHC for single-top hadro-production. We use the inclusive cross sections of s- and t-channel top-quark production to extract m_t and to minimize the dependence on the strong coupling constant and the gluon distribution in the proton compared to the hadro-production of top-quark pairs. As part of our analysis we compute the next-to-next-to-leading order approximation for the s-channel cross section in perturbative QCD based on the known soft-gluon corrections and implement it in the program HatHor for the numerical evaluation of the hadronic cross section. Results for the top-quark mass are reported in the MS and in the on-shell renormalization scheme.

D OE top quark mass analysis

International Nuclear Information System (INIS)

Strovink, M.

1995-07-01

Based on (44-48 pb -1 ) of lepton + jets data, we review D0's initial analysis of the top quark mass. The result, M top = 199 ± 19/21 (stat.) ± 22 (syst.) GeV/c 2 , is insensitive to background normalization. The errors are based on ISAJET top Monte Carlo, with its more severe gluon radiation, and allow for ISAJET/HERWIG differences. Good progress is being made in reducing the systematic error. We present a new study based on two-dimensional distributions of reconstructed top quark vs. dijet mass. With 98.7% confidence we observe a peak in the top mass - dijet mass plane. The peak and its projections are similar both in shape and magnitude to expectations based on the decay sequence 1 → bW, W → jj

Recent CMS measurements of the top quark mass

CERN Multimedia

CERN. Geneva

2014-01-01

The top quark is the heaviest known particle, and the only colored one that decays before hadronization. Its mass is a fundamental parameter of the standard model. Precision measurements of the top-quark mass can be used to test the self-consistency of the standard model and, at the same time, to study effects of non-perturbative QCD. CMS recently completed the set of standard top quark mass measurements at 8 TeV in all three decay channels, reaching sub-GeV uncertainty for the first time in a single analysis and combining to the most precise single-experiment measurement. With the steady increase in experimental precision comes a theoretical challenge of interpreting the results and the motivation of using alternative methods. In this talk we present the CMS set of analyses using the 8 TeV dataset, both with conventional methods and non-standard techniques targeting different definitions of the top quark mass. Furthermore we give an outlook at expected future improvements in both standard and alternative app...

On the gauge (in)dependence of the dynamical quark mass

International Nuclear Information System (INIS)

Reinders, L.J.; Stam, K.

1987-04-01

We compute the contribution of the mixed quark-gluon condensate to the quark self-energy to all orders in the dynamical quark mass. We investigate the consistency of different expansion schemes. It is found that nonabelian interactions form an obstruction to defining a true dynamical gauge independent mass shell. (orig.)

Results on top-quark physics and top-quark-like signatures by CMS

Science.gov (United States)

Chabert, Eric; CMS Collaboration

2017-07-01

This report reviews the results obtained by the CMS Collaboration on top quark physics, focusing on the latest ones based on p-p collisions provided by the LHC at \\sqrt{s}=13{{TeV}} during Run II. It covers measurements of single-top, top quark pairs and associated productions as well as measurements of top quark properties. Finally several beyond the standard model searches involving top quark in the final states are presented, such as searches for supersymmetry in the third generation, heavy resonances decaying into a top quark pair, or dark matter produced in association to a single-top or a top quark pair.

Precision Determination of the Top Quark Mass

Energy Technology Data Exchange (ETDEWEB)

Movilla Fernandez, Pedro A.; /LBL, Berkeley

2007-05-01

The CDF and D0 collaborations have updated their measurements of the mass of the top quark using proton-antiproton collisions at {radical}s = 1.96 TeV produced at the Tevatron. The uncertainties in each of the top-antitop decay channels have been reduced. The new Tevatron average for the mass of the top quark based on about 1 fb{sup -1} of data per experiment is 170.9 {+-} 1.8 GeV/c{sup 2}.

Asymptotic behavior of quark masses induced by instantons

International Nuclear Information System (INIS)

Carneiro, C.E.I.; Frenkel, J.

1984-02-01

A simple argument which shows that the dynamical mass induced by interactions of massless quarks with pseudo-particle configurations, behaves like p -6 for asymptotically large quark momenta is presented. (Author) [pt

Quark masses, isospin breaking and the vector piece of pi --> enugamma

CERN Document Server

Bernabeu, J; Ynduráin, F

1978-01-01

The authors discuss a direct way to detect isospin breaking generated by the current quark mass matrix. With PCAC the vector form factor of pi to e nu gamma can be described by a pure current process. In the chiral symmetry limit they prove, to all orders in QCD, that xi =m/sub d//m/sub u/ zero or infinity induces a 50% isospin breaking in the physical amplitude. Detailed effects, as function of xi , are calculated from the quark triangle diagram. Experiments to look for this possible departure from isospin invariance are feasible. (15 refs).

Top quark mass measurement in the dilepton electron-muon channel with the matrix element method in the ATLAS experiment at LHC

International Nuclear Information System (INIS)

Demilly, A.

2014-01-01

The LHC produced proton-proton collisions data at 7 TeV of center of mass energy in 2011 and 8 TeV in 2012, corresponding to an integrated luminosity of, respectively, 5 fb"-"1 and 23 fb"-"1. Data acquired by ATLAS have led to a better understanding of the detector and its performance, to many measurements of physical quantities and the discovery of the Higgs boson. Top quark is involved in many processes beyond the Standard Model. Its mass is an important parameter for the Standard Model and any New Physics theory, thus measuring its mass accurately is necessary. After a description of the Standard Model of Particle Physics, and the role of the top quark in it, the first half of this thesis describes the ATLAS detector and its electromagnetic calorimeter, for which a study of the calibration constant patching is detailed. The second half details top quark physics events detected in ATLAS and their selection. Theoretical aspects of the matrix element method and its implementation for the top quark mass measurement in the dilepton electron-muon channel in the experimental framework of ATLAS are discussed. The measurement calibration and optimisation studies for the analysis are presented. Finally, systematic uncertainties are described and estimated. This measurement yields a top quark mass of (173.65 ± 0.70 ± 2.36) GeV ; showing no discrepancy with current worldwide measurements. (author)

Quark mass relations to four-loop order in perturbative QCD.

Science.gov (United States)

Marquard, Peter; Smirnov, Alexander V; Smirnov, Vladimir A; Steinhauser, Matthias

2015-04-10

We present results for the relation between a heavy quark mass defined in the on-shell and minimal subtraction (MS[over ¯]) scheme to four-loop order. The method to compute the four-loop on-shell integral is briefly described and the new results are used to establish relations between various short-distance masses and the MS[over ¯] quark mass to next-to-next-to-next-to-leading order accuracy. These relations play an important role in the accurate determination of the MS[over ¯] heavy quark masses.

An algebraic model for quark mass matrices with heavy top

International Nuclear Information System (INIS)

Krolikowski, W.; Warsaw Univ.

1991-01-01

In terms of an intergeneration U(3) algebra, a numerical model is constructed for quark mass matrices, predicting the top-quark mass around 170 GeV and the CP-violating phase around 75 deg. The CKM matrix is nonsymmetric in moduli with |V ub | being very small. All moduli are consistent with their experimental limits. The model is motivated by the author's previous work on three replicas of the Dirac particle, presumably resulting into three generations of leptons and quarks. The paper may be also viewed as an introduction to a new method of intrinsic dynamical description of lepton and quark mass matrices. (author)

Measurement of the top quark mass using single top quark events in proton-proton collisions at $\\sqrt{s}= $ 8 TeV

CERN Document Server

Sirunyan, Albert M; Adam, Wolfgang; Aşılar, Ece; Bergauer, Thomas; Brandstetter, Johannes; Brondolin, Erica; Dragicevic, Marko; Erö, Janos; Flechl, Martin; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Hartl, Christian; Hörmann, Natascha; Hrubec, Josef; Jeitler, Manfred; König, Axel; Krätschmer, Ilse; Liko, Dietrich; Matsushita, Takashi; Mikulec, Ivan; Rabady, Dinyar; Rad, Navid; Rahbaran, Babak; Rohringer, Herbert; Schieck, Jochen; Strauss, Josef; Waltenberger, Wolfgang; Wulz, Claudia-Elisabeth; Dvornikov, Oleg; Makarenko, Vladimir; Mossolov, Vladimir; Suarez Gonzalez, Juan; Zykunov, Vladimir; Shumeiko, Nikolai; Alderweireldt, Sara; De Wolf, Eddi A; Janssen, Xavier; Lauwers, Jasper; Van De Klundert, Merijn; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Van Spilbeeck, Alex; Abu Zeid, Shimaa; Blekman, Freya; D'Hondt, Jorgen; Daci, Nadir; De Bruyn, Isabelle; Deroover, Kevin; Lowette, Steven; Moortgat, Seth; Moreels, Lieselotte; Olbrechts, Annik; Python, Quentin; Skovpen, Kirill; Tavernier, Stefaan; Van Doninck, Walter; Van Mulders, Petra; Van Parijs, Isis; Brun, Hugues; Clerbaux, Barbara; De Lentdecker, Gilles; Delannoy, Hugo; Fasanella, Giuseppe; Favart, Laurent; Goldouzian, Reza; Grebenyuk, Anastasia; Karapostoli, Georgia; Lenzi, Thomas; Léonard, Alexandre; Luetic, Jelena; Maerschalk, Thierry; Marinov, Andrey; Randle-conde, Aidan; Seva, Tomislav; Vander Velde, Catherine; Vanlaer, Pascal; Vannerom, David; Yonamine, Ryo; Zenoni, Florian; Zhang, Fengwangdong; Cimmino, Anna; Cornelis, Tom; Dobur, Didar; Fagot, Alexis; Gul, Muhammad; Khvastunov, Illia; Poyraz, Deniz; Salva Diblen, Sinem; Schöfbeck, Robert; Tytgat, Michael; Van Driessche, Ward; Yazgan, Efe; Zaganidis, Nicolas; Bakhshiansohi, Hamed; Beluffi, Camille; Bondu, Olivier; Brochet, Sébastien; Bruno, Giacomo; Caudron, Adrien; De Visscher, Simon; Delaere, Christophe; Delcourt, Martin; Francois, Brieuc; Giammanco, Andrea; Jafari, Abideh; Komm, Matthias; Krintiras, Georgios; Lemaitre, Vincent; Magitteri, Alessio; Mertens, Alexandre; Musich, Marco; Piotrzkowski, Krzysztof; Quertenmont, Loic; Selvaggi, Michele; Vidal Marono, Miguel; Wertz, Sébastien; Beliy, Nikita; Aldá Júnior, Walter Luiz; Alves, Fábio Lúcio; Alves, Gilvan; Brito, Lucas; Hensel, Carsten; Moraes, Arthur; Pol, Maria Elena; Rebello Teles, Patricia; Belchior Batista Das Chagas, Ewerton; Carvalho, Wagner; Chinellato, Jose; Custódio, Analu; Melo Da Costa, Eliza; Da Silveira, Gustavo Gil; De Jesus Damiao, Dilson; De Oliveira Martins, Carley; Fonseca De Souza, Sandro; Huertas Guativa, Lina Milena; Malbouisson, Helena; Matos Figueiredo, Diego; Mora Herrera, Clemencia; Mundim, Luiz; Nogima, Helio; Prado Da Silva, Wanda Lucia; Santoro, Alberto; Sznajder, Andre; Tonelli Manganote, Edmilson José; Torres Da Silva De Araujo, Felipe; Vilela Pereira, Antonio; Ahuja, Sudha; Bernardes, Cesar Augusto; Dogra, Sunil; Tomei, Thiago; De Moraes Gregores, Eduardo; Mercadante, Pedro G; Moon, Chang-Seong; Novaes, Sergio F; Padula, Sandra; Romero Abad, David; Ruiz Vargas, José Cupertino; Aleksandrov, Aleksandar; Hadjiiska, Roumyana; Iaydjiev, Plamen; Rodozov, Mircho; Stoykova, Stefka; Sultanov, Georgi; Vutova, Mariana; Dimitrov, Anton; Glushkov, Ivan; Litov, Leander; Pavlov, Borislav; Petkov, Peicho; Fang, Wenxing; Ahmad, Muhammad; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Chen, Mingshui; Chen, Ye; Cheng, Tongguang; Jiang, Chun-Hua; Leggat, Duncan; Liu, Zhenan; Romeo, Francesco; Ruan, Manqi; Shaheen, Sarmad Masood; Spiezia, Aniello; Tao, Junquan; Wang, Chunjie; Wang, Zheng; Zhang, Huaqiao; Zhao, Jingzhou; Ban, Yong; Chen, Geng; Li, Qiang; Liu, Shuai; Mao, Yajun; Qian, Si-Jin; Wang, Dayong; Xu, Zijun; Avila, Carlos; Cabrera, Andrés; Chaparro Sierra, Luisa Fernanda; Florez, Carlos; Gomez, Juan Pablo; González Hernández, Carlos Felipe; Ruiz Alvarez, José David; Sanabria, Juan Carlos; Godinovic, Nikola; Lelas, Damir; Puljak, Ivica; Ribeiro Cipriano, Pedro M; Sculac, Toni; Antunovic, Zeljko; Kovac, Marko; Brigljevic, Vuko; Ferencek, Dinko; Kadija, Kreso; Mesic, Benjamin; Susa, Tatjana; Attikis, Alexandros; Mavromanolakis, Georgios; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Rykaczewski, Hans; Tsiakkouri, Demetra; Finger, Miroslav; Finger Jr, Michael; Carrera Jarrin, Edgar; El-khateeb, Esraa; Elgammal, Sherif; Mohamed, Amr; Kadastik, Mario; Perrini, Lucia; Raidal, Martti; Tiko, Andres; Veelken, Christian; Eerola, Paula; Pekkanen, Juska; Voutilainen, Mikko; Härkönen, Jaakko; Jarvinen, Terhi; Karimäki, Veikko; Kinnunen, Ritva; Lampén, Tapio; Lassila-Perini, Kati; Lehti, Sami; Lindén, Tomas; Luukka, Panja-Riina; Tuominiemi, Jorma; Tuovinen, Esa; Wendland, Lauri; Talvitie, Joonas; Tuuva, Tuure; Besancon, Marc; Couderc, Fabrice; Dejardin, Marc; Denegri, Daniel; Fabbro, Bernard; Faure, Jean-Louis; Favaro, Carlotta; Ferri, Federico; Ganjour, Serguei; Ghosh, Saranya; Givernaud, Alain; Gras, Philippe; Hamel de Monchenault, Gautier; Jarry, Patrick; Kucher, Inna; Locci, Elizabeth; Machet, Martina; Malcles, Julie; Rander, John; Rosowsky, André; Titov, Maksym; Abdulsalam, Abdulla; Antropov, Iurii; Baffioni, Stephanie; Beaudette, Florian; Busson, Philippe; Cadamuro, Luca; Chapon, Emilien; Charlot, Claude; Davignon, Olivier; Granier de Cassagnac, Raphael; Jo, Mihee; Lisniak, Stanislav; Miné, Philippe; Nguyen, Matthew; Ochando, Christophe; Ortona, Giacomo; Paganini, Pascal; Pigard, Philipp; Regnard, Simon; Salerno, Roberto; Sirois, Yves; Stahl Leiton, Andre Govinda; Strebler, Thomas; Yilmaz, Yetkin; Zabi, Alexandre; Zghiche, Amina; Agram, Jean-Laurent; Andrea, Jeremy; Aubin, Alexandre; Bloch, Daniel; Brom, Jean-Marie; Buttignol, Michael; Chabert, Eric Christian; Chanon, Nicolas; Collard, Caroline; Conte, Eric; Coubez, Xavier; Fontaine, Jean-Charles; Gelé, Denis; Goerlach, Ulrich; Le Bihan, Anne-Catherine; Van Hove, Pierre; Gadrat, Sébastien; Beauceron, Stephanie; Bernet, Colin; Boudoul, Gaelle; Carrillo Montoya, Camilo Andres; Chierici, Roberto; Contardo, Didier; Courbon, Benoit; Depasse, Pierre; El Mamouni, Houmani; Fay, Jean; Gascon, Susan; Gouzevitch, Maxime; Grenier, Gérald; Ille, Bernard; Lagarde, Francois; Laktineh, Imad Baptiste; Lethuillier, Morgan; Mirabito, Laurent; Pequegnot, Anne-Laure; Perries, Stephane; Popov, Andrey; Sabes, David; Sordini, Viola; Vander Donckt, Muriel; Verdier, Patrice; Viret, Sébastien; Khvedelidze, Arsen; Tsamalaidze, Zviad; Autermann, Christian; Beranek, Sarah; Feld, Lutz; Kiesel, Maximilian Knut; Klein, Katja; Lipinski, Martin; Preuten, Marius; Schomakers, Christian; Schulz, Johannes; Verlage, Tobias; Albert, Andreas; Brodski, Michael; Dietz-Laursonn, Erik; Duchardt, Deborah; Endres, Matthias; Erdmann, Martin; Erdweg, Sören; Esch, Thomas; Fischer, Robert; Güth, Andreas; Hamer, Matthias; Hebbeker, Thomas; Heidemann, Carsten; Hoepfner, Kerstin; Knutzen, Simon; Merschmeyer, Markus; Meyer, Arnd; Millet, Philipp; Mukherjee, Swagata; Olschewski, Mark; Padeken, Klaas; Pook, Tobias; Radziej, Markus; Reithler, Hans; Rieger, Marcel; Scheuch, Florian; Sonnenschein, Lars; Teyssier, Daniel; Thüer, Sebastian; Cherepanov, Vladimir; Flügge, Günter; Kargoll, Bastian; Kress, Thomas; Künsken, Andreas; Lingemann, Joschka; Müller, Thomas; Nehrkorn, Alexander; Nowack, Andreas; Pistone, Claudia; Pooth, Oliver; Stahl, Achim; Aldaya Martin, Maria; Arndt, Till; Asawatangtrakuldee, Chayanit; Beernaert, Kelly; Behnke, Olaf; Behrens, Ulf; Bin Anuar, Afiq Aizuddin; Borras, Kerstin; Campbell, Alan; Connor, Patrick; Contreras-Campana, Christian; Costanza, Francesco; Diez Pardos, Carmen; Dolinska, Ganna; Eckerlin, Guenter; Eckstein, Doris; Eichhorn, Thomas; Eren, Engin; Gallo, Elisabetta; Garay Garcia, Jasone; Geiser, Achim; Gizhko, Andrii; Grados Luyando, Juan Manuel; Grohsjean, Alexander; Gunnellini, Paolo; Harb, Ali; Hauk, Johannes; Hempel, Maria; Jung, Hannes; Kalogeropoulos, Alexis; Karacheban, Olena; Kasemann, Matthias; Keaveney, James; Kleinwort, Claus; Korol, Ievgen; Krücker, Dirk; Lange, Wolfgang; Lelek, Aleksandra; Lenz, Teresa; Leonard, Jessica; Lipka, Katerina; Lobanov, Artur; Lohmann, Wolfgang; Mankel, Rainer; Melzer-Pellmann, Isabell-Alissandra; Meyer, Andreas Bernhard; Mittag, Gregor; Mnich, Joachim; Mussgiller, Andreas; Pitzl, Daniel; Placakyte, Ringaile; Raspereza, Alexei; Roland, Benoit; Sahin, Mehmet Özgür; Saxena, Pooja; Schoerner-Sadenius, Thomas; Spannagel, Simon; Stefaniuk, Nazar; Van Onsem, Gerrit Patrick; Walsh, Roberval; Wissing, Christoph; Blobel, Volker; Centis Vignali, Matteo; Draeger, Arne-Rasmus; Dreyer, Torben; Garutti, Erika; Gonzalez, Daniel; Haller, Johannes; Hoffmann, Malte; Junkes, Alexandra; Klanner, Robert; Kogler, Roman; Kovalchuk, Nataliia; Lapsien, Tobias; Marchesini, Ivan; Marconi, Daniele; Meyer, Mareike; Niedziela, Marek; Nowatschin, Dominik; Pantaleo, Felice; Peiffer, Thomas; Perieanu, Adrian; Scharf, Christian; Schleper, Peter; Schmidt, Alexander; Schumann, Svenja; Schwandt, Joern; Stadie, Hartmut; Steinbrück, Georg; Stober, Fred-Markus Helmut; Stöver, Marc; Tholen, Heiner; Troendle, Daniel; Usai, Emanuele; Vanelderen, Lukas; Vanhoefer, Annika; Vormwald, Benedikt; Akbiyik, Melike; Barth, Christian; Baur, Sebastian; Baus, Colin; Berger, Joram; Butz, Erik; Caspart, René; Chwalek, Thorsten; Colombo, Fabio; De Boer, Wim; Dierlamm, Alexander; Fink, Simon; Freund, Benedikt; Friese, Raphael; Giffels, Manuel; Gilbert, Andrew; Goldenzweig, Pablo; Haitz, Dominik; Hartmann, Frank; Heindl, Stefan Michael; Husemann, Ulrich; Katkov, Igor; Kudella, Simon; Mildner, Hannes; Mozer, Matthias Ulrich; Müller, Thomas; Plagge, Michael; Quast, Gunter; Rabbertz, Klaus; Röcker, Steffen; Roscher, Frank; Schröder, Matthias; Shvetsov, Ivan; Sieber, Georg; Simonis, Hans-Jürgen; Ulrich, Ralf; Wayand, Stefan; Weber, Marc; Weiler, Thomas; Williamson, Shawn; Wöhrmann, Clemens; Wolf, Roger; Anagnostou, Georgios; Daskalakis, Georgios; Geralis, Theodoros; Giakoumopoulou, Viktoria Athina; Kyriakis, Aristotelis; Loukas, Demetrios; Topsis-Giotis, Iasonas; Kesisoglou, Stilianos; Panagiotou, Apostolos; Saoulidou, Niki; Tziaferi, Eirini; Evangelou, Ioannis; Flouris, Giannis; Foudas, Costas; Kokkas, Panagiotis; Loukas, Nikitas; Manthos, Nikolaos; Papadopoulos, Ioannis; Paradas, Evangelos; Filipovic, Nicolas; Pasztor, Gabriella; Bencze, Gyorgy; Hajdu, Csaba; Horvath, Dezso; Sikler, Ferenc; Veszpremi, Viktor; Vesztergombi, Gyorgy; Zsigmond, Anna Julia; Beni, Noemi; Czellar, Sandor; Karancsi, János; Makovec, Alajos; Molnar, Jozsef; Szillasi, Zoltan; Bartók, Márton; Raics, Peter; Trocsanyi, Zoltan Laszlo; Ujvari, Balazs; Komaragiri, Jyothsna Rani; Bahinipati, Seema; Bhowmik, Sandeep; Choudhury, Somnath; Mal, Prolay; Mandal, Koushik; Nayak, Aruna; Sahoo, Deepak Kumar; Sahoo, Niladribihari; Swain, Sanjay Kumar; Bansal, Sunil; Beri, Suman Bala; Bhatnagar, Vipin; Chawla, Ridhi; Bhawandeep, Bhawandeep; Kalsi, Amandeep Kaur; Kaur, Anterpreet; Kaur, Manjit; Kumar, Ramandeep; Kumari, Priyanka; Mehta, Ankita; Mittal, Monika; Singh, Jasbir; Walia, Genius; Kumar, Ashok; Bhardwaj, Ashutosh; Choudhary, Brajesh C; Garg, Rocky Bala; Keshri, Sumit; Malhotra, Shivali; Naimuddin, Md; Ranjan, Kirti; Sharma, Ramkrishna; Sharma, Varun; Bhattacharya, Rajarshi; Bhattacharya, Satyaki; Chatterjee, Kalyanmoy; Dey, Sourav; Dutt, Suneel; Dutta, Suchandra; Ghosh, Shamik; Majumdar, Nayana; Modak, Atanu; Mondal, Kuntal; Mukhopadhyay, Supratik; Nandan, Saswati; Purohit, Arnab; Roy, Ashim; Roy, Debarati; Roy Chowdhury, Suvankar; Sarkar, Subir; Sharan, Manoj; Thakur, Shalini; Behera, Prafulla Kumar; Chudasama, Ruchi; Dutta, Dipanwita; Jha, Vishwajeet; Kumar, Vineet; Mohanty, Ajit Kumar; Netrakanti, Pawan Kumar; Pant, Lalit Mohan; Shukla, Prashant; Topkar, Anita; Aziz, Tariq; Dugad, Shashikant; Kole, Gouranga; Mahakud, Bibhuprasad; Mitra, Soureek; Mohanty, Gagan Bihari; Parida, Bibhuti; Sur, Nairit; Sutar, Bajrang; Banerjee, Sudeshna; Dewanjee, Ram Krishna; Ganguly, Sanmay; Guchait, Monoranjan; Jain, Sandhya; Kumar, Sanjeev; Maity, Manas; Majumder, Gobinda; Mazumdar, Kajari; Sarkar, Tanmay; Wickramage, Nadeesha; Chauhan, Shubhanshu; Dube, Sourabh; Hegde, Vinay; Kapoor, Anshul; Kothekar, Kunal; Pandey, Shubham; Rane, Aditee; Sharma, Seema; Chenarani, Shirin; Eskandari Tadavani, Esmaeel; Etesami, Seyed Mohsen; Khakzad, Mohsen; Mohammadi Najafabadi, Mojtaba; Naseri, Mohsen; Paktinat Mehdiabadi, Saeid; Rezaei Hosseinabadi, Ferdos; Safarzadeh, Batool; Zeinali, Maryam; Felcini, Marta; Grunewald, Martin; Abbrescia, Marcello; Calabria, Cesare; Caputo, Claudio; Colaleo, Anna; Creanza, Donato; Cristella, Leonardo; De Filippis, Nicola; De Palma, Mauro; Fiore, Luigi; Iaselli, Giuseppe; Maggi, Giorgio; Maggi, Marcello; Miniello, Giorgia; My, Salvatore; Nuzzo, Salvatore; Pompili, Alexis; Pugliese, Gabriella; Radogna, Raffaella; Ranieri, Antonio; Selvaggi, Giovanna; Sharma, Archana; Silvestris, Lucia; Venditti, Rosamaria; Verwilligen, Piet; Abbiendi, Giovanni; Battilana, Carlo; Bonacorsi, Daniele; Braibant-Giacomelli, Sylvie; Brigliadori, Luca; Campanini, Renato; Capiluppi, Paolo; Castro, Andrea; Cavallo, Francesca Romana; Chhibra, Simranjit Singh; Codispoti, Giuseppe; Cuffiani, Marco; Dallavalle, Gaetano-Marco; Fabbri, Fabrizio; Fanfani, Alessandra; Fasanella, Daniele; Giacomelli, Paolo; Grandi, Claudio; Guiducci, Luigi; Marcellini, Stefano; Masetti, Gianni; Montanari, Alessandro; Navarria, Francesco; Perrotta, Andrea; Rossi, Antonio; Rovelli, Tiziano; Siroli, Gian Piero; Tosi, Nicolò; Albergo, Sebastiano; Costa, Salvatore; Di Mattia, Alessandro; Giordano, Ferdinando; Potenza, Renato; Tricomi, Alessia; Tuve, Cristina; Barbagli, Giuseppe; Ciulli, Vitaliano; Civinini, Carlo; D'Alessandro, Raffaello; Focardi, Ettore; Lenzi, Piergiulio; Meschini, Marco; Paoletti, Simone; Russo, Lorenzo; Sguazzoni, Giacomo; Strom, Derek; Viliani, Lorenzo; Benussi, Luigi; Bianco, Stefano; Fabbri, Franco; Piccolo, Davide; Primavera, Federica; Calvelli, Valerio; Ferro, Fabrizio; Monge, Maria Roberta; Robutti, Enrico; Tosi, Silvano; Brianza, Luca; Brivio, Francesco; Ciriolo, Vincenzo; Dinardo, Mauro Emanuele; Fiorendi, Sara; Gennai, Simone; Ghezzi, Alessio; Govoni, Pietro; Malberti, Martina; Malvezzi, Sandra; Manzoni, Riccardo Andrea; Menasce, Dario; Moroni, Luigi; Paganoni, Marco; Pedrini, Daniele; Pigazzini, Simone; Ragazzi, Stefano; Tabarelli de Fatis, Tommaso; Buontempo, Salvatore; Cavallo, Nicola; De Nardo, Guglielmo; Di Guida, Salvatore; Esposito, Marco; Fabozzi, Francesco; Fienga, Francesco; Iorio, Alberto Orso Maria; Lanza, Giuseppe; Lista, Luca; Meola, Sabino; Paolucci, Pierluigi; Sciacca, Crisostomo; Thyssen, Filip; Azzi, Patrizia; Bacchetta, Nicola; Benato, Lisa; Bisello, Dario; Boletti, Alessio; Carlin, Roberto; Carvalho Antunes De Oliveira, Alexandra; Checchia, Paolo; Dall'Osso, Martino; De Castro Manzano, Pablo; Dorigo, Tommaso; Dosselli, Umberto; Gasparini, Fabrizio; Gasparini, Ugo; Gozzelino, Andrea; Lacaprara, Stefano; Margoni, Martino; Meneguzzo, Anna Teresa; Pazzini, Jacopo; Pozzobon, Nicola; Ronchese, Paolo; Simonetto, Franco; Torassa, Ezio; Zanetti, Marco; Zotto, Pierluigi; Zumerle, Gianni; Braghieri, Alessandro; Fallavollita, Francesco; Magnani, Alice; Montagna, Paolo; Ratti, Sergio P; Re, Valerio; Riccardi, Cristina; Salvini, Paola; Vai, Ilaria; Vitulo, Paolo; Alunni Solestizi, Luisa; Bilei, Gian Mario; Ciangottini, Diego; Fanò, Livio; Lariccia, Paolo; Leonardi, Roberto; Mantovani, Giancarlo; Menichelli, Mauro; Saha, Anirban; Santocchia, Attilio; Androsov, Konstantin; Azzurri, Paolo; Bagliesi, Giuseppe; Bernardini, Jacopo; Boccali, Tommaso; Castaldi, Rino; Ciocci, Maria Agnese; Dell'Orso, Roberto; Donato, Silvio; Fedi, Giacomo; Giassi, Alessandro; Grippo, Maria Teresa; Ligabue, Franco; Lomtadze, Teimuraz; Martini, Luca; Messineo, Alberto; Palla, Fabrizio; Rizzi, Andrea; Savoy-Navarro, Aurore; Spagnolo, Paolo; Tenchini, Roberto; Tonelli, Guido; Venturi, Andrea; Verdini, Piero Giorgio; Barone, Luciano; Cavallari, Francesca; Cipriani, Marco; Del Re, Daniele; Diemoz, Marcella; Gelli, Simone; Longo, Egidio; Margaroli, Fabrizio; Marzocchi, Badder; Meridiani, Paolo; Organtini, Giovanni; Paramatti, Riccardo; Preiato, Federico; Rahatlou, Shahram; Rovelli, Chiara; Santanastasio, Francesco; Amapane, Nicola; Arcidiacono, Roberta; Argiro, Stefano; Arneodo, Michele; Bartosik, Nazar; Bellan, Riccardo; Biino, Cristina; Cartiglia, Nicolo; Cenna, Francesca; Costa, Marco; Covarelli, Roberto; Degano, Alessandro; Demaria, Natale; Finco, Linda; Kiani, Bilal; Mariotti, Chiara; Maselli, Silvia; Migliore, Ernesto; Monaco, Vincenzo; Monteil, Ennio; Monteno, Marco; Obertino, Maria Margherita; Pacher, Luca; Pastrone, Nadia; Pelliccioni, Mario; Pinna Angioni, Gian Luca; Ravera, Fabio; Romero, Alessandra; Ruspa, Marta; Sacchi, Roberto; Shchelina, Ksenia; Sola, Valentina; Solano, Ada; Staiano, Amedeo; Traczyk, Piotr; Belforte, Stefano; Casarsa, Massimo; Cossutti, Fabio; Della Ricca, Giuseppe; Zanetti, Anna; Kim, Dong Hee; Kim, Gui Nyun; Kim, Min Suk; Lee, Sangeun; Lee, Seh Wook; Oh, Young Do; Sekmen, Sezen; Son, Dong-Chul; Yang, Yu Chul; Lee, Ari; Kim, Hyunchul; Brochero Cifuentes, Javier Andres; Kim, Tae Jeong; Cho, Sungwoong; Choi, Suyong; Go, Yeonju; Gyun, Dooyeon; Ha, Seungkyu; Hong, Byung-Sik; Jo, Youngkwon; Kim, Yongsun; Lee, Kisoo; Lee, Kyong Sei; Lee, Songkyo; Lim, Jaehoon; Park, Sung Keun; Roh, Youn; Almond, John; Kim, Junho; Lee, Haneol; Oh, Sung Bin; Radburn-Smith, Benjamin Charles; Seo, Seon-hee; Yang, Unki; Yoo, Hwi Dong; Yu, Geum Bong; Choi, Minkyoo; Kim, Hyunyong; Kim, Ji Hyun; Lee, Jason Sang Hun; Park, Inkyu; Ryu, Geonmo; Ryu, Min Sang; Choi, Young-Il; Goh, Junghwan; Hwang, Chanwook; Lee, Jongseok; Yu, Intae; Dudenas, Vytautas; Juodagalvis, Andrius; Vaitkus, Juozas; Ahmed, Ijaz; Ibrahim, Zainol Abidin; Md Ali, Mohd Adli Bin; Mohamad Idris, Faridah; Wan Abdullah, Wan Ahmad Tajuddin; Yusli, Mohd Nizam; Zolkapli, Zukhaimira; Castilla-Valdez, Heriberto; De La Cruz-Burelo, Eduard; Heredia-De La Cruz, Ivan; Hernandez-Almada, Alberto; Lopez-Fernandez, Ricardo; Magaña Villalba, Ricardo; Mejia Guisao, Jhovanny; Sánchez Hernández, Alberto; Carrillo Moreno, Salvador; Oropeza Barrera, Cristina; Vazquez Valencia, Fabiola; Carpinteyro, Severiano; Pedraza, Isabel; Salazar Ibarguen, Humberto Antonio; Uribe Estrada, Cecilia; Morelos Pineda, Antonio; Krofcheck, David; Butler, Philip H; Ahmad, Ashfaq; Ahmad, Muhammad; Hassan, Qamar; Hoorani, Hafeez R; Khan, Wajid Ali; Saddique, Asif; Shah, Mehar Ali; Shoaib, Muhammad; Waqas, Muhammad; Bialkowska, Helena; Bluj, Michal; Boimska, Bożena; Frueboes, Tomasz; Górski, Maciej; Kazana, Malgorzata; Nawrocki, Krzysztof; Romanowska-Rybinska, Katarzyna; Szleper, Michal; Zalewski, Piotr; Bunkowski, Karol; Byszuk, Adrian; Doroba, Krzysztof; Kalinowski, Artur; Konecki, Marcin; Krolikowski, Jan; Misiura, Maciej; Olszewski, Michal; Walczak, Marek; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Calpas, Betty; Di Francesco, Agostino; Faccioli, Pietro; Ferreira Parracho, Pedro Guilherme; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Nemallapudi, Mythra Varun; Rodrigues Antunes, Joao; Seixas, Joao; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Afanasiev, Serguei; Bunin, Pavel; Gavrilenko, Mikhail; Golutvin, Igor; Gorbunov, Ilya; Kamenev, Alexey; Karjavin, Vladimir; Lanev, Alexander; Malakhov, Alexander; Matveev, Viktor; Palichik, Vladimir; Perelygin, Victor; Shmatov, Sergey; Shulha, Siarhei; Skatchkov, Nikolai; Smirnov, Vitaly; Voytishin, Nikolay; Zarubin, Anatoli; Chtchipounov, Leonid; Golovtsov, Victor; Ivanov, Yury; Kim, Victor; Kuznetsova, Ekaterina; Murzin, Victor; Oreshkin, Vadim; Sulimov, Valentin; Vorobyev, Alexey; Andreev, Yuri; Dermenev, Alexander; Gninenko, Sergei; Golubev, Nikolai; Karneyeu, Anton; Kirsanov, Mikhail; Krasnikov, Nikolai; Pashenkov, Anatoli; Tlisov, Danila; Toropin, Alexander; Epshteyn, Vladimir; Gavrilov, Vladimir; Lychkovskaya, Natalia; Popov, Vladimir; Pozdnyakov, Ivan; Safronov, Grigory; Spiridonov, Alexander; Toms, Maria; Vlasov, Evgueni; Zhokin, Alexander; Aushev, Tagir; Bylinkin, Alexander; Danilov, Mikhail; Popova, Elena; Rusinov, Vladimir; Andreev, Vladimir; Azarkin, Maksim; Dremin, Igor; Kirakosyan, Martin; Leonidov, Andrey; Terkulov, Adel; Baskakov, Alexey; Belyaev, Andrey; Boos, Edouard; Bunichev, Viacheslav; Dubinin, Mikhail; Dudko, Lev; Klyukhin, Vyacheslav; Kodolova, Olga; Korneeva, Natalia; Lokhtin, Igor; Miagkov, Igor; Obraztsov, Stepan; Perfilov, Maxim; Savrin, Viktor; Volkov, Petr; Blinov, Vladimir; Skovpen, Yuri; Shtol, Dmitry; Azhgirey, Igor; Bayshev, Igor; Bitioukov, Sergei; Elumakhov, Dmitry; Kachanov, Vassili; Kalinin, Alexey; Konstantinov, Dmitri; Krychkine, Victor; Petrov, Vladimir; Ryutin, Roman; Sobol, Andrei; Troshin, Sergey; Tyurin, Nikolay; Uzunian, Andrey; Volkov, Alexey; Adzic, Petar; Cirkovic, Predrag; Devetak, Damir; Dordevic, Milos; Milosevic, Jovan; Rekovic, Vladimir; Alcaraz Maestre, Juan; Barrio Luna, Mar; Calvo, Enrique; Cerrada, Marcos; Chamizo Llatas, Maria; Colino, Nicanor; De La Cruz, Begona; Delgado Peris, Antonio; Escalante Del Valle, Alberto; Fernandez Bedoya, Cristina; Fernández Ramos, Juan Pablo; Flix, Jose; Fouz, Maria Cruz; Garcia-Abia, Pablo; 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2017-05-29

A measurement of the top quark mass is reported in events containing a single top quark produced via the electroweak $t$ channel. The analysis is performed using data from proton-proton collisions collected with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb$^{-1}$. The top quark is reconstructed from its decay to a W boson and a b quark, with the W boson decaying leptonically to a muon and a neutrino. The specific topology and kinematic properties of single top quark events in the $t$ channel are used to enhance the purity of the sample, suppressing the contribution from top quark pair production. A fit to the invariant mass distribution of reconstructed top quark candidates yields a value of the top quark mass of 172.95 $\\pm$ 0.77 (stat) $^{+0.97}_{-0.93}$ (syst) GeV. This result is in agreement with the current world average, and represents the first measurement of the top quark mass in event topologies not dominated by top quark pair p...

