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Sample records for hard qcd processes

  1. Hard exclusive QCD processes

    Energy Technology Data Exchange (ETDEWEB)

    Kugler, W.

    2007-01-15

    Hard exclusive processes in high energy electron proton scattering offer the opportunity to get access to a new generation of parton distributions, the so-called generalized parton distributions (GPDs). This functions provide more detailed informations about the structure of the nucleon than the usual PDFs obtained from DIS. In this work we present a detailed analysis of exclusive processes, especially of hard exclusive meson production. We investigated the influence of exclusive produced mesons on the semi-inclusive production of mesons at fixed target experiments like HERMES. Further we give a detailed analysis of higher order corrections (NLO) for the exclusive production of mesons in a very broad range of kinematics. (orig.)

  2. Relating hard QCD processes through universality of mass singularities

    International Nuclear Information System (INIS)

    Amati, D.; Petronzio, R.; Veneziano, G.

    1978-01-01

    Hard QCD processes involving final jets are studied and compared by means of a simple approach to mass singularities. This is based on the Lee-Nauenberg-Kinoshita theorem and on a rather subtle use of gauge invariance in hard collinear gluon bremsstrahlung. One-loop results are easily derived for processes involving any number of initial quarks and/or currents. The method greatly simplifies the computation of higher-order loops at the leading log level and the preliminary results allow one to conclude that the crucial features encountered at the one-loop level will persist. The authors are thus able to relate different hard processes and to show that suitable ratios of cross sections, being free from mass singularities, can be computed perturbatively, as usually assumed in QCD-inspired parton models. It is also possible to relate the universal leading mass singularities to leading scaling violations and to extend therefor the results of the operator product expansion method to processes outside the range of the light-cone analysis. Some delicate points caused by confinement-related singularities (e.g. narrow resonance poles) are also discussed. (Auth.)

  3. Soft gluon resummation formulae for hard proton processes in QCD

    International Nuclear Information System (INIS)

    Craigie, N.S.; Jones, H.F.

    1980-01-01

    We briefly review the treatment of leading logarithmic behaviour of the parton distributions in QCD within the Bethe-Salpeter framework by analysing directly parton hadron Green functions in the limit of parton four-momentum k 2 → - infinitely in a special light-like gauge involving a spectator vector. This technique allows us to derive the factorization of parton probabilities in leading logarithmic order in QCD in the various inclusive processes involving a single short-distance scale. The proof requires us to show that the use of planar gauges eta = psub(A) + psub(B) + ..., where psub(A), psub(B)... are the observed hadron momenta, reduces to choosing the appropriate light-like gauge for each hadron-parton BS channel, after demonstrating a Bloch-Nordsieck cancellation of the real and virtual soft left-over gluons. In the case where two large momentum scales appear, by restricting the transverse phase space into which the gluons are radiated, we derive the double logarithmic eikonal renormalization of the hard scattering formula of the type proposed recently by Parisi and Petronzio. (orig.)

  4. Resummation of the QCD perturbative series for hard processes

    International Nuclear Information System (INIS)

    Catani, S.

    1989-01-01

    We study the region of inhibited radiation in hard hadronic processes, as for jet cross sections and heavy flavour production near threshold. The cases of deep inelastic scattering and Drell-Yan annihilation are explicitly considered. A general method to exponentiate leading and next-to-leading logarithms to all orders in perturbation theory is developed. A complete formula for the large N-moments is given and shown to agree with previous two-loop calculations. The resummation procedure suggests how to connect the perturbative and nonperturbative regions. The natural limit within the perturbative phase is shown to be the intrinsic transverse momentum. (orig.)

  5. A treatment of hard processes sensitive to the infrared structure of QCD

    International Nuclear Information System (INIS)

    Amati, D.; Veneziano, G.; Bassetto, A.; Marchesini, F.

    1980-01-01

    We propose a modified jet evolution equation which resums large corrections to the usual leading logarithmic approximation when phase-space constraints expose the singular infrared structure of QCD. The modification, which consists simply of a rescaling of the argument of the running coupling constant, is based on perturbative arguments verified at the fourth-order level. Processes analyzed by this method include the quark (Sudakov) form factor, the large moments of structure and fragmentation functions, the asymptotic behaviour of multiplicities and the clustering of final quanta in colourless systems which occupy finite regions of (momentum and position) phase space. (orig.)

  6. Hard QCD Measurements at LHC

    CERN Document Server

    Pasztor, Gabriella

    2018-01-01

    The rich proton-proton collision data of the LHC allow to study QCD processes in a previously unexplored region with ever improving precision. This paper summarises recent results of the ATLAS, CMS and LHCb Collaborations using primarily multi-jet and vector boson plus jet data collected at $\\sqrt s$ = 8 and 13 TeV. Comparisons to higher-order theoretical calculations and sophisticated Monte Carlo predictions are presented, as well as the impact of the data on the determination of the parton distribution functions and the measurement of the strong coupling constant, $\\alpha_s$.

  7. Tests of hard and soft QCD with $e^{+}e^{-}$ Annihilation Data

    CERN Document Server

    Kluth, S

    2002-01-01

    Experimental tests of QCD predictions for event shape distributions combining contributions from hard and soft processes are discussed. The hard processes are predicted by perturbative QCD calculations. The soft processes cannot be calculated directly using perturbative QCD, they are treated by a power correction model based on the analysis of infrared renormalons. Furthermore, an analysis of the gauge structure of QCD is presented using fits of the colour factors within the same combined QCD predictions.

  8. Parton saturation and $N_{part}$ scaling of semi-hard processes in QCD

    CERN Document Server

    Kharzeev, Dima E; McLerran, L; 10.1016/S0370-2693(03)00420-9

    2003-01-01

    We argue that the suppression of high p/sub t/ hadrons discovered recently in heavy ion collisions at RHIC may be a consequence of saturation in the color glass condensate. We qualitatively and semi- quantitatively describe the data, in particular, the dependence upon the number of nucleon participants. We show that if parton saturation sets in at sufficiently small energy, then in nucleus-nucleus collisions at RHIC and LHC energies the cross sections of semi-hard processes should scale approximately with the number of participants, N/sub part/. Our results provide a possible explanation of both the absence of apparent jet quenching at SPS energies and its presence at RHIC. Under the same assumption we predict that in semi-central and central pA (dA) collisions at collider energies the dependence of semi-hard processes on the number of participating nucleons of the nucleus will change to ~(N/sub part//sup A/)/sup 1/2/. The forthcoming data on dA collisions will provide a crucial test of this description. (61 ...

  9. Hard QCD at hadron colliders

    Energy Technology Data Exchange (ETDEWEB)

    Moch, S

    2008-02-15

    We review the status of QCD at hadron colliders with emphasis on precision predictions and the latest theoretical developments for cross sections calculations to higher orders. We include an overview of our current information on parton distributions and discuss various Standard Model reactions such as W{sup {+-}}/Z-boson, Higgs boson or top quark production. (orig.)

  10. Hard QCD at hadron colliders

    International Nuclear Information System (INIS)

    Moch, S.

    2008-02-01

    We review the status of QCD at hadron colliders with emphasis on precision predictions and the latest theoretical developments for cross sections calculations to higher orders. We include an overview of our current information on parton distributions and discuss various Standard Model reactions such as W ± /Z-boson, Higgs boson or top quark production. (orig.)

  11. Novel Aspects of Hard Diffraction in QCD

    International Nuclear Information System (INIS)

    Brodsky, Stanley J.

    2005-01-01

    Initial- and final-state interactions from gluon-exchange, normally neglected in the parton model have a profound effect in QCD hard-scattering reactions, leading to leading-twist single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, and nuclear shadowing and antishadowing--leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also discuss the use of diffraction to materialize the Fock states of a hadronic projectile and test QCD color transparency

  12. Hard And Soft QCD Physics In ATLAS

    Directory of Open Access Journals (Sweden)

    Adomeit Stefanie

    2014-04-01

    Full Text Available Hard and soft QCD results using proton-proton collisions recorded with the ATLAS detector at the LHC are reported. Charged-particle distributions and forward-backward correlations have been studied in low-luminosity minimum bias data taken at centre-of-mass energies of √s = 0.9, 2.36 and 7 TeV. Recent measurements on underlying event characteristics using charged-particle jets are also presented. The results are tested against various phenomenological soft QCD models implemented in Monte-Carlo generators. A summary of hard QCD measurements involving high transverse momentum jets is also given. Inclusive jet and dijet cross-sections have been measured at a centre-of-mass energy of 7 TeV and are compared to expectations based on NLO pQCD calculations corrected for non-perturbative effects as well as to NLO Monte Carlo predictions. Recent studies exploiting jet substructure techniques to identify hadronic decays of boosted massive particles are reported.

  13. Hard Electromagnetic Processes

    International Nuclear Information System (INIS)

    Richard, F.

    1987-09-01

    Among hard electromagnetic processes, I will use the most recent data and focus on quantitative test of QCD. More specifically, I will retain two items: - hadroproduction of direct photons, - Drell-Yan. In addition, I will briefly discuss a recent analysis of ISR data obtained with AFS (Axial Field Spectrometer) which sheds a new light on the e/π puzzle at low P T

  14. Power corrections to exclusive processes in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Mankiewicz, Lech

    2002-02-01

    In practice applicability of twist expansion crucially depends on the magnitude to power corrections to the leading-twist amplitude. I illustrate this point by considering explicit examples of two hard exclusive processes in QCD. In the case of {gamma}{sup *}{gamma} {yields} {pi}{pi} amplitude power corrections are small enough such that it should be possible to describe current experimental data by the leading-twist QCD prediction. The photon helicity-flip amplitude in DVCS on a nucleon receives large kinematical power corrections which screen the leading-twist prediction up to large values of the hard photon virtuality.

  15. Hard processes. Vol. 1

    International Nuclear Information System (INIS)

    Ioffe, B.L.; Khoze, V.A.; Lipatov, L.N.