Measurement of the top quark mass at D0

International Nuclear Information System (INIS)

Protopopescu, S.

1996-01-01

The mass of the top quark is measured using a sample of 93 lepton + 4 or more jets events collected with the D0 detector at the FNAL Tevatron collider. The authors find the top quark mass is 169 ± 8(stat.) ± 8(syst.) GeV/c 2 . The analysis assumes that top quarks are produced as t anti t pairs that decay to W bosons and b quarks. The final states result when one W decays to eν or μν and the other W to q anti q. More than four jets may be present because of final and initial state radiation

Theoretical origin of quark mass matrices

International Nuclear Information System (INIS)

Mohapatra, R.N.

1987-01-01

This paper presents the theoretical origin of specific quark mass matrices in the grand unified theories. The author discusses the first natural derivation of the Stech-type mass matrix in unified gauge theories. A solution to the strong CP-problem is provided

Vector-like quarks: t’ and partners

International Nuclear Information System (INIS)

PANIZZI, L.

2014-01-01

Vector-like quarks are predicted in various scenarios of new physics, and their peculiar signatures from both pair and single production have been already investigated in detail. However no signals of vector-like quarks have been detected so far, pushing limits on their masses above 600–700GeV, depending on assumptions on their couplings. Experimental searches consider specific final states to pose bounds on the mass of a vector-like quark, usually assuming it is the only particle that contributes to the signal of new physics in that specific final state. However, realistic scenarios predict the existence of multiple vector-like quarks, possibly with similar masses. The reinterpretation of mass bounds from experimental searches is therefore not always straightforward. In this analysis I briefly summarise the constraints on vector-like quarks and their possible signatures at the LHC, focusing in particular on a model-independent description of single production processes for vector-like quark that mix with all generations and on the development of a framework to study scenarios with multiple vector-like quarks.

Measurement of the top quark mass using single top quark events in proton-proton collisions at √(s) = 8 TeV

Energy Technology Data Exchange (ETDEWEB)

Sirunyan, A.M.; Tumasyan, A. [Yerevan Physics Institute, Yerevan (Armenia); Adam, W. [Institut fuer Hochenergiephysik, Vienna (Austria); Collaboration: CMS Collaboration; and others

2017-05-15

A measurement of the top quark mass is reported in events containing a single top quark produced via the electroweak t channel. The analysis is performed using data from proton-proton collisions collected with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb{sup -1}. Top quark candidates are reconstructed from their decay to a W boson decaying leptonically to a muon and a neutrino. The final state signature and kinematic properties of single top quark events in the t channel are used to enhance the purity of the sample, suppressing the contribution from top quark pair production. A fit to the invariant mass distribution of reconstructed top quark candidates yields a value of the top quark mass of 172.95 ± 0.77(stat){sup +0.97}{sub -0.93}(syst) GeV. This result is in agreement with the current world average, and represents the first measurement of the top quark mass in event topologies not dominated by top quark pair production, therefore contributing to future averages with partially uncorrelated systematic uncertainties and a largely uncorrelated statistical uncertainty. (orig.)

Disconnected quark loop contributions to nucleon observables using Nf=2 twisted clover fermions at the physical value of the light quark mass

International Nuclear Information System (INIS)

Abdel-Rehim, Abdou; Kallidonis, Christos; Koutsou, Giannis

2015-11-01

We compute the disconnected quark loops contributions entering the determination of nucleon observables, by using a N f =2 ensemble of twisted mass fermions with a clover term at a pion mass m π =133 MeV. We employ exact deflation and implement all calculations in GPUs, enabling us to achieve large statistics and a good signal.

Formulating weak CP-violation in terms of quark mass hierarchies

International Nuclear Information System (INIS)

Davidson, A.

1982-06-01

That physics which explains Cabibbo mixing is shown to also put a lower bound on Kobayashi-Maskawa CP-violation. The observed amount epsilon = 0.002 of CP-violation in the Ksub(L) - Ksub(S) system in turn sharply requires 25 GeV <= msub(t) <= 59 GeV; msub(t) being the top-quark mass. Assuming a vanishing weak (ala strong) CP-violation amplitude for msub(u) → 0, as strongly indicated by the data, epsilon is formulated as a second order quantity in the fermionic mass hierarchy. (author)

Quark nuclear physics at JHF

International Nuclear Information System (INIS)

Toki, H.

2000-01-01

We discuss the research fields to be studied by the Japan Hadron Facility being planned in the site of JAERI as a joint project with Neutron Science Project. We would expect to reveal the most microscopic structure of matter using the intensity frontier proton machine. In particular, we would like to develop Quark Nuclear Physics to describe hadrons and nuclei in terms of quarks and gluons. (author)

Jet calibration and top quark mass measurement in the semi-leptonic channel in the ATLAS experiment

International Nuclear Information System (INIS)

Balli, Fabrice

2014-01-01

The main goal of this thesis is to provide a measurement as accurate as possible of the top quark mass in the semi-leptonic decay channel. This experimental measurement is made thanks to the ATLAS detector near LHC, a proton-proton collider. The main interests for this precision measurement are the physics constraints to the theoretical models of fundamental constituents. Besides, the top quark mass is a parameter allowing to have more information on the vacuum stability at the Planck scale within the Standard Model. Jet energy calibration is crucial to this measurement. The impact of real data taking conditions on this calibration and on jet performance is detailed. The top quark mass measurement using 2011 data collected at an energy in the center-of-mass of 7 TeV is presented. It is using a tri dimensional template analysis method. The measured top quark mass is: m(top) = 172.01 ± 0.92 (stat) ± 1.17 (syst) GeV. The 2012 data collected at an energy in the center-of-mass of 8 TeV are also analysed, and a preliminary result for the top quark mass is provided: m(top) = 172.82 ± 0.39 (stat) ± 1.12 (syst) GeV, the combination of both measurements being the most accurate result of this thesis: m(top) = 172.64 ± 0.37 (stat) ± 1.10 (syst) GeV. (author) [fr

On the ultimate uncertainty of the top quark pole mass

Science.gov (United States)

Beneke, M.; Marquard, P.; Nason, P.; Steinhauser, M.

2017-12-01

We combine the known asymptotic behaviour of the QCD perturbation series expansion, which relates the pole mass of a heavy quark to the MS ‾ mass, with the exact series coefficients up to the four-loop order to determine the ultimate uncertainty of the top-quark pole mass due to the renormalon divergence. We perform extensive tests of our procedure by varying the number of colours and flavours, as well as the scale of the strong coupling and the MS ‾ mass. Including an estimate of the internal bottom and charm quark mass effect, we conclude that this uncertainty is around 110 MeV. We further estimate the additional contribution to the mass relation from the five-loop correction and beyond to be around 300 MeV.

Quark Physics without Quarks: A Review of Recent Developments in S-Matrix Theory.

Science.gov (United States)

Capra, Fritjof

1979-01-01

Reviews the developments in S-matrix theory over the past five years which have made it possible to derive results characteristic of quark models without any need to postulate the existence of physical quarks. In the new approach, the quark patterns emerge as a consequence of combining the general S-matrix principles with the concept of order.…

Measurement of the top quark mass using single top quark events in proton-proton collisions at [Formula: see text] TeV.

Science.gov (United States)

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Vilela Pereira, A; Ahuja, S; Bernardes, C A; Dogra, S; Fernandez Perez Tomei, T R; Gregores, E M; Mercadante, P G; Moon, C S; Novaes, S F; Padula, Sandra S; Romero Abad, D; Ruiz Vargas, J C; Aleksandrov, A; Hadjiiska, R; Iaydjiev, P; Rodozov, M; Stoykova, S; Sultanov, G; Vutova, M; Dimitrov, A; Glushkov, I; Litov, L; Pavlov, B; Petkov, P; Fang, W; Ahmad, M; Bian, J G; Chen, G M; Chen, H S; Chen, M; Chen, Y; Cheng, T; Jiang, C H; Leggat, D; Liu, Z; Romeo, F; Ruan, M; Shaheen, S M; Spiezia, A; Tao, J; Wang, C; Wang, Z; Zhang, H; Zhao, J; Ban, Y; Chen, G; Li, Q; Liu, S; Mao, Y; Qian, S J; Wang, D; Xu, Z; Avila, C; Cabrera, A; Chaparro Sierra, L F; Florez, C; Gomez, J P; González Hernández, C F; Ruiz Alvarez, J D; Sanabria, J C; Godinovic, N; Lelas, D; Puljak, I; Ribeiro Cipriano, P M; Sculac, T; Antunovic, Z; Kovac, M; Brigljevic, V; Ferencek, D; Kadija, K; Mesic, B; Susa, T; Attikis, A; Mavromanolakis, G; Mousa, J; Nicolaou, C; Ptochos, F; Razis, P A; Rykaczewski, H; Tsiakkouri, D; Finger, M; 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2017-01-01

A measurement of the top quark mass is reported in events containing a single top quark produced via the electroweak t channel. The analysis is performed using data from proton-proton collisions collected with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb[Formula: see text]. Top quark candidates are reconstructed from their decay to a [Formula: see text] boson and a b quark, with the [Formula: see text] boson decaying leptonically to a muon and a neutrino. The final state signature and kinematic properties of single top quark events in the t channel are used to enhance the purity of the sample, suppressing the contribution from top quark pair production. A fit to the invariant mass distribution of reconstructed top quark candidates yields a value of the top quark mass of [Formula: see text]. This result is in agreement with the current world average, and represents the first measurement of the top quark mass in event topologies not dominated by top quark pair production, therefore contributing to future averages with partially uncorrelated systematic uncertainties and a largely uncorrelated statistical uncertainty.

Charge asymmetries of top quarks: A window to new physics at hadron colliders

International Nuclear Information System (INIS)

Ferrario, Paola; Rodrigo, German

2009-01-01

With the next start of LHC, a huge production of top quarks is expected. There are several models that predict the existence of heavy colored resonances decaying to top quarks in the TeV energy range. A peak in the differential cross section could reveal the existence of such a resonance, but this is experimentally challenging, because it requires selecting data samples where top and antitop quarks are highly boosted. Nonetheless, the production of such resonances might generate a sizable charge asymmetry of top versus antitop quarks. We consider a toy model with general flavour independent couplings of the resonance to quarks, of both vector and axial-vector kind. The charge asymmetry turns out to be a more powerful observable to detect new physics than the differential cross section, because its highest statistical significance is achieved with data samples of top-antitop quark pairs of low invariant masses.

Probing high scale physics with top quarks at the Large Hadron Collider

Science.gov (United States)

Dong, Zhe

With the Large Hadron Collider (LHC) running at TeV scale, we are expecting to find the deviations from the Standard Model in the experiments, and understanding what is the origin of these deviations. Being the heaviest elementary particle observed so far in the experiments with the mass at the electroweak scale, top quark is a powerful probe for new phenomena of high scale physics at the LHC. Therefore, we concentrate on studying the high scale physics phenomena with top quark pair production or decay at the LHC. In this thesis, we study the discovery potential of string resonances decaying to t/tbar final state, and examine the possibility of observing baryon-number-violating top-quark production or decay, at the LHC. We point out that string resonances for a string scale below 4 TeV can be detected via the t/tbar channel, by reconstructing center-of-mass frame kinematics of the resonances from either the t/tbar semi-leptonic decay or recent techniques of identifying highly boosted tops. For the study of baryon-number-violating processes, by a model independent effective approach and focusing on operators with minimal mass-dimension, we find that corresponding effective coefficients could be directly probed at the LHC already with an integrated luminosity of 1 inverse femtobarns at 7 TeV, and further constrained with 30 (100) inverse femtobarns at 7 (14) TeV.

Measurements of the top quark mass with the ATLAS detector

CERN Document Server

Brandt, Oleg; The ATLAS collaboration

2018-01-01

The top quark mass is one of the fundamental parameters of the Standard Model. The latest ATLAS measurements of the top quark mass are presented. A measurement using lepton+jets events is presented, where a multidimensional template fit is used to constrain the uncertainties on the energy measurements of jets. The measurement is combined with a measurement using dilepton events. In addition, novel measurements aiming to measure the mass in a welldefined scheme are presented. These measurements use precision theoretical QCD calculations for both inclusive ttbar production and ttbar production with an additional jet to extract the top quark mass in the polemass scheme.

More sum rules for quark and lepton masses

International Nuclear Information System (INIS)

Terazawa, Hidezumi.

1990-04-01

Sum rules for quark and lepton masses are derived from the Ward identity of Chanowitz and Ellis for the vertex function of the trace of the energy-momentum tensor and the two axial-vector currents and the partially conserved axial-vector current hypothesis. They indicate, among other things, that the constituent quark masses of u and d and those of the techniquarks, if any, are about 300 MeV and 300 GeV, respectively. (author)

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

Measurement of the top quark mass in the dilepton final state using the matrix element method

Energy Technology Data Exchange (ETDEWEB)

Grohsjean, Alexander [Ludwig Maximilian Univ., Munich (Germany)

2008-12-15

The top quark, discovered in 1995 by the CDF and D0 experiments at the Fermilab Tevatron Collider, is the heaviest known fundamental particle. The precise knowledge of its mass yields important constraints on the mass of the yet-unobserved Higgs boson and allows to probe for physics beyond the Standard Model. The first measurement of the top quark mass in the dilepton channel with the Matrix Element method at the D0 experiment is presented. After a short description of the experimental environment and the reconstruction chain from hits in the detector to physical objects, a detailed review of the Matrix Element method is given. The Matrix Element method is based on the likelihood to observe a given event under the assumption of the quantity to be measured, e.g. the mass of the top quark. The method has undergone significant modifications and improvements compared to previous measurements in the lepton+jets channel: the two undetected neutrinos require a new reconstruction scheme for the four-momenta of the final state particles, the small event sample demands the modeling of additional jets in the signal likelihood, and a new likelihood is designed to account for the main source of background containing tauonic Z decay. The Matrix Element method is validated on Monte Carlo simulated events at the generator level. For the measurement, calibration curves are derived from events that are run through the full D0 detector simulation. The analysis makes use of the Run II data set recorded between April 2002 and May 2008 corresponding to an integrated luminosity of 2.8 fb^-1. A total of 107 t$\\bar{t}$ candidate events with one electron and one muon in the final state are selected. Applying the Matrix Element method to this data set, the top quark mass is measured to be m_top^{Run IIa} = 170.6 ± 6.1(stat.)_-1.5^+2.1(syst.)GeV; m_top^{Run IIb} = 174.1 ± 4.4(stat.)_-1.8^+2.5(syst.)GeV; m

Mass extrapolation of quarks and leptons to higher generations

Energy Technology Data Exchange (ETDEWEB)

Barik, N [Utkal Univ., Bhubaneswar (India). Dept. of Physics

1981-05-01

An empirical mass formula is tested for the basic fermion sequences of charged quarks and leptons. This relation is a generalization of Barut's mass formula for the lepton sequence (e, ..mu.., tau ....). It is found that successful mass extrapolation to the third and possibly to other higher generations (N > 2) can be obtained with the first and second generation masses as inputs, which predicts the top quark mass msub(t) to be around 20 GeV. This also leads to the mass ratios between members of two different sequences (i) and (i') corresponding to the same higher generations (N > 2).

Mass extrapolation of quarks and leptons to higher generations

International Nuclear Information System (INIS)

Barik, N.

1981-01-01

An empirical mass formula is tested for the basic fermion sequences of charged quarks and leptons. This relation is a generalization of Barut's mass formula for the lepton sequence (e, μ, tau ....). It is found that successful mass extrapolation to the third and possibly to other higher generations (N > 2) can be obtained with the first and second generation masses as inputs, which predicts the top quark mass msub(t) to be around 20 GeV. This also leads to the mass ratios between members of two different sequences (i) and (i') corresponding to the same higher generations (N > 2). (author)

Light meson physics from maximally twisted mass lattice QCD

International Nuclear Information System (INIS)

Baron, R.; Boucaud, P.

2009-12-01

We present a comprehensive investigation of light meson physics using maximally twisted mass fermions for N f =2 mass-degenerate quark flavours. By employing four values of the lattice spacing, spatial lattice extents ranging from 2.0 fm to 2.5 fm and pseudo scalar masses in the range 280 PS < or similar 650 MeV we control the major systematic effects of our calculation. This enables us to confront our data with chiral perturbation theory and extract low energy constants of the effective chiral Lagrangian and derived quantities, such as the light quark mass, with high precision. (orig.)

Quark effects in nuclear physics

International Nuclear Information System (INIS)

Scholten, O.

1990-01-01

The magnitude of the quark effect for low-energy nuclear physics is investigated. Coulomb energy is studied in the A=3 system in order to determine the effect of the composite structure of the nucleon. In the actual calculations a non-relativistic quark-cluster model description has been used. A nucleon size b=0.617 fm, the width of the relative wave function Φ of the quarks in the nucleon, has been assumed. It is concluded that the contribution to Coulomb energies due to quark effects are significant compared to the observed Nolen-Schiffer anomaly. However these do not provide the long searched for 'smoking gun'. When the free parameters that appear in the calculation are adjusted to reproduce the same charge form factor, the calculated anomalies are not significantly different. 2 figs., 2 tabs., 8 refs.2

D-Zero top quark mass analysis

International Nuclear Information System (INIS)

Strovink, M.

1996-10-01

I report on D null's preliminary analyses of the top quark mass m t based on an exposure at √s = 1.8 TeV with integrated luminosity ∼100 pb -1 at the Fermilab Tevatron p anti p collider. From three e + μ + ≥ 2 jet events (with background 0.36 ± 0.09), using partly original methods, we obtain m t = 158 ± 24(stat) ± 10(syst) GeV/c 2 . From 30 e or μ + ±4 jets events (with background 17.4 ±2.2), we find m t = 170 ± 15(stat) ± 10(syst) GeV/c 2 . Recently, using multivariate methods based on particular kinematic variables, we have learned how to improve the background suppression in the latter sample without unduly distorting the reconstructed top mass spectra. Applying these methods should improve considerably the accuracy of our top quark mass determination

Constituent quark mass and nucleon properties in nuclei

International Nuclear Information System (INIS)

Beyer, M.; Singh, S.K.

1986-01-01

It is shown that the Nolen-Schiffer anomaly, the quenching of gsub(A) and the increase in some electromagnetic properties of nucleons in nuclei can all be explained qualitatively in a constituent quark model if the quark mass is assumed to depend on its confinement size. (author)

Weak interactions, quark masses and spontaneous violation of parity

International Nuclear Information System (INIS)

Kingsley, R.L.

1976-09-01

A six quark model is discussed for the weak interactions of hadrons in which parity is violated spontaneously in an SU(2) x U(1) gauge theory. Quarks with very small masses are required and their weak interactions approximate those of the Weinberg-Salam model. Suppression of strangeness-changing neutral currents requires at least seven quarks. (author)

Heavy quark masses in the continuum limit of quenched Lattice QCD

International Nuclear Information System (INIS)

De Divitiis, G.M.; Guagnelli, M.; Palombi, F.; Petronzio, R.; Tantalo, N.

2003-01-01

We compute charm and bottom quark masses in the quenched approximation and in the continuum limit of lattice QCD. We make use of a step scaling method, previously introduced to deal with two scale problems, that allows to take the continuum limit of the lattice data. We determine the RGI quark masses and make the connection to the MS-bar scheme. The continuum extrapolation gives us a value m b RGI =6.73(16) GeV for the b-quark and m c RGI =1.681(36) GeV for the c-quark, corresponding, respectively, to m b MS-bar (m b MS-bar =4.33(10) GeV and m c MS-bar (m c MS-bar =1.319(28) GeV. The latter result, in agreement with current estimates, is for us a check of the method. Using our results on the heavy quark masses we compute the mass of the B c meson, M B c =6.46(15) GeV

On the quark-mass dependence of baryon ground-state masses

International Nuclear Information System (INIS)

Semke, Alexander

2010-01-01

Baryon masses of the flavour SU(3) octet and decuplet baryons are calculated in the framework of the Chiral Perturbations Theory - the effective field theory of the strong interaction. The chiral extrapolation to the higher meson (quark) masses is carried out. The comparison with the recent results on the baryon masses from lattice calculations are presented. (orig.)

On the quark-mass dependence of baryon ground-state masses

Energy Technology Data Exchange (ETDEWEB)

Semke, Alexander

2010-02-17

Baryon masses of the flavour SU(3) octet and decuplet baryons are calculated in the framework of the Chiral Perturbations Theory - the effective field theory of the strong interaction. The chiral extrapolation to the higher meson (quark) masses is carried out. The comparison with the recent results on the baryon masses from lattice calculations are presented. (orig.)

Hadron masses and decay constants with Wilson quarks at β=5.85 and 6.0

International Nuclear Information System (INIS)

Anon.

1996-01-01

We present results of a high statistics calculation of hadron masses and meson decay constants in the quenched approximation to lattice QCD with Wilson quarks at β= 5.85 and 6.0 on 24 3 x54 lattices. We analyze the data paying attention in particular to the systematic errors due to the choice of fitting range and due to the contamination from excited states. We find that the systematic errors for the hadron masses with quarks lighter than the strange quark amount to 1 to 2 times the statistical errors. When the lattice scale is fixed from the ρ meson mass, the masses of the Ω - baryon and the φ meson at two β close-quote s agree with experiment within about one standard deviation. On the other hand, the central value of the nucleon mass at β=6.0 (5.85) is larger than its experimental value by about 15% (20%) and that of the Δ mass by about 15% (4%): Even when the systematic errors are included, the baryon masses at β=6.0 do not agree with experiment. Vector meson decay constants at two values of β agree well with each other and are consistent with experiment for a wide range of the quark mass, when we use current renormalization constants determined nonperturbatively by numerical simulations. The pion decay constant agrees with experiment albeit with large errors. Results for the masses of excited states of the ρ meson and the nucleon are also presented. copyright 1996 The American Physical Society

PREFACE: 5th International Workshop on Top Quark Physics (TOP2012)

Science.gov (United States)

Salamanna, G.; Boisvert, V.; Cerrito, L.; Khan, A.; Moretti, S.; Owen, M.; Schwanenberger, C.

2013-07-01

The 5th International Workshop on Top Quark Physics (TOP 2012) took place in Winchester, UK, from the 16-21 September. It gathered students as well as people active in the top quark sector and provided a framework to highlight the newest results and matters related to top quark physics. Discovered in 1995, the top quark is the sixth and heaviest of all quarks, and it is the only one with a lifetime short enough to be observed 'naked'. This makes it an important testing ground in the search for new physics. In fact, the fact of its mass being so much larger than the other quarks, hints at its special role in the Higgs mechanism. For the same reason, in many models of New Physics, new heavy resonances are expected to couple mostly with top quarks. Even if no new particles are observed, the direct correlation between its angular momentum and that of its detectable decay products allows us to probe indirectly New Physics in action when top quarks are created. In this edition of the TOP conference series, for the first time, the agenda was equally balanced between 'traditional' measurements and the now vast number of searches for physics BSM in the top quark sector, thanks mostly to the amount of data collected at the LHC in its Run I. New results were presented by both the Tevatron and the LHC collaborations: improved ttbar and single top cross-section measurements, refined techniques to measure the top quark mass and a large number of results on properties such as spin correlation and W boson polarization in top quark decays were shown. More technical discussions on the experimental issues, both from the detector and the simulation side also took place, drawing together experimentalists and theorists. Reviews of the latest results on ttbar asymmetry both from CDF and D0 and from ATLAS and CMS were shown, and theorists active in the field made some interesting points on this hot topic. Additionally, results on the search for fourth generation fermions and new

The Top Quark Mass, Systematic Limitations, and my Tracker-Driven Measurements

Energy Technology Data Exchange (ETDEWEB)

Garberson, Ford [Univ. of California, Santa Barbara, CA (United States)

2008-08-01

Top quark mass measurements have achieved an unexpected level of accu- racy in the last several years. This accuracy is only possible because of a new procedure that calibrates away the dominant jet energy uncertainty of past mea- surements. In this thesis I present some studies illustrating my suspicions that this procedure is leading them to claim overly optimistic results. Additionally, I present three measurements of the top quark mass that will be almost entirely independent of jet energies, and will thus serve as important cross checks of the standard measurements once enough statistics have been collected. I perform my measurements of the top quark mass in the lepton plus jets channel with approximately 1.9 fb^-1 of integrated luminosity collected with the CDF detector using quantities with minimal dependence on the jet energies. One measurement exploits the transverse decay length of b-tagged jets to determine a top quark mass of 166.9+9.5 (stat)±2.9 (syst) GeV/c², and another the transverse momentum of electrons and muons from W decays to determine a top quark mass of 173.5+8.8 - (stat) ± 3.8 (syst) GeV/c². I combine these quantities in a vi third, simultaneous mass measurement to determine a top quark mass of 170.7 ± 6.3 (stat) ± 2.6 (syst) GeV/c².

Physics and astrophysics of quark-gluon plasma

Energy Technology Data Exchange (ETDEWEB)

Anon.

1993-06-15

The quark gluon plasma - matter too hot or dense for quarks to crystallize into particles - played a vital role in the formation of the Universe. Efforts to recreate and understand this type of matter are forefront physics and astrophysics, and progress was highlighted in the Second International Conference on Physics and Astrophysics of Quark Gluon Plasma (ICPA-QGP 93), held in Calcutta from 19-23 January. (The first conference in the series was held in Bombay in February 1988). Although primarily motivated towards enlightening the Indian physics community in this new and rapidly evolving area, in which India now plays an important role, the conference also catered for an international audience. Particular emphasis was placed on the role of quark gluon plasma in astrophysics and cosmology. While Charles Alcock of Lawrence Livermore looked at a less conventional picture giving inhomogeneous ('clumpy') nucleosynthesis, David Schramm (Chicago) covered standard big bang nucleosynthesis. The abundances of very light elements do not differ appreciably for these contrasting scenarios; the crucial difference between them shows up for heavier elements like lithium-7 and -8 and boron-11. Richard Boyd (Ohio State) highlighted the importance of accurate measurements of the primordial abundances of these elements for clues to the cosmic quark hadron phase transition. B. Banerjee (Bombay) argued, on the basis of lattice calculations, for only slight supercooling in the cosmic quark phase transition - an assertion which runs counter to the inhomogeneous nucleosynthesis scenario.

Physics and astrophysics of quark-gluon plasma

International Nuclear Information System (INIS)

Anon.

1993-01-01

The quark gluon plasma - matter too hot or dense for quarks to crystallize into particles - played a vital role in the formation of the Universe. Efforts to recreate and understand this type of matter are forefront physics and astrophysics, and progress was highlighted in the Second International Conference on Physics and Astrophysics of Quark Gluon Plasma (ICPA-QGP 93), held in Calcutta from 19-23 January. (The first conference in the series was held in Bombay in February 1988). Although primarily motivated towards enlightening the Indian physics community in this new and rapidly evolving area, in which India now plays an important role, the conference also catered for an international audience. Particular emphasis was placed on the role of quark gluon plasma in astrophysics and cosmology. While Charles Alcock of Lawrence Livermore looked at a less conventional picture giving inhomogeneous ('clumpy') nucleosynthesis, David Schramm (Chicago) covered standard big bang nucleosynthesis. The abundances of very light elements do not differ appreciably for these contrasting scenarios; the crucial difference between them shows up for heavier elements like lithium-7 and -8 and boron-11. Richard Boyd (Ohio State) highlighted the importance of accurate measurements of the primordial abundances of these elements for clues to the cosmic quark hadron phase transition. B. Banerjee (Bombay) argued, on the basis of lattice calculations, for only slight supercooling in the cosmic quark phase transition - an assertion which runs counter to the inhomogeneous nucleosynthesis scenario

Overlap valence quarks on an twisted mass sea

Energy Technology Data Exchange (ETDEWEB)

Cichy, K. [Adam Mickiewicz Univ., Poznan (Poland). Faculty of Physics; Drach, V.; Garcia-Ramos, E.; Herdoiza, G.; Jansen, K. [DESY, Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC

2010-12-15

We present the results of an investigation of a mixed action approach of overlap valence and maximally twisted mass sea quarks. Employing a particular matching condition on the pion mass, we analyze the continuum limit scaling of the pion decay constant and the role of chiral zero modes of the overlap operator in this process. We employ gauge field configurations generated by the European Twisted Mass Collaboration with linear lattice size L ranging from 1.3 to 1.9 fm. The continuum limit is taken at a fixed value of L=1.3 fm, employing three values of the lattice spacing and two values of the pion mass constructed from sea quarks only. (orig.)

Light quark masses with Nf = 2 Wilson fermions

International Nuclear Information System (INIS)

Eicker, N.; Lippert, Th.; Orth, B.; Schilling, K.

2002-01-01

We present new data on the mass of the light and strange quarks from SESAM/TχL. The results were obtained on lattice-volumes of 16 3 x 32 and 24 3 x 40 points, with the possibility to investigate finite-size effects. Since the SESAM/TχL ensembles at β = 5.6 have been complemented by configurations with β = 5.5, moreover, we are now able to attempt the continuum extrapolation (CE) of the quark masses with standard Wilson fermions

Continuum limit of overlap valence quarks on a twisted mass sea

International Nuclear Information System (INIS)

Cichy, Krzysztof; Herdoiza, Gregorio; Univ. Autonoma de Madrid; Jansen, Karl

2010-12-01

We study a lattice QCD mixed action with overlap valence quarks on two flavours of Wilson maximally twisted mass sea quarks. Employing three different matching conditions to relate both actions to each other, we investigate the continuum limit by using three values of the lattice spacing ranging from a∼0.05 fm to 0.08 fm. A particular emphasis is put on the effect on physical observables of the topological zero modes appearing in the valence overlap operator. We estimate the region of parameter space where the contribution from these zero modes is sufficiently small such that their effects can be safely controlled and a restoration of unitarity of the mixed action in the continuum limit is reached. (orig.)

Statistical and systematic treatment issues in top quark mass combinations

CERN Document Server

Maier, Andreas Alexander; The ATLAS collaboration

2015-01-01

The past years have seen tremendous improvements in the precision of top quark mass measurements at hadron colliders. Since these measurements are mostly limited by systematic uncertainties, the achievable precision of a single measurement depends on developments in the experimental and theoretical understanding of top quark events. Complementing these efforts, a precision gain can also be obtained by a combination of measurements, exploiting their correlation. With ever increasing precision of single experiment top quark mass measurements, this approach becomes more and more promising, because the absolute precision gain of refined techniques in both theory and experiment tends to saturate. This requires a precise matching of uncertainty categories and a detailed evaluation of the correlations of observables. This article reviews the status and points out the challenges faced in the ATLAS and CMS LHC top quark mass combination effort.

Measurements of the top quark mass using the ATLAS detector at the LHC

CERN Document Server

Pinamonti, Michele; The ATLAS collaboration

2018-01-01

The latest measurements of the top quark mass using the ATLAS experiment are presented. A measurement based on a multi-dimensional template fit that can constrain the uncertainties on the energy measurements of jets is presented and combined with measurements using dilepton and all-hadronic events. In addition an analysis of the top quark mass using leptonic kinematic variables is discussed. The measurement uses a novel technique to measure the top quark mass with minimal dependence on hadronic jets. A measurement of the top quark width and the measurements that use precision theoretical QCD calculations for both inclusive ttbar production and ttbar production with an additional jet to extract the top quark mass in the pole-mass scheme are also presented.

Top quark mass measurement in the lepton+jets channel using full simulation of the CMS detector

International Nuclear Information System (INIS)

Kasselmann, S.

2007-01-01

In summer 2008 the world largest proton-proton storage ring, the Large Hadron Collider (LHC), at CERN close to Geneva (Switzerland) will go into service. With a collision energy of 14 TeV the production cross section for top/antitop quarks (t anti t) is about 830 pb (NLO). The top quarks almost exclusively decay into a W boson and a b quark via the weak interaction. In about 44.4% of all events one of the top quarks decays into a lepton and neutrino while the other one decays into two light quarks (semileptonic decay chain). This channel therefore provides a good selection purity (lepton b tagging) and the possibility for the complete reconstruction of the hadronically decaying top quark into three jets. After a short introduction of top quark physics at the LHC and the Compact Muon Solenoid (CMS) detector, this thesis deals with the analyses of top quark reconstruction and mass measurement in two different scenarios. In the first analysis a first physics scenario is taken as a basis where no jet flavour information (e.g. b tagging) and only a reduced detector acceptance region for electron identification is assumed. It is shown that semileptonic top quark pair decays can nevertheless be identified with a signal over background ratio of about S/B=2.4. For this study signal and main background processes using full simulation of the CMS detector have been produced for an integrated luminosity of 0.1 fb -1 . Especially event shape variables are adequate to compensate the missing b jet tagging. The semileptonic channel is the most promising one to rediscover the top quark at the LHC due to the lepton in the final state. In this scenario the needed integrated luminosity has been calculated to be about 2 pb -1 assuming Poisson distributions for the number of signal and background events. A second analysis focusses on the top quark mass measurement in a scenario where the CMS detector is fully equipped and has almost reached its design performance. Therefore data for an

Top quark mass measurement in the lepton+jets channel using full simulation of the CMS detector

Energy Technology Data Exchange (ETDEWEB)

Kasselmann, S

2007-11-22

In summer 2008 the world largest proton-proton storage ring, the Large Hadron Collider (LHC), at CERN close to Geneva (Switzerland) will go into service. With a collision energy of 14 TeV the production cross section for top/antitop quarks (t anti t) is about 830 pb (NLO). The top quarks almost exclusively decay into a W boson and a b quark via the weak interaction. In about 44.4% of all events one of the top quarks decays into a lepton and neutrino while the other one decays into two light quarks (semileptonic decay chain). This channel therefore provides a good selection purity (lepton b tagging) and the possibility for the complete reconstruction of the hadronically decaying top quark into three jets. After a short introduction of top quark physics at the LHC and the Compact Muon Solenoid (CMS) detector, this thesis deals with the analyses of top quark reconstruction and mass measurement in two different scenarios. In the first analysis a first physics scenario is taken as a basis where no jet flavour information (e.g. b tagging) and only a reduced detector acceptance region for electron identification is assumed. It is shown that semileptonic top quark pair decays can nevertheless be identified with a signal over background ratio of about S/B=2.4. For this study signal and main background processes using full simulation of the CMS detector have been produced for an integrated luminosity of 0.1 fb{sup -1}. Especially event shape variables are adequate to compensate the missing b jet tagging. The semileptonic channel is the most promising one to rediscover the top quark at the LHC due to the lepton in the final state. In this scenario the needed integrated luminosity has been calculated to be about 2 pb{sup -1} assuming Poisson distributions for the number of signal and background events. A second analysis focusses on the top quark mass measurement in a scenario where the CMS detector is fully equipped and has almost reached its design performance. Therefore data

Measurements and searches with top quarks

International Nuclear Information System (INIS)

Peters, Reinhild Yvonne

2008-01-01

In 1995 the last missing member of the known families of quarks, the top quark, was discovered by the CDF and D0 experiments at the Tevatron, a proton-antiproton collider at Fermilab near Chicago. Until today, the Tevatron is the only place where top quarks can be produced. The determination of top quark production and properties is crucial to understand the Standard Model of particle physics and beyond. The most striking property of the top quark is its mass--of the order of the mass of a gold atom and close to the electroweak scale--making the top quark not only interesting in itself but also as a window to new physics. Due to the high mass, much higher than of any other known fermion, it is expected that the top quark plays an important role in electroweak symmetry breaking, which is the most prominent candidate to explain the mass of particles. In the Standard Model, electroweak symmetry breaking is induced by one Higgs field, producing one additional physical particle, the Higgs boson. Although various searches have been performed, for example at the Large Electron Positron Collider (LEP), no evidence for the Higgs boson could yet be found in any experiment. At the Tevatron, multiple searches for the last missing particle of the Standard Model are ongoing with ever higher statistics and improved analysis techniques. The exclusion or verification of the Higgs boson can only be achieved by combining many techniques and many final states and production mechanisms. As part of this thesis, the search for Higgs bosons produced in association with a top quark pair (t(bar t)H) has been performed. This channel is especially interesting for the understanding of the coupling between Higgs and the top quark. Even though the Standard Model Higgs boson is an attractive candidate, there is no reason to believe that the electroweak symmetry breaking is induced by only one Higgs field. In many models more than one Higgs boson are expected to exist, opening even more channels

Light meson physics from maximally twisted mass lattice QCD

Energy Technology Data Exchange (ETDEWEB)

Baron, R.; Boucaud, P. [Paris XI Univ., 91 - Orsay (France). Lab. de Physique Theorique; Dimopoulos, P. [Roma Tor Vergata Univ. (Italy). Dipt. di Fisica; INFN, Rome (IT)] (and others)

2009-12-15

We present a comprehensive investigation of light meson physics using maximally twisted mass fermions for N{sub f}=2 mass-degenerate quark flavours. By employing four values of the lattice spacing, spatial lattice extents ranging from 2.0 fm to 2.5 fm and pseudo scalar masses in the range 280quark mass, with high precision. (orig.)

Top quark kinematics and mass determination

International Nuclear Information System (INIS)

Williams, H.H.

1994-10-01

An analysis is presented of 10 W + ≥ 3 jet events, each with evidence for the presence of a b quark, that were recently observed by the CDF collaboration. Seven of these events include a fourth jet and can be explicitly reconstructed as t bar t production. The best estimate of the top quark mass is M t = 174 ± 10 -12 +13 GeV/c 2 . A study has also been performed to see if the kinematical properties of events with W + ≥ 3 jets gives evidence for top production. An excess of events with large jet energies, compared to that expected from direct production of W + ≥ 3 jets, is observed. A large fraction of these events also contain a b-quark and a fourth jet

Probing new physics at the LHC: searches for heavy top-like quarks with the ATLAS experiment

CERN Document Server

Succurro, Antonella; Casado Lechuga, María Pilar

Is our Standard Model (SM) of the fundamental particle interactions complete? Apparently, the answer is “no”. Many theories have been proposed to explain what is currently not understood, like the nature of Dark Matter, or the reason why the Higgs boson is so light. Now that the Large Hadron Collider (LHC) at CERN is fully operational, it is possible for experiments like ATLAS to explore very high-energy regimes where new physics can be probed. The work presented in this dissertation consists of two analyses aimed at the discovery (or exclusion) of a signal from a new particle: a quark similar to the top quark (the heaviest particle of the Standard Model) but with a larger mass. This new “top-like” quark could be a simple replica of the SM top quark, just with higher mass, i.e. a chiral fourth-generation up-type quark, or it could have exotic features. The latter hypothesis is particularly interesting as many “beyond-Standard Model” theories predict new heavy so-called vector-like quarks. Both sea...

Quark masses from quark-gluon condensates in a modified perturbative QCD

CERN Document Server

Cabo-Montes de Oca, Alejandro

2003-01-01

In this note, it is argued that the mass matrix for the six quarks can be generated in first approximation by introducing fermion condensates on the same lines as was done before for gluons, within the modified perturbative expansion for QCD proposed in former works. Thus, the results point in the direction of the conjectured link of the approximate `Democratic' symmetry of the quark mass matrix and `gap' effects similar to the ones occuring in superconductivity. The condensates are introduced here non-dynamically and therefore the question of the possibility for their spontaneous generation remains open. However, possible ways out of the predicted lack of the `Democratic' symmetry of the condensates resulting from the spontaneous breaking of the flavour symmetry are suggested. They come from an analysis based on the Cornwall--Jackiw--Tomboulis (CJT) effective potential for composite operators

Soap opera: the sad tale of the quark

International Nuclear Information System (INIS)

Lipkin, H.

1984-01-01

The history of quark physics is briefly reviewed, followed by an introduction to quantum chromodynamics, leading terms, and the OZI rule. The basic physics of hadron structure as revealed by experiment is then discussed, followed by the models used to treat it. The two complementary models are the quasinuclear colored quark model and the quark-parton model. Another model for orthogonal physical properties is the bag model. Several applications of the constituent quark model are considered, including hadron masses, spin physics, and multiquark physics. The theoretical basis and phenomenology of the OZI rule forbids processes described by disconnected quark line diagrams

Systematics of quark mass matrices in the standard electroweak model

International Nuclear Information System (INIS)

Frampton, P.H.; Jarlskog, C.; Stockholm Univ.

1985-01-01

It is shown that the quark mass matrices in the standard electroweak model satisfy the empirical relation M = M' + O(lambda 2 ), where M(M') refers to the mass matrix of the charge 2/3 (-1/3) quarks normalized to the largest eigenvalue, msub(t) (msub(b)), and lambda = Vsub(us) approx.= 0.22. (orig.)

Measuring the running top-quark mass

International Nuclear Information System (INIS)

Langenfeld, Ulrich; Uwer, Peter

2010-06-01

In this contribution we discuss conceptual issues of current mass measurements performed at the Tevatron. In addition we propose an alternative method which is theoretically much cleaner and to a large extend free from the problems encountered in current measurements. In detail we discuss the direct determination of the top-quark's running mass from the cross section measurements performed at the Tevatron. (orig.)

New Methods for Top-Quark Mass Measurements at the LHC

CERN Document Server

Stieger, Benjamin

2016-01-01

Several recent new measurements of the top-quark mass that use alternative observables and reconstruction techniques are presented, performed by the ATLAS and CMS collaborations at the CERN LHC. Alternative observables can help provide insight by presenting different systematic sensitivities and by constraining prevailing systematic uncertainties of standard measurements, such as jet energy calibrations. Furthermore, the top-quark mass is extracted from theoretically well-defined observables, such as the inclusive production cross section for top quark pairs. Finally, the mass is measured in event topologies dominated by electroweak-mediated single top production by both experiments. The results of different techniques and production modes are found to be consistent with what is obtained in standard measurements.

The strange quark mass and Lambda parameter of two flavor QCD

Energy Technology Data Exchange (ETDEWEB)

Fritzsch, Patrick; Marinkovic, Marina [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Knechtli, Francesco; Leder, Bjoern [Wuppertal Univ. (Germany). Fachbereich C - Mathematik und Naturwissenschaften; Schaefer, Stefan [CERN, Geneva (Switzerland). Physics Dept.; Sommer, Rainer; Virotta, Francesco [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

2012-06-15

We complete the non-perturbative calculations of the strange quark mass and the {lambda} parameter in two flavor QCD by the ALPHA collaboration. The missing lattice scale is determined via the kaon decay constant, for whose chiral extrapolation complementary strategies are compared. We also give a value for the scale r{sub 0} in physical units as well as an improved determination of the renormalization constant Z{sub A}.

Measurement of the top quark mass using dilepton events and a neutrino weighting algorithm with the DOe experiment at the Tevatron (Run II)

Energy Technology Data Exchange (ETDEWEB)

Meyer, J.

2007-07-01

Several measurements of the top quark mass in the dilepton final states with the DOe experiment are presented. The theoretical and experimental properties of the top quark are described together with a brief introduction of the Standard Model of particle physics and the physics of hadron collisions. An overview over the experimental setup is given. The Tevatron at Fermilab is presently the highest-energy hadron collider in the world with a center-of-mass energy of 1.96 TeV. There are two main experiments called CDF and DOe, A description of the components of the multipurpose DOe detector is given. The reconstruction of simulated events and data events is explained and the criteria for the identification of electrons, muons, jets, and missing transverse energy is given. The kinematics in the dilepton final state is underconstraint. Therefore, the top quark mass is extracted by the so-called Neutrino Weighting method. This method is introduced and several different approaches are described, compared, and enhanced. Results for the international summer conferences 2006 and winter 2007 are presented. The top quark mass measurement for the combination of all three dilepton channels with a dataset of 1.05 1/fb yields: mtop=172.5{+-}5.5 (stat.) {+-} 5.8 (syst.) GeV. This result is presently the most precise top quark mass measurement of the DOe experiment in the dilepton chann el. It entered the top quark mass wold average from March 2007. (orig.)

Early nucleosynthesis, particle physics and the quark-lithium connection

International Nuclear Information System (INIS)

Reeves, H.; Audouze, J.; Delbourgo-Salvador, P.; Salati, P.; California Univ., Berkeley

1987-01-01

Three questions relevant to the primordial nucleosynthesis of the very light elements are discussed in this contribution: 1. It is argued that the ''standard'' Big Bang nucleosynthesis models are strenghtened if D is destroyed thoroughly during the galactic history. This can be achieved by specific models of chemical evolution of galaxies like those assuming a rate of star formation varying with time. 2. The existence of non baryonic particles such as massive neutrinos or supersymetric particles (gravitinos, photinos ...) might affect this early nucleosynthesis. If they are massive (≥ 500 MeV) and long lived enough (≥ 10 5 sec) the energetic photons released by their possible decay might affect the relative abundances of the light elements. In the case of the photinos, which are the supersymetric particles and which might be experimentally detectable in a near future, this possible effect can be used as to constrain the predictions on their physical properties (mass, lifetime...). 3. The early nucleosynthesis can be affected by the inhomogeneities triggered by the quark-hadron phase transition. It is argued that the primordial abundance of 7 Li limits very severely this possibility. As in the case of photinos the relation between the early synthesis of 7 Li and the characteristics of this quark-hadron phase transition may provide interesting constraints on some important physical parameters such as the constant B of the quark-bag model

8th International Workshop on Top Quark Physics

CERN Document Server

2015-01-01

This workshop, at its 8th edition, will bring together the community of experimental and theoretical physicists working on top quark physics, 20 years after its first discovery, and at the beginning of the exploration of the new energy regime at the Large Hadron Collider. The workshop will provide a comprehensive overview of the latest results from the LHC and Tevatron experiments as well as the most recent theoretical developments and an outlook on top-quark physics at future colliders. The programme will consist of plenary presentations, a poster session and 'question and answers' sessions, targeted for young researchers. A significant fraction of the workshop time will be devoted to discussions. The goal of the workshop is to provide a comprehensive picture of top-quark physics and a forum where experimentalists and theorists can discuss the interpretation of top quark results and plan future measurements. The venue will take place in the Hotel Continental Terme, Ischia, the largest island in the bay of Na...

The top quark physics of the final flavor

CERN Document Server

Franklin, Melissa

1996-01-01

This will be a series of lectures concerning the recent discovery of the top quark. These lectures will cover things I have learned from hanging around proton anti-proton colliders for the past 15 years, including : Proton colliders, top quark production and decay kinematics.The D0 and CDF detectors : the finer points. Identifying W's and b quark jets. Jet spectroscopy : measuring masses with jets. Jet spectroscopy : measuring masses with jets. Scrutinizing events in which real W's are produced : the counting experiments with the CDF and D0 detectors at Fermilab. Checking the kinematics and measuring the mass and cross-section. Doing spot checks : is it a W, is there another W, is it a b, are they from top ? Seeing if top fits into the rest of the so-called Standard Model (circa 1995) My future

Quark potential model of baryon spin-orbit mass splittings

International Nuclear Information System (INIS)

Wang Fan; Wong Chunwa

1987-01-01

We show that it is possible to make the P-wave spin-orbit mass splittings in Λ baryons consistent with those of nonstrange baryons in a naive quark model, but only by introducing additional terms in the quark-quark effective interaction. These terms might be related to contributions due to pomeron exchange and sea excitations. The implications of our model in meson spectroscopy and nuclear forces are discussed. (orig.)

Continuum limit of overlap valence quarks on a twisted mass sea

Energy Technology Data Exchange (ETDEWEB)

Cichy, Krzysztof [Adam Mickiewicz Univ., Poznan (Poland). Faculty of Physics; Herdoiza, Gregorio [DESY, Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC; Univ. Autonoma de Madrid (Spain). Dept. de Fisica Teorica; Jansen, Karl [DESY, Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC

2010-12-15

We study a lattice QCD mixed action with overlap valence quarks on two flavours of Wilson maximally twisted mass sea quarks. Employing three different matching conditions to relate both actions to each other, we investigate the continuum limit by using three values of the lattice spacing ranging from a{approx}0.05 fm to 0.08 fm. A particular emphasis is put on the effect on physical observables of the topological zero modes appearing in the valence overlap operator. We estimate the region of parameter space where the contribution from these zero modes is sufficiently small such that their effects can be safely controlled and a restoration of unitarity of the mixed action in the continuum limit is reached. (orig.)

Radiatively generated hierarchy of lepton and quark masses

Energy Technology Data Exchange (ETDEWEB)

Hernández, A.E. Cárcamo; Kovalenko, Sergey; Schmidt, Ivan [Centro Científico Tecnológico de Valparaíso-CCTVal, Universidad Técnica Federico Santa María,Casilla 110-V, Valparaíso (Chile)

2017-02-24

We propose a model for radiatively generating the hierarchy of the Standard Model (SM) fermion masses: tree-level top quark mass; 1-loop bottom, charm, tau and muon masses; 2-loop masses for the light up, down and strange quarks as well as for the electron; and 4-loop masses for the light active neutrinos. Our model is based on a softly-broken S{sub 3}×Z{sub 2} discrete symmetry. Its scalar sector consists only of one SM Higgs doublet and three electrically neutral SM-singlet scalars. We do not need to invoke either electrically charged scalar fields, or an extra SU{sub 2L} scalar doublet, or the spontaneous breaking of the discrete group, which are typical for other radiative models in the literature. The model features a viable scalar dark matter candidate.

Four-loop relation between the MS and on-shell quark mass

International Nuclear Information System (INIS)

Marquard, Peter; Smirnov, Alexander V.; Smirnov, Vladimir A.; Steinhauser, Matthias

2016-01-01

In this contribution we discuss the four-loop relation between the on-shell and MS definition of heavy quark masses which is applied to the top, bottom and charm case. We also present relations between the MS quark mass and various threshold mass definitions and discuss the uncertainty at next-to-next-to-next-to-leading order.

Quark mass correction to the string potential

International Nuclear Information System (INIS)

Lambiase, G.; Nesterenko, V.V.

1995-01-01

A consistent method for calculating the interquark potential generated by the relativistic string with massive ends is proposed. In this approach the interquark potential in the model of the Nambu-Goto string with point-like masses at its ends is calculated. At first the calculation is done in the one-loop approximation and then the variational estimation is performed. The quark mass correction results in decreasing the critical distance (deconfinement radius). When quark mass decreases the critical distance also decreases. For obtaining a finite result under summation over eigenfrequencies of the Nambu-Goto string with massive ends a suitable mode-by-mode subtraction is proposed. This renormalization procedure proves to be completely unique. In the framework of the developed approach the one-loop interquark potential in the model of the relativistic string with rigidity is also calculated. 34 refs., 2 figs

Hadron energy spectrum in polarized top-quark decays considering the effects of hadron and bottom quark masses

Energy Technology Data Exchange (ETDEWEB)

Nejad, S.M.M. [Yazd University, Faculty of Physics, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of); Institute for Research in Fundamental Sciences (IPM), School of Particles and Accelerators, P.O.Box 19395-5531, Tehran (Iran, Islamic Republic of); Balali, Mahboobe [Yazd University, Faculty of Physics, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of)

2016-03-15

We present the analytical expressions for the next-to-leading order corrections to the partial decay width t(↑) → bW{sup +}, followed by b @→ H{sub b}X, for nonzero b-quark mass (m{sub b} ≠ 0) in the fixed-flavor-number scheme (FFNs). To make the predictions for the energy distribution of outgoing hadrons H{sub b}, as a function of the normalized H{sub b}-energy fraction x{sub H}, we apply the general-mass variable-flavor-number scheme (GM-VFNs) in a specific helicity coordinate system where the polarization of top quark is evaluated relative to the b-quark momentum. We also study the effects of gluon fragmentation and finite hadron mass on the hadron energy spectrum so that hadron masses are responsible for the low x{sub H} threshold. In order to describe both the b-quark and the gluon hadronizations in top decays we apply realistic and nonperturbative fragmentation functions extracted through a global fit to the e{sup +}e{sup -} annihilation data from CERN LEP1 and SLAC SLC by relying on their universality and scaling violations. (orig.)

Disconnected quark loop contributions to nucleon observables using N{sub f}=2 twisted clover fermions at the physical value of the light quark mass

Energy Technology Data Exchange (ETDEWEB)

Abdel-Rehim, Abdou; Kallidonis, Christos; Koutsou, Giannis [Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center; Alexandrou, Constantia; Constantinou, Martha; Hadjiyiannakou, Kyriakos [Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center; Cyprus Univ. (Cyprus). Dept. of Physics; Jansen, Karl [DESY Zeuthen (Germany). NIC; Aviles-Casco, Alejandro Vaquero [INFN Sezione di Milano-Bicocca, Milano (Italy)

2015-11-15

We compute the disconnected quark loops contributions entering the determination of nucleon observables, by using a N{sub f}=2 ensemble of twisted mass fermions with a clover term at a pion mass m{sub π}=133 MeV. We employ exact deflation and implement all calculations in GPUs, enabling us to achieve large statistics and a good signal.

Physics of the Quark Model

Science.gov (United States)

Young, Robert D.

1973-01-01

Discusses the charge independence, wavefunctions, magnetic moments, and high-energy scattering of hadrons on the basis of group theory and nonrelativistic quark model with mass spectrum calculated by first-order perturbation theory. The presentation is explainable to advanced undergraduate students. (CC)

Up-down quark mass difference effect in nuclear many-body systems

International Nuclear Information System (INIS)

Nakamura, S.; Muto, K.; Oka, M.; Takeuchi, S.; Oda, T.

1995-01-01

A charge-symmetry-breaking nucleon-nucleon force due to the up-down quark mass difference is evaluated in the quark cluster model. It is applied to the shell-model calculation for the isovector mass shifts of isospin multiplets and the isospin-mixing matrix elements in 1s0d-shell nuclei. We find that the contribution of the quark mass difference effect is large and agrees with experiment. This contribution may explain the Okamoto-Nolen-Schiffer anomaly, alternatively to the meson-mixing contribution, which is recently predicted to be reduced by the large off-shell correction. (author)

Top quark mass effects in Higgs boson pair production up to NNLO

International Nuclear Information System (INIS)

Hoff, Jens

2016-09-01

We consider the production of pairs of Standard Model Higgs bosons via gluon fusion. Until recently the full dependence on the top quark mass M_t was not known at next-to-leading order. For this reason we apply an approximation based on the expansion for large top quark masses up to O(1/M"1"2_t). At next-to-next-to-leading order we avoid the calculation of real corrections via the soft-virtual approximation and obtain top quark mass corrections up to O(1/M"4_t). We use our results to estimate the residual uncertainty of the total cross section due to a finite top quark mass to be O(10%) at next-to-leading order and O(5%) at next-to-next-to-leading order.

The chiral condensate from lattice QCD with Wilson twisted mass quarks

Energy Technology Data Exchange (ETDEWEB)

Urbach, Carsten [Bonn Univ. (Germany). HISKP (Theorie)

2016-11-01

Lattice QCD is a very computer time demanding scientific application. Only with the computer time made available on supercomputers like SuperMUC significant progress, like the one reported here, can be reached. Moreover, the computing resources made available by LRZ are used to reduce the systematic uncertainties in our results even further: in another project we are generating ensembles with physical values of the quark masses, such that a chiral extrapolation is not needed anymore.

Heavy-quark physics in quantum chromodynamics

International Nuclear Information System (INIS)

Brodsky, S.J.

1991-04-01

Heavy quarks can expose new symmetries and novel phenomena in QCD not apparent in ordinary hadronic systems. In these lectures I discuss the use of effective-Lagrangian and light-cone Fock methods to analyze exclusive heavy hadron decays such as Υ → p bar p and B → ππ, and also to derive effective Schroedinger and Dirac equations for heavy quark systems. Two contributions to the heavy quark structure functions of the proton and other light hadrons are identified: an ''extrinsic'' contribution associated with leading twist QCD evolution of the gluon distribution, and a higher twist ''intrinsic'' contribution due to the hardness of high-mass fluctuations of multi-gluon correlations in hadronic wavefunctions. A non-perturbative calculation of the heavy quark distribution of a meson in QCD in one space and one time is presented. The intrinsic higher twist contributions to the pion and proton structure functions can dominate the hadronic production of heavy quark systems at large longitudinal momentum fraction x F and give anomalous contributions to the quark structure functions of ordinary hadrons at large x bj . I also discuss a number of ways in which heavy quark production in nuclear targets can test fundamental QCD phenomena and provide constraints on hadronic wavefunctions. The topics include color transparency, finite formation time, and predictions for charm production at threshold, including nuclear-bound quarkonium. I also discuss a number of QCD mechanisms for the suppression of J/ψ and Υ production in nuclear collisions, including gluon shadowing, the peripheral excitation of intrinsic heavy quark components at large x F , and the coalescence of heavy quarks with co-moving spectators at low x F

Murray Gell-Mann and the physics of quarks

CERN Document Server

2018-01-01

Murray Gell-Mann, Physics Nobel Prize Laureate in 1969 is known for his theoretical work on elementary particle physics and the introduction of quarks and together with H. Fritzsch the “Quantum Chromodynamics”. Based on four sections the Editor gives an overview on the work of Gell-Mann and his contributions to various aspects of the physics, related to quarks. His most important and influential papers were selected and reprinted so that the reader easily can check the original work of Gell-Mann.

Gauge-invariant screening masses and static quark free energies in Nf=2 +1 QCD at nonzero baryon density

Science.gov (United States)

Andreoli, Michele; Bonati, Claudio; D'Elia, Massimo; Mesiti, Michele; Negro, Francesco; Rucci, Andrea; Sanfilippo, Francesco

2018-03-01

We discuss the extension of gauge-invariant electric and magnetic screening masses in the quark-gluon plasma to the case of a finite baryon density, defining them in terms of a matrix of Polyakov loop correlators. We present lattice results for Nf=2 +1 QCD with physical quark masses, obtained using the imaginary chemical potential approach, which indicate that the screening masses increase as a function of μB. A separate analysis is carried out for the theoretically interesting case μB/T =3 i π , where charge conjugation is not explicitly broken and the usual definition of the screening masses can be used for temperatures below the Roberge-Weiss transition. Finally, we investigate the dependence of the static quark free energy on the baryon chemical potential, showing that it is a decreasing function of μB, which displays a peculiar behavior as the pseudocritical transition temperature at μB=0 is approached.

and density-dependent quark mass model

Indian Academy of Sciences (India)

Since a fair proportion of such dense proto stars are likely to be ... the temperature- and density-dependent quark mass (TDDQM) model which we had em- ployed in .... instead of Tc ~170 MeV which is a favoured value for the ud matter [26].

Measurements of the top quark mass using the CMS and ATLAS detectors at the LHC

CERN Document Server

Menke, Sven; The ATLAS collaboration

2018-01-01

Measurements of the top quark mass obtained by the ATLAS and CMS experiments in proton-proton collisions at the LHC for centre-of-mass energies of $7$, $8$ and $13\\,$TeV are presented. The mass of the top quark is measured using several methods and channels, including the reconstructed invariant mass distribution of the top quark and shapes of kinematic observables from top quark decay products. Measurements of the top-quark pole-mass based on the inclusive and differential ${\\sf t}\\bar{\\sf t}$ production cross sections and observables based on the differential cross section in the ${\\sf t}\\bar{\\sf t}+1\\textsf{jet}$ channel are also discussed.

Measurements of the top quark mass using the CMS and ATLAS detectors at the LHC

CERN Document Server

Menke, Sven; The ATLAS collaboration

2018-01-01

Measurements of the top quark mass obtained by the ATLAS and CMS experiments in proton-proton collisions at the LHC for centre-of-mass energies of 7, 8 and 13 TeV are presented. The mass of the top quark is measured using several methods and channels, including the reconstructed invariant mass distribution of the top quark and shapes of kinematic observables from top quark decay products. Measurements of the top-quark pole-mass based on the inclusive and differential top-anti-top production cross sections and observables based on the differential cross section in the top-pair plus 1 jet channel are also discussed.

Quark mass effects in QCD

International Nuclear Information System (INIS)

Shirkov, D.V.

1982-01-01

In this paper recent studies of invariant QCD coupling anti asub(s)(Qsup(2)) in the 2-loop approximation with account of fermionic mass effects are summarized. The main results are: An explicit expression for anti asub(s)(Qsup(2)) in the 2-loop approximation with accurate account of heavy quark masses. A quantitative analysis on the basis of the above-mentioned expression for anti asub(s)(Qsup(2)) of the energy dependence of the scale QCD parameter ν and the conclusion about its inadequacy in the modern energy range

Latest Results on Top Quark Properties: \\\\ Deciphering the DNA of the heaviest quark

CERN Document Server

Gallinaro, Michele

2017-01-01

The top quark, the heaviest known elementary particle discovered at the Fermilab Tevatron more than twenty years ago, has taken a central role in the study of fundamental interactions. Due to its large mass, the top quark provides a unique environment for tests of the standard model. With a cumulative luminosity of more than 100~fb$^{-1}$ collected at $\\sqrt{s}=7,8,13$~TeV by each of the ATLAS and CMS experiments at the Large Hadron Collider in the first ten years of operation, top quark physics is probing uncharted territories in precision and rare measurements with sensitivity to New Physics processes. This document summarizes the latest experimental measurements and studies of top quark properties.

Charm and beauty quark masses in the MMHT2014 global PDF analysis.

Science.gov (United States)

Harland-Lang, L A; Martin, A D; Motylinski, P; Thorne, R S

We investigate the variation in the MMHT2014 PDFs when we allow the heavy-quark masses [Formula: see text] and [Formula: see text] to vary away from their default values. We make PDF sets available in steps of [Formula: see text] and [Formula: see text], and present the variation in the PDFs and in the predictions. We examine the comparison to the HERA data on charm and beauty structure functions and note that in each case the heavy-quark data, and the inclusive data, have a slight preference for lower masses than our default values. We provide PDF sets with three and four active quark flavours, as well as the standard value of five flavours. We use the pole mass definition of the quark masses, as in the default MMHT2014 analysis, but briefly comment on the [Formula: see text] definition.

Correlations among static quark masses

International Nuclear Information System (INIS)

Lewin, K.; Motz, G.B.

1987-01-01

Nonrelativistic heavy quarkonia potentials with Coulomb and linearly rising limiting behaviour are correlated additively by Taylor expansion extracting the limiting structure and a constant term. Relations between fit parameters of different potentials including the quark masses m b and m c , are obtained. The known stability of the difference m b -m c , appears as direct consequence of flavour invariance of the potentials

Method for a top quark mass measurement with the ATLAS detector at LHC: Study of the ATLAS level-1 electromagnetic calorimeter trigger

International Nuclear Information System (INIS)

Marzin, A.

2010-01-01

The ATLAS detector at the LHC (CERN) is designed to study the Standard Model, with the precise measurement of its parameters and the search of the Higgs boson, and the physics beyond the Standard Model with the search of new particles predicted by several theories such as Supersymmetry. The top quark is distinguished in the Standard Model by its mass close to the scale of electroweak symmetry breaking and is therefore a good probe to study physics beyond the Standard Model. A precise measurement of the top quark mass is also required to constrain the mass of the Higgs boson via the radiative corrections to the W boson propagator what would be a test of consistency of the standard Model if the Higgs boson is discovered. The first part of this thesis presents the theoretical aspects of the top quark mass. The second part is devoted to the calibration of the ATLAS level-1 electromagnetic calorimeter trigger, and more specifically to the processing of the analogue signal coming form the calorimeter. The performances of this system with cosmic muons and first LHC collisions are also described. At last, the third part describes the methods for a top quark mass measurement which have been developed in the lepton plus jets and dilepton channels. (author) [fr

Lattice investigation of nucleon structure at light quark masses

International Nuclear Information System (INIS)

Zanotti, James M.

2010-01-01

Lattice simulations of hadronic structure are now reaching a level where they are able to not only complement, but also provide guidance to current and forthcoming experimental programmes at, e.g. Jefferson Lab, COMPASS/CERN and FAIR/GSI. By considering new simulations at low quark masses and on large volumes, we review the recent progress that has been made in this exciting area by the QCDSF/UKQCD collaboration. In particular, results obtained close to the physical point for several quantities, including electromagnetic form factors and moments of ordinary parton distribution functions, show some indication of approaching their phenomenological values.

Addendum to "Charm and bottom quark masses: An update"

Science.gov (United States)

Chetyrkin, Konstantin G.; Kühn, Johann H.; Maier, Andreas; Maierhöfer, Philipp; Marquard, Peter; Steinhauser, Matthias; Sturm, Christian

2017-12-01

We update the experimental moments for the charm quark as computed in [J. H. Kühn, M. Steinhauser, and C. Sturm, Nucl. Phys. B778, 192 (2007), 10.1016/j.nuclphysb.2007.04.036] and used in [K. G. Chetyrkin, J. H. Kühn, A. Maier, P. Maierhöfer, P. Marquard, M. Steinhauser, and C. Sturm, Phys. Rev. D 80, 074010 (2009),, 10.1103/PhysRevD.80.074010 K. Chetyrkin, J. H. Kühn, A. Maier, P. Maierhöfer, P. Marquard, M. Steinhauser, and C. Sturm, Theor. Math. Phys. 170, 217 (2012), 10.1007/s11232-012-0024-7] for the determination of the charm-quark mass. The new value for the MS ¯ charm-quark mass reads mc(3 GeV )=0.993 ±0.008 GeV .

Measurement of top-quark mass and inclusive top-quark-pair production cross section in pp collisions at √(s)=7/8 TeV with CMS

International Nuclear Information System (INIS)

Schlieckau, Eike Steffen

2014-09-01

One of the most intriguing particles in the Standard Model is the top quark, the heaviest fundamental particle known to date. In this thesis, the mass of the top quark and the production cross section for top-quark pairs are measured from events with a top-quark pair decaying only into hadrons. This challenging decay mode features a high rate but is drowned by multijet background events. The top quarks are produced at the Large Hadron Collider and the decay products are detected with the Compact Muon Solenoid experiment. Data collected at centre-of-mass energies of 7 and 8 TeV with integrated luminosities of 3.54 fb -1 and 18.2 fb -1 is used for the presented measurements. In order to improve the reconstruction and identification of the desired events, constrained least-squares fitting is utilised, which exploits the kinematics of top-quark pair events. The top-quark mass and the production cross section for top-quark pairs are extracted using likelihoods from events with at least six jets created from the hadrons in the final state. In order to reduce systematic uncertainties on the result, their main sources are incorporated into the likelihoods and are estimated in parallel with the mass itself. Combining all these methods, the most precise measurement of the top-quark mass from all-jets events so far is achieved. The top-quark mass is measured to be 172.08±0.90 GeV.

Flavour blindness and patterns of flavour symmetry breaking in lattice simulations of up, down and strange quarks

Energy Technology Data Exchange (ETDEWEB)

Bietenholz, W. [Univ. Autonoma de Mexico, Mexico City (Mexico). Inst. de Ciencias Nucleares; Bornyakov, V. [Inst. for High Energy Physics, Protovino (Russian Federation); Inst. for Theoretical and Experimental Physics, Moscow (Russian Federation); Goeckeler, M. [Regensburg Univ. (DE). Inst. fuer Theoretische Physik] (and others)

2011-02-15

QCD lattice simulations with 2+1 flavours typically start at rather large up-down and strange quark masses and extrapolate first the strange quark mass to its physical value and then the up-down quark mass. An alternative method of tuning the quark masses is discussed here in which the singlet quark mass is kept fixed, which ensures that the kaon always has mass less than the physical kaon mass. Using group theory the possible quark mass polynomials for a Taylor expansion about the flavour symmetric line are found, first for the general 1+1+1 flavour case and then for the 2+1 flavour case (when two quark flavours are mass degenerate). These enable highly constrained fits to be used in the extrapolation of hadrons to the physical pion mass. Numerical results for the 2+1 flavour case confirm the usefulness of this expansion and an extrapolation to the physical pion mass gives hadron mass values to within a few percent of their experimental values. Singlet quantities remain constant which allows the lattice spacing to be determined from hadron masses (without necessarily being at the physical point). Furthermore an extension of this programme to include partially quenched results is also given. (orig.)

Review of Physics Results from the Tevatron: Top Quark Physics

Energy Technology Data Exchange (ETDEWEB)

Gerber, Cecilia E.; Vellidis, Costas

2014-09-17

We present results on top quark physics from the CDF and D0 collaborations at the Fermilab Tevatron proton anti-proton collider. These include legacy results from Run II that were published or submitted for publication before mid-2014, as well as a summary of Run I results. The historical perspective of the discovery of the top quark in Run I is also described.

Charm and beauty quark masses in the MMHT2014 global PDF analysis

Energy Technology Data Exchange (ETDEWEB)

Harland-Lang, L.A.; Motylinski, P.; Thorne, R.S. [University College London, Department of Physics and Astronomy, London (United Kingdom); Martin, A.D. [Durham University, Institute for Particle Physics Phenomenology, Durham (United Kingdom)

2016-01-15

We investigate the variation in the MMHT2014 PDFs when we allow the heavy-quark masses m{sub c} and m{sub b} to vary away from their default values.Wemake PDF sets available in steps of Δm{sub c} = 0.05 GeV and Δm{sub b} = 0.25 GeV, and present the variation in the PDFs and in the predictions. We examine the comparison to the HERA data on charm and beauty structure functions and note that in each case the heavy-quark data, and the inclusive data, have a slight preference for lower masses than our default values.We provide PDF sets with three and four active quark flavours, as well as the standard value of five flavours. We use the pole mass definition of the quark masses, as in the default MMHT2014 analysis, but briefly comment on the MS definition. (orig.)