    1984-01-01

    Deep inelastic (hard) processes are now at the epicenter of modern high-energy physics. These processes are governed by short-distance dynamics, which reveals the intrinsic structure of elementary particles. The theory of deep inelastic processes is now sufficiently well settled. The authors' aim was to give an effective tool to theoreticians and experimentalists who are engaged in high-energy physics. This book is intended primarily for physicists who are only beginning to study the field. To read the book, one should be acquainted with the Feynman diagram technique and with some particular topics from elementary particle theory (symmetries, dispersion relations, Regge pole theory, etc.). Theoretical consideration of deep inelastic processes is now based on quantum chromodynamics (QCD). At the same time, analysis of relevant physical phenomena demands a synthesis of QCD notions (quarks, gluons) with certain empirical characteristics. Therefore, the phenomenological approaches presented are a necessary stage in a study of this range of phenomena which should undoubtedly be followed by a detailed description based on QCD and electroweak theory. The authors were naturally unable to dwell on experimental data accumulated during the past decade of intensive investigations. Priority was given to results which allow a direct comparison with theoretical predictions. (Auth.)

  16. RIKEN WINTER SCHOOL: STRUCTURE OF HADRONS - INTRODUCTION TO QCD HARD PROCESSES. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP, DECEMBER 9-12, 1998

    International Nuclear Information System (INIS)

    Saito, N.

    1999-01-01

    In this lecture I give a pedagogical introduction to the Perturbative QCD to understand the short-distance dynamics of the strong interaction. Starting with fundamental concepts such as the color degree of freedom of QCD, non-abelian gauge field theory, renormalization group equation etc., I explain a basic idea of the perturbative QCD and apply this idea to the e + e - processes and the structure functions. The notion of mass singularity and the necessity of its factorization is discussed in some detail

  17. QCD and hard diffraction at the LHC

    International Nuclear Information System (INIS)

    Albrow, Michael G.; Fermilab

    2005-01-01

    As an introduction to QCD at the LHC I given an overview of QCD at the Tevatron, emphasizing the high Q 2 frontier which will be taken over by the LHC. After describing briefly the LHC detectors I discuss high mass diffraction, in particular central exclusive production of Higgs and vector boson pairs. I introduce the FP420 project to measure the scattered protons 420 m downstream of ATLAS and CMS

  18. Early Run 2 Hard QCD Results from the ATLAS Collaboration

    Directory of Open Access Journals (Sweden)

    Orlando Nicola

    2016-01-01

    Full Text Available We provide an overview of hard QCD results based on data collected with the ATLAS detector in proton-proton collision at √s = 13 TeV at the Large Hadron Collider. The production of high transverse momentum jets, photons and photon-pairs were studied; the inclusive jet cross section is found to agree well with the prediction of perturbative QCD calculations performed at next-to-leading accuracy. The production cross sections for W and Z bosons in their e and μ decays was measured; in general, agreement is found with the expectation of next-to-next-to leading order QCD calculations and interesting sensitivities to the proton structure functions are already observed. The top production cross sections were measured in different top decay channels and found to agree with the state of the art QCD predictions.

  19. Perturbative QCD and exclusive processes

    International Nuclear Information System (INIS)

    Bennett, J.; Hawes, F.; Zhao, M.; Zyla, P.

    1991-01-01

    The authors discuss perturbation theory as applied to particle physics calculations. In particle physics one is generally interested in the scattering amplitude for a system going from some initial state to a final state. The intermediate state or states are unknown. To get the scattering amplitude it is necessary to sum the contributions from processes which pass through all possible intermediate states. Intermediate states involve the exchange of intermediate vector bosons between the particles, and with this interaction is associated a coupling constant α. Each additional boson exchange involves an additional contribution of α to the coupling. If α is less than 1, one can see that the relative contribution of higher order processes is less and less important as α falls. In QCD the gluons serve as the intermediate vector bosons exchanged by quarks and gluons, and the interaction constant is not really a constant, but depends upon the distance between the particles. At short distances the coupling is small, and one can assume perturbative expansions may converge rapidly. Exclusive scattering processes, as opposed to inclusive, are those in which all of the final state products are detected. The authors then discuss the application of perturbative QCD to the deuteron. The issues of chiral conservation and color transparancy are also discussed, in the scheme of large Q 2 interations, where perturbative QCD should be applicable

  20. Hard-Thermal-Loop QCD thermodynamics and quark number susceptibility

    Directory of Open Access Journals (Sweden)

    Mogliacci Sylvain

    2014-04-01

    Full Text Available The weak-coupling expansion of the QCD pressure is known up to the order g6 log g. However, at experimentally relevant temperatures, the corresponding series is poorly convergent. In this proceedings, we discuss at which extent the gauge-invariant resummation scheme, Hard-Thermal-Loop perturbation theory (HTLpt, improves the apparent convergence. We first present HTLpt results for QCD thermodynamic functions up to three-loop order at vanishing chemical potential. Then, we report a preliminary HTLpt result of one-loop quark number susceptibility, probing the finite density equation of state. Our results are consistent with lattice data down to 2 − 3Tc, reinforcing the weakly-coupled quasiparticle picture in the intermediate coupling regime.

  1. Exclusive processes in QCD

    International Nuclear Information System (INIS)

    Mueller, A.H.

    1981-01-01

    In this talk I concentrate on purely exclusive processes. In Sec. II form factors and exclusive decays of heavy quarkonium states will be discussed. In Sec. III elastic wide angle elastic scattering will be considered with emphasis placed on the energy dependence for a fixed angle. The x → 1 limit of structure functions is discussed in Sec. IV. This is a limit which matches on, in a rather complicated way, with transition form factors. In Sec. V the idea of intrinsic charm is considered, mostly from a conceptual viewpoint as to its definition and possible existence. In Sec. VI there is a brief discussion of calculations of matrix elements which occur in deeply inelastic scattering by use of a bag model. In Sec. VII wee parton cancellations and Sudakov corrections for μ-pair production are considered. Sec. VIII concerns soft particle production and the mutliplicity of hadrons in a jet. (orig./HSI)

  2. Hard processes in hadronic interactions

    International Nuclear Information System (INIS)

    Satz, H.; Wang, X.N.

    1995-01-01

    Quantum chromodynamics is today accepted as the fundamental theory of strong interactions, even though most hadronic collisions lead to final states for which quantitative QCD predictions are still lacking. It therefore seems worthwhile to take stock of where we stand today and to what extent the presently available data on hard processes in hadronic collisions can be accounted for in terms of QCD. This is one reason for this work. The second reason - and in fact its original trigger - is the search for the quark-gluon plasma in high energy nuclear collisions. The hard processes to be considered here are the production of prompt photons, Drell-Yan dileptons, open charm, quarkonium states, and hard jets. For each of these, we discuss the present theoretical understanding, compare the resulting predictions to available data, and then show what behaviour it leads to at RHIC and LHC energies. All of these processes have the structure mentioned above: they contain a hard partonic interaction, calculable perturbatively, but also the non-perturbative parton distribution within a hadron. These parton distributions, however, can be studied theoretically in terms of counting rule arguments, and they can be checked independently by measurements of the parton structure functions in deep inelastic lepton-hadron scattering. The present volume is the work of Hard Probe Collaboration, a group of theorists who are interested in the problem and were willing to dedicate a considerable amount of their time and work on it. The necessary preparation, planning and coordination of the project were carried out in two workshops of two weeks' duration each, in February 1994 at CERn in Geneva andin July 1994 at LBL in Berkeley

  3. Soft gluon contributions to hard processes

    International Nuclear Information System (INIS)

    Ciafaloni, M.

    1981-10-01

    The main concern of this paper is in trying to elucidate the origin of large QCD perturbative corrections and explain how to deal with them to all orders. They come essentially from the phase space regions close to the kinematical boundary of a hard process, in which one or many gluons become soft

  4. A QCD motivated model for soft processes

    International Nuclear Information System (INIS)

    Kormilitzin, A.; Levin, E.

    2009-01-01

    In this talk we give a brief description of a QCD motivated model for both hard and soft interactions at high energies. In this model the long distance behaviour of the scattering amplitude is determined by the dipole scattering amplitude in the saturation domain.

  5. Death to perturbative QCD in exclusive processes?

    Energy Technology Data Exchange (ETDEWEB)

    Eckardt, R.; Hansper, J.; Gari, M.F. [Institut fuer Theoretische Physik, Bochum (Germany)

    1994-04-01

    The authors discuss the question of whether perturbative QCD is applicable in calculations of exclusive processes at available momentum transfers. They show that the currently used method of determining hadronic quark distribution amplitudes from QCD sum rules yields wave functions which are completely undetermined because the polynomial expansion diverges. Because of the indeterminacy of the wave functions no statement can be made at present as to whether perturbative QCD is valid. The authors emphasize the necessity of a rigorous discussion of the subject and the importance of experimental data in the range of interest.

  6. Scattering processes and resonances from lattice QCD

    Science.gov (United States)

    Briceño, Raúl A.; Dudek, Jozef J.; Young, Ross D.

    2018-04-01

    The vast majority of hadrons observed in nature are not stable under the strong interaction; rather they are resonances whose existence is deduced from enhancements in the energy dependence of scattering amplitudes. The study of hadron resonances offers a window into the workings of quantum chromodynamics (QCD) in the low-energy nonperturbative region, and in addition many probes of the limits of the electroweak sector of the standard model consider processes which feature hadron resonances. From a theoretical standpoint, this is a challenging field: the same dynamics that binds quarks and gluons into hadron resonances also controls their decay into lighter hadrons, so a complete approach to QCD is required. Presently, lattice QCD is the only available tool that provides the required nonperturbative evaluation of hadron observables. This article reviews progress in the study of few-hadron reactions in which resonances and bound states appear using lattice QCD techniques. The leading approach is described that takes advantage of the periodic finite spatial volume used in lattice QCD calculations to extract scattering amplitudes from the discrete spectrum of QCD eigenstates in a box. An explanation is given of how from explicit lattice QCD calculations one can rigorously garner information about a variety of resonance properties, including their masses, widths, decay couplings, and form factors. The challenges which currently limit the field are discussed along with the steps being taken to resolve them.

  7. Exclusive hadronic and nuclear processes in QCD

    International Nuclear Information System (INIS)

    Brodsky, S.J.

    1985-12-01

    Hadronic and nuclear processes are covered, in which all final particles are measured at large invariant masses compared with each other, i.e., large momentum transfer exclusive reactions. Hadronic wave functions in QCD and QCD sum rule constraints on hadron wave functions are discussed. The question of the range of applicability of the factorization formula and perturbation theory for exclusive processes is considered. Some consequences of quark and gluon degrees of freedom in nuclei are discussed which are outside the usual domain of traditional nuclear physics. 44 refs., 7 figs

  8. QCD phenomenology

    International Nuclear Information System (INIS)

    Gaillard, M.K.

    1979-01-01

    Selected topics in QCD phenomenology are reviewed: the development of an effective jet perturbation series with applications to factorization, energy flow analysis and photon physics; implications of non-perturbative phenomena for hard scattering processes and the pseudoscalar mass spectrum; resonance properties as extracted from the combined technologies of perturbative and non-perturbative QCD. (orig.)

  9. High momentum transfer processes in QCD

    International Nuclear Information System (INIS)

    Efremov, A.V.; Radyushkin, A.V.

    1978-01-01

    A unified approach to the investigation of inclusive high momentum transfer processes in the QCD framework is proposed. A modified parton model (with parton distribution functions depending on an additional renormalization parameter) is shown to be valid in all orders of perturbation theory. The approach is also applicable for studying wide-angle elastic scattering processes of colourless bound states of quarks (the hadrons). The asymptotic behaviour of pion electromagnetic form factor is calculated as an example

  10. The hard gluon component of the QCD Pomeron

    International Nuclear Information System (INIS)

    White, A.R.

    1996-01-01

    The authors argue that deep-inelastic diffractive scaling provides fundamental insight into the QCD Pomeron. The logarithmic scaling violations seen experimentally are in conflict with the scale-invariance of the BFKL Pomeron and with phenomenological two-gluon models. Instead the Pomeron appears as a single gluon at short-distances, indicating the appearance of a Super-Critical phase of Reggeon Field Theory. That the color compensation takes place at a longer distance is consistent with the Pomeron carrying odd color charge parity

  11. Hard processes in photon-photon interactions

    International Nuclear Information System (INIS)

    Duchovni, E.

    1985-03-01

    In this thesis, the existence of hard component in two-photon collisions is investigated. Due to the relative simplicity of the photon, such processes can be exactly calculated in QCD. Untagged (low Q 2 ) two-photon events are used. This leads to relatively high statistics, but to severe background problem due mainly to e + e - annihilation. The background contamination is reduced to a tolerable level using a special set of cuts. Moreover, the remaining contamination is shown to be calculable with a small systematic error. A large number of events of the hard ''γγ'' type is found. An attempt to explain these events using the simplest QCD diagram (the Born term) is done. This process is found to be capable of explaining only a 1/4 of the data. Other options like the constituent intercharge model, integer charged quarks, and higher order diagrams are therefore also discussed. The large cross-section for the production of ρ 0 ρ 0 pairs in ''γγ'' collisions has not been understood yet. Inorder to look at closely related processes, a search for φρ 0 and φφ was initiated. The cross-section for θπ + π - was found to be sizeable. Only upper limits for the production of φρ 0 and φφ are obtained

  12. Perturbative QCD contributions to inclusive processes

    International Nuclear Information System (INIS)

    Ritbergen, T. van.

    1996-01-01

    This thesis treats the calculation of quantum corrections to a number of high energy processes that are measured in current and future accelerator experiments. The main objective of these experiments is to accurately verify the generally accepted theory of electro-weak and strong interactions, known as the Standard model, and to look for possible deviations. Most of the processes that are treated in this thesis are of a type for which the final state of of a highly energetic scattering or decay process is measured inclusively. The higher order quantum corrections discussed in this thesis are due to strong interactions. To the inclusive decay rate of Z 0 bosons into all possible final states consisting of hadrons third order QCD contributions have been obtained. Also in the third order QCD an expansion for the inclusive hadronic decay rate of a τ-lepton was obtained. Then the top-quark-mass effects on the decay channels of a Higgs boson: Higgs→b-quarks and Higgs→gluons, were investigated. Thereafter the calculation of 3-loop contributions to the deep-inelastic lepton-nucleon scattering process is discussed. Finally the 3-loop contributions to the q 2 -dependence of the lower moments ∫ 0 1 x N-1 F(x,q 2 )dx, N=2,4,6,8 of the structure functions F 2 and F L were obtained. (orig./HSI)

  13. Perturbative QCD contributions to inclusive processes

    Energy Technology Data Exchange (ETDEWEB)

    Ritbergen, T. van

    1996-09-24

    This thesis treats the calculation of quantum corrections to a number of high energy processes that are measured in current and future accelerator experiments. The main objective of these experiments is to accurately verify the generally accepted theory of electro-weak and strong interactions, known as the Standard model, and to look for possible deviations. Most of the processes that are treated in this thesis are of a type for which the final state of of a highly energetic scattering or decay process is measured inclusively. The higher order quantum corrections discussed in this thesis are due to strong interactions. To the inclusive decay rate of Z{sup 0} bosons into all possible final states consisting of hadrons third order QCD contributions have been obtained. Also in the third order QCD an expansion for the inclusive hadronic decay rate of a {tau}-lepton was obtained. Then the top-quark-mass effects on the decay channels of a Higgs boson: Higgs{yields}b-quarks and Higgs{yields}gluons, were investigated. Thereafter the calculation of 3-loop contributions to the deep-inelastic lepton-nucleon scattering process is discussed. Finally the 3-loop contributions to the q{sup 2}-dependence of the lower moments {integral}{sub 0}{sup 1}x{sup N-1}F(x,q{sup 2})dx, N=2,4,6,8 of the structure functions F{sub 2} and F{sub L} were obtained. (orig./HSI).

  14. Experimental tests of QCD: Deep inelastic scattering, e+e- annihilation and hard hadron-hadron scattering

    International Nuclear Information System (INIS)

    Hansl-Kozanecka, T.

    1992-01-01

    In this set of lectures the author examines phenomenological aspects of quantum chromodynamics (QCD) which are relevant for lepton-hadron, electron-positron, and hadron-hadron collisions. He points how the strength of the strong coupling constant, αs, makes QCD calculations converge much more slowly in powers of αs, and missing higher order terms must be carefully estimated. The most stringent test of QCD can be performed in deep inelastic lepton scattering and in e + e - annihilation. In deep inelastic scattering the virtual γ or W/Z are used as a probe of the nucleon structure. They couple to quarks, not gluons. Only the incoming and outgoing lepton have to be measured. The hadronic fluid state does not have to be analyzed. In e + e - annihilation the virtual γ or Z 0 decays to lepton and quark pairs. The branching ratio into quarks is a counter for the number of colours available, the detailed structure of the final state reflects the radiation of gluons as the initial quark-antiquark separate from each other. Quarks and gluons are observed here, though in the presence of hadron formation. Hard hadron-hadron, or parton-parton collisions provide cross sections dominated by the gluon component, which is only weakly measured in deep inelastic collisions. Recent experimental results in these three areas are reviewed, and compared to QCD calculations. Scaling violations and analysis of structure functions in deep inelastic scattering are reviewed. QCD in e + e - branching to hadrons is reviewed near the Z 0 resonance, and a number of cross sections and jet related properties which can be calculated as a function of the single parameter αs are reviewed. Hadron-hadron collisions are reviewed for three processes; jet production, direct photon production, and high p perpendicular W/Z boson production

  15. The AdS/QCD Correspondence and Exclusive Processes

    International Nuclear Information System (INIS)

    Brodsky, Stanley

    2010-01-01

    The AdS/CFT correspondence between theories in AdS space and conformal field theories in physical space-time provides an analytic, semi-classical, color-confining model for strongly-coupled QCD. The soft-wall AdS/QCD model modified by a positive-sign dilaton metric leads to a remarkable one-parameter description of nonperturbative hadron dynamics at zero quark mass, including a zero-mass pion and a Regge spectrum of linear trajectories with the same slope in orbital angular momentum L and radial quantum number n for both mesons and baryons. One also predicts the form of the non-perturbative effective coupling α s AdS (q) and its β-function which agrees with the effective coupling α ga extracted from the Bjorken sum rule. Light-front holography, which connects the fifth-dimensional coordinate of AdS space z to an invariant impact separation variable ζ, allows one to compute the analytic form of the frame-independent light-front wavefunctions, the fundamental entities which encode hadron properties as well as decay constants, form factors, deeply virtual Compton scattering, exclusive heavy hadron decays and other exclusive scattering amplitudes. One thus obtains a relativistic description of hadrons in QCD at the amplitude level with dimensional counting for hard exclusive reactions at high momentum transfer. As specific examples we discuss the behavior of the pion and nucleon form factors in the space-like and time-like regions. We also review the phenomenology of exclusive processes including some anomalous empirical results.

  16. QCD

    CERN Document Server

    Catani, S; Soper, Davison Eugene; Stirling, William James; Tapprogge, Stefan; Alekhin, S I; Aurenche, Patrick; Balázs, C; Ball, R D; Battistoni, G; Berger, E L; Binoth, T; Brock, R L; Casey, D; Corcella, Gennaro; Del Duca, V; Fabbro, A D; de Roeck, A; Ewerz, C; de Florian, D; Fontannaz, M; Frixione, Stefano; Giele, W T; Grazzini, Massimiliano; Guillet, J P; Marlen-Heinrich, G; Huston, J; Kalk, J; Kataev, A L; Kato, K; Keller, S; Klasen, M; Kosower, D A; Kulesza, A; Kunszt, Zoltán; Kupco, A; Ilyin, V A; Magnea, L; Mangano, Michelangelo L; Martin, A D; Mazumdar, K; Miné, P; Moretti, M; van Neerven, W L; Parente, G; Perret-Gallix, D; Pilon, E; Pukhov, A E; Puljak, I; Pumplin, Jon; Richter-Was, Elzbieta; Roberts, R G; Salam, Gavin P; Seymour, Michael H; Skachkov, N B; Sidorov, A V; Stenzel, H; Stump, D R; Thorne, R S; Treleani, D; Tung, W K; Vogt, A; Webber, Bryan R; Werlen, M; Zmouchko, S; Mine, Ph.