Charm and beauty quark masses in the MMHT2014 global PDF analysis

Energy Technology Data Exchange (ETDEWEB)

Harland-Lang, L. A. [Department of Physics and Astronomy, University College London, WC1E 6BT, London (United Kingdom); Martin, A. D. [Institute for Particle Physics Phenomenology, Durham University, DH1 3LE, Durham (United Kingdom); Motylinski, P.; Thorne, R. S., E-mail: thorne@hep.ucl.ac.uk [Department of Physics and Astronomy, University College London, WC1E 6BT, London (United Kingdom)

2016-01-06

We investigate the variation in the MMHT2014 PDFs when we allow the heavy-quark masses m{sub c} and m{sub b} to vary away from their default values. We make PDF sets available in steps of Δm{sub c}=0.05 GeV and Δm{sub b}=0.25 GeV, and present the variation in the PDFs and in the predictions. We examine the comparison to the HERA data on charm and beauty structure functions and note that in each case the heavy-quark data, and the inclusive data, have a slight preference for lower masses than our default values. We provide PDF sets with three and four active quark flavours, as well as the standard value of five flavours. We use the pole mass definition of the quark masses, as in the default MMHT2014 analysis, but briefly comment on the (MS)-bar definition.

Measurement of the Top Quark Mass using Dilepton Events and a Neutrino Weighting Algorithm with the D0 Experiment at the Tevatron (Run II)

International Nuclear Information System (INIS)

Meyer, Joerg; Bonn U

2007-01-01

Elementary particle physics raises questions that are several thousand years old. What are the fundamental components of matter and how do they interact? These questions are linked to the question of what happened in the very first moments after the creation of the universe. Modern physics systematically tests nature to find answers to these and other fundamental questions. Precise theories are developed that describe various phenomena and at the same time are reduced to a few basic principals of nature. Simplification and reduction have always been guiding concepts of physics. The interplay between experimental data and theoretical descriptions led to the Standard Model of elementary particle physics. It summarizes the laws of nature and is one of most precise descriptions of nature achieved by mankind. Despite the great success of the Standard Model it is not the ultimate theory of everything. Models beyond the Standard Model try to unify all interactions in one grand unified theory. The number of free parameters is attempted to be reduced. Gravity is attempted to be incorporated. Extensions to the Standard Model like supersymmetry address the so-called hierarchy problem. Precision measurements are the key for searches of new particles and new physics. A powerful tool of experimental particle physics are particle accelerators. They provide tests of the Standard Model at smallest scales. New particles are produced and their properties are investigated. In 1995 the heaviest known elementary particle, called top quark, has been discovered at Fermilab. It differs from all other lighter quarks due to the high mass and very short lifetime. This makes the top quark special and an interesting object to be studied. A rich program of top physics at Fermilab investigates whether the top quark is really the particle as described by the Standard Model. The top quark mass is a free parameter of the theory that has been measured precisely. This thesis presents a precise

Measurement of the Top Quark Mass using Dilepton Events and a Neutrino Weighting Algorithm with the D0 Experiment at the Tevatron (Run II)

Energy Technology Data Exchange (ETDEWEB)

Meyer, Joerg [Univ. of Bonn (Germany)

2007-01-01

Elementary particle physics raises questions that are several thousand years old. What are the fundamental components of matter and how do they interact? These questions are linked to the question of what happened in the very first moments after the creation of the universe. Modern physics systematically tests nature to find answers to these and other fundamental questions. Precise theories are developed that describe various phenomena and at the same time are reduced to a few basic principals of nature. Simplification and reduction have always been guiding concepts of physics. The interplay between experimental data and theoretical descriptions led to the Standard Model of elementary particle physics. It summarizes the laws of nature and is one of most precise descriptions of nature achieved by mankind. Despite the great success of the Standard Model it is not the ultimate theory of everything. Models beyond the Standard Model try to unify all interactions in one grand unified theory. The number of free parameters is attempted to be reduced. Gravity is attempted to be incorporated. Extensions to the Standard Model like supersymmetry address the so-called hierarchy problem. Precision measurements are the key for searches of new particles and new physics. A powerful tool of experimental particle physics are particle accelerators. They provide tests of the Standard Model at smallest scales. New particles are produced and their properties are investigated. In 1995 the heaviest known elementary particle, called top quark, has been discovered at Fermilab. It differs from all other lighter quarks due to the high mass and very short lifetime. This makes the top quark special and an interesting object to be studied. A rich program of top physics at Fermilab investigates whether the top quark is really the particle as described by the Standard Model. The top quark mass is a free parameter of the theory that has been measured precisely. This thesis presents a precise

A precise determination of the top-quark pole mass

International Nuclear Information System (INIS)

Wang, Sheng-Quan; Wu, Xing-Gang; Si, Zong-Guo; Brodsky, Stanley J.

2018-01-01

The Principle of Maximum Conformality (PMC) provides a systematic way to eliminate the renormalization scheme and renormalization scale uncertainties for high-energy processes. We have observed that by applying PMC scale setting, one obtains comprehensive and self-consistent pQCD predictions for the top-quark pair total cross section and the top-quark pair forward-backward asymmetry in agreement with the measurements at the Tevatron and LHC. As a step forward, in the present paper, we determine the top-quark pole mass via a detailed comparison of the top-quark pair cross section with the measurements at the Tevatron and LHC. The results for the top-quark pole mass are m t = 174.6 +3.1 -3.2 GeV for the Tevatron with √(S) = 1.96 TeV, m t = 173.7 ± 1.5 and 174.2 ± 1.7 GeV for the LHC with √(S) = 7 and 8 TeV, respectively. Those predictions agree with the average, 173.34 ± 0.76 GeV, obtained from various collaborations via direct measurements. The consistency of the pQCD predictions using the PMC with all of the collider measurements at different energies provides an important verification of QCD. (orig.)

A precise determination of the top-quark pole mass

Science.gov (United States)

Wang, Sheng-Quan; Wu, Xing-Gang; Si, Zong-Guo; Brodsky, Stanley J.

2018-03-01

The Principle of Maximum Conformality (PMC) provides a systematic way to eliminate the renormalization scheme and renormalization scale uncertainties for high-energy processes. We have observed that by applying PMC scale setting, one obtains comprehensive and self-consistent pQCD predictions for the top-quark pair total cross section and the top-quark pair forward-backward asymmetry in agreement with the measurements at the Tevatron and LHC. As a step forward, in the present paper, we determine the top-quark pole mass via a detailed comparison of the top-quark pair cross section with the measurements at the Tevatron and LHC. The results for the top-quark pole mass are m_t=174.6^{+3.1}_{-3.2} GeV for the Tevatron with √{S}=1.96 TeV, m_t=173.7± 1.5 and 174.2± 1.7 GeV for the LHC with √{S} = 7 and 8 TeV, respectively. Those predictions agree with the average, 173.34± 0.76 GeV, obtained from various collaborations via direct measurements. The consistency of the pQCD predictions using the PMC with all of the collider measurements at different energies provides an important verification of QCD.

Heavy quark physics in ep collisions at LEP+LHC

International Nuclear Information System (INIS)

Ali, A.; Barreiro, F.; Troconiz, J.F. de; Schuler, G.A.; Bij, J.J. van der

1990-12-01

We study electroweak production of heavy quarks - charm, beauty, and top - in deep inelastic electron-proton collisions at the proposed LEP+LHC collider at CERN. The assumed energy for the collisions is E e =50 GeV, E p =8000 GeV, providing an ep center of mass energy, √s≅1.26 TeV. We invoke the boson-gluon fusion model to estimate theoretical cross sections and distributions for the heavy quarks. Higher order QCD corrections are only approximately taken into account, by assuming a (normalization) K-factor of 2 for the charm and beauty quark production rates and incorporating the parton shower cascades. With these assumptions and the parameterization of Eichten et al. for the structure functions (EHLQ, set 1), we find the following cross sections: σ(ep→c+X)≅O(3 μb), σ(ep→b+X)≅O(40 nb), and σ(ep→t+X)≅4 pb for m t =120 GeV, decreasing to 0.5 pb for m t =250 GeV. These cross sections would provide O(6x10 9 ) charmed hadrons, O(8x10 7 ) beauty hadrons, and O(10 3 ) top hadrons, for an integrated ep luminosity of 1000 pb -1 . The heavy quark rates in ep collisions are considerably smaller than the corresponding rates in pp collisions at LHC, with √s=16 TeV. This gives a clear advantage to pp collisions for top searches. However, for the charmed and beauty quarks only a tiny fraction of the cross sections in p+p→Q+X can be triggered in comparison to the corresponding cross sections in e+p→Q+X, resulting in comparable number of measured heavy quark events in the ep and pp mode. We sketch the energy-momentum profile of heavy quark events in ep collisions and illustrate the kind of analyses that experiments at the LEP+LHC collider would undertake to quantitatively study heavy quark physics. In particular, prospects of measuring the particle-antiparticle mixing parameter x s =ΔM/Γ for the B s 0 -anti B s 0 meson system are evaluated, and search strategies for the top quark in ep collisions are presented. (orig.)

On the ultimate uncertainty of the top quark pole mass

Energy Technology Data Exchange (ETDEWEB)

Beneke, M. [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Marquard, P. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Nason, P. [INFN, Sezione di Milano Bicocca (Italy); Steinhauser, M. [Karlsruher Institut fuer Technologie (Germany). Inst. fuer Theoretische Teilchenphysik

2016-05-15

We combine the known asymptotic behaviour of the QCD perturbation series expansion, which relates the pole mass of a heavy quark to the MS mass, with the exact series coefficients up to the four-loop order to determine the ultimate uncertainty of the top-quark pole mass due to the renormalon divergence. We perform extensive tests of our procedure by varying the number of colours and flavours, as well as the scale of the strong coupling and the MS mass, and conclude that this uncertainty is around 70 MeV. We further estimate the additional contribution to the mass relation from the five-loop correction and beyond to be 250 MeV.

On the ultimate uncertainty of the top quark pole mass

International Nuclear Information System (INIS)

Beneke, M.; Nason, P.; Steinhauser, M.

2016-05-01

We combine the known asymptotic behaviour of the QCD perturbation series expansion, which relates the pole mass of a heavy quark to the MS mass, with the exact series coefficients up to the four-loop order to determine the ultimate uncertainty of the top-quark pole mass due to the renormalon divergence. We perform extensive tests of our procedure by varying the number of colours and flavours, as well as the scale of the strong coupling and the MS mass, and conclude that this uncertainty is around 70 MeV. We further estimate the additional contribution to the mass relation from the five-loop correction and beyond to be 250 MeV.

Higgs boson pair production: Top quark mass effects at NLO and NNLO

Directory of Open Access Journals (Sweden)

Jonathan Grigo

2015-11-01

Full Text Available We compute next-to-next-to-leading order QCD corrections to the gluon-induced production cross section of Higgs boson pairs in the large top quark mass limit using the soft-virtual approximation. In the limit of infinitely-heavy top quark we confirm the results in the literature. We add two more expansion terms in the inverse top quark mass to the Mt→∞ result. Since the 1/Mt expansion converges poorly, we try to improve on it by factorizing the exact leading order cross section. We discuss two ways of doing that and conclude that the finite top quark mass effects shift the cross section at most by about 10% at next-to-leading order and by about 5% at next-to-next-to-leading order.

Towards OPE based local quark-hadron duality: light-quark channels

International Nuclear Information System (INIS)

Hofmann, Ralf

2002-01-01

Various light-quark channel current-current correlators are subjected to the concept of a non-perturbative component of coarse graining in operator product expansions introduced in a parallel work. This procedure allows for low-energy structure of the OPE-derived spectral function. With naive vacuum saturation for 4-quark operators and using lattice data for the gauge invariant scalar quark correlator the results are far off the experimentally measured behavior. However, using the correlation length of the gauge invariant vector quark correlator, which is about 10 times smaller than the scalar one, the qualitative results are rather realistic. Namely, the input of information on the mass of the lowest resonance in one channel yields the corresponding masses within acceptable errors in other channels. Still, the shapes of the calculated spectral functions are considerably deformed as compared to experiment. This may be a consequence of vacuum saturation and the truncation at a mass dimension which is below the critical dimension from which on the asymptotic expansion does not approximate anymore. To improve on this high-resolution lattice information on gauge invariant n>2 point correlators would be needed. Motivated by the small effective correlation length in the 4-quark contributions the relevance of the approach for heavy quark physics, in particular in the calculation of non-leptonic, inclusive ΔΓ, is discussed

Measurement of the Top Quark Mass Simultaneously in Dilepton and Lepton + Jets Decay Channels

Energy Technology Data Exchange (ETDEWEB)

Fedorko, Wojciech T. [Univ. of Chicago, IL (United States)

2008-12-01

The authors present the first measurement of the top quark mass using simultaneously data from two decay channels. They use a data sample of √s = 1.96 TeV collisions with integrated luminosity of 1.9 fb^-1 collected by the CDF II detector. They select dilepton and lepton + jets channel decays of t$\\bar{t}$ pairs and reconstruct two observables in each topology. They use non-parametric techniques to derive probability density functions from simulated signal and background samples. The observables are the reconstructed top quark mass and the scalar sum of transverse energy of the event in the dilepton topology and the reconstructed top quark mass and the invariant mass of jets from the W boson decay in lepton + jets channel. They perform a simultaneous fit for the top quark mass and the jet energy scale which is constrained in situ by the hadronic W boson resonance from the lepton + jets channel. Using 144 dilepton candidate events and 332 lepton + jets candidate events they measure: M_top = 171.9 ± 1.7 (stat. + JES) ± 1.1 (other sys.) GeV/c² = 171.9 ± 2.0 GeV/c². The measurement features a robust treatment of the systematic uncertainties, correlated between the two channels and develops techniques for a future top quark mass measurement simultaneously in all decay channels. Measurements of the W boson mass and the top quark mass provide a constraint on the mass of the yet unobserved Higgs boson. The Higgs boson mass implied by measurement presented here is higher than Higgs boson mass implied by previously published, most precise CDF measurements of the top quark mass in lepton + jets and dilepton channels separately.

Triplicity of hadrons, quarks and subquarks

International Nuclear Information System (INIS)

Terazawa, Hidezumi.

1989-11-01

Triplicity of hadrons, quarks and subquarks asserting that a certain physical quantity such as the weak current is taken equally well as either one of a composite operator of hadrons, that of quarks and that of subquarks is proposed. Among other things, the weak mixing angle, the quark mixing matrix and the mass sum rules for quarks and leptons are revisited, reinterpreted and discussed in detail in triplicity. (author)

Calibration of the top-quark Monte-Carlo mass

International Nuclear Information System (INIS)

Kieseler, Jan; Lipka, Katerina; Moch, Sven-Olaf

2015-11-01

We present a method to establish experimentally the relation between the top-quark mass m MC t as implemented in Monte-Carlo generators and the Lagrangian mass parameter m t in a theoretically well-defined renormalization scheme. We propose a simultaneous fit of m MC t and an observable sensitive to m t , which does not rely on any prior assumptions about the relation between m t and m MC t . The measured observable is independent of m MC t and can be used subsequently for a determination of m t . The analysis strategy is illustrated with examples for the extraction of m t from inclusive and differential cross sections for hadro-production of top-quarks.

Search for New Physics in Top Quark Production and Upgrade of the CMS Hadron Calorimeter

International Nuclear Information System (INIS)

Yumiceva, Francisco

2016-01-01

Our goal is to measure precisely the properties of the heaviest subatomic particle ever discovered, the top quark. In the proton-proton collisions at the LHC, top quarks are produced copiously. The largest set of top quarks recorded by the CMS detector make it an ideal laboratory to measure properties such as its mass and the rate at which pair of top quarks are produced in association with energetic photons. Quantum electrodynamics, or QED, describes the emission of light by charged particles and is the most precise physics theory ever devised. Typically this means light emitted by electrons, but any charged particles will do, such as the top quark. Studies of the light-emitting properties of top quarks help us to refine our current theoretical predictions at the finest level, and provide additional tools to study in more detail the recently discovered Higgs boson particle. However, during this process, the studies may reveal interesting features not yet observed. Deviations from the standard predictions would be a strong sign of something entirely new. These new physics theories are motivated to answer the current big mysteries in the universe such as what is the nature of mass or what is dark matter. As the LHC increases the collision energy and its luminosity, the detectors need to be improved to cope with these high-luminosity scenarios. New sensors will be installed in the hadron calorimeter detectors along with new front and end electronics at the end of 2016. We are testing and calibrating the new front-end readout electronics that will allow us to have more options to reduce the noise on these detectors. In order to do this calibration, we have developed a system that can inject electric charge in the full range of the charge integrator chip, the QIE ASICs.

Search for New Physics in Top Quark Production and Upgrade of the CMS Hadron Calorimeter

Energy Technology Data Exchange (ETDEWEB)

Yumiceva, Francisco [Florida Inst. of Technology, Melbourne, FL (United States)

2016-10-07

Our goal is to measure precisely the properties of the heaviest subatomic particle ever discovered, the top quark. In the proton-proton collisions at the LHC, top quarks are produced copiously. The largest set of top quarks recorded by the CMS detector make it an ideal laboratory to measure properties such as its mass and the rate at which pair of top quarks are produced in association with energetic photons. Quantum electrodynamics, or QED, describes the emission of light by charged particles and is the most precise physics theory ever devised. Typically this means light emitted by electrons, but any charged particles will do, such as the top quark. Studies of the light-emitting properties of top quarks help us to refine our current theoretical predictions at the finest level, and provide additional tools to study in more detail the recently discovered Higgs boson particle. However, during this process, the studies may reveal interesting features not yet observed. Deviations from the standard predictions would be a strong sign of something entirely new. These new physics theories are motivated to answer the current big mysteries in the universe such as what is the nature of mass or what is dark matter. As the LHC increases the collision energy and its luminosity, the detectors need to be improved to cope with these high-luminosity scenarios. New sensors will be installed in the hadron calorimeter detectors along with new front and end electronics at the end of 2016. We are testing and calibrating the new front-end readout electronics that will allow us to have more options to reduce the noise on these detectors. In order to do this calibration, we have developed a system that can inject electric charge in the full range of the charge integrator chip, the QIE ASICs.

Search for exotic light-flavor quark partners in pp collisions at a center of mass energy of 8 TeV with the CMS detector

Energy Technology Data Exchange (ETDEWEB)

Onsem, Gerrit van [Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, D-22607 Hamburg (Germany)

2016-07-01

Vector-like quarks appear in many new-physics models extending the standard model. We search for vector-like quarks coupling to first-generation quarks using 8 TeV pp collision data collected by the CMS detector at the CERN Large Hadron Collider. The exotic quarks are assumed to be produced both singly and in pairs, and to decay via a W, Z or Higgs boson. We have defined various sets of selections on the reconstructed physics objects, subdividing the data set in different event categories, considering final states with at least one muon or electron. No significant excess over standard model expectations has been found, and exclusion limits on the mass of the exotic quarks are set.

A new observable to measure the top-quark mass at hadron colliders

Energy Technology Data Exchange (ETDEWEB)

Alioli, S. [Lawrence Berkeley National Lab., CA (United States); California Univ., Berkeley, CA (United States); Fernandez, P.; Fuster, J.; Irles, A.; Vos, M. [Valencia Univ. (Spain). IFIC; CSIC, Paterna (Spain); Moch, S. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Uwer, P. [Humboldt-Universitaet, Berlin (Germany)

2013-03-15

A new method to measure the top-quark mass in high energetic hadron collisions is presented. We use theoretical predictions calculated at next-to-leading order accuracy in quantum chromodynamics to study the (normalized) differential distribution of the t anti t+1-jet cross section with respect to its invariant mass {radical}(s{sub t} {sub anti} {sub tj}). The sensitivity of the method to the top-quark mass together with the impact of various theoretical and experimental uncertainties has been investigated and quantified. The new method allows for a complementary measurement of the top-quark mass parameter and has a high potential to become competitive in precision with respect to established approaches. Furthermore we emphasize that in the proposed method the mass parameter is uniquely defined through one-loop renormalization.

A new observable to measure the top-quark mass at hadron colliders

International Nuclear Information System (INIS)

Alioli, S.; Fernandez, P.; Fuster, J.; Irles, A.; Vos, M.; Moch, S.; Uwer, P.

2013-03-01

A new method to measure the top-quark mass in high energetic hadron collisions is presented. We use theoretical predictions calculated at next-to-leading order accuracy in quantum chromodynamics to study the (normalized) differential distribution of the t anti t+1-jet cross section with respect to its invariant mass √(s t anti tj ). The sensitivity of the method to the top-quark mass together with the impact of various theoretical and experimental uncertainties has been investigated and quantified. The new method allows for a complementary measurement of the top-quark mass parameter and has a high potential to become competitive in precision with respect to established approaches. Furthermore we emphasize that in the proposed method the mass parameter is uniquely defined through one-loop renormalization.

Top quark properties and mass measurements with the ATLAS detector

CERN Document Server

Moreno Llacer, Maria; The ATLAS collaboration

2017-01-01

ID# 104 Top quark properties and mass measurements with the ATLAS detector The top quark is unique among the known quarks in that it decays before it has an opportunity to form hadronic bound states. This makes measurements of its properties particularly interesting as one can access directly the properties of a bare quark. The latest measurements of these properties with the ATLAS detector at the LHC are presented using 8 TeV and 13 TeV data. Measurements of top quark spin observables in top-antitop events, each sensitive to a different coefficient of the spin density matrix, are presented and compared to the Standard Model predictions. The helicity of the W boson from the top decays and the production angles of the top quark are further discussed. Limits on the rate of flavour changing neutral currents in the production or decay of the top quark are reported. The production of top-quark pairs in association with W and Z bosons is also presented. The measurement probes the coupling between the top quark and ...

Searches for exotic heavy quarks decaying into a W-Boson and a b-Quark with the ATLAS experiment

CERN Document Server

Nektarijevic, Snezana

In this thesis, searches for two hypothetical heavy quarks are presented: the fourth Standard Model generation up-type quark t’, and the vector-like quark T, predicted by the new physics models involving extra dimensions or a composite Higgs boson. Both searches assume pair production of the heavy quarks decaying to a W-boson and a b-quark, and are performed in final states with one electron or muon, at least three jets, and significant missing transverse energy. The first search employs the kinematic fitting of the reconstructed quark mass, while the second relies on the artificial neural network method. In both searches no excess of data over the Standard Model expectation is observed, resulting in observed lower bounds on the quark masses of mt’>404 GeV and mT>618 GeV. Both searches are based on proton-proton collision data at 7 TeV centre-of-mass energy collected by the ATLAS experiment at CERN’s Large Hadron Collider in 2011.

Mass spectrum of low-lying baryons in the ground state in a relativistic potential model of independent quarks with chiral symmetry

International Nuclear Information System (INIS)

Barik, N.; Dash, B.K.

1986-01-01

Under the assumption that baryons are an assembly of independent quarks, confined in a first approximation by an effective potential U(r) = 1/2(1+γ 0 )(ar 2 +V 0 ) which presumably represents the nonperturbative gluon interactions, the mass spectrum of the low-lying ground-state baryons has been calculated by considering perturbatively the contributions of the residual quark-pion coupling arising out of the requirement of chiral symmetry and that of the quark-gluon coupling due to one-gluon exchange over and above the necessary center-of-mass correction. The physical masses of the baryons so obtained agree quite well with the corresponding experimental value. The strong coupling constant α/sub c/ = 0.58 required here to describe the QCD mass splittings is quite consistent with the idea of treating one-gluon-exchange effects in lowest-order perturbation theory

Recent results on top quark physics with the CMS detector

CERN Multimedia

CERN. Geneva

2016-01-01

The dawn of the LHC Run II brings the prospect of pushing precision in top quark physics to a new level probing further the standard model and beyond. The inclusive production of top quark pairs and single top quarks has been rapidly established with as much as 42/pb of integrated luminosity and has been further probed with increased precision using up to 2.7/fb of proton-proton collision data acquired by the CMS detector during 2015. Inclusive and differential production cross sections of top-quark pairs and single-top quarks have been measured using new selection and top kinematics reconstruction techniques. The results have been compared to several predictions which include the state of the art next-to-leading order matched to parton shower generators as well as several fixed-order theory calculations. In addition the associated production of top quark pairs with a Z boson has also been re-established at 13 TeV. These results re-open the door to an exciting top quark physics programme ahead of us during th...

The phase diagram of high temperature QCD with three flavors of improved staggered quarks

International Nuclear Information System (INIS)

Bernard, C.; Burch, T.; DeTar, C.E.; Gottlieb, Steven; Gregory, E.B.; Heller, U.M.; Hetrick, J.E.; Sugar, R.L.; Toussaint, D.

2004-01-01

We report on progress in our study of high temperature QCD with three flavors of improved staggered quarks. Simulations are being carried out with three degenerate quarks with masses less than or equal to the strange quark mass, m s , and with degenerate up and down quarks with masses in the range 0.1 m s ≤ m u,d ≤ 0.6 m s , and the strange quark mass fixed near its physical value. For the quark masses studied to date we find rapid crossovers, which sharpen as the quark mass is reduced, rather than bona fide phase transitions

Top quark properties and mass measurements with the ATLAS detector

CERN Document Server

Negrini, Matteo; The ATLAS collaboration

2017-01-01

Highlights on recent measurements of top quark properties in ATLAS, using pp collision data at \\sqrt{s}= 8 TeV and 13 TeV, are presented. The measurements of the top quark polarization and spin correlation coefficients, the W boson helicity fractions, the structure of the Wtb vertex, the associated production of a t anti-t pair with a vector boson or a photon, and the top quark mass are all in agreement with the Standard Model expectations.

Measurements of the top-quark properties with the ATLAS detector at the LHC

CERN Document Server

Yu, J; The ATLAS collaboration

2013-01-01

The top-quark discovered in 1995 is the third-generation up-type quark of the standard model (SM) of particle physics. Precise measurements of the top-quark properties at the Large Hadron Collider (LHC) energies are of great interest, providing an opportunity to test the SM and to search for new physics in the top-quark sector. This review covers recent results from the ATLAS experiment on measurements of top-quark mass, polarization, spin correlations between top-quark and antitop-quark, $t\\bar{t}\\gamma$ cross section, $W$-boson polarization in top-quark decays and searches for new physics in events with top-quarks in the final state. Measurements have been performed on data collected by the ATLAS detector corresponding up to 5 $fb^{-1}$ of integrated luminosity at centre-of-mass energy of $\\sqrt{s}$ = 7 TeV.

Quarked!--Adventures in Particle Physics Education

Science.gov (United States)

MacDonald, Teresa; Bean, Alice

2009-01-01

Particle physics is a subject that can send shivers down the spines of students and educators alike--with visions of long mathematical equations and inscrutable ideas. This perception, along with a full curriculum, often leaves this topic the road less traveled until the latter years of school. Particle physics, including quarks, is typically not…

Measurements of the top quark mass with the D0 detector

Energy Technology Data Exchange (ETDEWEB)

Brandt, Oleg [Kirchhoff Inst. Phys.

2016-06-02

The mass of the top quark is a fundamental parameter of the standard model (SM) and has to be determined experimentally. In this talk, I present the most recent measurements of the top quark mass in $p\\bar p$ collisions at $\\sqrt s=1.96$~TeV recorded by the D0 experiment at the Fermilab Tevatron Collider. The measurements are performed in final states containing two leptons, using 5.4~\\fb of integrated luminosity, and one lepton, using 9.7~\\fb of integrated luminosity. The latter constitutes the most precise single measurement of the mass of the top quark, corresponding to a relative precision of 0.43\\%. I conclude with a combination of our results with the results by the CDF collaboration, attaining a relative precision of 0.37\\%

Evading the top-quark mass bound at the Fermilab Tevatron: New signals for the top quark

International Nuclear Information System (INIS)

Mukhopadhyaya, B.; Nandi, S.

1991-01-01

If an SU(2)-singlet charge-2/3 quark exists, current data allow a wide range for the parameters of the 4x4 mixing matrix in which the usual ''hard-lepton'' signal of the top quark is suppressed. For a light Higgs boson, the top quark decays predominantly via the flavor-changing Yukawa interaction, thus evading the Fermilab Tevatron bounds on its mass. For a heavier Higgs boson, flavor-changing neutral-current decays become important, giving rise to anomalous Z-pair production, testable at the upgraded Tevetron, at the CERN Large Hardon Collider, and at the Superconducting Super Collider

Fritzsch-type mass matrices and the Wolfenstein parametrization of quark mixing

International Nuclear Information System (INIS)

Kang, K.; Hadjitheodoridis, S.; Brown Univ., Providence, RI

1987-01-01

We give approximate and analytic expressions of polynomial type in small parameters defined in terms of quark mass ratios for the elements of the flavor-mixing matrix predicted from the Fritzsch-type mass matrices of quarks. The results are successfully tested against experiments as represented by the Wolfenstein parametrization of quark mixing. From the reality of the CP phases we get an allowed range for m s , which in turn implies that m t can be as large as 80.8 GeV. In addition we find that the two CP phases α and β are very close, i.e., vertical strokeα-βvertical stroke ≅ O(λ). (orig.)

Differential distributions for top-quark hadro-production with a running mass

International Nuclear Information System (INIS)

Dowling, M.; Moch, S.; Hamburg Univ.

2013-05-01

We take a look at how the differential distributions for top-quark production are affected by changing to the running mass scheme. Specifically we consider the transverse momentum, rapidity and pair-invariant mass distributions at NLO for the top-quark mass in the MS scheme. It is found that, similar to the total cross section, the perturbative expansion converges faster and the scale dependence improves using the mass in the MS scheme as opposed to the on-shell scheme. We also update the analysis for the total cross section using the now available full NNLO contribution.

Differential distributions for top-quark hadro-production with a running mass

Energy Technology Data Exchange (ETDEWEB)

Dowling, M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

2013-05-15

We take a look at how the differential distributions for top-quark production are affected by changing to the running mass scheme. Specifically we consider the transverse momentum, rapidity and pair-invariant mass distributions at NLO for the top-quark mass in the MS scheme. It is found that, similar to the total cross section, the perturbative expansion converges faster and the scale dependence improves using the mass in the MS scheme as opposed to the on-shell scheme. We also update the analysis for the total cross section using the now available full NNLO contribution.

Scaling studies of QCD with the dynamical highly improved staggered quark action

International Nuclear Information System (INIS)

Bazavov, A.; Freeman, W.; Toussaint, D.; Bernard, C.; Laiho, J.; DeTar, C.; Levkova, L.; Oktay, M.; Gottlieb, Steven; Heller, U. M.; Hetrick, J. E.; Osborn, J.; Sugar, R. L.; Van de Water, R. S.

2010-01-01

We study the lattice spacing dependence, or scaling, of physical quantities using the highly improved staggered quark (HISQ) action introduced by the HPQCD/UKQCD Collaboration, comparing our results to similar simulations with the asqtad fermion action. Results are based on calculations with lattice spacings approximately 0.15, 0.12, and 0.09 fm, using four flavors of dynamical HISQ quarks. The strange and charm quark masses are near their physical values, and the light-quark mass is set to 0.2 times the strange-quark mass. We look at the lattice spacing dependence of hadron masses, pseudoscalar meson decay constants, and the topological susceptibility. In addition to the commonly used determination of the lattice spacing through the static quark potential, we examine a determination proposed by the HPQCD Collaboration that uses the decay constant of a fictitious ''unmixed ss'' pseudoscalar meson. We find that the lattice artifacts in the HISQ simulations are much smaller than those in the asqtad simulations at the same lattice spacings and quark masses.

Measurements of the top-quark decay width and mass at CDF using the template method.

Energy Technology Data Exchange (ETDEWEB)

Tang, Jian [Univ. of Chicago, IL (United States)

2012-05-10

Measurements of the top quark decay width and mass are presented using the tt events produced in p p collisions at Fermilab's Tevatron collider and collected by the CDF II detector. A data sample corresponding to 4.3 fb^-1 of integrated luminosity is used for the top quark width measurement. Two estimators, the reconstructed top quark mass and the mass of hadronically decaying W boson that comes from the top-quark decay are reconstructed for each event and compared with templates of different input top quark widths and deviations from nominal CDF jet energy scale (ΔJES) to perform a simultaneous fit for both parameters. ΔJES is used for the in situ calibration of the jet energy scale at CDF. By applying a Feldman-Cousins limit-setting approach, we establish an upper limit at 95% confidence level (CL) of Γtop < 7.6 GeV and a two-sided 68% CL interval of (0.3 GeV, 4.4) GeV assuming a top quark mass of 172.5 GeV/c², which are consistent with the standard model prediction. The measurement of the top quark mass uses a data sample of tt events in 5.7 fb^-1 of integrated luminosity collected by the same detector. Candidate events in the top quark mass measurement are required to have large missing transverse energy, no identified charged leptons, and four, five, or six jets with at least one jet tagged as coming from a b quark. This analysis considers events from the semileptonic tt decay channel, including events that contain tau leptons. The measurement is based on a multidimensional template method, in a similar way to the top quark width measurement, and the top quark mass is measured to be Mtop = 172.32 ± 2.37 ± 0.98 GeV/c² .

Predicting {theta}{sub 13} and the neutrino mass scale from quark lepton mass hierarchies

Energy Technology Data Exchange (ETDEWEB)

Buchmueller, W.; Domcke, V.; Schmitz, K.

2011-11-15

Flavour symmetries of Froggatt-Nielsen type can naturally reconcile the large quark and charged lepton mass hierarchies and the small quark mixing angles with the observed small neutrino mass hierarchies and their large mixing angles. We point out that such a flavour structure, together with the measured neutrino mass squared differences and mixing angles, strongly constrains yet undetermined parameters of the neutrino sector. Treating unknown O(1) parameters as random variables, we obtain surprisingly accurate predictions for the smallest mixing angle, sin{sup 2}2{theta}{sub 13}=0.07{sup +0.11}{sub -0.05}, the smallest neutrino mass, m{sub 1}=2.5{sup +1.7}{sub -1.6} x 10{sup -3} eV, and one Majorana phase, {alpha}{sub 21}/{pi}=1.0{sup +0.2}{sub -0.2}. (orig.)

Physics of the top quark at D0 new measurement of the production cross section and mass

International Nuclear Information System (INIS)

Genser, K.

1997-07-01

We present a measurement of the t anti t production cross section in p anti p collisions at √s = 1.8 TeV and a measurement of top quark mass m t by the D0 experiment at the Fermilab Tevatron. The measurements are based on the data from the 1992- 1996 run during which the D0 detector was exposed to the integrated luminosity of approximately 125 pb -1 . We observe 39 t anti t candidate events in the dilepton and lepton+jets decay channels with an expected background of 13.7 ± 2.2 events. We measure the top quark mass m t using a two constraint fit to m t in t anti t → bW + anti bW - final states with one W decaying to q anti q and the other to eν or μν. Events are binned in the fit mass versus a measure of probability for events to be the signal rather than a background. Likelihood fits to the data yield m t = 173.3 ± 5.6 (stat) ± 6.2 (syst) GeV/c 2 . For this mass we measure the t anti t production cross section to be 5.5 ± 1.8 pb

PDFs, α_s, and quark masses from global fits

International Nuclear Information System (INIS)

Alekhin, Sergey; Bluemlein, Johannes; Moch, Sven-Olaf

2016-09-01

The strong coupling constant α_s and the heavy-quark masses, m_c, m_b, m_t are extracted simultaneously with the parton distribution functions (PDFs) in the updated ABM12 fit including recent data from CERN-SPS, HERA, Tevatron, and the LHC. The values of α_s(M_Z)=0.1147±0.0008(exp.), m_c(m_c)=1.252±0.018(exp.) GeV, m_b(m_b)=3.83±0.12(exp.) GeV, m_t(m_t)=160.9±1.1(exp.) GeV are obtained with the MS heavy-quark mass definition being employed throughout the analysis.

Eleven lectures on the physics of the quark-gluon plasma

International Nuclear Information System (INIS)

McLerran, L.

1984-10-01

These lectures are intended to be an introduction to the physics of the quark-gluon plasma, and were presented at a workshop on The Physics of the Quark-Gluon Plasma held at Hua-Zhong Normal University in Wuhan, People's Republic of China in September, 1983. The lectures cover perturbation theory of the plasma at high temperature as well as the non-perturbative methods and results of lattice gauge theory computations. Physical models of the confinement-deconfinement phase transition and the modes of chiral symmetry breaking are presented. The possibility that a quark-gluon plasma might be produced in ultra-relativistic nuclear collisions is analyzed. Separate entries were prepared for the data base for the eleven lectures

General structure of democratic mass matrix of quark sector in E{sub 6} model

Energy Technology Data Exchange (ETDEWEB)

Ciftci, R., E-mail: rciftci@cern.ch [Ankara (Turkey); Çiftci, A. K., E-mail: abbas.kenan.ciftci@cern.ch [Ankara University, Ankara (Turkey)

2016-03-25

An extension of the Standard Model (SM) fermion sector, which is inspired by the E{sub 6} Grand Unified Theory (GUT) model, might be a good candidate to explain a number of unanswered questions in SM. Existence of the isosinglet quarks might explain great mass difference of bottom and top quarks. Also, democracy on mass matrix elements is a natural approach in SM. In this study, we have given general structure of Democratic Mass Matrix (DMM) of quark sector in E6 model.

Controlling quark mass determinations non-perturbatively in three-flavour QCD

CERN Document Server

Campos, Isabel

2017-01-01

The determination of quark masses from lattice QCD simulations requires a non-perturbative renormalization procedure and subsequent scale evolution to high energies, where a conversion to the commonly used MS-bar scheme can be safely established. We present our results for the non-perturbative running of renormalized quark masses in Nf=3 QCD between the electroweak and a hadronic energy scale, where lattice simulations are at our disposal. Recent theoretical advances in combination with well-established techniques allows to follow the scale evolution to very high statistical accuracy, and full control of systematic effects.

Origin of CP-violation through quark mass matrix

International Nuclear Information System (INIS)

Kang, K.

1990-01-01

After a brief review of the CP violation models, we trace the origin of CP-phases from the phases of a class of quark mass matrices compatible with the calculability condition. The case of three generations corresponding to the standard milliweak CP model is discussed explicitly for the generic case of Fritzsch-type mass matrices. (orig.)

Properties of the Top Quark

Energy Technology Data Exchange (ETDEWEB)

Wicke, Daniel; /Wuppertal U., Dept. Math.

2009-08-01

Tevatron experiments CDF and D0 and was the last of the quarks to be discovered. As the partner of the bottom quark the top quark is expected to have quantum numbers identical to that of the other known up-type quarks. Only the mass is a free parameter. We now know that it is more than 30 times heavier than the next heaviest quark, the bottom quark. Thus, within the Standard Model all production and decay properties are fully defined. Having the complete set of quarks further allows to verify constraints that the Standard Model puts on the sum of all quarks or particles. This alone is reason enough to experimentally study the top quark properties. The high value of the top quark mass and its closeness to the electroweak scale has inspired people to speculate that the top quark could have a special role in the electroweak symmetry breaking. Confirming the expected properties of the top quark experimentally establishes the top quark as we expect it to be. Any deviation from the expectations gives hints to new physics that may help to solve the outstanding questions. In this review the recent results on top quark properties obtained by the Tevatron experiments CDF and D0 are summarized. At the advent of the LHC special emphasis is given to the basic measurement methods and the dominating systematic uncertainties. After a short introduction to the Standard Model and the experimental environment in the remainder of this chapter, Chapter 2 describes the current status of top quark mass measurements. Then measurments of interaction properties are described in Chapter 3. Finally, Chapter 4 deals with analyses that consider hypothetical particles beyond the Standard Model in the observed events.

Properties of the Top Quark

International Nuclear Information System (INIS)

Wicke, Daniel

2009-01-01

Tevatron experiments CDF and D0 and was the last of the quarks to be discovered. As the partner of the bottom quark the top quark is expected to have quantum numbers identical to that of the other known up-type quarks. Only the mass is a free parameter. We now know that it is more than 30 times heavier than the next heaviest quark, the bottom quark. Thus, within the Standard Model all production and decay properties are fully defined. Having the complete set of quarks further allows to verify constraints that the Standard Model puts on the sum of all quarks or particles. This alone is reason enough to experimentally study the top quark properties. The high value of the top quark mass and its closeness to the electroweak scale has inspired people to speculate that the top quark could have a special role in the electroweak symmetry breaking. Confirming the expected properties of the top quark experimentally establishes the top quark as we expect it to be. Any deviation from the expectations gives hints to new physics that may help to solve the outstanding questions. In this review the recent results on top quark properties obtained by the Tevatron experiments CDF and D0 are summarized. At the advent of the LHC special emphasis is given to the basic measurement methods and the dominating systematic uncertainties. After a short introduction to the Standard Model and the experimental environment in the remainder of this chapter, Chapter 2 describes the current status of top quark mass measurements. Then measurments of interaction properties are described in Chapter 3. Finally, Chapter 4 deals with analyses that consider hypothetical particles beyond the Standard Model in the observed events.

Search for Top Quark Pair Resonances with the CMS Detector at the LHC

CERN Document Server

AUTHOR|(CDS)2159607

2013-07-15

The Standard Model of particle physics is not the final theory. It breaks at larger (TeV) scales and thus can not explain the hierarchy problem, the unification of couplings and some physical phenomena. Several physical models, referred to as Beyond the Standard Model, have been proposed to account for the phenomena which are not explained by the Standard Model, and to answer to some of these open questions. As the top quark has as an enormous mass of about 173.3 GeV, it plays an essential role in searches for new physics. Various models beyond the Standard Model predict the existence of heavy particles decaying into top quark pairs. These particles manifest themselves as resonant structures in the invariant mass spectrum of the top quark pairs. In this thesis, a model-independent search has been performed for top quark pair resonances in the mass range close to the top quark pair production threshold. The Topcolor Z' model is considered as a reference model. The presented search focuses on top quark pair eve...

Top-quark mass measurement from dilepton events at CDF II.

Science.gov (United States)

Abulencia, A; Acosta, D; Adelman, J; Affolder, T; Akimoto, T; Albrow, M G; Ambrose, D; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arguin, J-F; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Bachacou, H; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Bedeschi, F; Behari, S; Belforte, S; Bellettini, G; Bellinger, J; Belloni, A; Ben-Haim, E; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bishai, M; Blair, R E; Blocker, C; Bloom, K; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Bourov, S; Boveia, A; Brau, B; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carlsmith, D; Carosi, R; Carron, S; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chapman, J; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Chu, P H; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Ciljak, M; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Coca, M; Connolly, A; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Cruz, A; Cuevas, J; Culbertson, R; Cyr, D; DaRonco, S; D'Auria, S; D'Onofrio, M; Dagenhart, D; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; Dell'Orso, M; Demers, S; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Dionisi, C; Dittmann, J; Dituro, P; Dörr, C; Dominguez, A; Donati, S; Donega, M; Dong, P; Donini, J; Dorigo, T; Dube, S; Ebina, K; Efron, J; Ehlers, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Field, R; Flanagan, G; Flores-Castillo, L R; Foland, A; Forrester, S; Foster, G W; Franklin, M; Freeman, J C; Fujii, Y; Furic, I; Gajjar, A; Gallinaro, M; Galyardt, J; Garcia, J E; Garcia Sciverez, M; Garfinkel, A F; Gay, C; Gerberich, H; Gerchtein, E; Gerdes, D; Giagu, S; Giannetti, P; Gibson, A; Gibson, K; Ginsburg, C; Giolo, K; Giordani, M; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Gotra, Y; Goulianos, K; Gresele, A; Griffiths, M; Grinstein, S; Grosso-Pilcher, C; Grundler, U; Guimaraes da Costa, J; Haber, C; Hahn, S R; Hahn, K; Halkiadakis, E; Hamilton, A; Han, B-Y; Handler, R; Happacher, F; Hara, K; Hare, M; Harper, S; Harr, R F; Harris, R M; Hatakeyama, K; Hauser, J; Hays, C; Hayward, H; Heijboer, A; Heinemann, B; Heinrich, J; Hennecke, M; Herndon, M; Heuser, J; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Holloway, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Huston, J; Ikado, K; Incandela, J; Introzzi, G; Iori, M; Ishizawa, Y; Ivanov, A; Iyutin, B; James, E; Jang, D; Jayatilaka, B; Jeans, D; Jensen, H; Jeon, E J; Jones, M; Joo, K K; Jun, S Y; Junk, T R; Kamon, T; Kang, J; Karagoz-Unel, M; Karchin, P E; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, M S; Kim, S B; Kim, S H; Kim, Y K; Kirby, M; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kobayashi, H; Kondo, K; Kong, D J; Konigsberg, J; Kordas, K; Korytov, A; Kotwal, A V; Kovalev, A; Kraus, J; Kravchenko, I; Kreps, M; Kreymer, A; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kuhlmann, S E; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; Lecci, C; LeCompte, T; Lee, J; Lee, J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Li, K; Lin, C; Lin, C S; Lindgren, M; Lipeles, E; Liss, T M; Lister, A; Litvintsev, D O; Liu, T; Liu, Y; Lockyer, N S; Loginov, A; Loreti, M; Loverre, P; Lu, R-S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; MacQueen, D; Madrak, R; Maeshima, K; Maki, T; Maksimovic, P; Manca, G; Margaroli, F; Marginean, R; Marino, C; Martin, A; Martin, M; Martin, V; Martínez, M; Maruyama, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McFarland, K S; McGivern, D; McIntyre, P; McNamara, P; McNulty, R; Mehta, A; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; von der Mey, M; Miao, T; Miladinovic, N; Miles, J; Miller, R; Miller, J S; Mills, C; Milnik, M; Miquel, R; Miscetti, S; Mitselmakher, G; Miyamoto, A; Moggi, N; Mohr, B; Moore, R; Morello, M; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Mulhearn, M; Muller, Th; Mumford, R; Murat, P; Nachtman, J; Nahn, S; Nakano, I; Napier, A; Naumov, D; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nigmanov, T; Nodulman, L; Norniella, O; Ogawa, T; Oh, S H; Oh, Y D; Okusawa, T; Oldeman, R; Orava, R; Osterberg, K; Pagliarone, C; Palencia, E; Paoletti, R; Papadimitriou, V; Papikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pitts, K; Plager, C; Pondrom, L; Pope, G; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Rakitin, A; Rappoccio, S; Ratnikov, F; Reisert, B; Rekovic, V; van Remortel, N; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Rinnert, K; Ristori, L; Robertson, W J; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Rott, C; Ruiz, A; Russ, J; Rusu, V; Ryan, D; Saarikko, H; Sabik, S; Safonov, A; Sakumoto, W K; Salamanna, G; Salto, O; Saltzberg, D; Sanchez, C; Santi, L; Sarkar, S; Sato, K; Savard, P; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Semeria, F; Sexton-Kennedy, L; Sfiligoi, I; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sill, A; Sinervo, P; Sisakyan, A; Sjolin, J; Skiba, A; Slaughter, A J; Sliwa, K; Smirnov, D; Smith, J R; Snider, F D; Snihur, R; Soderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Squillacioti, P; Stanitzki, M; Staveris-Polykalas, A; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sumorok, K; Sun, H; Suzuki, T; Taffard, A; Tafirout, R; Takashima, R; Takeuchi, Y; Takikawa, K; Tanaka, M; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Tether, S; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tollefson, K; Tomura, T; Tonelli, D; Tönnesmann, M; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tsuchiya, R; Tsuno, S; Turini, N; Ukegawa, F; Unverhau, T; Uozumi, S; Usynin, D; Vacavant, L; Vaiciulis, A; Vallecorsa, S; Varganov, A; Vataga, E; Velev, G; Veramendi, G; Veszpremi, V; Vickey, T; Vidal, R; Vila, I; Vilar, R; Vollrath, I; Volobouev, I; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner, W; Wallny, R; Walter, T; Wan, Z; Wang, M J; Wang, S M; Warburton, A; Ward, B; Waschke, S; Waters, D; Watts, T; Weber, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Worm, S; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, Y; Yang, C; Yang, U K; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zetti, F; Zhang, X; Zhou, J; Zucchelli, S

2006-04-21

We report a measurement of the top-quark mass using events collected by the CDF II detector from pp collisions at square root of s = 1.96 TeV at the Fermilab Tevatron. We calculate a likelihood function for the top-quark mass in events that are consistent with tt --> bl(-)nu(l)bl'+ nu'(l) decays. The likelihood is formed as the convolution of the leading-order matrix element and detector resolution functions. The joint likelihood is the product of likelihoods for each of 33 events collected in 340 pb(-1) of integrated luminosity, yielding a top-quark mass M(t) = 165.2 +/- 6.1(stat) +/- 3.4(syst) GeV/c2. This first application of a matrix-element technique to tt --> bl+ nu(l)bl'- nu(l') decays gives the most precise single measurement of M(t) in dilepton events. Combined with other CDF run II measurements using dilepton events, we measure M(t) = 167.9 +/- 5.2(stat) +/- 3.7(syst) GeV/c2.

Quark model and QCD

International Nuclear Information System (INIS)

Anisovich, V.V.

1989-06-01

Using the language of the quarks and gluons for description of the soft hadron physics it is necessary to take into account two characteristic phenomena which prevent one from usage of QCD Lagrangian in the straightforward way, chiral symmetry breaking, and confinement of colour particles. The topics discussed in this context are: QCD in the domain of soft processes, phenomenological Lagrangian for soft processes and exotic mesons, spectroscopy of low-lying hadrons (mesons, baryons and mesons with heavy quarks - c,b -), confinement forces, spectral integration over quark masses. (author) 3 refs.; 19 figs.; 3 tabs

Precise measurement of the top-quark mass in the lepton+jets topology at CDF II.

Science.gov (United States)

Aaltonen, T; Abulencia, A; Adelman, J; Affolder, T; Akimoto, T; Albrow, M G; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carrillo, S; Carlsmith, D; Carosi, R; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Cilijak, M; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Coca, M; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cully, J C; DaRonco, S; Datta, M; D'Auria, S; Davies, T; Dagenhart, D; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; De Lorenzo, G; Dell'Orso, M; Delli Paoli, F; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Dörr, C; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Field, R; Flanagan, G; Forrest, R; Forrester, S; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garcia, J E; Garberson, F; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D; Giagu, S; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Group, R C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Holloway, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; Iyutin, B; James, E; Jang, D; Jayatilaka, B; Jeans, D; Jeon, E J; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kraan, A C; Kraus, J; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kulkarni, N P; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lu, R-S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; MacQueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis, A; Margaroli, F; Marginean, R; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyamoto, A; Moed, S; Moggi, N; Mohr, B; Moon, C S; Moore, R; Morello, M; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Osterberg, K; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Safonov, A; Sakumoto, W K; Salamanna, G; Saltó, O; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savard, P; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyrla, A; Shalhout, S Z; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; Staveris-Polykalas, A; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suslov, I; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tsuno, S; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; Vallecorsa, S; van Remortel, N; Varganov, A; Vataga, E; Vazquez, F; Velev, G; Vellidis, C; Veramendi, G; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vogel, M; Vollrath, I; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner, J; Wagner, W; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zhou, J; Zucchelli, S

2007-11-02

We present a measurement of the mass of the top quark from proton-antiproton collisions recorded at the CDF experiment in Run II of the Fermilab Tevatron. We analyze events from the single lepton plus jets final state (tt-->W(+)bW(-)b-->lnubqq'b). The top-quark mass is extracted using a direct calculation of the probability density that each event corresponds to the tt final state. The probability is a function of both the mass of the top quark and the energy scale of the calorimeter jets, which is constrained in situ by the hadronic W boson mass. Using 167 events observed in 955 pb(-1) of integrated luminosity, we achieve the single most precise measurement of the top-quark mass, 170.8+/-2.2(stat.)+/-1.4(syst.) GeV/c(2).

The quark mass spectrum in the Universal Seesaw model

International Nuclear Information System (INIS)

Ranfone, S.

1993-03-01

In the context of a Universal Seesaw model implemented in a left-right symmetric theory, we show that, by allowing the two left-handed doublet Higgs fields to develop different vacuum-expectation-values (VEV's), it is possible to account for the observed structure of the quark mass spectrum without the need of any hierarchy among the Yukawa couplings. In this framework the top-quark mass is expected to be of the order of its present experimental lower bound, m t ≅ 90 to 100 GeV. Moreover, we find that, while one of the Higgs doublets gets essentially the standard model VEV of approximately 250 GeV, the second doublet is expected to have a much smaller VEV, of order 10 GeV. The identification of the large mass scale of the model with the Peccei-Quinn scale fixes the mass of the right-handed gauge bosons in the range 10 7 to 10 10 GeV, far beyond the reach of present collider experiments. (author)

The significance of the heavy top quark

International Nuclear Information System (INIS)

Simmons, Elizabeth H.

1997-01-01

Experiment shows that the top quark is far heavier than the other elementary fermions. This finding has stimulated research on theories of electroweak and flavor symmetry breaking that include physics beyond the standard model. Efforts to accommodate a heavy top quark within existing frameworks have revealed constraints on model-building. Other investigations have started from the premise that a large top quark mass could signal a qualitative difference between the top quark and other fermions, perhaps in the form of new interactions peculiar to the top quark. Such new dynamics may also help answer existing questions about electroweak and flavor physics. This talk explores the implications of the heavy top quark in the context of weakly-coupled (e.g., SUSY) and strongly-coupled (e.g., technicolor) theories of electroweak symmetry breaking

Charge symmetry breaking via Δ I = 1 group theory or by the u-d quark mass difference and direct photon exchange

International Nuclear Information System (INIS)

Coon, S.A.; Scadron, M.D.

2000-01-01

Charge symmetry breaking (CSB) in the strong N N interaction is believed to have its origins at the quark level. However, the meson-exchange potentials which successfully describe the empirical CSB utilize instead values of the Δ I = 1 π η and ρ ω mixing obtained with the aid of group theory from a hadronic tadpole Hamiltonian introduced by Coleman and Glashow to describe electromagnetic mass splitting in hadronic isospin multiplets. We review i) the CSB N N potentials so constructed and their nuclear charge asymmetry effects, i i) the universal scale of the Coleman-Glashow tadpole, and i i i) the quark loop evaluation of both meson mass differences and meson mixing. The latter quark loop calculations, which use chiral symmetry to evaluate the integrals, demonstrate clearly that the u-d constituent quark mass difference, long suspected as the origin of CSB, does quantitatively yield the universal Coleman-Glashow tadpole scale which underlies the successful meson-exchange description of CSB in nuclear physics. (Author) 38 refs., 3 figs

Up and Down Quark Masses and Corrections to Dashen's Theorem from Lattice QCD and Quenched QED.

Science.gov (United States)

Fodor, Z; Hoelbling, C; Krieg, S; Lellouch, L; Lippert, Th; Portelli, A; Sastre, A; Szabo, K K; Varnhorst, L

2016-08-19

In a previous Letter [Borsanyi et al., Phys. Rev. Lett. 111, 252001 (2013)] we determined the isospin mass splittings of the baryon octet from a lattice calculation based on N_{f}=2+1 QCD simulations to which QED effects have been added in a partially quenched setup. Using the same data we determine here the corrections to Dashen's theorem and the individual up and down quark masses. Our ensembles include 5 lattice spacings down to 0.054 fm, lattice sizes up to 6 fm, and average up-down quark masses all the way down to their physical value. For the parameter which quantifies violations to Dashen's theorem, we obtain ϵ=0.73(2)(5)(17), where the first error is statistical, the second is systematic, and the third is an estimate of the QED quenching error. For the light quark masses we obtain, m_{u}=2.27(6)(5)(4) and m_{d}=4.67(6)(5)(4)  MeV in the modified minimal subtraction scheme at 2  GeV and the isospin breaking ratios m_{u}/m_{d}=0.485(11)(8)(14), R=38.2(1.1)(0.8)(1.4), and Q=23.4(0.4)(0.3)(0.4). Our results exclude the m_{u}=0 solution to the strong CP problem by more than 24 standard deviations.

Precise charm-quark mass from deep-inelastic scattering

International Nuclear Information System (INIS)

Alekhin, S.; Bluemlein, J.; Daum, K.; Lipka, K.; Moch, S.; Hamburg Univ.

2012-12-01

We present a determination of the charm-quark mass in the MS scheme using the data combination of charm production cross section measurements in deep-inelastic scattering at HERA. The framework of global analyses of the proton structure accounts for all correlations of the charm-quark mass with the other non-perturbative parameters, most importantly the gluon distribution function in the proton and the strong coupling constant α s (M Z ). We obtain at next-to-leading order in QCD the value m c (m c ) = 1.15 ± 0.04 (exp) +0.04 -0.00 (scale) GeV and at approximate next-to-next-to-leading order m c (m c ) = 1.24 ± 0.03 (exp) +0.03 -0.02 (scale) +0.00 -0.07 (theory) GeV with an accuracy competitive with other methods.

RELATING BOTTOM QUARK MASS IN DR-BAR AND MS-BAR REGULARIZATION SCHEMES

International Nuclear Information System (INIS)

2002-01-01

The value of the bottom quark mass at Q = M Z in the (bar D)(bar R) scheme is an important input for the analysis of supersymmetric models with a large value of tan β. Conventionally, however, the running bottom quark mass extracted from experimental data is quoted in the (bar M)(bar S) scheme at the scale Q = m b . We describe a two loop procedure for the conversion of the bottom quark mass from (bar M)(bar S) to (bar D)(bar R) scheme. The Particle Data Group value m b # bar M# # bar S#(m b # bar M# # bar S#) = 4.2 ± 0.2 GeV corresponds to a range of 2.65-3.03 GeV for m b # bar D# # bar R#(M Z )

The mass spectrum of double heavy baryons in new potential quark models

Directory of Open Access Journals (Sweden)

Kovalenko Vladimir

2017-01-01

Full Text Available A new approach to study the mass spectrum of double heavy baryons (QQ′q containing strange and charmed quarks is proposed. It is based on the separation of variables in the Schrodinger equation in the prolate spheroidal coordinates. Two nonrelativistic potential models are considered. In the first model, the interaction potential of the quarks is the sum of the Coulomb and non-spherically symmetrical linear confinement potential. In the second model it is assumed that the quark confinement provided by a spherically symmetric harmonic oscillator potential. In both models the mass spectrum is calculated, and a comparison with previous results from other models is performed.

Running of the charm-quark mass from HERA deep-inelastic scattering data

International Nuclear Information System (INIS)

Gizhko, A.; Geiser, A.; Moch, S.

2017-04-01

Combined HERA data on charm production in deep-inelastic scattering have previously been used to determine the charm-quark running mass m_c(m_c) in the MS renormalisation scheme. Here, the same data are used as a function of the photon virtuality Q"2 to evaluate the charm-quark running mass at different scales to one-loop order, in the context of a next-to-leading order QCD analysis. The scale dependence of the mass is found to be consistent with QCD expectations.

Top quark forward-backward asymmetry from new t-channel physics

CERN Document Server

Jung, Sunghoon; Pierce, Aaron; Wells, James D

2010-01-01

Motivated by recent measurements of the top quark forward-backward asymmetry at the Tevatron, we study how t-channel new physics can contribute to a large value. We concentrate on a theory with an abelian gauge boson possessing flavor changing couplings between up and top quarks, but satisfies flavor physics constraints. Collider constraints are strong, but can be consistent with the aid of small flavor diagonal couplings. We find that M_Z' ~ 160 GeV can yield a total lab-frame asymmetry of ~18% without being in conflict with other observables. There are implications for future collider searches, including exotic top quark decays, like-sign top quark production, and detailed measurements of the top production cross section. An alternate model with a gauged non-Abelian flavor symmetry would have similar phenomenology, but lacks the like-sign top signal.

The A=3 Nolen-Schiffer anomaly and the up-down quark mass difference

International Nuclear Information System (INIS)

Encinosa, M.; Robson, D.

1990-01-01

A recently proposed nonrelativistic many-body quark model is used to generate class III nucleon-nucleon potentials in a Born-Oppenheimer approach. These potentials, when treated in first-order perturbation theory with a simple ansatz for the three-nucleon wave function, allow us to make an estimate of the 3 He- 3 H mass difference. For accepted values of the constituent up-down quark mass difference we find that approximately sixty percent of the A=3 Nolen-Schiffer anomaly can be accounted for solely from the up-down quark kinetic energy difference. (orig.)

Quark and lepton masses at the GUT scale including supersymmetric threshold corrections

International Nuclear Information System (INIS)

Antusch, S.; Spinrath, M.

2008-01-01

We investigate the effect of supersymmetric (SUSY) threshold corrections on the values of the running quark and charged lepton masses at the grand unified theory (GUT) scale within the large tanβ regime of the minimal supersymmetric standard model. In addition to the typically dominant SUSY QCD contributions for the quarks, we also include the electroweak contributions for quarks and leptons and show that they can have significant effects. We provide the GUT scale ranges of quark and charged lepton Yukawa couplings as well as of the ratios m μ /m s , m e /m d , y τ /y b and y t /y b for three example ranges of SUSY parameters. We discuss how the enlarged ranges due to threshold effects might open up new possibilities for constructing GUT models of fermion masses and mixings.

Higgs boson mass and new physics

International Nuclear Information System (INIS)

Bezrukov, Fedor; Brookhaven National Lab., Upton, NY; Kalmykov, Mikhail Yu.; Kniehl, Bernd A.; Shaposhnikov, Mikhail

2012-05-01

We discuss the lower Higgs boson mass bounds which come from the absolute stability of the Standard Model (SM) vacuum and from the Higgs inflation, as well as the prediction of the Higgs boson mass coming from asymptotic safety of the SM. We account for the 3-loop renormalization group evolution of the couplings of the Standard Model and for a part of two-loop corrections that involve the QCD coupling α s to initial conditions for their running. This is one step above the current state of the art procedure (''one-loop matching-two-loop running''). This results in reduction of the theoretical uncertainties in the Higgs boson mass bounds and predictions, associated with the Standard Model physics, to 1-2 GeV. We find that with the account of existing experimental uncertainties in the mass of the top quark and α s (taken at 2σ level) the bound reads M H ≥ M min (equality corresponds to the asymptotic safety prediction), where M min =129±6 GeV. We argue that the discovery of the SM Higgs boson in this range would be in agreement with the hypothesis of the absence of new energy scales between the Fermi and Planck scales, whereas the coincidence of M H with M min would suggest that the electroweak scale is determined by Planck physics. In order to clarify the relation between the Fermi and Planck scale a construction of an electron-positron or muon collider with a center of mass energy ∝200+200 GeV (Higgs and t-quark factory) would be needed.

Higgs boson mass and new physics

Energy Technology Data Exchange (ETDEWEB)

Bezrukov, Fedor [Connecticut Univ., Storrs, CT (United States). Dept. of Physics; Brookhaven National Lab., Upton, NY (United States). RIKEN-BNL Research Center; Kalmykov, Mikhail Yu.; Kniehl, Bernd A. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Shaposhnikov, Mikhail [Ecole Polytechnique Federale de Lausanne (Switzerland). Inst. de Theorie des Phenomenes Physiques

2012-05-15

We discuss the lower Higgs boson mass bounds which come from the absolute stability of the Standard Model (SM) vacuum and from the Higgs inflation, as well as the prediction of the Higgs boson mass coming from asymptotic safety of the SM. We account for the 3-loop renormalization group evolution of the couplings of the Standard Model and for a part of two-loop corrections that involve the QCD coupling {alpha}{sub s} to initial conditions for their running. This is one step above the current state of the art procedure (''one-loop matching-two-loop running''). This results in reduction of the theoretical uncertainties in the Higgs boson mass bounds and predictions, associated with the Standard Model physics, to 1-2 GeV. We find that with the account of existing experimental uncertainties in the mass of the top quark and {alpha}{sub s} (taken at 2{sigma} level) the bound reads M{sub H} {>=} M{sub min} (equality corresponds to the asymptotic safety prediction), where M{sub min}=129{+-}6 GeV. We argue that the discovery of the SM Higgs boson in this range would be in agreement with the hypothesis of the absence of new energy scales between the Fermi and Planck scales, whereas the coincidence of M{sub H} with M{sub min} would suggest that the electroweak scale is determined by Planck physics. In order to clarify the relation between the Fermi and Planck scale a construction of an electron-positron or muon collider with a center of mass energy {proportional_to}200+200 GeV (Higgs and t-quark factory) would be needed.

Tests of the t quark mass from B meson decays

International Nuclear Information System (INIS)

Campbell, B.A.; O'Donnell, P.

1984-01-01

This chapter examines the constraints one may put on the mass of the as yet unobserved top(t) quark from limits on the mixing or neutral current decay of B mesons. Those decays of the b quark which involve the emission of a neutral gage boson are considered. The branching ratios are estimated by dividing the computed width for the decay in question by the total B decay width. The standard six quark model is used. It is determined that b→s+γ is the only rare decay process to proceed at a sufficiently large rate to be experimentally feasible

More on heavy tetraquarks in lattice QCD at almost physical pion mass

Science.gov (United States)

Francis, Anthony; Hudspith, Renwick J.; Lewis, Randy; Maltman, Kim

2018-03-01

We report on our progress in studying exotic, heavy tetraquark states, qq' Q̅Q̅'. Using publicly available dynamical nf = 2 + 1 Wilson-Clover gauge configurations, generated by the PACS-CS collaboration, with pion masses ≃ 164, 299 and 415 MeV, we extend our previous analysis to heavy quark components containing heavier than physical bottom quarks Q̅Q̅' = b̅'b̅' or Q̅Q̅' = b̅b̅', charm and bottom quarks c̅b̅ and also only charm quarks c̅ c̅. Throughout we employ NRQCD and relativistic heavy quarks for the heavier than bottom, bottom and charm quarks. Using our previously established diquark-antidiquark and meson-meson operator basis we comment in particular on the dependence of the binding energy on the mass of the heavy quark component Q̅Q̅, with heavy quarks ranging from mQ = 0:85… 6.3 · mb. In the heavy flavor non-degenerate case, Q̅Q̅', and especially for the tetraquark channel udc̅d̅, we extend our work to utilize a 3 × 3 GEVP to study the ground and threshold states thereby enabling a clear identification of possible binding. Finally, we present initial work on the Q̅Q̅' = c̅c̅ system where a much larger operator basis is available in comparison to flavor combinations with NRQCD quarks.

Top quark mass measurement at the Tevatron

Energy Technology Data Exchange (ETDEWEB)

Guimaraes da Costa, Joao; /Harvard U.

2004-12-01

The authors report on the latest experimental measurements of the top quark mass by the CDF and D0 Collaborations at the Fermilab Tevatron. They present a new top mass measurement using the t{bar t} events collected by the D0 Collaboration in Run I between 1994 and 1996. This result is combined with previous measurements to yield a new world top mass average. They also describe several preliminary results using up to 193 pb{sup -1} of t{bar t} events produced in {bar p}p collisions at {radical}s = 1.96 TeV during the Run II of the Tevatron.

On QCD sum rules of the Laplace transform type and light quark masses

International Nuclear Information System (INIS)

Narison, S.

1981-04-01

We discuss the relation between the usual dispersion relation sum rules and the Laplace transform type sum rules in quantum chromodynamics. Two specific examples corresponding to the S-coupling constant sum rule and the light quark masses sum rules are considered. An interpretation, within QCD, of Leutwyler's formula for the current algebra quark masses is also given

Current s - quark mass corrections to the form factors of D - meson semileptonic decays

International Nuclear Information System (INIS)

Hussain, F.; Ivanov, A.N.; Troitskaya, N.I.

1994-11-01

The infinite mass effective theory, when a heavy quark mass tends to infinity, and Chiral perturbation theory at the quark level, based on the extended Nambu - Jona - Lasinio model with linear realization of chiral U(3) x U(3) symmetry, are applied to the calculations of current s - quark mass corrections to the form factors of the D → K-bar e + ν e and D → K-bar * e + ν e decays. These corrections turn out to be quite significant, of the order of 7 - 20%. The theoretical results are compared with experimental data. (author). 17 refs

Flavor Mixing, CP-Violation and the Masses of the Light Quarks

CERN Document Server

Fritzsch, Harald

1998-01-01

The observed hierarchy of the quark masses is interpreted as a signal for an underlying ``subnuclear democracy'' as the relevant symmetry of the quark mass terms. A simple breaking of the symmetry leads to a mixing between the second and the third family, in agreement with observation. Introducing the mixing between the first and the second family, one finds an interesting pattern of maximal CP--violation as well as a complete determination of the elements of the CKM matrix and of the unitarity triangle.

Flavor mixing, CP-violation and the masses of the light quarks

International Nuclear Information System (INIS)

Fritzsch, H.

1998-01-01

The observed hierarchy of the quark masses is interpreted as a signal for an underlying ''subnuclear democracy'' as the relevant symmetry of the quark mass terms. A simple breaking of the symmetry leads to a mixing between the second and the third family, in agreement with observation. Introducing the mixing between the first and the second family, one finds an interesting pattern of maximal CP-violation as well as a complete determination of the elements of the CKM matrix and of the unitarity triangle. (orig.)

arXiv Top quark measurements in the CMS experiment

CERN Document Server

INSPIRE-00102167

2017-01-01

Experimental results on top-quark physics obtained at the CMS experiment are reported based on the data recorded at centre-of-mass energy up to 13 TeV. Inclusive and differential cross sections for both top-quark pair and single top-quark production are presented, as well as measurements of top-quark properties in production and decay, and searches for anomalous couplings. The presented measurements test theoretical predictions, including recent perturbative QCD calculations, provide constraints of fundamental standard model parameters, and set limits on physics beyond the standard model.

The b-quark mass from non-perturbative $N_f=2$ Heavy Quark Effective Theory at $O(1/m_h)$

DEFF Research Database (Denmark)

Bernardoni, F.; Blossier, B.; Bulava, J.

2014-01-01

We report our final estimate of the b-quark mass from $N_f=2$ lattice QCD simulations using Heavy Quark Effective Theory non-perturbatively matched to QCD at $O(1/m_h)$. Treating systematic and statistical errors in a conservative manner, we obtain $\\overline{m}_{\\rm b}^{\\overline{\\rm MS}}(2 {\\rm...

Search for top quark pair resonances with the CMS detector at the LHC

Energy Technology Data Exchange (ETDEWEB)

Ahmad, Wael Haj

2013-05-29

The Standard Model of particle physics is not the final theory. It breaks at larger (TeV) scales and thus can not explain the hierarchy problem, the unification of couplings and some physical phenomena. Several physical models, referred to as Beyond the Standard Model, have been proposed to account for the phenomena which are not explained by the Standard Model, and to answer to some of these open questions. As the top quark has as an enormous mass of about 173.3 GeV, it plays an essential role in searches for new physics. Various models beyond the Standard Model predict the existence of heavy particles decaying into top quark pairs. These particles manifest themselves as resonant structures in the invariant mass spectrum of the top quark pairs. In this thesis, a model-independent search has been performed for top quark pair resonances in the mass range close to the top quark pair production threshold. The Topcolor Z' model is considered as a reference model. The presented search focuses on top quark pair events selected from data samples corresponding to 1.09 fb{sup -1} of integrated luminosity collected with the CMS detector in the 2011 run period at a center-of-mass energy of {radical}(s)=7 TeV at the large hadron collider (LHC). A cut based selection is implemented to identify top quark pair candidates decaying in the muon+jets channel, by requiring one isolated muon, missing transverse energy and at least four jets. The identified final state objects are used to reconstruct the invariant top quark pair mass spectrum. No excess is observed in the CMS data over the expectation of the standard model processes, namely no considerable evidence of new physics was found. Therefore, a limit is set on the topcolor Z' boson production cross section as a function of the Z' mass. Leptophobic topcolor Z' bosons with narrow (wide) width 1.2% (10%) are excluded at 95% confidence level for masses below 710 (1145) GeV.