    2000-01-01

    We discuss issues of QCD at the LHC including parton distributions, Monte Carlo event generators, the available next-to-leading order calculations, resummation, photon production, small x physics, double parton scattering, and backgrounds to Higgs production.

  17. Nonperturbative QCD and elastic processes at CEBAF energies

    Energy Technology Data Exchange (ETDEWEB)

    Radyushkin, A.V. [Old Dominion Univ., Norfolk, VA (United States)]|[Continuous Electron Beam Accelerator Facility, Newport News, VA (United States)

    1994-04-01

    The author outlines how one can approach nonperturbative aspects of the QCD dynamics studying elastic processes at energies accessible at upgraded CEBAF. The author`s point is that, in the absence of a complete theory of the nonperturbative effects, a possible way out is based on a systematic use of the QCD factorization procedure which separates theoretically understood ({open_quotes}known{close_quotes}) short-distance effects and nonperturbative ({open_quotes}unknown{close_quotes}) long-distance ones. The latter include hadronic distribution amplitudes, soft components of hadronic form factors etc. Incorporating the QCD sum rule version of the QCD factorization approach, one can relate these nonperturbative functions to more fundamental objects, vacuum condensates, which accumulate information about the nonperturbative structure of the QCD vacuum. The emerging QCD sum rule picture of hadronic form factors is characterized by a dominant role of essentially nonperturbative effects in the few GeV region, with perturbative mechanisms starting to show up for momentum transfers Q{sup 2} closer to 10 GeV{sup 2} and higher. Thus, increasing CEBAF energy provides a unique opportunity for a precision study of interplay between the perturbative and nonperturbative phenomena in the QCD description of elastic processes.

  18. Nonperturbative QCD and elastic processes at CEBAF energies

    International Nuclear Information System (INIS)

    Radyushkin, A.V.

    1994-01-01

    The author outlines how one can approach nonperturbative aspects of the QCD dynamics studying elastic processes at energies accessible at upgraded CEBAF. The author's point is that, in the absence of a complete theory of the nonperturbative effects, a possible way out is based on a systematic use of the QCD factorization procedure which separates theoretically understood (open-quotes knownclose quotes) short-distance effects and nonperturbative (open-quotes unknownclose quotes) long-distance ones. The latter include hadronic distribution amplitudes, soft components of hadronic form factors etc. Incorporating the QCD sum rule version of the QCD factorization approach, one can relate these nonperturbative functions to more fundamental objects, vacuum condensates, which accumulate information about the nonperturbative structure of the QCD vacuum. The emerging QCD sum rule picture of hadronic form factors is characterized by a dominant role of essentially nonperturbative effects in the few GeV region, with perturbative mechanisms starting to show up for momentum transfers Q 2 closer to 10 GeV 2 and higher. Thus, increasing CEBAF energy provides a unique opportunity for a precision study of interplay between the perturbative and nonperturbative phenomena in the QCD description of elastic processes

  19. QCD

    CERN Multimedia

    1999-01-01

    Basic Properties of QCD: the Lagrangian, the running coupling, asymptotic freedom and colour confinement. Examples of perturbative calculations in electron- positron physics (total cross sections and event) Parton branching approach will be used to derive the evolution equations for hadron structure functions Comarison with data on deep inelastic scattering and jet production will be for hadron structure functions and jet fragmentation functions

  20. Implications of confining force field structures in hard hadronic processes

    International Nuclear Information System (INIS)

    Bengtsson, H.-U.

    1983-04-01

    This thesis is centered on the study of confining force field structures in hard scattering processes. Perturbative QCD provides the means of calculating any process on the parton level, but to be able accurately to describe the actual outcome of an event, one still needs a phenomenological model for how quarks and gluons transform into observable hadrons. One such model is based on the assumption that the particles are produced by the confining fields stretched between the partons. The actual particle distributions will then depend on the topology of the confining fields. We have developed a Monte Carlo program to simulate complete events in hard scattering, and we use this to study the properties of the confining field in different trigger situations. We further look at the amount of hard processes that can be expected in experiments that trigger on transverse energy sum (calorimeter experiments). Finally, we investigate charm production within our model. (author)

  1. Heavy quark production processes in QCD

    International Nuclear Information System (INIS)

    Brodsky, S.J.; Gunion, J.F.

    1984-12-01

    We have identified two novel effects in QCD, each of which acts to enhance the production of heavy quark and supersymmetric particles beyond what is conventionally expected from gluon fusion. Both effects are present in QED, but are compounded in QCD because of the increased number of diagrams and the much larger coupling constant. The intrinsic charm quark distribution in the nucleon could account for the observed enhancements of the charm structure function at large x and features of the charm production data but this mechanism is relatively suppressed for heavier systems. Prebinding distortion of the fusion cross section is, however, likely to be significant for the production at low p/sub T/ of all particles containing heavy colored constituents. At this stage the QCD calculations are highly model dependent although they agree with the general properties which can be inferred from the operator product expansion in the heavy quark mass. Much more theoretical analysis of these effects is clearly needed. It is also clear that much more experimental work is necessary to extend and confirm the reported anomalous heavy quark signals. 22 references

  2. Analysis of hard inclusive processes in quantum chromodynamics

    International Nuclear Information System (INIS)

    Radyushkin, A.V.

    1983-01-01

    An approach to the investigation of hard processes in QCD based on a regular usage of α-representation analysis of Feynman diagram asymptotics is described. Analysis is examplified by two simplest inclusive processes: E + e - annihilation into hadrons and deep inelastic lepton-hadron scattering. The separation procedure of factorization of contributions stipulated by short- and long-range particle interactions is reported. The relation between expansion operators and methods based on direct analysis of diagrams as well as between theoretical field approaches and the parton model is discussed. Specific features of factorization of short- and long-range contributions in non-Abelian gauge theories are investigated

  3. Implications of QCD for soft hadronic and nuclear processes

    International Nuclear Information System (INIS)

    Hwa, R.C.

    1981-01-01

    Physical implications of QCD for strong forces in soft processes are discussed. Topics include long-range force, Van der Waals force, nuclear force, hadron and quark structures. In the absence of a reliable calculational scheme, phenomenological models have been built that incorporate QCD ideas as far as possible. In the framework of those models calculations have been made that provide an understanding of the soft processes in terms of quarks and gluons. We review recent work on nuclear potential, form factors at low Q 2 , pion decay constant, inclusive distribution of low p/sub T/, and radiation length of fast quark in nuclear matter

  4. QCD factorization beyond leading twist in exclusive processes: rhoT-meson production

    International Nuclear Information System (INIS)

    Wallon, S.; Anikin, I.; ); Ivanov, D.; Pire, B.; Szymanowski, L.

    2009-01-01

    Exclusive processes in hard electroproduction with asymptotic γ * p center of mass energy is one of the best place for understanding QCD in the perturbative Regge limit. The HERA experiment recently provided precise data for rho electroproduction, including all spin density matrix elements. From QCD, it is expected that such a process should factorize between a hard (calculable) coefficient function, and hadronic (P and ρ) matrix elements. Such a factorization is up to now only proven for a longitudinally polarized rho. Within the kt-factorization approach (valid at large s γ * p), we evaluate the impact factor of the transition γ * → ρT taking into account the twist 3 contributions. We show that a gauge invariant expression is obtained with the help of QCD equations of motion. More generally, relying on these equations and on the gauge invariance of the factorized amplitude, the non-perturbative Distribution Amplitudes can be reduced to a minimal set. This opens the way to a consistent treatment of factorization for exclusive processes with a transversally polarized vector meson. (author)

  5. Perturbative QCD (1/3)

    CERN Multimedia

    CERN. Geneva

    2013-01-01

    Perturbative QCD is the general theoretical framework for describing hard scattering processes yielding multiparticle production at hadron colliders. In these lectures, we shall introduce fundamental features of perturbative QCD and describe its application to several high energy collider processes, including jet production in electron-positron annihilation, deep inelastic scattering, Higgs boson and gauge boson production at the LHC.

  6. The High Energy Asymptotics of Scattering Processes in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Enberg, Rikard; Golec-Biernat, K.; Munier, S.

    2005-05-12

    High energy scattering in the QCD parton model was recently shown to be a reaction-diffusion process, and thus to lie in the universality class of the stochastic Fisher-Kolmogorov-Petrovsky-Piscounov equation. We recall that the latter appears naturally in the context of the parton model. We provide a thorough numerical analysis of the mean field approximation, given in QCD by the Balitsky-Kovchegov equation. In the framework of a simple stochastic toy model that captures the relevant features of QCD, we discuss and illustrate the universal properties of such stochastic models. We investigate in particular the validity of the mean field approximation and how it is broken by fluctuations. We find that the mean field approximation is a good approximation in the initial stages of the evolution in rapidity.

  7. QCD phenomenology of the large P/sub T/ processes

    International Nuclear Information System (INIS)

    Stroynowski, R.

    1979-11-01

    Quantum Chromodynamics (QCD) provides a framework for the possible high-accuracy calculations of the large-p/sub T/ processes. The description of the large-transverse-momentum phenomena is introduced in terms of the parton model, and the modifications expected from QCD are described by using as an example single-particle distributions. The present status of available data (π, K, p, p-bar, eta, particle ratios, beam ratios, direct photons, nuclear target dependence), the evidence for jets, and the future prospects are reviewed. 80 references, 33 figures, 3 tables

  8. On exact account of heavy quark thresholds in hard processes

    International Nuclear Information System (INIS)

    Dokshitzer, Yu. L.

    1993-01-01

    We study the problem to accurately account for the heavy quark threshold effects in hard processes. We employ the direction perturbative Feynman diagram analysis and the Stueckelberg-Bogoliubov massive renormalization group formalism to show that both methods results in the same prescription for the 'physical' mass-dependent QCD effective coupling as an argument of anomalous dimensions that determine the evolution of structure function (parton distributions). By considering the one-loop example, we demonstrate that an intrinsic ambiguity of the standard approach based on the notion of 'effective number of quark flavours' may affect the α s determination at the level of two-loop effects

  9. The underlying event in hard scattering processes

    International Nuclear Information System (INIS)

    Field, R.

    2002-01-01

    The authors study the behavior of the underlying event in hard scattering proton-antiproton collisions at 1.8 TeV and compare with the QCD Monte-Carlo models. The underlying event is everything except the two outgoing hard scattered jets and receives contributions from the beam-beam remnants plus initial and final-state radiation. The data indicate that neither ISAJET or HERWIG produce enough charged particles (with p T > 0.5 GeV/c) from the beam-beam remnant component and that ISAJET produces too many charged particles from initial-state radiation. PYTHIA which uses multiple parton scattering to enhance the underlying event does the best job describing the data

  10. How hadron collider experiments contributed to the development of QCD: from hard-scattering to the perfect liquid

    Science.gov (United States)

    Tannenbaum, M. J.

    2018-05-01

    A revolution in elementary particle physics occurred during the period from the ICHEP1968 to the ICHEP1982 with the advent of the parton model from discoveries in Deeply Inelastic electron-proton Scattering at SLAC, neutrino experiments, hard-scattering observed in p+p collisions at the CERN ISR, the development of QCD, the discovery of the J/ Ψ at BNL and SLAC and the clear observation of high transverse momentum jets at the CERN SPS p¯ + p collider. These and other discoveries in this period led to the acceptance of QCD as the theory of the strong interactions. The desire to understand nuclear physics at high density such as in neutron stars led to the application of QCD to this problem and to the prediction of a Quark-Gluon Plasma (QGP) in nuclei at high energy density and temperatures. This eventually led to the construction of the Relativistic Heavy Ion Collider (RHIC) at BNL to observe superdense nuclear matter in the laboratory. This article discusses how experimental methods and results which confirmed QCD at the first hadron collider, the CERN ISR, played an important role in experiments at the first heavy ion collider, RHIC, leading to the discovery of the QGP as a perfect liquid as well as discoveries at RHIC and the LHC which continue to the present day.

  11. Effective field theory approach to parton-hadron conversion in high energy QCD processes

    CERN Document Server

    Kinder-Geiger, Klaus

    1995-01-01

    A QCD based effective action is constructed to describe the dynamics of confinement and symmetry breaking in the process of parton-hadron conversion. The deconfined quark and gluon degrees of freedom of the perturbative QCD vacuum are coupled to color singlet collective fields representing the non-perturbative vacuum with broken scale and chiral symmetry. The effective action recovers QCD with its scale and chiral symmetry properties at short space-time distances, but yields at large distances (r > 1 fm) to the formation of symmetry breaking gluon and quark condensates. The approach is applied to the evolution of a fragmenting q\\bar q pair with its generated gluon distribution, starting from a large hard scale Q^2. The modification of the gluon distribution arising from the coupling to the non-perturbative collective field results eventually in a complete condensation of gluons. Color flux tube configurations of the gluons in between the q\\bar q pair are obtained as solutions of the equations of motion. With ...

  12. Interplay of hard and soft physics in small x deep inelastic processes

    International Nuclear Information System (INIS)

    Abramowicz, H.

    1995-01-01

    Coherence phenomena, the increase with energy of coherence length and the nonuniversality of parton structure of the effective pomeron are explained. New hard phenomena directly calculable in QCD such as diffractive electroproduction of states with M 2 2 and the color transparency phenomenon as well as new options to measure the light-cone wave functions of various hadrons are considered. An analogue of Bjorken scaling is predicted for the diffractive electroproduction of ρ mesons at large momentum transfers and for the production of large rapidity gap events, as observed at HERA. A phenomenological QCD evolution equation is suggested to calculate the basic characteristics of the large rapidity gap events. The increase of parton densities at small x as well as new means to disentangle experimentally soft and hard physics are considered. We discuss constraints on the increase of deep inelastic amplitudes with Q 2 derived from the inconsistency of QCD predictions for inclusive and exclusive processes and from unitarity of the S matrix for collisions of wave packets. New ways to probe QCD physics of hard processes at large longitudinal distances and to answer the long standing problems on the origin of the pomeron are suggested. Unresolved problems and perspectives of small x physics are also outlined. (orig.)

  13. The ADS/QCD correspondence and exclusive processes

    International Nuclear Information System (INIS)

    Brodsky, Stanley J.; De Teramond, Guy F.; Deur, Alexandre

    2011-01-01

    The AdS/CFT correspondence between theories in AdS space and conformal field theories in physical space-time provides an analytic, semi-classical, color-confining model for strongly-coupled QCD. The soft-wall AdS/QCD model, modified by a positive-sign dilaton metric, leads to a remarkable one-parameter description of nonperturbative hadron dynamics at zero quark mass, including a zero-mass pion and meson and baryon Regge spectra of linear trajectories with the same slope in orbital angular momentum L and radial quantum number n. One also predicts the form of the non-perturbative effective coupling alpha AdS/s (Q) and its Beta-function which agrees with the effective coupling alphag1 extracted from the Bjorken sum rule. Light-front holography, which connects the fifth-dimensional coordinate of AdS space z to an invariant impact separation variable zeta, allows one to compute the analytic form of the frame-independent light-front wave functions, the fundamental entities which encode hadron properties as well as decay constants, form factors, deeply-virtual Compton scattering, exclusive heavy hadron decays, and other exclusive scattering amplitudes. One thus obtains a relativistic description of hadrons in QCD at the amplitude level with dimensional counting for exclusive reactions at high momentum transfer. As specific examples, we discuss the behavior of the pion and nucleon form factors in the space-like and time-like regions. We also review the phenomenology of exclusive processes including some anomalous empirical results.

  14. Lattice QCD results on soft and hard probes of strongly interacting matter

    Science.gov (United States)

    Kaczmarek, Olaf

    2017-11-01

    We present recent results from lattice QCD relevant for the study of strongly interacting matter as it is produced in heavy ion collision experiments. The equation of state at non-vanishing density from a Taylor expansion up to 6th order will be discussed for a strangeness neutral system and using the expansion coefficients of the series limits on the critical point are estimated. Chemical freeze-out temperatures from the STAR and ALICE Collaborations will be compared to lines of constant physics calculated from the Taylor expansion of QCD bulk thermodynamic quantities. We show that qualitative features of the √{sNN} dependence of skewness and kurtosis ratios of net proton-number fluctuations measured by the STAR Collaboration can be understood from QCD results for cumulants of conserved baryon-number fluctuations. As an example for recent progress towards the determination of spectral and transport properties of the QGP from lattice QCD, we will present constraints on the thermal photon rate determined from a spectral reconstruction of continuum extrapolated lattice correlation functions in combination with input from most recent perturbative calculations.

  15. Delving into QCD jets

    International Nuclear Information System (INIS)

    Konishi, K.

    1980-01-01

    The author discusses, in an introductory fashion, the latest developments in the study of hadronic jets produced in hard processes, based on perturbative QCD. Emphasis is on jet calculus (and its applications and generalizations), and on the appearance of a parton-like consistent, over-all picture of jet evolution in momentum, colour, and real space-time. (Auth.)

  16. Resummations in QCD hard-scattering at large and small x

    CERN Document Server

    Kidonakis, Nikolaos; Stephens, Philip

    2008-01-01

    We discuss different resummations of large logarithms that arise in hard-scattering cross sections of quarks and gluons in regions of large and small x. The large-x logarithms are typically dominant near threshold for the production of a specified final state. These soft and collinear gluon corrections produce large enhancements of the cross section for many processes, notably top quark and Higgs production, and typically the higher-order corrections reduce the factorization and renormalization scale dependence of the cross section. The small-x logarithms are dominant in the regime where the momentum transfer of the hard sub-process is much smaller than the total collision energy. These logarithms are important to describe multijet final states in deep inelastic scattering and hadron colliders, and in the study of parton distribution functions. The resummations at small and large x are linked by the eikonal approximation and are dominated by soft gluon anomalous dimensions. We will review their role in both c...

  17. Some experience in applying the REDUCE algebraic system to the calculation of scattering processes in QED and QCD

    International Nuclear Information System (INIS)

    Mohring, H.J.; Schiller, A.

    1980-01-01

    The problems arising in the use of the REDUCE algebraic system for calculating traces of the Dirac matrix products describing scattering processes in quantum electrodynamics (QED) and quantum chromodynamics (QCD) are considered. Application of the REDUCE system for describing two-photon processes in e + e - reactions is discussed. An example of using the REDUCE system for calculating matrix elements of elementary processes of hard scattering is described. The calculations were performed by means of the REDUCE2 version on an EC1040 computer. The computations take almost 10 minutes of machine time and computer storage capacity of abo t 800 kiuobites

  18. Spin structure of nucleon in QCD: inclusive and exclusive processes

    International Nuclear Information System (INIS)

    Teryaev, O.V.