Search for top quark pair resonances with the CMS detector at the LHC

International Nuclear Information System (INIS)

Ahmad, Wael Haj

2013-01-01

The Standard Model of particle physics is not the final theory. It breaks at larger (TeV) scales and thus can not explain the hierarchy problem, the unification of couplings and some physical phenomena. Several physical models, referred to as Beyond the Standard Model, have been proposed to account for the phenomena which are not explained by the Standard Model, and to answer to some of these open questions. As the top quark has as an enormous mass of about 173.3 GeV, it plays an essential role in searches for new physics. Various models beyond the Standard Model predict the existence of heavy particles decaying into top quark pairs. These particles manifest themselves as resonant structures in the invariant mass spectrum of the top quark pairs. In this thesis, a model-independent search has been performed for top quark pair resonances in the mass range close to the top quark pair production threshold. The Topcolor Z' model is considered as a reference model. The presented search focuses on top quark pair events selected from data samples corresponding to 1.09 fb -1 of integrated luminosity collected with the CMS detector in the 2011 run period at a center-of-mass energy of √(s)=7 TeV at the large hadron collider (LHC). A cut based selection is implemented to identify top quark pair candidates decaying in the muon+jets channel, by requiring one isolated muon, missing transverse energy and at least four jets. The identified final state objects are used to reconstruct the invariant top quark pair mass spectrum. No excess is observed in the CMS data over the expectation of the standard model processes, namely no considerable evidence of new physics was found. Therefore, a limit is set on the topcolor Z' boson production cross section as a function of the Z' mass. Leptophobic topcolor Z' bosons with narrow (wide) width 1.2% (10%) are excluded at 95% confidence level for masses below 710 (1145) GeV.

Theory of quark mixing matrix and invariant functions of mass matrices

International Nuclear Information System (INIS)

Jarlskog, C.

1987-10-01

The outline of this talk is as follows: The origin of the quark mixing matrix. Super elementary theory of flavour projection operators. Equivalences and invariances. The commutator formalism and CP violation. CP conditions for any number of families. The 'angle' between the quark mass matrices. Application to Fritzsch and Stech matrices. References. (author)

Color-flavor locked strange quark matter in a mass density-dependent model

International Nuclear Information System (INIS)

Chen Yuede; Wen Xinjian

2007-01-01

Properties of color-flavor locked (CFL) strange quark matter have been studied in a mass-density-dependent model, and compared with the results in the conventional bag model. In both models, the CFL phase is more stable than the normal nuclear matter for reasonable parameters. However, the lower density behavior of the sound velocity in this model is completely opposite to that in the bag model, which makes the maximum mass of CFL quark stars in the mass-density-dependent model larger than that in the bag model. (authors)

Masses and decay constants of bound states containing fourth family quarks from QCD sum rules

International Nuclear Information System (INIS)

Bashiry, V.; Azizi, K.; Sultansoy, S.

2011-01-01

The heavy fourth generation of quarks that have sufficiently small mixing with the three known standard model families form hadrons. In the present work, we calculate the masses and decay constants of mesons containing either both quarks from the fourth generation or one from the fourth family and the other from known third family standard model quarks in the framework of the QCD sum rules. In the calculations, we take into account two-gluon condensate diagrams as nonperturbative contributions. The obtained results reduce to the known masses and decay constants of the bb and cc quarkonia when the fourth family quark is replaced by the bottom or charm quark.

Dual Ginzburg-Landau theory and quark nuclear physics

International Nuclear Information System (INIS)

Toki, Hiroshi

1999-01-01

The elementary building blocks of matter are quarks. Hence, it is fundamental to describe hadrons and nuclei in terms of quarks and gluons, the subject of which is called Quark Nuclear Physics. The quark-dynamics is described by Quantum Chromodynamics (QCD). Our interest is the non-perturbative aspect of QCD as confinement, chiral symmetry breaking, hadronization etc. We introduce the dual Ginzburg-Landau theory (DGL), where the color monopole fields and their condensation is the QCD vacuum, play essential roles in describing these non-perturbative phenomena. We emphasize its connection to QCD through the use of the Abelian gauge. We apply the DGL theory to various observables. We discuss then the connection of the monopole fields with instantons, which are the classical solutions of the non-Abelian gauge theory and connect through the tunneling process QCD vacuum with different winding numbers. (author)

Precise measurement of the top quark mass in the lepton+jets topology at CDF II

Energy Technology Data Exchange (ETDEWEB)

Abulencia, A.; /Illinois U., Urbana; Adelman, J.; /Chicago U.; Affolder, T.; /UC, Santa Barbara; Akimoto, T.; /Tsukuba U.; Albrow, M.G.; /Fermilab; Amerio, S.; /Padua U.; Amidei, D.; /Michigan U.; Anastassov, A.; /Rutgers U., Piscataway; Anikeev, K.; /Fermilab; Annovi, A.; /Frascati; Antos, J.; /Comenius U. /Tsukuba U.

2007-03-01

The authors present a measurement of the mass of the top quark from proton-antiproton collisions recorded at the CDF experiment in Run II of the Fermilab Tevatron. They analyze events from the single lepton plus jets final state (t{bar t} {yields} W{sup +}bW{sup -}{bar b} {yields} lvbq{bar q}{bar b}). The top quark mass is extracted using a direct calculation of the probability density that each event corresponds to the t{bar t} final state. The probability is a function of both the mass of the top quark and the energy scale of the calorimeter jets, which is constrained in situ by the hadronic W boson mass. Using 167 events observed in 955 pb{sup -1} of integrated luminosity, they achieve the single most precise measurement of the top quark mass, 170.8 {+-} 2.2(stat.) {+-} 1.4(syst.) GeV/c{sup 2}.

submitter Preparatory studies on the determination of the top-quark mass in single top-quark events with the ATLAS detector at the LHC

CERN Document Server

Wahdan, Shayma'; Wagner, Wolfgang

In this thesis, a measurement of the single top quark mass produced in the t -channel is presented, using the data sample recorded recently in 2015 with the ATLAS detector at the LHC, at a centre of mass energy of √ s = 13 TeV and corresponding to an integrated luminosity of 3.2 f b−1 . The selected events contain one charged lepton (electron or muon), missing transverse energy, and two jets with high transverse momentum with one of them being b-tagged. The template method is used to extract the top quark mass from the distribution of the invariant mass of the lepton and the b-jet (m(`b)) in the selected events. The result of the measured top quark mass is: mtop = [174.56 ± 3.11(syst.) ± 1.02(stat.)] GeV.

Possible reason why leptons are lighter than quarks

International Nuclear Information System (INIS)

Volkas, R.R.

1994-01-01

The minimal model of spontaneously broken leptonic colour and discrete quark-lepton symmetry predicts that charged leptons have the same masses as their partner charge +2/3 quarks up to small radiative corrections. By invoking a different pattern of symmetry braking, a similar model can be constructed with the structural feature that charged leptons have to be lighter than their partner quarks because of fermion mixing effects. As well as furnishing a new model-building tool, this is phenomenologically interesting because the scale of the new physics responsible for the quark-lepton mass hierarchy could be as low as several hundred GeV. 8 refs

The quark mass and baryon numbers of empty chiral bags

International Nuclear Information System (INIS)

Jezabek, M.; Zalewski, K.

1984-01-01

We show that for spherical chiral bags the baryon number of the Dirac vacuum inside the bag does not depend on quark masses. Thus, the sum of the baryon numbers of an empty chiral bag and the skyrmion surrounding the bag is an integer, which depends on the boundary condition on the surface of the bag. This extends the result obtained by Goldstone and Jaffe for massless quarks. (orig.)

A nucleon description based on confinement and a dynamic generation of the quark masses

International Nuclear Information System (INIS)

Caillon, J.C.

2010-01-01

We have considered the nucleon as an MIT bag, but instead of a perturbative vacuum, we use a QCD vacuum modified as compared to the outside space and hence a modified quark-condensate. Quarks acquire their constituent-masses through their interactions with this modified QCD vacuum in a framework of an NJL model. The value of the quark condensate modified in the nucleon is then determined self-consistently by the equilibrium condition for the bag: the outward pressure due to both the motion of three quarks and the modified vacuum in the nucleon must be counterbalanced by the inward pressure of the vacuum outside the bag. We are able to pass continuously from a nucleon description in a pure MIT bag model to a description using constituent quark masses determined in an NJL model.

On the b-quark running mass in QCD and the SM

International Nuclear Information System (INIS)

Bednyakov, A.V.; Kniehl, B.A.; Pikelner, A.F.; Veretin, O.L.

2016-12-01

We consider electroweak corrections to the relation between the running MS mass m_b of the b quark in the five-flavor QCD x QED effective theory and its counterpart in the Standard Model (SM). As a bridge between the two parameters, we use the pole mass M_b of the b quark, which can be calculated in both models. The running mass is not a fundamental parameter of the SM Lagrangian, but the product of the running Yukawa coupling y_b and the Higgs vacuum expectation value. Since there exist different prescriptions to define the latter, the relations considered in the paper involve a certain amount of freedom. All the definitions can be related to each other in perturbation theory. Nevertheless, we argue in favor of a certain gauge-independent prescription and provide a relation which can be directly used to deduce the value of the Yukawa coupling of the b quark at the electroweak scale from its effective QCD running mass. This approach allows one to resum large logarithms ln(m_b/M_t) systematically. Numerical analysis shows that, indeed, the corrections to the proposed relation are much smaller than those between y_b and M_b.

Quark charges and colour gluon mass from deep-inelastic bremsstrahlung

International Nuclear Information System (INIS)

Pandita, P.N.

1978-01-01

Sum rules are derived for the structure function V(x) for the 'three-photon' process e +- + p →e +- + γ +X which can distinguish between various colour models below colour threshold, independently of the quark and gluon distributions. A careful study of the sum rule for V(x) in the broken colour gauge theory model can in principle be used to determine the colour gluon mass. Invoking the specific assumptions of the dominance of p-type quarks and neglecting the sea of quark-antiquark pairs, bounds for V(x) are obtained in terms of νW 2 (x) which can distinguish between various colour models below colour threshold. (author)

The impact of quark masses on pQCD thermodynamics

Energy Technology Data Exchange (ETDEWEB)

Graf, Thorben; Schaffner-Bielich, Juergen [Goethe University, Institute for Theoretical Physics, Frankfurt am Main (Germany); Fraga, Eduardo S. [Universidade Federal do Rio de Janeiro, Instituto de Fisica, Rio de Janeiro (Brazil)

2016-07-15

We present results for several thermodynamic quantities within the next-to-leading order calculation of the thermodynamic potential in perturbative QCD at finite temperature and chemical potential including non-vanishing quark masses. These results are compared to lattice data and to higher-order optimized perturbative calculations to investigate the trend brought about by mass corrections. (orig.)

Light quarks and small X physics

International Nuclear Information System (INIS)

White, A.R.

1992-01-01

The significance of the low k perpendicular part of the Lipatov equation for the QCD soft Pomeron is discussed. It is then argued that light quarks are essential for the emergence of confinement and a Pomeron with the right physical properties. The implications for small x parton distributions are considered

Indirect handle on the down-quark Yukawa coupling.

Science.gov (United States)

Goertz, Florian

2014-12-31

To measure the Yukawa couplings of the up and down quarks, Yu,d, seems to be far beyond the capabilities of current and (near) future experiments in particle physics. By performing a general analysis of the potential misalignment between quark masses and Yukawa couplings, we derive predictions for the magnitude of induced flavor-changing neutral currents (FCNCs), depending on the shift in the physical Yukawa coupling of first-generation quarks. We find that a change of more than 50% in Yd would generically result in ds transitions in conflict with kaon physics. This could already be seen as evidence for a nonvanishing direct coupling of the down quark to the newly discovered Higgs boson. The nonobservation of certain--already well-constrained--processes is thus turned into a powerful indirect measure of otherwise basically unaccessible physical parameters of the effective standard model. Similarly, improvements in limits on FCNCs in the up-type quark sector can lead to valuable information on Yu.

Sensitivity of the Top quark mass measurement with the CMS experiment at LHC using t-tbar multijet simulated events

CERN Document Server

Codispoti, Giuseppe

This thesis comes after a strong contribution on the realization of the CMS computing system, which can be seen as a relevant part of the experiment itself. A physics analysis completes the road from Monte Carlo production and analysis tools realization to the final physics study which is the actual goal of the experiment. The topic of physics work of this thesis is the study of tt events fully hadronic decay in the CMS experiment. A multi-jet trigger has been provided to fix a reasonable starting point, reducing the multi-jet sample to the nominal trigger rate. An offline selection has been provided to reduce the S/B ratio. The b-tag is applied to provide a further S/B improvement. The selection is applied to the background sample and to the samples generated at different top quark masses. The top quark mass candidate is reconstructed for all those samples using a kinematic fitter. The resulting distributions are used to build p.d.f.’s, interpolating them with a continuous arbitrary curve. These curves are...

A basis independent formulation of the connection between quark mass matrices, CP violation and experiment

International Nuclear Information System (INIS)

Jarlskog, C.; Stockholm Univ.; Bergen Univ.

1985-01-01

In the standard electroweak model, with three families, a one-to-one correspondence between certain determinants involving quark mass matrices (m and m' for charge 2/3 and -1/3 quarks respectively) and the presence/absence of CP violation is given. In an arbitrary basis for mass matrices, the quantity Im det[mm + , m'm' + ] appropriately normalized is introduced as a measure of CP violation. By this measure, CP is not maximally violated in any transition in Nature. Finally, constraints on quark mass matrices are derived from experiment. Any model of mass matrices, with the ambition to explain Nature, must satisfy these conditions. (orig.)

Measurement of the top-quark mass in the fully hadronic decay channel from ATLAS data at [Formula: see text].

Science.gov (United States)

Aad, G; Abbott, B; Abdallah, J; Abdel Khalek, S; Abdinov, O; Aben, R; Abi, B; Abolins, M; AbouZeid, O S; Abramowicz, H; Abreu, H; Abreu, R; Abulaiti, Y; Acharya, B S; Adamczyk, L; Adams, D L; Adelman, J; Adomeit, S; Adye, T; Agatonovic-Jovin, T; Aguilar-Saavedra, J A; Agustoni, M; Ahlen, S P; Ahmadov, F; Aielli, G; Akerstedt, H; Åkesson, T P A; Akimoto, G; Akimov, A V; Alberghi, G L; Albert, J; Albrand, S; Alconada Verzini, M J; Aleksa, M; Aleksandrov, I N; Alexa, C; Alexander, G; Alexandre, G; Alexopoulos, T; Alhroob, M; Alimonti, G; Alio, L; Alison, J; Allbrooke, B M M; Allison, L J; Allport, P P; Almond, J; Aloisio, A; Alonso, A; Alonso, F; Alpigiani, C; Altheimer, A; Alvarez Gonzalez, B; Alviggi, M G; Amako, K; Amaral Coutinho, Y; Amelung, C; Amidei, D; Amor Dos Santos, S P; Amorim, A; Amoroso, S; Amram, N; Amundsen, G; Anastopoulos, C; Ancu, L S; Andari, N; Andeen, T; Anders, C F; Anders, G; Anderson, K J; Andreazza, A; Andrei, V; Anduaga, X S; Angelidakis, S; Angelozzi, I; Anger, P; Angerami, A; Anghinolfi, F; Anisenkov, A V; Anjos, N; Annovi, A; Antonaki, A; Antonelli, M; Antonov, A; Antos, J; Anulli, F; Aoki, M; Aperio Bella, L; Apolle, R; Arabidze, G; Aracena, I; Arai, Y; Araque, J P; Arce, A T H; Arguin, J-F; Argyropoulos, S; Arik, M; Armbruster, A J; Arnaez, O; Arnal, V; Arnold, H; Arratia, M; Arslan, O; Artamonov, A; Artoni, G; Asai, S; Asbah, N; Ashkenazi, A; Åsman, B; Asquith, L; Assamagan, K; Astalos, R; Atkinson, M; Atlay, N B; Auerbach, B; Augsten, K; Aurousseau, M; Avolio, G; Azuelos, G; Azuma, Y; Baak, M A; Baas, A E; Bacci, C; Bachacou, H; Bachas, K; Backes, M; Backhaus, M; Backus Mayes, J; Badescu, E; Bagiacchi, P; Bagnaia, P; Bai, Y; Bain, T; Baines, J T; Baker, O K; Balek, P; Balli, F; Banas, E; Banerjee, Sw; Bannoura, A A E; Bansal, V; Bansil, H S; Barak, L; Baranov, S P; Barberio, E L; Barberis, D; Barbero, M; Barillari, T; Barisonzi, M; Barklow, T; Barlow, N; Barnett, B M; Barnett, R M; Barnovska, Z; Baroncelli, A; Barone, G; Barr, A J; Barreiro, F; Barreiro Guimarães da Costa, J; Bartoldus, R; Barton, A E; Bartos, P; Bartsch, V; Bassalat, A; Basye, A; Bates, R L; Batley, J R; Battaglia, M; Battistin, M; Bauer, F; Bawa, H S; Beattie, M D; Beau, T; Beauchemin, P H; Beccherle, R; Bechtle, P; Beck, H P; Becker, K; Becker, S; Beckingham, M; Becot, C; Beddall, A J; Beddall, A; Bedikian, S; Bednyakov, V A; Bee, C P; Beemster, L J; Beermann, T A; Begel, M; Behr, K; Belanger-Champagne, C; Bell, P J; Bell, W H; Bella, G; Bellagamba, L; Bellerive, A; Bellomo, M; Belotskiy, K; Beltramello, O; Benary, O; Benchekroun, D; Bendtz, K; Benekos, N; Benhammou, Y; Benhar Noccioli, E; Benitez Garcia, J A; Benjamin, D P; Bensinger, J R; Benslama, K; Bentvelsen, S; Berge, D; Bergeaas Kuutmann, E; Berger, N; Berghaus, F; Beringer, J; Bernard, C; Bernat, P; Bernius, C; Bernlochner, F U; Berry, T; Berta, P; Bertella, C; Bertoli, G; Bertolucci, F; Bertsche, C; Bertsche, D; Besana, M I; Besjes, G J; Bessidskaia Bylund, O; Bessner, M; Besson, N; Betancourt, C; 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Yoshihara, K; Young, C; Young, C J S; Youssef, S; Yu, D R; Yu, J; Yu, J M; Yu, J; Yuan, L; Yurkewicz, A; Yusuff, I; Zabinski, B; Zaidan, R; Zaitsev, A M; Zaman, A; Zambito, S; Zanello, L; Zanzi, D; Zeitnitz, C; Zeman, M; Zemla, A; Zengel, K; Zenin, O; Ženiš, T; Zerwas, D; Zevi Della Porta, G; Zhang, D; Zhang, F; Zhang, H; Zhang, J; Zhang, L; Zhang, X; Zhang, Z; Zhao, Z; Zhemchugov, A; Zhong, J; Zhou, B; Zhou, L; Zhou, N; Zhu, C G; Zhu, H; Zhu, J; Zhu, Y; Zhuang, X; Zhukov, K; Zibell, A; Zieminska, D; Zimine, N I; Zimmermann, C; Zimmermann, R; Zimmermann, S; Zimmermann, S; Zinonos, Z; Ziolkowski, M; Zobernig, G; Zoccoli, A; Zur Nedden, M; Zurzolo, G; Zutshi, V; Zwalinski, L

The mass of the top quark is measured in a data set corresponding to 4.6 [Formula: see text] of proton-proton collisions with centre-of-mass energy [Formula: see text] TeV collected by the ATLAS detector at the LHC. Events consistent with hadronic decays of top-antitop quark pairs with at least six jets in the final state are selected. The substantial background from multijet production is modelled with data-driven methods that utilise the number of identified [Formula: see text]-quark jets and the transverse momentum of the sixth leading jet, which have minimal correlation. The top-quark mass is obtained from template fits to the ratio of three-jet to dijet mass. The three-jet mass is calculated from the three jets produced in a top-quark decay. Using these three jets the dijet mass is obtained from the two jets produced in the [Formula: see text] boson decay. The top-quark mass obtained from this fit is thus less sensitive to the uncertainty in the energy measurement of the jets. A binned likelihood fit yields a top-quark mass of [Formula: see text].

Measurement of the top-quark mass from the b jet energy spectrum

CERN Document Server

CMS Collaboration

2015-01-01

The top-quark mass is measured using the peak position of the energy distribution of b jets produced from top-quark decays. The analysis is based on a recent theoretical proposal. The measurement is carried out selecting $\\mathrm{t\\overline{t}}$ events with one electron and one muon in the final state in proton-proton collision data at $\\sqrt{s}=8~\\mathrm{TeV}$, corresponding to an integrated luminosity of 19.7$~\\mathrm{fb}^{-1}$. The fitted peak position of the observed energy distribution is calibrated using simulated events and translated to a top-quark mass measurement using relativistic kinematics, with the result $m_{\\mathrm{t}}=172.29\\pm1.17\\,(\\mathrm{stat.})\\pm2.66\\,(\\mathrm{syst.})~\\mathrm{GeV}$.

Top quark physics

International Nuclear Information System (INIS)

Menzione, A.

1995-10-01

Most of the material presented in this report, comes from contributions to the parallel session PL20 of this conference. We summarise the experimental results of direct production of Top quarks, coming from the CDF and C0 Collaborations at Fermilab, and compare these results to what one expects within current theoretical understanding. Particular attention is given to new results such as all hadronic modes of t bar t decay. As far as the mass is concerned, a comparison is made with precision measurements of related quantities, coming from LEP and other experiments. An attempt is made to look at the medium-term future and understand which variables and with what accuracy one can measure them with increased integrated luminosity

A quark interpretation of the combinatorial hierarchy

International Nuclear Information System (INIS)

Enqvist, Kari.

1979-01-01

We propose a physical interpretation of the second level of the combinatorial hierarchy in terms of three quarks, three antiquarks and the vacuum. This interpretation allows us to introduce a new quantum number, which measures electromagnetic mass splitting of the quarks. We extend our argument by analogue to baryons, and find some SU(3) and some new mass formulas for baryons. The generalization of our approach to other hierarchy levels is discussed. We present also an empirical mass formula for baryons, which seems to be loosely connected with the combinatorial hierarchy. (author)

Lifting scalar-quark and -lepton masses with sideways U(1)-II

International Nuclear Information System (INIS)

McCabe, J.F.; Wada, W.W.

1984-01-01

We investigate the phenomenological consequences of an SUSY model with a gauged O'Raifeartaigh sector on scalar partner masses. The model has the gauge symmetry SU(5) x U(1). We find that this form of spontaneous SUSY breaking leads to large scalar partner masses through one loop graphs without changing quark and lepton masses from tree values, and without breaking SU(5) symmetries by the scalar partner sector. To calculate the scalar partner masses we extend previous work on supergraph techniques to include cases when SUSY is broken at tree level. We are able to sum exactly the corrections to unbroken propagators with the aid of a supersymmetric version of tree-level Dyson equations. We show how the same ideas can be implemented in an SU(5) gauge model where the normal Higgs give large masses radiatively to the scalar-quarks and -leptons. 7 references

Direct measurement of the top quark mass in $p\\bar p$ collisions at D0

Energy Technology Data Exchange (ETDEWEB)

Brandt, Oleg [Kirchhoff Inst. Phys.

2017-10-11

The mass of the top quark is a fundamental parameter of the Standard Model and has to be determined experimentally. In these proceedings, I review recent direct measurements of the top quark mass in $p\\bar p$ collisions at $\\sqrt s=1.96$ TeV recorded by the D0 experiment at the Tevatron. The measurements are performed in final states containing one and two charged leptons. I will present the legacy combination of all top quark mass measurements from the D0 experiment and their combination with results from the CDF experiment. A relative precision of down to 0.3\\% is attained.

Top quark soliton and its anomalous chromomagnetic moment

International Nuclear Information System (INIS)

Berger, J.; Blotz, A.; Kim, H.; Goeke, K.

1996-01-01

We show that under the assumption of dynamical symmetry breaking of electroweak interactions by a top quark condensate, motivated by the top mode standard model, the top quark in this effective theory can be considered then as a chiral color soliton. This is realized in an effective four-fermion interaction with chiral SU(3) c as well as SU(2) L circle-times U Y (1) symmetry. In the pure top quark sector the soliton consists of a top valence quark and a Dirac sea of top quarks and top antiquarks coupled to a color octet of Goldstone pions. The mass spectra, isoscalar quadratic radii, and the anomalous chromomagnetic moment because of a nontrivial color form factor are calculated with zero and finite current top quark masses and effects at the hadron colliders are discussed. The anomalous chromomagnetic moment turns out to have a value consistent with the top quark production rates of the D0 and CDF measurements. copyright 1996 The American Physical Society

On the b-quark running mass in QCD and the SM

Energy Technology Data Exchange (ETDEWEB)

Bednyakov, A.V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Dubna State Univ. (Russian Federation); Kniehl, B.A.; Pikelner, A.F.; Veretin, O.L. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

2016-12-15

We consider electroweak corrections to the relation between the running MS mass m{sub b} of the b quark in the five-flavor QCD x QED effective theory and its counterpart in the Standard Model (SM). As a bridge between the two parameters, we use the pole mass M{sub b} of the b quark, which can be calculated in both models. The running mass is not a fundamental parameter of the SM Lagrangian, but the product of the running Yukawa coupling y{sub b} and the Higgs vacuum expectation value. Since there exist different prescriptions to define the latter, the relations considered in the paper involve a certain amount of freedom. All the definitions can be related to each other in perturbation theory. Nevertheless, we argue in favor of a certain gauge-independent prescription and provide a relation which can be directly used to deduce the value of the Yukawa coupling of the b quark at the electroweak scale from its effective QCD running mass. This approach allows one to resum large logarithms ln(m{sub b}/M{sub t}) systematically. Numerical analysis shows that, indeed, the corrections to the proposed relation are much smaller than those between y{sub b} and M{sub b}.

Spontaneous chiral symmetry breaking and effective quark masses in quantum chromodynamics

International Nuclear Information System (INIS)

Miransky, V.A.

1982-01-01

The ultraviolet asymptotics of the dynamical effective quark mass is determined directly from the equation for the fermion mass function. The indications about the character of the dynamics of the spontaneous chiral symmetry breaking in QCD are obtained

Constraints on constituent quark masses from potential models

International Nuclear Information System (INIS)

Silvestre-Brac, B.

1998-01-01

Starting from reasonable hypotheses, the magnetic moments for the baryons are revisited dat the light of general space wave functions. They allow to put very severe bounds on the quark masses as derived from usual potential models. The experimental situation cannot be explained in the framework of such models. (author)

Precise measurement of the top-quark mass at the CMS experiment using the ideogram method

CERN Document Server

Seidel, Markus; Stadie, Hartmut

2015-01-01

The mass of the top quark is measured using a sample of tt candidate events with oneelectron or muon and at least four jets in the final state, collected by CMS in proton√proton collisions at s = 8 TeV at the LHC. The candidate events are selected fromdata corresponding to an integrated luminosity of 19.7 fb−1 . For each event thetop-quark mass is reconstructed from a kinematic fit of the decay products to att hypothesis. In order to minimize the uncertainties from jet energy corrections,the top-quark mass is determined simultaneously with a jet energy scale factor(JSF), constrained by the known mass of the W boson decaying to quark-antiquarkpairs. A joint likelihood fit taking into account multiple interpretations per event– the ideogram method – is used. From the simultaneous fit, a top-quark massof 172.15 ± 0.19 (stat.+JSF) ± 0.61 (syst.) GeV is obtained. Using an additionalconstraint from the determination of the jet energy scale in γ/Z+jet events yieldsmt = 172.38 ± 0.16 (stat.+JSF) ± 0....

Quark matter and quark stars at finite temperature in Nambu-Jona-Lasinio model

Energy Technology Data Exchange (ETDEWEB)

Chu, Peng-Cheng; Wang, Bin; Dong, Yu-Min; Jia, Yu-Yue; Wang, Shu-Mei; Ma, Hong-Yang [Qingdao Technological University, School of Science, Qingdao (China); Li, Xiao-Hua [University of South China, School of Nuclear Science and Technology, Hengyang (China); University of South China, Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment, Hengyang (China)

2017-08-15

We extend the SU(3) Nambu-Jona-Lasinio (NJL) model to include two types of vector interaction. Using these two types of vector interaction in NJL model, we study the quark symmetry free energy in asymmetric quark matter, the constituent quark mass, the quark fraction, the equation of state (EOS) for β-equilibrium quark matter, the maximum mass of QSs at finite temperature, the maximum mass of proto-quark stars (PQSs) along the star evolution, and the effects of the vector interaction on the QCD phase diagram. We find that comparing zero temperature case, the values of quark matter symmetry free energy get larger with temperature increasing, which will reduce the difference between the fraction of u, d and s quarks and stiffen the EoS for β-equilibrium quark matter. In particular, our results indicate that the maximum masses of the quark stars increase with temperature because of the effects of the quark matter symmetry free energy, and we find that the heating(cooling) process for PQSs will increase (decrease) the maximum mass within NJL model. (orig.)

Strange star candidates revised within a quark model with chiral mass scaling

Institute of Scientific and Technical Information of China (English)

Ang Li; Guang-Xiong Peng; Ju-Fu Lu

2011-01-01

We calculate the properties of static strange stars using a quark model with chiral mass scaling. The results are characterized by a large maximum mass (～ 1.6 M⊙) and radius (～ 10 km). Together with a broad collection of modern neutron star models, we discuss some recent astrophysical observational data that could shed new light on the possible presence of strange quark matter in compact stars. We conclude that none of the present astrophysical observations can prove or confute the existence of strange stars.

The top quark and Higgs boson masses and the stability of the elcetroweak vacuum

Energy Technology Data Exchange (ETDEWEB)

Alekhin, S. [Institut Fiziki Vysokikh Ehnergij, Protvino (Russian Federation); Djouadi, A. [CNRS, Paris (France). Laboratoire de Physique Theorique; Paris-11 Univ., 91 - Orsay (France); CERN, Geneva (Switzerland). Dept. of Physics; Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

2012-07-15

The ATLAS and CMS experiments observed a particle at the LHC with a mass {approx}126 GeV, which is compatible with the Higgs boson of the Standard Model. A crucial question is, if for such a Higgs mass value, one could extrapolate the model up to high scales while keeping the minimum of the scalar potential that breaks the electroweak symmetry stable. Vacuum stability requires indeed the Higgs boson mass to be M{sub H}>or similar 129{+-}1 GeV, but the precise value depends critically on the input top quark pole mass which is usually taken to be the one measured at the Tevatron, m{sub t}{sup exp}=173.2{+-}0.9 GeV. However, for an unambiguous and theoretically well-defined determination of the top quark mass one should rather use the total cross section for top quark pair production at hadron colliders. Confronting the latest predictions of the inclusive p anti p{yields}t anti t+X cross section up to next-to-next-to-leading order in QCD to the experimental measurement at the Tevatron, we determine the running mass in the MS-scheme to be m{sub t}{sup MS}(m{sub t})=163.3{+-}2.7 GeV which gives a top quark pole mass of m{sup pole}{sub t}=173.3{+-}2.8 GeV. This leads to the vacuum stability constraint M{sub H}{>=}129.4{+-}5.6 GeV to which a {approx}126 GeV Higgs boson complies as the uncertainty is large. A very precise assessment of the stability of the electroweak vacuum can only be made at a future high-energy electron-positron collider, where the top quark pole mass could be determined with a few hundred MeV accuracy.

Fragmentation uncertainties in hadronic observables for top-quark mass measurements

Directory of Open Access Journals (Sweden)

Gennaro Corcella

2018-04-01

Full Text Available We study the Monte Carlo uncertainties due to modeling of hadronization and showering in the extraction of the top-quark mass from observables that use exclusive hadronic final states in top decays, such as t→anything+J/ψ or t→anything+(B→charged tracks, where B is a B-hadron. To this end, we investigate the sensitivity of the top-quark mass, determined by means of a few observables already proposed in the literature as well as some new proposals, to the relevant parameters of event generators, such as HERWIG 6 and PYTHIA 8. We find that constraining those parameters at O(1%–10% is required to avoid a Monte Carlo uncertainty on mt greater than 500 MeV. For the sake of achieving the needed accuracy on such parameters, we examine the sensitivity of the top-quark mass measured from spectral features, such as peaks, endpoints and distributions of EB, mBℓ, and some mT2-like variables. We find that restricting oneself to regions sufficiently close to the endpoints enables one to substantially decrease the dependence on the Monte Carlo parameters, but at the price of inflating significantly the statistical uncertainties. To ameliorate this situation we study how well the data on top-quark production and decay at the LHC can be utilized to constrain the showering and hadronization variables. We find that a global exploration of several calibration observables, sensitive to the Monte Carlo parameters but very mildly to mt, can offer useful constraints on the parameters, as long as such quantities are measured with a 1% precision.

Fragmentation uncertainties in hadronic observables for top-quark mass measurements

Science.gov (United States)

Corcella, Gennaro; Franceschini, Roberto; Kim, Doojin

2018-04-01

We study the Monte Carlo uncertainties due to modeling of hadronization and showering in the extraction of the top-quark mass from observables that use exclusive hadronic final states in top decays, such as t →anything + J / ψ or t →anything + (B →charged tracks), where B is a B-hadron. To this end, we investigate the sensitivity of the top-quark mass, determined by means of a few observables already proposed in the literature as well as some new proposals, to the relevant parameters of event generators, such as HERWIG 6 and PYTHIA 8. We find that constraining those parameters at O (1%- 10%) is required to avoid a Monte Carlo uncertainty on mt greater than 500 MeV. For the sake of achieving the needed accuracy on such parameters, we examine the sensitivity of the top-quark mass measured from spectral features, such as peaks, endpoints and distributions of EB, mBℓ, and some mT2-like variables. We find that restricting oneself to regions sufficiently close to the endpoints enables one to substantially decrease the dependence on the Monte Carlo parameters, but at the price of inflating significantly the statistical uncertainties. To ameliorate this situation we study how well the data on top-quark production and decay at the LHC can be utilized to constrain the showering and hadronization variables. We find that a global exploration of several calibration observables, sensitive to the Monte Carlo parameters but very mildly to mt, can offer useful constraints on the parameters, as long as such quantities are measured with a 1% precision.

Study of Strange Quark Mass in CFL Phase

Institute of Scientific and Technical Information of China (English)

LI Xin; L(U) Xiao-Fu

2006-01-01

In this paper we introduce bilocal fields in the global color symmetry model and consider color and electrical neutrality conditions simultaneously to study the effect of strange quark mass Ms for the momentum-dependent condensate of color-flavor locked phase. Consequently we find that there will be a quantum phase transition occurring.

Quark-gluon plasma: Status of heavy ion physics

Indian Academy of Sciences (India)

Department of Theoretical Physics, Tata Institute of Fundamental Research, ... such as quark confinement and chiral symmetry breaking, and quantitative details ... attempts have been made, and are being made, to address these issues.

Flavour physics beyond the standard model in top and bottom quarks

International Nuclear Information System (INIS)

Stamou, Emmanuel

2013-01-01

The Large Hadron Collider is currently exploring dynamics at high energies where we expect physics beyond the standard model to emerge as an answer to at least some of the questions the standard model cannot address. We consider the low-energy flavour signatures of a model with a dynamical explanation of quark masses and mixings, construct a model with new strong interactions that account for the anomalously large measurement of an asymmetry in top antitop production at Tevatron, and compute next-to-leading-order electroweak corrections to the recently observed rare decay B s →μ + μ - .