    2001-01-01

    There are two basically independent ways to describe the nucleon spin structure. One is related to quark and gluon spins and another one to their total angular momenta. The latter spin structure may be studied, in principle, in hard exclusive processes

  19. Hard Break-Up of Two-Nucleons and QCD Dynamics of NN Interaction

    International Nuclear Information System (INIS)

    Sargsian, Misak

    2008-01-01

    We discus recent developments in theory of high energy two-body break-up of few-nucleon systems. The characteristics of these reactions are such that the hard two-body quasielastic subprocess can be clearly separated from the accompanying soft subprocesses. We discuss in details the hard rescattering model (HRM) in which hard photodisintegration develops in two stages. At first, photon knocks-out an energetic quark which rescatters subsequently with a quark of the other nucleon. The latter provides a mechanism of sharing the initial high momentum of the photon between two outgoing nucleons. This final state hard rescattering can be expressed through the hard NN scattering amplitude. Within HRM we discuss hard break-up reactions involving D and 3 He targets and demonstrate how these reactions are sensitive to the dynamics of hard pn and pp interaction. Another development of HRM is the prediction of new helicity selection mechanism for hard two-body reactions, which was apparently confirmed in the recent JLab experiment.

  20. Improved hard-thermal-loop effective action for hot QED and QCD

    International Nuclear Information System (INIS)

    Flechsig, F.; Rebhan, A.K.

    1995-01-01

    The conventional results for hard thermal loops, which are the building blocks of resummed perturbation theory in thermal field theories, have collinear singularities when external momenta are light-like. It is shown that by taking into account asymptotic thermal masses these singularities are removed. The thus improved hard thermal loops can be summarized by compact gauge-invariant effective actions, generalizing the ones found by Taylor and Wong, and by Braaten and Pisarski. (orig.)

  1. Novel QCD Phenomena

    International Nuclear Information System (INIS)

    Brodsky, Stanley J.; SLAC

    2007-01-01

    I discuss a number of novel topics in QCD, including the use of the AdS/CFT correspondence between Anti-de Sitter space and conformal gauge theories to obtain an analytically tractable approximation to QCD in the regime where the QCD coupling is large and constant. In particular, there is an exact correspondence between the fifth-dimension coordinate z of AdS space and a specific impact variable ζ which measures the separation of the quark constituents within the hadron in ordinary space-time. This connection allows one to compute the analytic form of the frame-independent light-front wavefunctions of mesons and baryons, the fundamental entities which encode hadron properties and allow the computation of exclusive scattering amplitudes. I also discuss a number of novel phenomenological features of QCD. Initial- and final-state interactions from gluon-exchange, normally neglected in the parton model, have a profound effect in QCD hard-scattering reactions, leading to leading-twist single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, the breakdown of the Lam Tung relation in Drell-Yan reactions, and nuclear shadowing and non-universal antishadowing--leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also discuss tests of hidden color in nuclear wavefunctions, the use of diffraction to materialize the Fock states of a hadronic projectile and test QCD color transparency, and anomalous heavy quark effects. The presence of direct higher-twist processes where a proton is produced in the hard subprocess can explain the large proton-to-pion ratio seen in high centrality heavy ion collisions

  2. Two-dimensional QCD as a model for strong interaction

    International Nuclear Information System (INIS)

    Ellis, J.

    1977-01-01

    After an introduction to the formalism of two-dimensional QCD, its applications to various strong interaction processes are reviewed. Among the topics discussed are spectroscopy, deep inelastic cross-sections, ''hard'' processes involving hadrons, ''Regge'' behaviour, the existence of the Pomeron, and inclusive hadron cross-sections. Attempts are made to abstracts features useful for four-dimensional QCD phenomenology. (author)

  3. Tomography for amplitudes of hard exclusive processes

    International Nuclear Information System (INIS)

    Polyakov, M.V.

    2008-01-01

    We discuss which part of information about hadron structure encoded in the Generalized Parton Distributions (GPDs) [part of total GPD image] can be restored from the known amplitude of a hard exclusive process. The physics content of this partial image is analyzed. Among other things, we show that this partial image contains direct information about how the target hadron responses to the (string) quark-antiquark operator of arbitrary spin J. Explicit equations relating physics content of the partial image of GPDs directly to the data are derived. Also some new results concerning the dual parametrization of GPDs are presented

  4. The structure of gluon radiation in QCD

    International Nuclear Information System (INIS)

    Parke, S.; Mangano, M.

    1989-08-01

    For massless QCD the hard scattering amplitudes are naturally written in terms of the dual color expansion. here I present this expansion for purely gluonic processes and processes involving quark-antiquark pairs and gluons. The properties of the sub-amplitudes as well as explicit algebraic expressions are given for a number of these processes. Also, I demonstrate how to recover massless QED amplitudes from the dual expansion of massless QCD. 16 refs., 3 figs., 1 tab

  5. Semihard QCD

    International Nuclear Information System (INIS)

    Kwiecinski, J.

    1989-01-01

    Recent results concerning the small x limit of parton distributions in perturbative QCD are reviewed. This includes in particular discussion of the bare Pomeron in perturbative QCD and of shadowing corrections. The minijet production processes and possible manifestation of semihard interactions in high energy pp-bar elastic scattering are also discussed. 46 refs., 8 figs. (author)

  6. Basics of QCD perturbation theory

    International Nuclear Information System (INIS)

    Soper, D.E.

    1997-01-01

    This is an introduction to the use of QCD perturbation theory, emphasizing generic features of the theory that enable one to separate short-time and long-time effects. The author also covers some important classes of applications: electron-positron annihilation to hadrons, deeply inelastic scattering, and hard processes in hadron-hadron collisions. 31 refs., 38 figs

  7. Basics of QCD perturbation theory

    Energy Technology Data Exchange (ETDEWEB)

    Soper, D.E. [Univ. of Oregon, Eugene, OR (United States). Inst. of Theoretical Science

    1997-06-01

    This is an introduction to the use of QCD perturbation theory, emphasizing generic features of the theory that enable one to separate short-time and long-time effects. The author also covers some important classes of applications: electron-positron annihilation to hadrons, deeply inelastic scattering, and hard processes in hadron-hadron collisions. 31 refs., 38 figs.

  8. The structure of gluon radiation in QCD

    International Nuclear Information System (INIS)

    Parke, S.; Mangano, M.

    1990-01-01

    For massless QCD the hard scattering amplitudes are naturally written in terms of the dual color expansion. Here I present this expansion for purely gluonic processes and processes involving quark-antiquark pairs and gluons. The properties of the sub-amplitudes as well as explicit algebraic expressions are given for a number of these processess. Finally, I demonstrate how to recover massless QED amplitudes from the dual expansion of massless QCD

  9. QCD processes and search for supersymmetry at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Schum, Torben

    2012-07-15

    In this thesis, a data-driven method to estimate the number of QCD background events in a multijet search for supersymmetry at the LHC was developed. The method makes use of two models which predict the correlation of two key search variables, the missing transverse momentum and an angular variable, in order to extrapolate from a QCD dominated control region to the signal region. A good performance of the method was demonstrated by its application to 36 pb{sup -1} data, taken by the CMS experiment in 2010, and by the comparison with an alternative method. Comparing the number of data events to a combined background expectation of QCD and data-driven estimates of the electroweak and top background, no statistically significant excess was observed for three pre-defined search regions. Limits were calculated for the (m{sub 0},m{sub 1/2}) parameter space of the cMSSM, exceeding previous measurements. The expected sensitivity for further refined search regions was investigated.

  10. QCD processes and search for supersymmetry at the LHC

    International Nuclear Information System (INIS)

    Schum, Torben

    2012-07-01

    In this thesis, a data-driven method to estimate the number of QCD background events in a multijet search for supersymmetry at the LHC was developed. The method makes use of two models which predict the correlation of two key search variables, the missing transverse momentum and an angular variable, in order to extrapolate from a QCD dominated control region to the signal region. A good performance of the method was demonstrated by its application to 36 pb -1 data, taken by the CMS experiment in 2010, and by the comparison with an alternative method. Comparing the number of data events to a combined background expectation of QCD and data-driven estimates of the electroweak and top background, no statistically significant excess was observed for three pre-defined search regions. Limits were calculated for the (m 0 ,m 1/2 ) parameter space of the cMSSM, exceeding previous measurements. The expected sensitivity for further refined search regions was investigated.

  11. Hard scattering processes in high energy γ-induced reactions

    International Nuclear Information System (INIS)

    D'Agostini, G.

    1994-09-01

    Recent results from photoproduction and γγ collisions are reviewed, with special focus on hard interactions, featuring the jets as the best evidence, as manifestation of parton-parton and photon-parton scattering. The experimental results are in good agreement with perturbative QCD expectations and the data are going to have the appropriate accuracy to discriminate between the available parameterizations of the photon structure functions. In particular, the combination of F 2 γ measured in γγ and the jet cross sections measured in γγ and γp will probably constrain in the near future the gluon content of the photon. (orig.)

  12. Meson effective mass in the isospin medium in hard-wall AdS/QCD model

    Energy Technology Data Exchange (ETDEWEB)

    Mamedov, Shahin [Gazi University, Department of Physics, Ankara (Turkey); Baku State University, Institute for Physical Problems, Baku (Azerbaijan); Azerbaijan National Academy of Sciences, Institute of Physics, Baku (Azerbaijan)

    2016-02-15

    We study a mass splitting of the light vector, axial-vector, and pseudoscalar mesons in the isospin medium in the framework of the hard-wall model. We write an effective mass definition for the interacting gauge fields and scalar field introduced in gauge field theory in the bulk of AdS space-time. Relying on holographic duality we obtain a formula for the effective mass of a boundary meson in terms of derivative operator over the extra bulk coordinate. The effective mass found in this way coincides with the one obtained from finding of poles of the two-point correlation function. In order to avoid introducing distinguished infrared boundaries in the quantization formula for the different mesons from the same isotriplet we introduce extra action terms at this boundary, which reduces distinguished values of this boundary to the same value. Profile function solutions and effective mass expressions were found for the in-medium ρ, a{sub 1}, an π mesons. (orig.)

  13. Experimental status QCD

    International Nuclear Information System (INIS)

    Radyushkin, A.V.; Slepchenko, L.A.

    1983-01-01

    Analysis of experimental status of quantum chromodynamics (QCD) has been carried out. A short introduction into QCD is given. QCD sum rules are considered. Jets in e + e - annihilation and inclusive processes of lepton-hadron and hadron-hadron scattering are considered. Effect of QCD corrections to perturbation theory on quark count is analyzed

  14. Phenomenology of the proton and the nucleus through hard processes in quantum chromodynamics

    International Nuclear Information System (INIS)

    Gousset, T.

    2005-01-01

    My scientific domain is the phenomenology of the non-perturbative quantum chromodynamics (QCD). In the introduction I quickly present the history of QCD since its establishing in the seventies. The first chapter is dedicated to the achievements of the last decade concerning first the hard electroproduction at low impulse transfer in electron-proton reactions and secondly the search for the quark-gluon plasma in ultra-relativistic heavy ion reactions with the help of hard probes. In the second chapter I detail the hard electroproduction reactions with the aim of explaining their factorization in a sub-process including partons and whose amplitude can be computed in the theory of perturbations. Generalized parton distributions, that describe the transition from hadrons to partons could be useful to get more information on hadronic wave functions. Experimental implications are reviewed. The third chapter is dedicated to the J/ψ production in proton-nucleus collisions. J/ψ and the quarkonium family offer, thanks to their easy identification a useful tool to shed light on different sides of QCD such as the production of heavy quarks or the existence of the quark-gluon plasma. In the last chapter I present my last works that concern first the nuclear effects that appear in proton-nucleus collisions when we want to describe the relationship between the production cross-section of a particle and the value of the transverse momentum of the particle, and secondly the observation through radio-detection of big showers due to the interaction with the atmosphere of an ultra-high energy cosmic ray [fr

  15. W production at LHC: lepton angular distributions and reference frames for probing hard QCD

    International Nuclear Information System (INIS)

    Richter-Was, E.; Was, Z.

    2017-01-01

    Precision tests of the Standard Model in the Strong and Electroweak sectors play a crucial role, among the physics program of LHC experiments. Because of the nature of proton-proton processes, observables based on the measurement of the direction and energy of final state leptons provide the most precise probes of such processes. In the present paper, we concentrate on the angular distribution of leptons from W → lν decays in the lepton-pair rest-frame. The vector nature of the intermediate state imposes that distributions are to a good precision described by spherical harmonics of at most second order. We argue, that contrary to general belief often expressed in the literature, the full set of angular coefficients can be measured experimentally, despite the presence of escaping detection neutrino in the final state. There is thus no principle difference with respect to the phenomenology of the Z/γ → l"+l"- Drell-Yan process. We show also, that with the proper choice of the reference frames, only one coefficient in this polynomial decomposition remains sizable, even in the presence of one or more high p_T jets. The necessary stochastic choice of the frames relies on probabilities independent from any coupling constants. In this way, electroweak effects (dominated by the V - A nature of W couplings to fermions), can be better separated from the ones of strong interactions. The separation is convenient for the measurements interpretation. (orig.)

  16. Two-particle lepton-nucleon processes in the dual QCD approach

    International Nuclear Information System (INIS)

    Bel'kov, A.A.

    1984-01-01

    The data on elastic and quasielastic lepton-nucleon scattering and on Δ 33 electro- and neutrino-production are analyzed in the dual approach based on finite-energy sum rules and QCD. A large class of two-particle lepton-nucleon processes at small and moderate momentum transfers 0.4 (GeV/c) 2 2 2 are described. It is shown that the data on these processes, used as an additional information, essentially decrease the ambiguity in determination of QCD parameters from analysis of deep inelastic lepton-nucleon scattering

  17. Two-particle lepton--nucleon processes in the dual QCD approach

    International Nuclear Information System (INIS)

    Bel'kov, A.A.; Ivanov, Y.P.; Kovalenko, S.G.

    1984-01-01

    Using a dual approach based on finite-energy sum rules and QCD, an analysis is made of data on elastic and quasielastic lepton--nucleon scattering and on the reactions of electron- and neutrino-induced production of the Δ 33 isobar. A description is obtained of a wide range of two-particle lepton--nucleon processes in the region of small and moderate momentum transfers 0.4 (GeV/c) 2 2 2 . It is shown that the use of data on these processes as additional information substantially reduces the ambiguity in the determination of the QCD parameters in the analysis of deep inelastic lepton--nucleon scattering

  18. Novel QCD Aspects of Hard Diffraction,Antishadowing, and Single-Spin Asymmetries

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.

    2004-10-15

    It is usually assumed--following the parton model--that the leading-twist structure functions measured in deep inelastic lepton-proton scattering are simply the probability distributions for finding quarks and gluons in the target nucleon. In fact, gluon exchange between the outgoing quarks and the target spectators effects the leading-twist structure functions in a profound way, leading to diffractive leptoproduction processes, shadowing and antishadowing of nuclear structure functions, and target spin asymmetries, physics not incorporated in the light-front wavefunctions of the target computed in isolation. In particular, final-state interactions from gluon exchange lead to single-spin asymmetries in semi-inclusive deep inelastic lepton-proton scattering which are not power-law suppressed in the Bjorken limit. The shadowing and antishadowing of nuclear structure functions in the Gribov-Glauber picture is due respectively to the destructive and constructive interference of amplitudes arising from the multiple-scattering of quarks in the nucleus. The effective quark-nucleon scattering amplitude includes Pomeron and Odderon contributions from multi-gluon exchange as well as Reggeon quark-exchange contributions. Part of the anomalous NuTeV result for sin{sup 2} {theta}{sub W} could be due to the non-universality of nuclear antishadowing for charged and neutral currents. Detailed measurements of the nuclear dependence of individual quark structure functions are thus needed to establish the distinctive phenomenology of shadowing and antishadowing and to make the NuTeV results definitive. I also discuss diffraction dissociation as a tool for resolving hadron substructure Fock state by Fock state and for producing leading heavy quark systems.

  19. QCD as a Theory of Hadrons

    Science.gov (United States)

    Narison, Stephan

    2007-07-01

    About Stephan Narison; Outline of the book; Preface; Acknowledgements; Part I. General Introduction: 1. A short flash on particle physics; 2. The pre-QCD era; 3. The QCD story; 4. Field theory ingredients; Part II. QCD Gauge Theory: 5. Lagrangian and gauge invariance; 6. Quantization using path integral; 7. QCD and its global invariance; Part III. MS scheme for QCD and QED: Introduction; 8. Dimensional regularization; 9. The MS renormalization scheme; 10. Renormalization of operators using the background field method; 11. The renormalization group; 12. Other renormalization schemes; 13. MS scheme for QED; 14. High-precision low-energy QED tests; Part IV. Deep Inelastic Scattering at Hadron Colliders: 15. OPE for deep inelastic scattering; 16. Unpolarized lepton-hadron scattering; 17. The Altarelli-Parisi equation; 18. More on unpolarized deep inelastic scatterings; 19. Polarized deep-inelastic processes; 20. Drell-Yan process; 21. One 'prompt photon' inclusive production; Part V. Hard Processes in e+e- Collisions: Introduction; 22. One hadron inclusive production; 23. gg scatterings and the 'spin' of the photon; 24. QCD jets; 25. Total inclusive hadron productions; Part VI. Summary of QCD Tests and as Measurements; Part VII. Power Corrections in QCD: 26. Introduction; 27. The SVZ expansion; 28. Technologies for evaluating Wilson coefficients; 29. Renormalons; 30. Beyond the SVZ expansion; Part VIII. QCD Two-Point Functions: 31. References guide to original works; 32. (Pseudo)scalar correlators; 33. (Axial-)vector two-point functions; 34. Tensor-quark correlator; 35. Baryonic correlators; 36. Four-quark correlators; 37. Gluonia correlators; 38. Hybrid correlators; 39. Correlators in x-space; Part IX. QCD Non-Perturbative Methods: 40. Introduction; 41. Lattice gauge theory; 42. Chiral perturbation theory; 43. Models of the QCD effective action; 44. Heavy quark effective theory; 45. Potential approaches to quarkonia; 46. On monopole and confinement; Part X. QCD

  20. QCD jet simulation with CMS at LHC and background studies to H to gamma gamma process

    CERN Document Server

    Litvin, V; Shevchenko, S; Wisniewski, N

    2002-01-01

    We have simulated and reconstructed one million of QCD jet events. This study was done with CMS full detector simulation, based on GEANT3 package, and object-oriented CMS C++ reconstruction program. The understanding of QCD jet background is important for the Higgs search in two-photon decay mode. The comparison with other types of backgrounds was also done. It was shown that the isolation tools were important ones to isolate the signal process from the huge background one. Using the isolation criteria based on the information from PbWO /sub 4/ electromagnetic calorimeter and the tracker we were able to reduce the QCD jet background to 15% of the total one. (9 refs).

  1. The QCD corrections of the process h → ηbZ

    Science.gov (United States)

    Zhu, Rong-Fei; Feng, Tai-Fu; Zhang, Hai-Bin

    2018-05-01

    We investigate the 125 GeV Higgs boson decay to a pseudoscalar quarkonium ηb and Z boson. We calculate the quantum chromodynamics (QCD) one-loop corrections to the branching ratio of the process, Br(h → ηbZ), both in the Standard Model (SM) and in the two Higgs double models (THDM). Adding the QCD one-loop corrections, the branching ratio of h → ηbZ in the SM is Br(h → ηbZ) = (4.739‑0.244+0.276) × 10‑5. The relative correction of that QCD one-loop level relative to the tree level of Br(h → ηbZ) is around 76% in the SM. Similarly, the relative correction in the THDM also can be around 75%. The key parameter, tan β, can affect the relative correction in the THDM.

  2. Non-perturbative QCD Effect on K-Factor of Drell-Yan Process

    International Nuclear Information System (INIS)

    Hou Zhaoyu; Zhi Haisu; Chen Junxiao

    2006-01-01

    By using a non-perturbative quark propagator with the lowest-dimensional condensate contributions from the QCD vacuum, the non-perturbative effect to K-factor of the Drell-Yan process is numerically investigated for 12 6 C- 12 6 C collision at the center-of-mass energy (s) 1/2 = 200 GeV, 630 GeV respectively. Calculated results show that the non-perturbative QCD effect has just a weak influence on K-factor in the two cases.