B-meson decay constants from 2+1-flavor lattice QCD with domain-wall light quarks and relativistic heavy quarks

Energy Technology Data Exchange (ETDEWEB)

Christ, Norman H. [Columbia Univ., New York, NY (United States); Flynn, Jonathan M. [Univ. of Southampton, Southampton (United Kingdom); Izubuchi, Taku [Brookhaven National Lab. (BNL), Upton, NY (United States); Kawanai, Taichi [RIKEN, Wako (Japan); Brookhaven National Lab. (BNL), Upton, NY (United States); Lehner, Christoph [Brookhaven National Lab. (BNL), Upton, NY (United States); Soni, Amarjit [Brookhaven National Lab. (BNL), Upton, NY (United States); Van de Water, Ruth S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Witzel, Oliver [Boston Univ., Boston, MA (United States)

2015-03-10

We calculate the B-meson decay constants f_B, f_Bs, and their ratio in unquenched lattice QCD using domain-wall light quarks and relativistic b-quarks. We use gauge-field ensembles generated by the RBC and UKQCD collaborations using the domain-wall fermion action and Iwasaki gauge action with three flavors of light dynamical quarks. We analyze data at two lattice spacings of a ≈ 0.11, 0.086 fm with unitary pion masses as light as M_π ≈ 290 MeV; this enables us to control the extrapolation to the physical light-quark masses and continuum. For the b-quarks we use the anisotropic clover action with the relativistic heavy-quark interpretation, such that discretization errors from the heavy-quark action are of the same size as from the light-quark sector. We renormalize the lattice heavy-light axial-vector current using a mostly nonperturbative method in which we compute the bulk of the matching factor nonperturbatively, with a small correction, that is close to unity, in lattice perturbation theory. We also improve the lattice heavy-light current through O(α_sa). We extrapolate our results to the physical light-quark masses and continuum using SU(2) heavy-meson chiral perturbation theory, and provide a complete systematic error budget. We obtain f_B⁰ = 196.2(15.7) MeV, f_B⁺ = 195.4(15.8) MeV, f_Bs = 235.4(12.2) MeV, f_Bs/f_B⁰ = 1.193(59), and f_Bs/f_B⁺ = 1.220(82), where the errors are statistical and total systematic added in quadrature. In addition, these results are in good agreement with other published results and provide an important independent cross check of other three-flavor determinations of B-meson decay constants using staggered light quarks.

Measurement of the top-quark mass with dilepton events selected using neuroevolution at CDF.

Science.gov (United States)

Aaltonen, T; Adelman, J; Akimoto, T; Albrow, M G; Alvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Apresyan, A; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzurri, P; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Bednar, P; Beecher, D; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Beringer, J; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Bridgeman, A; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Calancha, C; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Compostella, G; Convery, M E; Conway, J; Copic, K; Cordelli, M; Cortiana, G; Cox, D J; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cully, J C; Dagenhart, D; Datta, M; Davies, T; de Barbaro, P; De Cecco, S; Deisher, A; De Lorenzo, G; Dell'orso, M; Deluca, C; Demortier, L; Deng, J; Deninno, M; Derwent, P F; di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Elagin, A; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Ferrazza, C; Field, R; Flanagan, G; Forrest, R; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garberson, F; Garcia, J E; Garfinkel, A F; Genser, K; Gerberich, H; Gerdes, D; Gessler, A; Giagu, S; Giakoumopoulou, V; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C M; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hewamanage, S; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jayatilaka, B; Jeon, E J; Jha, M K; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Kar, D; Karchin, P E; Kato, Y; Kephart, R; Keung, J; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Knuteson, B; Ko, B R; Koay, S A; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kreps, M; Kroll, J; Krop, D; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhr, T; Kulkarni, N P; Kurata, M; Kusakabe, Y; Kwang, S; Laasanen, A T; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; Lecompte, T; Lee, E; Lee, S W; Leone, S; Lewis, J D; Lin, C S; Linacre, J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, C; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lovas, L; Lu, R-S; Lucchesi, D; Lueck, J; Luci, C; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; Macqueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis-Katsikakis, A; Margaroli, F; Marino, C; Marino, C P; Martin, A; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Mattson, M E; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzione, A; Merkel, P; Mesropian, C; Miao, T; Miladinovic, N; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyake, H; Moggi, N; Moon, C S; Moore, R; Morello, M J; Morlok, J; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norman, M; Norniella, O; Nurse, E; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Osterberg, K; Pagan Griso, S; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Pianori, E; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Pueschel, E; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rodriguez, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Safonov, A; Sakumoto, W K; Saltó, O; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, A; Schmidt, E E; Schmidt, M A; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyrla, A; Shalhout, S Z; Shears, T; Shekhar, R; Shepard, P F; Sherman, D; Shimojima, M; Shiraishi, S; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spreitzer, T; Squillacioti, P; Stanitzki, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Suslov, I; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thompson, G A; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Totaro, P; Tourneur, S; Tu, Y; Turini, N; Ukegawa, F; Vallecorsa, S; van Remortel, N; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Vellidis, C; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vogel, M; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner-Kuhr, J; Wagner, W; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Whiteson, S; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Xie, S; Yagil, A; Yamamoto, K; Yamaoka, J; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zheng, Y; Zucchelli, S

2009-04-17

We report a measurement of the top-quark mass M_{t} in the dilepton decay channel tt[over ] --> bl;{'+} nu_{l};{'}b[over ]l;{-}nu[over ]_{l}. Events are selected with a neural network which has been directly optimized for statistical precision in top-quark mass using neuroevolution, a technique modeled on biological evolution. The top-quark mass is extracted from per-event probability densities that are formed by the convolution of leading order matrix elements and detector resolution functions. The joint probability is the product of the probability densities from 344 candidate events in 2.0 fb;{-1} of pp[over ] collisions collected with the CDF II detector, yielding a measurement of M_{t} = 171.2 +/- 2.7(stat) +/- 2.9(syst) GeV / c;{2}.

Measurement of the Top-Quark Mass with Dilepton Events Selected Using Neuroevolution at CDF

International Nuclear Information System (INIS)

Aaltonen, T.; Maki, T.; Mehtala, P.; Orava, R.; Osterberg, K.; Saarikko, H.; Remortel, N. van; Adelman, J.; Brubaker, E.; Fedorko, W. T.; Grosso-Pilcher, C.; Kim, Y. K.; Krop, D.; Kwang, S.; Paramonov, A. A.; Schmidt, M. A.; Shiraishi, S.; Shochet, M.; Wolfe, C.; Yang, U. K.

2009-01-01

We report a measurement of the top-quark mass M t in the dilepton decay channel tt→bl '+ ν l ' bl - ν l . Events are selected with a neural network which has been directly optimized for statistical precision in top-quark mass using neuroevolution, a technique modeled on biological evolution. The top-quark mass is extracted from per-event probability densities that are formed by the convolution of leading order matrix elements and detector resolution functions. The joint probability is the product of the probability densities from 344 candidate events in 2.0 fb -1 of pp collisions collected with the CDF II detector, yielding a measurement of M t =171.2±2.7(stat)±2.9(syst) GeV/c 2

The quark propagator in a covariant gauge

International Nuclear Information System (INIS)

Bonnet, F.D.R.; Leinweber, D.B.; Williams, A.G.; Zanotti, J.M.

2000-01-01

Full text: The quark propagator is one of the fundamental building blocks of QCD. Results strongly depend on the ansatz for the propagator. Direct simulations of QCD on a space time lattice can provide guidance and constraints on the analytic structure of the quark propagator. On the lattice the infrared and asymptotic behaviour of the quark propagator is of particular interest since it is a reflection of the accuracy of the discretised quark action. In the deep infrared region, artefacts associated with the finite size of the lattice spacing become small. This is the most interesting region as nonperturbative physics lies here. However, the ultraviolet behaviour at large momentum of the propagator will in general strongly deviate from the correct continuum behaviour. This behaviour will be action dependent. Some interesting progress has been made in improving the ultraviolet behaviour of the propagator. A method, recently developed and referred to as tree-level correction, consists of using the knowledge of the tree-level behaviour to eliminate the obvious lattice artefacts. Tree-level correction represents a crucial step in extracting meaningful results for the mass function and the renormalisation function outside of the deep infrared region. The mass function is particularly interesting as it provides insights into the constituent quark mass as a measure of the nonperturbative physics. In this poster I will present results from the analytic structure of the propagator in recent lattice studies for a variety of fermion actions in lattice QCD. I will also present the new ratio method used to tree-level correct these quark propagators

High temperature QCD with three flavors of improved staggered quarks

International Nuclear Information System (INIS)

Bernard, C.; Burch, T.; Tar, C.E. de; Gottlieb, Steven; Gregory, Eric; Heller, U.M.; Osborn, J.; Sugar, R.L.; Toussaint, D.

2003-01-01

We present an update of our study of high temperature QCD with three flavors of quarks, using a Symanzik improved gauge action and the Asqtad staggered quark action. Simulations are being carried out on lattices with N t = 4, 6 and 8 for the case of three degenerate quarks with masses less than or equal to the strange quark mass, m s and on lattices with N t = 6 and 8 for degenerate up and down quarks with masses in the range 0.2m s ≤ m u,d ≤ 0.6m s and the strange quark fixed near its physical value. We also report on first computations of quark number susceptibilities with the Asqtad action. These susceptibilities are of interest because they can be related to event-by-event fluctuations in heavy ion collision experiments. Use of the improved quark action leads to a substantial reduction in lattice artifacts. This can be seen already for free fermions and carries over into our results for QCD

A Study of charm quark production in beauty quark decays with the OPAL detector at LEP

CERN Document Server

Waller, David

2003-01-01

The production of charm quarks in beauty quark decays has been studied with the OPAL detector at the Large Electron Positron collider near Geneva, Switzerland. The branching ratio Br(b -1 DDX) has been measured using hadronic zo decays collected between 1993 and 1995. Here b refers to the admixture of weakly decaying hadrons containing ab quark that are produced in electron-positron annihilations at a centre of mass energy equal to the mass of the zo boson. The impact parameter significance of tracks in tagged b-jets is used to differentiate b -1 DDX decays from other decays. The result is Br(b -1 DDX) = (10.0 ± 3.2(stat.)~~:~(syst. det.)~~~04 (syst. phys.))%. where syst. det. is the systematic uncertainty due to the modelling of the detector, and syst. phys. is the systematic uncertainty due to the modelling of the underlying particle physics. Using this result, the average number of charm and anti-charm quarks produced in a beauty quark decay, nc, is found to be l.12~8:i6- Ill

Higher order and heavy quark mass effects in the determination of parton distribution functions

Energy Technology Data Exchange (ETDEWEB)

Bertone, Valerio

2013-07-01

The present thesis was devoted to the study of the inclusion of higher-order corrections and heavy quark mass effects in a PDF determination. This has been carried out in the NNPDF framework resulting originally in the NNPDF2.1 sets, which were at a later stage supplemented by the first LHC data leading to the most recent NNPDF2.3 sets. In Chapter 1 the concept of Parton Distribution Function (PDF) was introduced. We have shown how the analytical computation of the Deep-Inelastic-Scattering (DIS) process at order α{sub s} in QCD leads to initial-stale collinear divergences which, using the factorization theorem, can be reabsorbed into the PDFs. The energy dependence of PDFs is fully determined and the task is then reduced to the determination of the x (Bjorken variable) dependence. In Chapter 2 a detailed discussion of the factorization schemes presently available to include heavy quark mass effects into DIS structure functions has been given. It emerged that there are two possible basic approaches to the calculation of the DIS structure functions. In the first approach, the so-called Fixed-Flavour-Number Scheme (FFNS), the calculation is performed retaining the quark mass of the heavy flavours which provide a ''natural'' regulator for the infrared divergences. In the second approach, called Zero-Mass Variable-Flavour-Number Scheme (ZM-VFNS), the heavy quark masses are instead set to zero and this gives rise to the usual final-state collinear divergences that are absorbed into the PDFs. In addition, in the ZM-VFNS, the number of active flavours is assumed to increase by one unity as the energy of the process crosses the energy threshold of a given heavy quark. In order to obtain a factorization scheme that is accurate both at large and low energies, several prescriptions that interpolate between FFNS at low energy and ZM-VFNS at large energy have been proposed and implemented in as many PDF fits. In Chapter 2 they have been described showing how they behave for

Higher order and heavy quark mass effects in the determination of parton distribution functions

Energy Technology Data Exchange (ETDEWEB)

Bertone, Valerio

2013-07-01

The present thesis was devoted to the study of the inclusion of higher-order corrections and heavy quark mass effects in a PDF determination. This has been carried out in the NNPDF framework resulting originally in the NNPDF2.1 sets, which were at a later stage supplemented by the first LHC data leading to the most recent NNPDF2.3 sets. In Chapter 1 the concept of Parton Distribution Function (PDF) was introduced. We have shown how the analytical computation of the Deep-Inelastic-Scattering (DIS) process at order α{sub s} in QCD leads to initial-stale collinear divergences which, using the factorization theorem, can be reabsorbed into the PDFs. The energy dependence of PDFs is fully determined and the task is then reduced to the determination of the x (Bjorken variable) dependence. In Chapter 2 a detailed discussion of the factorization schemes presently available to include heavy quark mass effects into DIS structure functions has been given. It emerged that there are two possible basic approaches to the calculation of the DIS structure functions. In the first approach, the so-called Fixed-Flavour-Number Scheme (FFNS), the calculation is performed retaining the quark mass of the heavy flavours which provide a ''natural'' regulator for the infrared divergences. In the second approach, called Zero-Mass Variable-Flavour-Number Scheme (ZM-VFNS), the heavy quark masses are instead set to zero and this gives rise to the usual final-state collinear divergences that are absorbed into the PDFs. In addition, in the ZM-VFNS, the number of active flavours is assumed to increase by one unity as the energy of the process crosses the energy threshold of a given heavy quark. In order to obtain a factorization scheme that is accurate both at large and low energies, several prescriptions that interpolate between FFNS at low energy and ZM-VFNS at large energy have been proposed and implemented in as many PDF fits. In Chapter 2 they have been described showing

Higher order and heavy quark mass effects in the determination of parton distribution functions

International Nuclear Information System (INIS)

Bertone, Valerio

2013-01-01

The present thesis was devoted to the study of the inclusion of higher-order corrections and heavy quark mass effects in a PDF determination. This has been carried out in the NNPDF framework resulting originally in the NNPDF2.1 sets, which were at a later stage supplemented by the first LHC data leading to the most recent NNPDF2.3 sets. In Chapter 1 the concept of Parton Distribution Function (PDF) was introduced. We have shown how the analytical computation of the Deep-Inelastic-Scattering (DIS) process at order α s in QCD leads to initial-stale collinear divergences which, using the factorization theorem, can be reabsorbed into the PDFs. The energy dependence of PDFs is fully determined and the task is then reduced to the determination of the x (Bjorken variable) dependence. In Chapter 2 a detailed discussion of the factorization schemes presently available to include heavy quark mass effects into DIS structure functions has been given. It emerged that there are two possible basic approaches to the calculation of the DIS structure functions. In the first approach, the so-called Fixed-Flavour-Number Scheme (FFNS), the calculation is performed retaining the quark mass of the heavy flavours which provide a ''natural'' regulator for the infrared divergences. In the second approach, called Zero-Mass Variable-Flavour-Number Scheme (ZM-VFNS), the heavy quark masses are instead set to zero and this gives rise to the usual final-state collinear divergences that are absorbed into the PDFs. In addition, in the ZM-VFNS, the number of active flavours is assumed to increase by one unity as the energy of the process crosses the energy threshold of a given heavy quark. In order to obtain a factorization scheme that is accurate both at large and low energies, several prescriptions that interpolate between FFNS at low energy and ZM-VFNS at large energy have been proposed and implemented in as many PDF fits. In Chapter 2 they have been described showing how

Precise measurement of the top-quark mass at the CMS experiment using the ideogram method

International Nuclear Information System (INIS)

Seidel, Markus

2015-08-01

The mass of the top quark is measured using a sample of t anti t candidate events with one electron or muon and at least four jets in the final state, collected by CMS in proton-proton collisions at √(s)=8 TeV at the LHC. The candidate events are selected from data corresponding to an integrated luminosity of 19.7 fb -1 . For each event the top-quark mass is reconstructed from a kinematic fit of the decay products to a t anti t hypothesis. In order to minimize the uncertainties from jet energy corrections, the top-quark mass is determined simultaneously with a jet energy scale factor (JSF), constrained by the known mass of the W boson decaying to quark-antiquark pairs. A joint likelihood fit taking into account multiple interpretations per event - the ideogram method - is used. From the simultaneous fit, a top-quark mass of 172.15±0.19(stat.+JSF)±0.61(syst.) GeV is obtained. Using an additional constraint from the determination of the jet energy scale in γ/Z+jet events yields m t =172.38±0.16(stat.+JSF)±0.49(syst.) GeV. The results are discussed in the context of different event generator implementations. Possible kinematic biases are studied by performing the measurement in different regions of the phase space.

Measurement of the Top Quark Mass at CDF Using the Template Method in the Lepton + Jets Channel

Energy Technology Data Exchange (ETDEWEB)

Adelman, Jahred A. [Univ. of Chicago, IL (United States)

2008-06-01

A measurement of the top quark mass in p$\\bar{p}$ collisions at √s = 1.96 TeV is presented. The analysis uses a template method, in which the overconstrained kinematics of the Lepton+Jets channel of the t$\\bar{t}$ system are used to measure a single quantity, the reconstructed top quark mass, that is strongly correlated with the true top quark mass. in addition, the dijet mass of the hadronically decaying W boson is used to constrain in situ the uncertain jet energy scale in the CDF detector. Two-dimensional probability density functions are derived using a kernel density estimate-based machinery. Using 1.9 fb^-1 of data, the top quark mass is measured to be 171.8$+1.9\\atop{-1.9}$(stat.) ± 1.0(syst.)GeV/c².

The double mass hierarchy pattern: Simultaneously understanding quark and lepton mixing

Science.gov (United States)

Hollik, Wolfgang Gregor; Saldaña Salazar, Ulises Jesús

2015-03-01

The charged fermion masses of the three generations exhibit the two strong hierarchies m3 ≫m2 ≫m1. We assume that also neutrino masses satisfy mν3 >mν2 >mν1 and derive the consequences of the hierarchical spectra on the fermionic mixing patterns. The quark and lepton mixing matrices are built in a general framework with their matrix elements expressed in terms of the four fermion mass ratios, mu /mc, mc /mt, md /ms and ms /mb, and me /mμ, mμ /mτ, mν1 /mν2 and mν2 /mν3, for the quark and lepton sector, respectively. In this framework, we show that the resulting mixing matrices are consistent with data for both quarks and leptons, despite the large leptonic mixing angles. The minimal assumption we take is the one of hierarchical masses and minimal flavor symmetry breaking that strongly follows from phenomenology. No special structure of the mass matrices has to be assumed that cannot be motivated by this minimal assumption. This analysis allows us to predict the neutrino mass spectrum and set the mass of the lightest neutrino well below 0.01 eV. The method also gives the 1σ allowed ranges for the leptonic mixing matrix elements. Contrary to the common expectation, leptonic mixing angles are found to be determined solely by the four leptonic mass ratios without any relation to symmetry considerations as commonly used in flavor model building. Still, our formulae can be used to build up a flavor model that predicts the observed hierarchies in the masses - the mixing follows then from the procedure which is developed in this work.

Studies for a top quark mass measurement and development of a jet energy calibration with the ATLAS detector

International Nuclear Information System (INIS)

Jantsch, Andreas

2012-01-01

In this thesis, the development of a new jet energy calibration method as well as studies for a top quark mass measurement with the ATLAS detector are presented. The new calibration method considers jet shape variables in order to improve the linearity and resolution of the jet energy response. Promising results are shown for jet events from Monte Carlo simulation as well as from first √(s)=900 GeV proton-proton collision data of the Large Hadron Collider. In addition, Monte Carlo studies for a top quark mass measurement in the lepton plus jets decay channel of top quark pair events are performed. Several top quark reconstruction methods are investigated in pseudo-experiments which are equivalent to an integrated luminosity of L=200 pb -1 at √(s)=10 TeV. Assuming a generated top quark mass of m t gen =172.5 GeV, the most promising result is achieved with the Max-p T reconstruction method which returns a top quark mass of m Max-p T t,el-channel =170.4±2.2 vertical stroke stat. ± 8.8 vertical stroke syst. GeV in the electron plus jets decay channel including a bias correction of +5.2 GeV for the central top quark mass value.

Precision measurement of the top-quark mass in lepton+jets final states

CERN Document Server

Abazov, Victor Mukhamedovich; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd; Agnew, James P; Alexeev, Guennadi D; Alkhazov, Georgiy D; Alton, Andrew K; Askew, Andrew Warren; Atkins, Scott; Augsten, Kamil; Avila, Carlos A; Badaud, Frederique; Bagby, Linda F; Baldin, Boris; Bandurin, Dmitry V; Banerjee, Sunanda; Barberis, Emanuela; Baringer, Philip S; Bartlett, JFrederick; Bassler, Ursula Rita; Bazterra, Victor; Bean, Alice L; Begalli, Marcia; Bellantoni, Leo; Beri, Suman B; Bernardi, Gregorio; Bernhard, Ralf Patrick; Bertram, Iain A; Besancon, Marc; Beuselinck, Raymond; Bhat, Pushpalatha C; Bhatia, Sudeep; Bhatnagar, Vipin; Blazey, Gerald Charles; Blessing, Susan K; Bloom, Kenneth A; Boehnlein, Amber S; Boline, Daniel Dooley; Boos, Edward E; Borissov, Guennadi; Borysova, Maryna; Brandt, Andrew; Brandt, Oleg; Brock, Raymond L; Bross, Alan D; Brown, Duncan Paul; Bu, Xue-Bing; Buehler, Marc; Buescher, Volker; Bunichev, Viacheslav Yevgenyevich; Burdin, Sergey; Buszello, Claus Peter; Camacho-Perez, Enrique; Casey, Brendan Cameron Kieran; Castilla-Valdez, Heriberto; Caughron, Seth Aaron; Chakrabarti, Subhendu; Chan, Kwok Ming Leo; Chandra, Avdhesh; Chapon, Emilien; Chen, Guo; Cho, Sung-Woong; Choi, Suyong; Choudhary, Brajesh C; Cihangir, Selcuk; Claes, Daniel R; Clutter, Justace Randall; Cooke, Michael P; Cooper, William Edward; Corcoran, Marjorie D; Couderc, Fabrice; Cousinou, Marie-Claude; Cutts, David; Das, Amitabha; Davies, Gavin John; de Jong, Sijbrand Jan; De La Cruz-Burelo, Eduard; Deliot, Frederic; Demina, Regina; Denisov, Dmitri S; Denisov, Sergei P; Desai, Satish Vijay; Deterre, Cecile; DeVaughan, Kayle Otis; Diehl, HThomas; Diesburg, Michael; Ding, Pengfei; Dominguez, DAaron M; Dubey, Abhinav Kumar; Dudko, Lev V; Duperrin, Arnaud; Dutt, Suneel; Eads, Michael T; Edmunds, Daniel L; Ellison, John A; Elvira, VDaniel; Enari, Yuji; Evans, Harold G; Evdokimov, Valeri N; Faure, Alexandre; Feng, Lei; Ferbel, Thomas; Fiedler, Frank; Filthaut, Frank; Fisher, Wade Cameron; Fisk, HEugene; Fortner, Michael R; Fox, Harald; Fuess, Stuart C; Garbincius, Peter H; Garcia-Bellido, Aran; Garcia-Gonzalez, Jose Andres; Gavrilov, Vladimir B; Geng, Weigang; Gerber, Cecilia Elena; Gershtein, Yuri S; Ginther, George E; Gogota, Olga; Golovanov, Georgy Anatolievich; Grannis, Paul D; Greder, Sebastien; Greenlee, Herbert B; Grenier, Gerald Jean; Gris, Phillipe Luc; Grivaz, Jean-Francois; Grohsjean, Alexander; Gruenendahl, Stefan; Gruenewald, Martin Werner; Guillemin, Thibault; Gutierrez, Gaston R; Gutierrez, Phillip; Haley, Joseph Glenn Biddle; Han, Liang; Harder, Kristian; Harel, Amnon; Hauptman, John Michael; Hays, Jonathan M; Head, Tim; Hebbeker, Thomas; Hedin, David R; Hegab, Hatim; Heinson, Ann; Heintz, Ulrich; Hensel, Carsten; Heredia-De La Cruz, Ivan; Herner, Kenneth Richard; Hesketh, Gavin G; Hildreth, Michael D; Hirosky, Robert James; Hoang, Trang; Hobbs, John D; Hoeneisen, Bruce; Hogan, Julie; Hohlfeld, Mark; Holzbauer, Jenny Lyn; Howley, Ian James; Hubacek, Zdenek; Hynek, Vlastislav; Iashvili, Ia; Ilchenko, Yuriy; Illingworth, Robert A; Ito, Albert S; Jabeen, Shabnam; Jaffre, Michel J; Jayasinghe, Ayesh; Jeong, Min-Soo; Jesik, Richard L; Jiang, Peng; Johns, Kenneth Arthur; Johnson, Emily; Johnson, Marvin E; Jonckheere, Alan M; Jonsson, Per Martin; Joshi, Jyoti; Jung, Andreas Werner; Juste, Aurelio; Kajfasz, Eric; Karmanov, Dmitriy Y; Katsanos, Ioannis; Kaur, Manbir; Kehoe, Robert Leo Patrick; Kermiche, Smain; Khalatyan, Norayr; Khanov, Alexander; Kharchilava, Avto; Kharzheev, Yuri N; Kiselevich, Ivan Lvovich; Kohli, Jatinder M; Kozelov, Alexander V; Kraus, James Alexander; Kumar, Ashish; Kupco, Alexander; Kurca, Tibor; Kuzmin, Valentin Alexandrovich; Lammers, Sabine Wedam; Lebrun, Patrice; Lee, Hyeon-Seung; Lee, Seh-Wook; Lee, William M; Lei, Xiaowen; Lellouch, Jeremie; Li, Dikai; Li, Hengne; Li, Liang; Li, Qi-Zhong; Lim, Jeong Ku; Lincoln, Donald W; Linnemann, James Thomas; Lipaev, Vladimir V; Lipton, Ronald J; Liu, Huanzhao; Liu, Yanwen; Lobodenko, Alexandre; Lokajicek, Milos; Lopes de Sa, Rafael; Luna-Garcia, Rene; Lyon, Adam Leonard; Maciel, Arthur KA; Madar, Romain; Magana-Villalba, Ricardo; Malik, Sudhir; Malyshev, Vladimir L; Mansour, Jason; Martinez-Ortega, Jorge; McCarthy, Robert L; Mcgivern, Carrie Lynne; Meijer, Melvin M; Melnitchouk, Alexander S; Menezes, Diego D; Mercadante, Pedro Galli; Merkin, Mikhail M; Meyer, Arnd; Meyer, Jorg Manfred; Miconi, Florian; Mondal, Naba K; Mulhearn, Michael James; Nagy, Elemer; Narain, Meenakshi; Nayyar, Ruchika; Neal, Homer A; Negret, Juan Pablo; Neustroev, Petr V; Nguyen, Huong Thi; Nunnemann, Thomas P; Hernandez Orduna, Jose de Jesus; Osman, Nicolas Ahmed; Osta, Jyotsna; Pal, Arnab; Parashar, Neeti; Parihar, Vivek; Park, Sung Keun; Partridge, Richard A; Parua, Nirmalya; Patwa, Abid; Penning, Bjoern; Perfilov, Maxim Anatolyevich; Peters, Reinhild Yvonne Fatima; Petridis, Konstantinos; Petrillo, Gianluca; Petroff, Pierre; Pleier, Marc-Andre; Podstavkov, Vladimir M; Popov, Alexey V; Prewitt, Michelle; Price, Darren; Prokopenko, Nikolay N; Qian, Jianming; Quadt, Arnulf; Quinn, Gene Breese; Ratoff, Peter N; Razumov, Ivan A; Ripp-Baudot, Isabelle; Rizatdinova, Flera; Rominsky, Mandy Kathleen; Ross, Anthony; Royon, Christophe; Rubinov, Paul Michael; Ruchti, Randal C; Sajot, Gerard; Sanchez-Hernandez, Alberto; Sanders, Michiel P; Santos, Angelo Souza; Savage, David G; Savitskyi, Mykola; Sawyer, HLee; Scanlon, Timothy P; Schamberger, RDean; Scheglov, Yury A; Schellman, Heidi M; Schwanenberger, Christian; Schwienhorst, Reinhard H; Sekaric, Jadranka; Severini, Horst; Shabalina, Elizaveta K; Shary, Viacheslav V; Shaw, Savanna; Shchukin, Andrey A; Simak, Vladislav J; Skubic, Patrick Louis; Slattery, Paul F; Smirnov, Dmitri V; Snow, Gregory R; Snow, Joel Mark; Snyder, Scott Stuart; Soldner-Rembold, Stefan; Sonnenschein, Lars; Soustruznik, Karel; Stark, Jan; Stoyanova, Dina A; Strauss, Michael G; Suter, Louise; Svoisky, Peter V; Titov, Maxim; Tokmenin, Valeriy V; Tsai, Yun-Tse; Tsybychev, Dmitri; Tuchming, Boris; Tully, Christopher George T; Uvarov, Lev; Uvarov, Sergey L; Uzunyan, Sergey A; Van Kooten, Richard J; van Leeuwen, Willem M; Varelas, Nikos; Varnes, Erich W; Vasilyev, Igor A; Verkheev, Alexander Yurievich; Vertogradov, Leonid S; Verzocchi, Marco; Vesterinen, Mika; Vilanova, Didier; Vokac, Petr; Wahl, Horst D; Wang, Michael HLS; Warchol, Jadwiga; Watts, Gordon Thomas; Wayne, Mitchell R; Weichert, Jonas; Welty-Rieger, Leah Christine; Williams, Mark Richard James; Wilson, Graham Wallace; Wobisch, Markus; Wood, Darien Robert; Wyatt, Terence R; Xie, Yunhe; Yamada, Ryuji; Yang, Siqi; Yasuda, Takahiro; Yatsunenko, Yuriy A; Ye, Wanyu; Ye, Zhenyu; Yin, Hang; Yip, Kin; Youn, Sungwoo; Yu, Jiaming; Zennamo, Joseph; Zhao, Tianqi Gilbert; Zhou, Bing; Zhu, Junjie; Zielinski, Marek; Zieminska, Daria; Zivkovic, Lidija

2015-06-04

We measure the mass of the top quark in lepton$+$jets final states using the full sample of $p\\bar{p}$ collision data collected by the D0 experiment in Run II of the Fermilab Tevatron Collider at $\\sqrt s=1.96 $TeV, corresponding to $9.7 {\\rm fb}^{-1}$ of integrated luminosity. We use a matrix element technique that calculates the probabilities for each event to result from $t\\bar t$ production or background. The overall jet energy scale is constrained in situ by the mass of the $W$ boson. We measure $m_t=174.98\\pm0.76$ GeV. This constitutes the most precise single measurement of the top-quark mass.

Cross-section-constrained top-quark mass measurement from dilepton events at the Tevatron.

Science.gov (United States)

Aaltonen, T; Adelman, J; Akimoto, T; Albrow, M G; Alvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Apresyan, A; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Bednar, P; Behari, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Bridgeman, A; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cully, J C; Dagenhart, D; Datta, M; Davies, T; de Barbaro, P; DeCecco, S; Deisher, A; De Lentdecker, G; De Lorenzo, G; Dell'Orso, M; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Ferrazza, C; Field, R; Flanagan, G; Forrest, R; Forrester, S; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garberson, F; Garcia, J E; Garfinkel, A F; Gerberich, H; Gerdes, D; Giagu, S; Giakoumopolou, V; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C M; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hewamanage, S; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; Iyutin, B; James, E; Jayatilaka, B; Jeans, D; Jeon, E J; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Kar, D; Karchin, P E; Kato, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Koay, S A; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kraus, J; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kulkarni, N P; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Linacre, J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lovas, L; Lu, R-S; Lucchesi, D; Lueck, J; Luci, C; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; MacQueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis, A; Margaroli, F; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Mattson, M E; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyake, H; Moed, S; Moggi, N; Moon, C S; Moore, R; Morello, M; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norman, M; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Osterberg, K; Pagan Griso, S; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Safonov, A; Sakumoto, W K; Salamanna, G; Saltó, O; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M A; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyria, A; Shalhout, S Z; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suslov, I; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thompson, G A; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; Vallecorsa, S; van Remortel, N; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Vellidis, C; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vogel, M; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner-Kuhr, J; Wagner, W; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zheng, Y; Zucchelli, S

2008-02-15

We report the first top-quark mass measurement that uses a cross-section constraint to improve the mass determination. This measurement is made with a dilepton tt event candidate sample collected with the Collider Detector II at Fermilab. From a data sample corresponding to an integrated luminosity of 1.2 fb(-1), we measure a top-quark mass of 170.7(-3.9)(+4.2)(stat)+/-2.6(syst)+/-2.4(theory) GeV/c(2). The measurement without the cross-section constraint is 169.7(-4.9)(+5.2)(stat)+/-3.1(syst) GeV/c(2).

Many Masses on One Stroke:. Economic Computation of Quark Propagators

Science.gov (United States)

Frommer, Andreas; Nöckel, Bertold; Güsken, Stephan; Lippert, Thomas; Schilling, Klaus

The computational effort in the calculation of Wilson fermion quark propagators in Lattice Quantum Chromodynamics can be considerably reduced by exploiting the Wilson fermion matrix structure in inversion algorithms based on the non-symmetric Lanczos process. We consider two such methods: QMR (quasi minimal residual) and BCG (biconjugate gradients). Based on the decomposition M/κ = 1/κ-D of the Wilson mass matrix, using QMR, one can carry out inversions on a whole trajectory of masses simultaneously, merely at the computational expense of a single propagator computation. In other words, one has to compute the propagator corresponding to the lightest mass only, while all the heavier masses are given for free, at the price of extra storage. Moreover, the symmetry γ5M = M†γ5 can be used to cut the computational effort in QMR and BCG by a factor of two. We show that both methods then become — in the critical regime of small quark masses — competitive to BiCGStab and significantly better than the standard MR method, with optimal relaxation factor, and CG as applied to the normal equations.

A Dynamical Origin of the Mass Hierarchy among Neutrinos, Charged Leptons, and Quarks

OpenAIRE

Akama, Keiichi; Katsuura, Kazuo

1998-01-01

We propose a dynamical mass-generation scenario which naturally realizes the mass hierarchy among the neutrinos, charged leptons and quarks, where the mass is dominated by the self-mass induced through the anomalous (i.e. non-minimal) gauge interactions.

1S and $\\overline{MS}$ Bottom Quark Masses from $\\Upsilon$ Sum Rules

CERN Document Server

Hoang, A.H.

2000-01-01

The bottom quark $1S$ mass, $M_b^{1S}$, is determined using sum rules which relate the masses and the electronic decay widths of the $\\Upsilon$ mesons to moments of the vacuum polarization function. The $1S$ mass is defined as half the perturbative mass of a fictitious ${}^3S_1$ bottom-antibottom quark bound state, and is free of the ambiguity of order $\\Lambda_{QCD}$ which plagues the pole mass definition. Compared to an earlier analysis by the same author, which had been carried out in the pole mass scheme, the $1S$ mass scheme leads to a much better behaved perturbative series of the moments, smaller uncertainties in the mass extraction and to a reduced correlation of the mass and the strong coupling. We arrive at $M_b^{1S}=4.71\\pm 0.03$ GeV taking m_b(\\bar m_b)$ can be reduced if the three-loop corrections to the relation of pole and $\\bar{MS}$ mass are known and if the error in the strong coupling is decreased.

arXiv Fragmentation Uncertainties in Hadronic Observables for Top-quark Mass Measurements

CERN Document Server

Corcella, Gennaro; Kim, Doojin

We study the Monte Carlo uncertainties due to modeling of hadronization and showering in the extraction of the top-quark mass from observables that use exclusive hadronic final states in top decays, such as t→anything+J/ψ or t→anything+(B→charged tracks) , where B is a B -hadron. To this end, we investigate the sensitivity of the top-quark mass, determined by means of a few observables already proposed in the literature as well as some new proposals, to the relevant parameters of event generators, such as HERWIG 6 and PYTHIA 8. We find that constraining those parameters at O(1%–10%) is required to avoid a Monte Carlo uncertainty on mt greater than 500 MeV. For the sake of achieving the needed accuracy on such parameters, we examine the sensitivity of the top-quark mass measured from spectral features, such as peaks, endpoints and distributions of EB , mBℓ , and some mT2 -like variables. We find that restricting oneself to regions sufficiently close to the endpoints enables one to substantially decr...

Quark matter in a chiral chromodielectric model

International Nuclear Information System (INIS)

Broniowski, W.; Kutschera, M.; Cibej, M.; Rosina, M.

1989-03-01

Zero and finite temperature quark matter is studied in a chiral chromodielectric model with quark, meson and chromodielectric degrees of freedom. Mean field approximation is used. Two cases are considered: two-flavor and three-flavor quark matter. It is found that at sufficiently low densities and temperatures the system is in a chirally broken phase, with quarks acquiring effective masses of the order of 100 MeV. At higher densities and temperatures a chiral phase transition occurs and the quarks become massless. A comparison to traditional nuclear physics suggests that the chirally broken phase with massive quark gas may be the ground state of matter at densities of the order of a few nuclear saturation densities. 24 refs., 5 figs. (author)

Measurement of the top quark mass with dilepton events selected using neuroevolution at CDF

International Nuclear Information System (INIS)

Aaltonen, T.; Helsinki Inst. of Phys.; Adelman, J.; Chicago U., EFI; Akimoto, T.; Tsukuba U.; Albrow, M.G.; Fermilab; Alvarez Gonzalez, B.; Cantabria U., Santander; Amerio, S.; Padua U.; Amidei, D.; Michigan U.; Anastassov, A.; Northwestern U.; Annovi, A.; Frascati; Antos, J.; Comenius U.; Apollinari, G.

2008-01-01

We report a measurement of the top quark mass M t in the dilepton decay channel t(bar t) to b(ell)(prime) + ν(prime) # ell# (bar b)(ell) - (bar ν) # ell#. Events are selected with a neural network which has been directly optimized for statistical precision in top quark mass using neuroevolution, a technique modeled on biological evolution. The top quark mass is extracted from per-event probability densities that are formed by the convolution of leading order matrix elements and detector resolution functions. The joint probability is the product of the probability densities from 344 candidate events in 2.0 fb -1 of p(bar p) collisions collected with the CDF II detector, yielding a measurement of M t = 171.2 ± 2.7(stat.) ± 2.9(syst.) GeV/c 2

New Physics Search in Dijet Mass Spectrum with Compact Muon Solenoid

Energy Technology Data Exchange (ETDEWEB)

Jeong, Chiyoung [Texas Tech Univ., Lubbock, TX (United States)

2011-01-01

Many extensions of the SM predict the existence of new massive objects that couple to quarks and gluons and result in resonances in the dijet mass spectrum. In this thesis we present a search for narrow resonances in the dijet mass spectrum using data corresponding to an integrated luminosity of 1 fb$^{-1}$ collected by the CMS experiment at the LHC, at a proton-proton collision energy of $\\sqrt{s}=7$ $TeV$. %This dijet analysis is searching for new particles in the dijet mass spectrum decaying to dijets. These new particles are predicted by new physics beyond Standard Model. This thesis presents a dijet analysis performed at the Compact Muon Solenoid (CMS) in pp collisions at $\\sqrt{s}=7$ $TeV$ for an integrated luminosities of 1.0 fb$^{-1}$. The dijet mass distribution of two leading jets is measured and compared to QCD predictions, simulated by PYTHIA with the CMS detector simulation. We select events which have two leading jets with $\\mid \\Delta\\eta \\mid < 1.3$ and $\\mid \\eta \\mid < 2.5$. We fit the dijet mass spectrum with QCD parameters. Since no evidence of new physics was found, we set upper limits at 95\\% CL on the resonance cross section and compare to the theoretical prediction for several models of new particles: string resonances, axigluons, colorons, excited quarks, $E_{6}$ diquarks, Randall-Sundrum gravitons, W' and Z'. We exclude at 95\\% CL string resonances in the mass range $1.0 < M(S) < 4.00$ TeV, excited quarks in the mass range $1.0mass range $1.0mass range $1.0mass range $1.0

Proceedings of the Helmholtz international school physics of heavy quarks and hadrons (HQ2013)

International Nuclear Information System (INIS)

Ali, Ahmed; Bystritskiy, Yury; Ivanov, Mikhail

2014-07-01

The following topics were dealt with: Higgs boson production and couplings with the ATLAS detector, recent CMS results on heavy quarks and hadrons, mesons with open charm and beauty, new-physics searches in B→D (*) τν τ , spectroscopy and Regge trajectories of heavy quarkonia, weak decays of B s mesons, the possible role of scalar glueball-quarkonia mixing in the f 0 (1370,1500,17100) resonances produced in charmonia decays, effective weak Lagrangians in the Standard Model and B decays, heavy-quark physics in the covariant quark model, application of QCD sum rules to heavy-quark physics, top-quark production, helicity amplitudes and angular decay distributions, small-x behavior of deep-inelastic structure functions F 2 and F 2 cc , XYZ stated, recent Belle results, light and heavy hadrons in AdS/QCD, renorm dynamics, valence quarks and multiparticle production, prompt photons and associated b,c-tagged jet production within the k T factorization approach, heavy quarkonium production at the LHC in the framework of NRQCD and parton Reggeization approach, light-cone distribution amplitudes of bottom baryons, rare semileptonic B + → π + l + l - decay, bimodality phenomenon in finite and infinite systems within an exactly solvable statistical model, CP violation in D meson decays, the scalar mesons in multichannel ππ scattering and decays of the ψ and Υ families, the latest results of the ATLAS experiment on heavy-quark physics, relativistic corrections to pair charmonium production at the LHC, the rise and fall of the fourth quark-lepton generation. (HSI)

Quark condensate contributions to the gluon self-energy and the ρ meson sum rule

International Nuclear Information System (INIS)

Steele, T.G.

1989-01-01

The operator-product expansion will be employed to obtain the lowest-order, quark condensate component of both the gluon self-energy and the ρ meson correlation function to all orders in the quark mass parameter. Field-theoretic aspects of the self-energy and correlation function will be considered, and physical effects to the quark condensate upon gluon mass generation will be examined. (orig.)

Quarks and gluons in nuclear and particle physics

International Nuclear Information System (INIS)

Van Hove, L.

1988-01-01

This paper provides a broad overview of strong interactions, or nuclear forces, as ones understanding has expanded over the past 25 years. The major particles and models are briefly touched upon. The author expands upon the field theories which have evolved to explain the experimental work, and the present model of quarks and gluons which form the components of hadrons. The standard model has been very successful in explaining much of the newly acquired experimental data. But the property of confinement, where the partons, (quarks and gluons), are not observed seperately has precluded observation of these particles. He touches on the manifestation of these particles in high energy physics, where they model the observed particles and resonances, and are responsible for the production of hadronic jets. However in nuclear physics, one does not need to postulate the existance of these particles to explain the properties of nuclei, until one deals with interaction energies in the range of GeV. The author then touches on the area of ultra-relativistic nuclear physics, where the partons must play a role in the effects which are observed. In particular he discusses deep inelastic lepton scattering on nuclei, the Drell-Yan process in nuclei, and ultra-relativistic nuclear collisions. Finally he gives a brief discussion of the quark-gluon plasma, which is postulated to form during very high energy collisions, manifesting itself as a brief deconfinement of the partons into an equilibrium plasma

Discovery of single top quark production

Energy Technology Data Exchange (ETDEWEB)

Gillberg, Dag [Simon Fraser Univ., Burnaby, BC (Canada)

2009-04-01

The top quark is by far the heaviest known fundamental particle with a mass nearing that of a gold atom. Because of this strikingly high mass, the top quark has several unique properties and might play an important role in electroweak symmetry breaking - the mechanism that gives all elementary particles mass. Creating top quarks requires access to very high energy collisions, and at present only the Tevatron collider at Fermilab is capable of reaching these energies. Until now, top quarks have only been observed produced in pairs via the strong interaction. At hadron colliders, it should also be possible to produce single top quarks via the electroweak interaction. Studies of single top quark production provide opportunities to measure the top quark spin, how top quarks mix with other quarks, and to look for new physics beyond the standard model. Because of these interesting properties, scientists have been looking for single top quarks for more than 15 years. This thesis presents the first discovery of single top quark production. An analysis is performed using 2.3 fb^-1 of data recorded by the D0 detector at the Fermilab Tevatron Collider at centre-of-mass energy √s = 1.96 TeV. Boosted decision trees are used to isolate the single top signal from background, and the single top cross section is measured to be σ(p$\\bar{p}$ → tb + X, tqb + X) = 3.74_-0.74^+0.95 pb. Using the same analysis, a measurement of the amplitude of the CKM matrix element V_tb, governing how top and b quarks mix, is also performed. The measurement yields: |V{sub tb}|f₁^L| = 1.05 -_0.12^+0.13, where f₁^L is the left-handed Wtb coupling. The separation of signal from background is improved by combining the boosted decision trees with two other multivariate techniques. A new cross section measurement is performed, and the significance for the excess over the predicted background exceeds 5

Progress in simulations with twisted mass fermions at the physical point

International Nuclear Information System (INIS)

Abdel-Rehim, A.

2014-11-01

In this contribution, results from N f =2 lattice QCD simulations at one lattice spacing using twisted mass fermions with a clover term at the physical pion mass are presented. The mass splitting between charged and neutral pions (including the disconnected contribution) is shown to be around 20(20) MeV. Further, a first measurement using the clover twisted mass action of the average momentum fraction of the pion is given. Finally, an analysis of pseudoscalar meson masses and decay constants is presented involving linear interpolations in strange and charm quark masses. Matching to meson mass ratios allows the calculation of quark mass ratios: μ s /μ l =27.63(13), μ c /μ l =339.6(2.2) and μ c /μ s =12.29(10). From this mass matching the quantities f K =153.9(7.5) MeV, f D =219(11) MeV, f D s =255(12) MeV and M D s =1894(93) MeV are determined without the application of finite volume or discretization artefact corrections and with errors dominated by a preliminary estimate of the lattice spacing.

Status of the top-quark

International Nuclear Information System (INIS)

Hill, C.T.

1981-10-01

Exactly two years ago at the 1979 Lepton, Photon Symposium at Fermilab, Mary K. Gaillard presented a histogram showing the number of papers predicting a given value of toponium mass as a function of mass. I have translated this into the t-quark mass and presented it including several other bounds arising from an assortment of physical principles and arguments. These include Veltman's rho-parameter bound, a well-known bound from grand unification due to Cabibbo, Maiani, Parisi and Petronzio, and considerations of Higgs potential stability and unitarity. The central popular mechanism for generating t-quark mass predictions, you will recall, was to employ discrete symmetries in the Higgs sector of left-right symmetric models, leading to a central popular prediction of m approx. 15 GeV. It should be noted that discrete symmetries can lead to larger values (and smaller ones), but clearly with diminished unanimity. We should also mention independent ideas which presume a basic universal ratio of m/sup (+2/3)//m/sup (-1/3)/ for all generations and lead to a prediction of m approx. 26 GeV. In the intervening two years physicists have kept busy generating new t-quark mass predictions and Petra has pushed the lower bound up to approx. 18.5 GeV. New physical ideas have emerged which now focus more directly upon dynamical aspects of grand-unification. uv versus ir behavior of field theory, and nonlinear renormalization group equations with quasi-fixed point behavior. Some of these ideas make statements about hypothetical fourth generation fermion masses. These ideas are reviewed with an eye to statements one can make about mass scales beyond the third generation, as well

Studies for a top quark mass measurement and development of a jet energy calibration with the ATLAS detector

Energy Technology Data Exchange (ETDEWEB)

Jantsch, Andreas

2012-06-11

In this thesis, the development of a new jet energy calibration method as well as studies for a top quark mass measurement with the ATLAS detector are presented. The new calibration method considers jet shape variables in order to improve the linearity and resolution of the jet energy response. Promising results are shown for jet events from Monte Carlo simulation as well as from first {radical}(s)=900 GeV proton-proton collision data of the Large Hadron Collider. In addition, Monte Carlo studies for a top quark mass measurement in the lepton plus jets decay channel of top quark pair events are performed. Several top quark reconstruction methods are investigated in pseudo-experiments which are equivalent to an integrated luminosity of L=200 pb{sup -1} at {radical}(s)=10 TeV. Assuming a generated top quark mass of m{sub t}{sup gen}=172.5 GeV, the most promising result is achieved with the Max-p{sub T} reconstruction method which returns a top quark mass of m{sup Max-p{sub Tt,el-channel}}=170.4{+-}2.2 vertical stroke {sub stat.}{+-} 8.8 vertical stroke {sub syst.} GeV in the electron plus jets decay channel including a bias correction of +5.2 GeV for the central top quark mass value.

Nonperturbative QCD simulations with 2+1 flavors of improved staggered quarks

International Nuclear Information System (INIS)

Bazavov, A.; Toussaint, D.; Bernard, C.; Laiho, J.; DeTar, C.; Levkova, L.; Oktay, M. B.; Gottlieb, Steven; Heller, U. M.; Hetrick, J. E.; Mackenzie, P. B.; Sugar, R.; Van de Water, R. S.

2010-01-01

Dramatic progress has been made over the last decade in the numerical study of quantum chromodynamics (QCD) through the use of improved formulations of QCD on the lattice (improved actions), the development of new algorithms, and the rapid increase in computing power available to lattice gauge theorists. In this article simulations of full QCD are described using the improved staggered quark formalism, ''asqtad'' fermions. These simulations were carried out with two degenerate flavors of light quarks (up and down) and with one heavier flavor, the strange quark. Several light quark masses, down to about three times the physical light quark mass, and six lattice spacings have been used. These enable controlled continuum and chiral extrapolations of many low energy QCD observables. The improved staggered formalism is reviewed, emphasizing both advantages and drawbacks. In particular, the procedure for removing unwanted staggered species in the continuum limit is reviewed. Then the asqtad lattice ensembles created by the MILC Collaboration are described. All MILC lattice ensembles are publicly available, and they have been used extensively by a number of lattice gauge theory groups. The physics results obtained with them are reviewed, and the impact of these results on phenomenology is discussed. Topics include the heavy quark potential, spectrum of light hadrons, quark masses, decay constants of light and heavy-light pseudoscalar mesons, semileptonic form factors, nucleon structure, scattering lengths, and more.

The electromagnetic penguin contribution to ε'/ε for large top quark mass

International Nuclear Information System (INIS)

Flynn, J.M.; Randall, L.

1989-04-01

We evaluate the electromagnetic penguin contribution to ε' under the assumption that the top quark mass can be large. We find a significant effect for top masses larger than the mass of the W. We also consider other operators which can affect the standard model prediction for ε'. (author)

A measurement of the top quark mass with a matrix element method

Energy Technology Data Exchange (ETDEWEB)

Gibson, Adam Paul [Univ. of California, Berkeley, CA (United States)

2006-01-01

The authors present a measurement of the mass of the top quark. The event sample is selected from proton-antiproton collisions, at 1.96 TeV center-of-mass energy, observed with the CDF detector at Fermilab's Tevatron. They consider a 318 pb^-1 dataset collected between March 2002 and August 2004. They select events that contain one energetic lepton, large missing transverse energy, exactly four energetic jets, and at least one displaced vertex b tag. The analysis uses leading-order t$\\bar{t}$ and background matrix elements along with parameterized parton showering to construct event-by-event likelihoods as a function of top quark mass. From the 63 events observed with the 318 pb^-1 dataset they extract a top quark mass of 172.0 ± 2.6(stat) ± 3.3(syst) GeV/c² from the joint likelihood. The mean expected statistical uncertainty is 3.2 GeV/c² for m $\\bar{t}$ = 178 GTeV/c² and 3.1 GeV/c² for m $\\bar{t}$ = 172.5 GeV/c². The systematic error is dominated by the uncertainty of the jet energy scale.

Higgs boson mass bounds in the presence of a heavy fourth quark family

Energy Technology Data Exchange (ETDEWEB)

Bulava, John [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Gerhold, Philipp; Kallarackal, Jim; Nagy, Attila [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

2013-01-15

We present Higgs boson mass bounds in a lattice regularization allowing thus for non-perturbative investigations. In particular, we employ a lattice modified chiral invariant Higgs-Yukawa model using the overlap operator. We show results for the upper and lower Higgs boson mass bounds in the presence of a heavy mass-degenerate quark doublet with masses ranging up to 700 GeV. We perform infinite volume extrapolations in most cases, and examine several values of the lattice cutoff. Furthermore, we argue that the lower Higgs boson mass bound is stable with respect to the addition of higher dimensional operators to the scalar field potential. Our results have severe consequences for the phenomenology of a fourth generation of quarks if a light Higgs boson is discovered at the LHC.

Higgs boson mass bounds in the presence of a heavy fourth quark family

CERN Document Server

Bulava, John; Nagy, Attila; Kallarackal, Jim; Jansen, Karl

2012-01-01

We present Higgs boson mass bounds in a lattice regularization allowing thus for non-perturbative investigations. In particular, we employ a lattice modified chiral invariant Higgs-Yukawa model using the overlap operator. We show results for the upper and lower Higgs boson mass bounds in the presence of a heavy mass-degenerate quark doublet with masses ranging up to 700 GeV. We perform infinite volume extrapolations in most cases, and examine several values of the lattice cutoff. Furthermore, we argue that the lower Higgs boson mass bound is stable with respect to the addition of higher dimensional operators to the scalar field potential. Our results have severe consequences for the phenomenology of a fourth generation of quarks if a light Higgs boson is discovered at the LHC.

Duality and quarks

International Nuclear Information System (INIS)

Volkov, D.V.; Zheltukhin, A.A.; Pashnev, A.I.

1975-01-01

As it has shown, the study of vacuum transitions in dual models makes it possible to establish certain relations between duality, on the one hand, and the quark structure of resonances and the internal symmetries, on the other. In the case of Veneziano model the corresponding quark structure of resonances is determined by the infinity number of quarks of increasing mass. The intercents of the main trajectory and all adopted trajectories are additive with respect to squares of mass-forming quarks. The latter circumstance results in a number of important consequences: the presence of quadratic mass formulas for resonance states; the exact SU(infinity)-symmetry for the three-resonance coupling constants; the validity of Adler's self-consistency principle for external particles composed of different quarks and anti-quarks, etc

Quark diquark symmetry breaking

International Nuclear Information System (INIS)

Souza, M.M. de

1980-01-01

Assuming the baryons are made of quark-diquark pairs, the wave functions for the 126 allowed ground states are written. The quark creation and annihilations operators are generalized to describe the quark-diquark structure in terms of a parameter σ. Assuming that all quark-quark interactions are mediated by gluons transforming like an octet of vector mesons, the effective Hamiltonian and the baryon masses as constraint equations for the elements of the mass matrix is written. The symmetry is the SU(6) sub(quark)x SU(21) sub(diquark) broken by quark-quark interactions respectively invariant under U(6), U(2) sub(spin), U(3) and also interactions transforming like the eighth and the third components of SU(3). In the limit of no quark-diquark structure (σ = 0), the ground state masses is titted to within 1% of the experimental data, except for the Δ(1232), where the error is almost 2%. Expanding the decuplet mass equations in terms of σ and keeping terms only up to the second order, this error is reduced to 67%. (Author) [pt

Hadron spectrum, quark masses and decay constants from light overlap fermions on large lattices

International Nuclear Information System (INIS)

Galletly, D.; Horsley, R.; Streuer, T.; Freie Univ. Berlin

2006-07-01

We present results from a simulation of quenched overlap fermions with Luescher-Weisz gauge field action on lattices up to 24 3 48 and for pion masses down to ∼250 MeV. Among the quantities we study are the pion, rho and nucleon masses, the light and strange quark masses, and the pion decay constant. The renormalization of the scalar and axial vector currents is done nonperturbatively in the RI-MOM scheme. The simulations are performed at two different lattice spacings, a ∼0.1 fm and ∼0.15 fm, and on two different physical volumes, to test the scaling properties of our action and to study finite volume effects. We compare our results with the predictions of chiral perturbation theory and compute several of its low-energy constants. The pion mass is computed in sectors of fixed topology as well. (orig.)

Hadron spectrum, quark masses and decay constants from light overlap fermions on large lattices

Energy Technology Data Exchange (ETDEWEB)

Galletly, D.; Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics; Guertler, M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Perlt, H.; Schiller, A. [Leipzig Univ. (Germany). Inst. fuer Theoretische Physik; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Division, Dept. of Mathematical Sciences; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC]|[Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Streuer, T. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC]|[Freie Univ. Berlin (Germany). Inst. fuer Theoretische Physik

2006-07-15

We present results from a simulation of quenched overlap fermions with Luescher-Weisz gauge field action on lattices up to 24{sup 3} 48 and for pion masses down to {approx}250 MeV. Among the quantities we study are the pion, rho and nucleon masses, the light and strange quark masses, and the pion decay constant. The renormalization of the scalar and axial vector currents is done nonperturbatively in the RI-MOM scheme. The simulations are performed at two different lattice spacings, a {approx}0.1 fm and {approx}0.15 fm, and on two different physical volumes, to test the scaling properties of our action and to study finite volume effects. We compare our results with the predictions of chiral perturbation theory and compute several of its low-energy constants. The pion mass is computed in sectors of fixed topology as well. (orig.)

QuarkNet: Teaching and learning 21st century physics

Energy Technology Data Exchange (ETDEWEB)

Jordan, Thomas [University of Florida, Fermilab (United States)

2011-07-01

QuarkNet is an extension of the US particle physics community. Started in 1998, the project has invited well over 1000 US teachers to attend workshops, perform research, assemble hardware and explore ways to teach modern physics topics to high school students. Teachers have built and tested components for Tevatron and LHC experiments, analyzed data from the sloan digital sky survey. They build and use classroom cosmic ray muon detectors, and have explored ways to introduce their students to topics such as the production of the Top Quark. Teachers can use their web-browser to access data from the LIGO observatory and share their findings with other student users across the globe. I will discuss the practices, tools and findings of this successful collaboration.

Quark models in hadron physics

International Nuclear Information System (INIS)

Phatak, Shashikant C.

2007-01-01

In this talk, we review the role played by the quark models in the study of interaction of strong, weak and electromagnetic probes with hadrons at intermediate and high momentum transfers. By hadrons, we mean individual nucleons as well as nuclei. We argue that at these momentum transfers, the structure of hadrons plays an important role. The hadron structure of the hadrons is because of the underlying quark structure of hadrons and therefore the quark models play an important role in determining the hadron structure. Further, the properties of hadrons are likely to change when these are placed in nuclear medium and this change should arise from the underlying quark structure. We shall consider some quark models to look into these aspects. (author)

Sea quarks contribution to the nucleon magnetic moment and charge radius at the physical point

Science.gov (United States)

Sufian, Raza Sabbir; Yang, Yi-Bo; Liang, Jian; Draper, Terrence; Liu, Keh-Fei; χ QCD Collaboration

2017-12-01

We report a comprehensive analysis of the light and strange disconnected-sea quarks contribution to the nucleon magnetic moment, charge radius, and the electric and magnetic form factors. The lattice QCD calculation includes ensembles across several lattice volumes and lattice spacings with one of the ensembles at the physical pion mass. We adopt a model-independent extrapolation of the nucleon magnetic moment and the charge radius. We have performed a simultaneous chiral, infinite volume, and continuum extrapolation in a global fit to calculate results in the continuum limit. We find that the combined light and strange disconnected-sea quarks contribution to the nucleon magnetic moment is μM(DI )=-0.022 (11 )(09 ) μN and to the nucleon mean square charge radius is ⟨r2⟩E(DI ) =-0.019 (05 )(05 ) fm2 which is about 1 /3 of the difference between the ⟨rp2⟩E of electron-proton scattering and that of a muonic atom and so cannot be ignored in obtaining the proton charge radius in the lattice QCD calculation. The most important outcome of this lattice QCD calculation is that while the combined light-sea and strange quarks contribution to the nucleon magnetic moment is small at about 1%, a negative 2.5(9)% contribution to the proton mean square charge radius and a relatively larger positive 16.3(6.1)% contribution to the neutron mean square charge radius come from the sea quarks in the nucleon. For the first time, by performing global fits, we also give predictions of the light and strange disconnected-sea quarks contributions to the nucleon electric and magnetic form factors at the physical point and in the continuum and infinite volume limits in the momentum transfer range of 0 ≤Q2≤0.5 GeV2 .

Strange and charm baryon masses with two flavors of dynamical twisted mass fermions

Energy Technology Data Exchange (ETDEWEB)

Alexandrou, C. [Univ. of Cyprus, Nicosia (Cyprus). Dept. of Physics; Cyprus Institute, Nicosia (Cyprus). Computation-Based Science and Technology Research Center; Carbonell, J. [CEA-Saclay, Gif-sur-Yvette (France). IRFU/Service de Physique Nucleaire; Christaras, D.; Gravina, M. [Univ. of Cyprus, Nicosia (Cyprus). Dept. of Physics; Drach, V. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Papinutto, M. [UFJ/CNRS/IN2P3, Grenoble (France). Laboratoire de Physique Subatomique et Cosmologie; Universidad Autonoma de Madrid (Spain). Dept. de Fisica Teorica; Universidad Autonoma de Madrid UAM/CSIC (Spain). Inst. de Fisica Teorica

2012-10-15

The masses of the low-lying strange and charm baryons are evaluated using two degenerate flavors of twisted mass sea quarks for pion masses in the range of about 260 MeV to 450 MeV. The strange and charm valence quark masses are tuned to reproduce the mass of the kaon and D-meson at the physical point. The tree-level Symanzik improved gauge action is employed. We use three values of the lattice spacing, corresponding to {beta}=3.9, {beta}=4.05 and {beta}=4.2 with r{sub 0}/a=5.22(2), r{sub 0}/a=6.61(3) and r{sub 0}/a=8.31(5) respectively. We examine the dependence of the strange and charm baryons on the lattice spacing and strange and charm quark masses. The pion mass dependence is studied and physical results are obtained using heavy baryon chiral perturbation theory to extrapolate to the physical point.

Relation between bottom-quark MS Yukawa coupling and pole mass

International Nuclear Information System (INIS)

Kniehl, B.A.; Piclum, J.H.; Steinhauser, M.

2004-04-01

We calculate the O (αα s ) corrections to the relationships between the MS Yukawa couplings and the pole masses of the first five quark flavours in the standard model. We also present the corresponding relationships between the MS and pole masses, which emerge as by-products of our main analysis. The occurring self-energies are evaluated using the method of asymptotic expansion. (orig.)

Lattice QCD with light quark masses: Does chiral symmetry get broken spontaneously

International Nuclear Information System (INIS)

Barbour, I.M.; Schierholz, G.; Teper, M.; Gilchrist, J.P.; Schneider, H.

1983-03-01

We present a first direct calculation of the properties of QCD for the small quark masses of phenomenological interest without extrapolations. We describe methods specially adapted to invert the fermion matrix at small quark masses. We use these methods to calculate directly on presently used lattice sizes with different boundary conditions. As is to be expected for a finite system, we do not observe spontaneous chiral symmetry breaking. By comparing the results obtained on lattices of different size we see, however, indications that are consistent with eventual spontaneous chiral symmetry breaking in the infinite volume limit. Our calculations underline the importance of using antiperiodic boundary conditions for fermions. (orig.)

Nambu mechanism of dynamical symmetry breaking by the top quark

Science.gov (United States)

Pham, Xuan-Yem

1990-05-01

It may be possible that the gauge symmetry breaking of the standard electroweak interactions is not due to the elementary scalar Higgs fields but has a dynamic origin intimately involving the top quark. A prototype of this dynamical scenario is the Nambu and Jona-Lasinio model in which both the top quark and the gauge bosons become massive by some strong attractive nonlinear interactions similar to the gap energy produced in BCS superconductivity. Self-consistent equations for the charged Goldstone boson and for the vector meson are used to get an upper bound for the top quark mass. In the bubble approximation of keeping only fermion loops, we obtain an equation relating the top quark mass to the W boson one; from the top mass is found to be around 84 GeV. Its typical dominant decay mode t→W+s then follows. Also discussed are distinctive signatures of the scalar overlinett bound state identified as the physical Higgs particle whose mass is twice that of the top quark.

Measurements of the top quark mass with the ATLAS detector

CERN Document Server

Nisius, Richard; The ATLAS collaboration

2017-01-01

The measurements of the top quark mass given are obtained from ATLAS data taken at proton--proton centre-of-mass energies of $\\sqrt{s}=7$ and $8$ TeV. An extraction of the top quark pole mass ($m_{\\mathrm{top}}^{\\mathrm{pole}}$) at next-to-leading order (NLO) is presented. This result is obtained from normalised differential cross-sections in the $t\\bar{t}\\to\\mbox{dilepton}$ channel leading to: $m_{\\mathrm{top}}^{\\mathrm{pole}} = 173.2 \\pm 0.9 (\\mathrm{stat.}) \\pm 0.8 (\\mathrm{syst.}) \\pm 1.2 (\\mathrm{theo.})$ GeV. In addition, measurements of $m_{\\mathrm{top}}$ are discussed that are based on the template method performed in three $t\\bar{t}$ decay channels. For all results the uncertainty is dominated by systematic effects. Finally, the 2016 ATLAS combined value of $m_{\\mathrm{top}}$ is: $m_{\\mathrm{top}}=172.84 \\pm 0.34 (\\mathrm{stat.}) \\pm 0.61 (\\mathrm{syst.})$ GeV, with a total uncertainty of 0.70 GeV, i.e.a precision of 0.4$\\%$.

Top quark pair production at the LHC

Energy Technology Data Exchange (ETDEWEB)

Baernreuther, Peter

2012-06-28

One of the most interesting and manifold processes in the Standard Model of elementary particle physics is the top quark pair production. It enabled the discovery of the top quark at the Tevatron in 1995 and the determination of many of its properties. By means of a precise measurement and calculation of the cross section of top quark pair production it is possible to extract the top quark mass. Improvements in the gluon parton distribution functions (important for the Higgs boson production) or improvements in the prediction of the Higgs mass are also closely linked with the top quark pair production. Furthermore, the production process plays an important role in the discovery of new physics. On the one hand the top quark pair decays form the largest part of the background in many BSM models, on the other hand BSM physics can be detected directly in the decay process by investigating the charge symmetry or the invariant mass spectrum. At the LHC it will be possible for the first time to produce a large amount of top quarks; thereby the statistical errors of the observables will be strongly reduced. The enormous increase in the production rate has two reasons. On the one hand, the acceleration energy of the LHC (14 TeV and 7 TeV) is significantly greater than that of the Tevatron (1.96 Tev). This leads to an increase of the cross section by a factor of 100 ({proportional_to}7.3 pb at the Tevatron to {proportional_to}800 pb at 14 TeV LHC). On the other hand, the luminosity of the LHC outperforms the Tevatron by a factor of 10-100. The reduced experimental errors for the observables demand an improvement of the theoretical error. The experimental accuracy of the LHC and the great relevance of the process led to an intensive activity of different research groups in order to improve the calculation of the cross section of top quark pair production. This work presents for the first time a complete numerical result for the full NNLO correction for the top quark pair

Top quark pair production at the LHC

International Nuclear Information System (INIS)

Baernreuther, Peter

2012-01-01

One of the most interesting and manifold processes in the Standard Model of elementary particle physics is the top quark pair production. It enabled the discovery of the top quark at the Tevatron in 1995 and the determination of many of its properties. By means of a precise measurement and calculation of the cross section of top quark pair production it is possible to extract the top quark mass. Improvements in the gluon parton distribution functions (important for the Higgs boson production) or improvements in the prediction of the Higgs mass are also closely linked with the top quark pair production. Furthermore, the production process plays an important role in the discovery of new physics. On the one hand the top quark pair decays form the largest part of the background in many BSM models, on the other hand BSM physics can be detected directly in the decay process by investigating the charge symmetry or the invariant mass spectrum. At the LHC it will be possible for the first time to produce a large amount of top quarks; thereby the statistical errors of the observables will be strongly reduced. The enormous increase in the production rate has two reasons. On the one hand, the acceleration energy of the LHC (14 TeV and 7 TeV) is significantly greater than that of the Tevatron (1.96 Tev). This leads to an increase of the cross section by a factor of 100 (∝7.3 pb at the Tevatron to ∝800 pb at 14 TeV LHC). On the other hand, the luminosity of the LHC outperforms the Tevatron by a factor of 10-100. The reduced experimental errors for the observables demand an improvement of the theoretical error. The experimental accuracy of the LHC and the great relevance of the process led to an intensive activity of different research groups in order to improve the calculation of the cross section of top quark pair production. This work presents for the first time a complete numerical result for the full NNLO correction for the top quark pair production in quark anti-quark

Mass spectra of four-quark states in the hidden charm sector

International Nuclear Information System (INIS)

Patel, Smruti; Shah, Manan; Vinodkumar, P.C.

2014-01-01

Masses of the low-lying four-quark states in the hidden charm sector (cq anti c anti q; q element of u,d) are calculated within the framework of a non-relativistic quark model. The four-body system is considered as two two-body systems such as diquark-antidiquark (Qq- anti Q anti q) and quark-antiquark-quark-antiquark (Q anti q- anti Qq) molecular-like four-quark states. Here, the Cornell-type potential has been used for describing the two-body interactions among Q-q, anti Q- anti q, Q- anti q, Qq- anti Q anti q and Q anti q- anti Qq, with appropriate string tensions. Our present analysis suggests the following exotic states: X(3823), Z c (3900), X(3915), Z c (4025), ψ (4040), Z 1 (4050) and X(4160) as Q anti q- anti Qq molecular-like four-quark states, while Z c (3885), X(3940) and Y(4140) as the diquark-antidiquark four-quark states. We have been able to assign the J PC values for many of the recently observed exotic states according to their structure. Apart from this, we have identified the charged state Z(4430) recently confirmed by LHCb as the first radial excitation of Zc(3885) with G = + 1 and Y(4360) state as the first radial excitation of Y(4008) with G = - 1 and the state ψ(4415) as the first radial excitation of the ψ(4040) state. (orig.)

Proceedings of the Summer institute on particle physics: The top quark and the electroweak interaction

Energy Technology Data Exchange (ETDEWEB)

Burke, D.; Dixon, L.; Leith, D.W.G.S.

1997-01-01

The XXIII SLAC Summer Institute on Particle Physics addressed the physics of the recently discovered top quark, and its connection to the electroweak interaction and to physics beyond the Standard Model. The seven-day school portion of the Institute covered many avenues for studying the top quark, from its direct production at hadron colliders and at future electron-positron colliders, to its virtual effects in precision electroweak quantities, in heavy flavor physics, and in the renormalization of supersymmetric theories, Vertex detectors - critical for identifying the b quark decay products of the top - and Cherenkov techniques for particle identification were also reviewed. The Institute concluded with a three-day topical conference covering recent developments in theory and experiment; this year, the highlights were the CDF and D0 top quark discovery. Also featured were updated precision electroweak measurements from SLC, LEP, and the Tevatron, heavy quark results from these facilities as well as CLEO, and new photoproduction and deep-inelastic scattering data from HERA. Separate abstracts have been submitted to the energy database for articles from this proceedings.

Proceedings of the Summer institute on particle physics: The top quark and the electroweak interaction

International Nuclear Information System (INIS)

Burke, D.; Dixon, L.; Leith, D.W.G.S.

1997-01-01

The XXIII SLAC Summer Institute on Particle Physics addressed the physics of the recently discovered top quark, and its connection to the electroweak interaction and to physics beyond the Standard Model. The seven-day school portion of the Institute covered many avenues for studying the top quark, from its direct production at hadron colliders and at future electron-positron colliders, to its virtual effects in precision electroweak quantities, in heavy flavor physics, and in the renormalization of supersymmetric theories, Vertex detectors - critical for identifying the b quark decay products of the top - and Cherenkov techniques for particle identification were also reviewed. The Institute concluded with a three-day topical conference covering recent developments in theory and experiment; this year, the highlights were the CDF and D0 top quark discovery. Also featured were updated precision electroweak measurements from SLC, LEP, and the Tevatron, heavy quark results from these facilities as well as CLEO, and new photoproduction and deep-inelastic scattering data from HERA. Separate abstracts have been submitted to the energy database for articles from this proceedings