  3. Possible connections between hard and soft processes

    International Nuclear Information System (INIS)

    Blankenbecler, R.

    1977-10-01

    Three topics in constituent hadron models are reviewed: the connection between fixed angle and Regge behavior, the validity of the hard scattering expansion and restrictions on the effects of the transverse momentum of constituents, and the x distribution in the fragmentation region at low transverse momentum. 6 figures

  4. Colour-symmetry-breaking effects in hard processes

    International Nuclear Information System (INIS)

    Efremov, A.V.

    1982-01-01

    A possibility of colour symmetry U(1)xSU(3)sub(C) spontaneous breaking and integer-charged quarks is considered. It is argued that one-photon processes are sensitive only to the colour-averaged charges of quarks and gluons. The true charges can be observed in rigid processes involving at least two real photons. The available now experimental data on processes #betta#p → #betta#X, #betta##betta# → jet+jet are in better agreement with the integer-charges than with the standard QCD

  5. Reaction-diffusion processes in zero transverse dimensions as toy models for high-energy QCD

    International Nuclear Information System (INIS)

    Armesto, Nestor; Bondarenko, Sergey; Quiroga-Arias, Paloma; Milhano, Jose Guilherme

    2008-01-01

    We examine numerically different zero-dimensional reaction-diffusion processes as candidate toy models for high-energy QCD evolution. Of the models examined-Reggeon Field Theory, Directed Percolation and Reversible Processes-only the latter shows the behaviour commonly expected, namely an increase of the scattering amplitude with increasing rapidity. Further, we find that increasing recombination terms, quantum loops and the heuristic inclusion of a running of the couplings, generically slow down the evolution.

  6. Hard and soft acids and bases: structure and process.

    Science.gov (United States)

    Reed, James L

    2012-07-05

    Under investigation is the structure and process that gives rise to hard-soft behavior in simple anionic atomic bases. That for simple atomic bases the chemical hardness is expected to be the only extrinsic component of acid-base strength, has been substantiated in the current study. A thermochemically based operational scale of chemical hardness was used to identify the structure within anionic atomic bases that is responsible for chemical hardness. The base's responding electrons have been identified as the structure, and the relaxation that occurs during charge transfer has been identified as the process giving rise to hard-soft behavior. This is in contrast the commonly accepted explanations that attribute hard-soft behavior to varying degrees of electrostatic and covalent contributions to the acid-base interaction. The ability of the atomic ion's responding electrons to cause hard-soft behavior has been assessed by examining the correlation of the estimated relaxation energies of the responding electrons with the operational chemical hardness. It has been demonstrated that the responding electrons are able to give rise to hard-soft behavior in simple anionic bases.

  7. Is It Hard Yet? The Qualitative Agreement of pQCD Energy Loss with RHIC and LHC Data

    International Nuclear Information System (INIS)

    Horowitz, W A

    2013-01-01

    Heavy flavor research is a vigorous and active topic in high-energy QCD physics. Comparing theoretical predictions to data as a function of flavor provides a unique opportunity to tease out properties of quark-gluon plasma. We explicitly demonstrate this utility with energy loss predictions based on the assumption of 1) a weakly-coupled plasma weakly coupled to a high-p T probe using pQCD and 2) a strongly-coupled plasma strongly coupled to a high-p T probe using AdS/CFT; we find that while the former enjoys broad qualitative agreement with data, it is difficult to reconcile the latter with experimental measurements

  8. Search for QCD Instanton-Induced Processes at HERA in the High-$Q^2$ Domain

    CERN Document Server

    Andreev, Vladimir; Begzsuren, Khurelbaatar; Belousov, Anatoli; Bolz, Arthur; Boudry, Vincent; Brandt, Gerhard; Brisson, Violette; Britzger, Daniel; Buniatyan, Armen; Bylinkin, Alexander; Bystritskaya, Lena; Campbell, Alan; Cantun Avila, Karla~Beatriz; Cerny, Karel; Chekelian, Vladimir; Contreras, Guillermo; Cvach, Jaroslav; Dainton, John; Daum, Karin; Diaconu, Cristinel; Dobre, Monica; Dodonov, Vitaliy; Eckerlin, Guenter; Egli, Stephan; Elsen, Eckhard; Favart, Laurent; Fedotov, Alexandre; Feltesse, Joel; Ferencei, Jozef; Fleischer, Manfred; Fomenko, Alexander; Gabathuler, Erwin; Gayler, Joerg; Ghazaryan, Samvel; Goerlich, Lidia; Gogitidze, Nelly; Gouzevitch, Maxime; Grab, Christoph; Grebenyuk, Anastasia; Greenshaw, Timothy; Grindhammer, Guenter; Haidt, Dieter; Henderson, Rob~CW; Hladky, Jan; Hoffmann, Dirk; Horisberger, Roland; Hreus, Tomas; Huber, Florian; Jacquet, Marie; Janssen, Xavier; Jung, Hannes; Kapichine, Mikhail; Katzy, Judith; Kiesling, Christian; Klein, Max; Kleinwort, Claus; Kogler, Roman; Kostka, Peter; Kretzschmar, Jan; Krücker, Dirk; Krüger, K.; Landon, Murrough; Lange, Wolfgang; Laycock, Paul; Lebedev, Andrei; Levonian, Sergey; Lipka, Katerina; List, Benno; List, Jenny; Lobodzinski, Bogdan; Malinovski, Evgenij; Martyn, Hans-Ulrich; Maxfield, Steve~J; Mehta, Andrew; Meyer, Andreas; Meyer, Hinrich; Meyer, Joachim; Mikocki, Stanislav; Morozov, Anatoly; Müller, Katharina; Naumann, Thomas; Newman, Paul~R; Niebuhr, Carsten; Nowak, Grazyna; Olsson, Jan~Erik; Ozerov, Dmitri; Pascaud, Christian; Patel, Girish; Perez, Emmanuelle; Petrukhin, Alexey; Picuric, Ivana; Pirumov, Hayk; Pitzl, Daniel; Placakyte, Ringaile; Pokorny, Boris; Polifka, Richard; Radescu, Voica; Raicevic, Natasa; Ravdandorj, Togoo; Reimer, Petr; Rizvi, Eram; Robmann, Peter; Roosen, Robert; Rostovtsev, Andrei; Rotaru, Marina; Rusakov, Serguei; Salek, David; Sankey, Dave~PC; Sauter, Michel; Sauvan, Emmanuel; Schmitt, Stefan; Schoeffel, Laurent; Schöning, Andre; Sefkow, Felix; Shushkevich, Stanislav; Soloviev, Yuri; Sopicki, Pawel; South, David; Spaskov, Vladimir; Specka, Arnd; Steder, Michael; Stella, Bruno; Straumann, Ulrich; Sykora, Tomas; Thompson, Paul; Traynor, Daniel; Truöl, Peter; Tsakov, Ivan; Tseepeldorj, Baatar; Turnau, Jacek; Valkarova, Alice; Vallee, Claude; Van Mechelen, Pierre; Vazdik, Iakov; Wegener, Dietrich; Wünsch, Eberhard; Zacek, Jozef; Zhang, Zhiqing; Zlebcik, Radek; Zohrabyan, Hamlet; Zomer, Fabian

    2016-07-07

    Signals of QCD instanton-induced processes are searched for in neutral current deep-inelastic scattering at the electron-proton collider HERA in the kinematic region defined by the Bjorken-scaling variable $x > 10^{-3}$, the inelasticity $0.2< y < 0.7$ and the photon virtuality $150 < Q^2 < 15000$ GeV$^2$. The search is performed using H1 data corresponding to an integrated luminosity of ~$351$ pb$^{-1}$. No evidence for the production of QCD instanton-induced events is observed. Upper limits on the cross section for instanton-induced processes between $1.5$~pb and $6$~pb, at $95\\%$~ confidence level, are obtained depending on the kinematic domain in which instantons could be produced. Compared to earlier publications, the limits are improved by an order of magnitude and for the first time are challenging theory predictions.

  9. Search for QCD instanton-induced processes at HERA in the high-Q2 domain

    International Nuclear Information System (INIS)

    Andreev, V.; Baghdasaryan, A.; Begzsuren, K.

    2016-03-01

    Signals of QCD instanton-induced processes are searched for in neutral current deep-inelastic scattering at the electron-proton collider HERA in the kinematic region defined by the Bjorken-scaling variable x>10 -3 , the inelasticity 0.2QCD instanton-induced events is observed. Upper limits on the cross section for instanton-induced processes between 1.5 pb and 6 pb, at 95% confidence level, are obtained depending on the kinematic domain in which instantons could be produced. Compared to earlier publications, the limits are improved by an order of magnitude and for the first time are challenging theory predictions.

  10. Energy- and cost-efficient lattice-QCD computations using graphics processing units

    Energy Technology Data Exchange (ETDEWEB)

    Bach, Matthias

    2014-07-01

    Quarks and gluons are the building blocks of all hadronic matter, like protons and neutrons. Their interaction is described by Quantum Chromodynamics (QCD), a theory under test by large scale experiments like the Large Hadron Collider (LHC) at CERN and in the future at the Facility for Antiproton and Ion Research (FAIR) at GSI. However, perturbative methods can only be applied to QCD for high energies. Studies from first principles are possible via a discretization onto an Euclidean space-time grid. This discretization of QCD is called Lattice QCD (LQCD) and is the only ab-initio option outside of the high-energy regime. LQCD is extremely compute and memory intensive. In particular, it is by definition always bandwidth limited. Thus - despite the complexity of LQCD applications - it led to the development of several specialized compute platforms and influenced the development of others. However, in recent years General-Purpose computation on Graphics Processing Units (GPGPU) came up as a new means for parallel computing. Contrary to machines traditionally used for LQCD, graphics processing units (GPUs) are a massmarket product. This promises advantages in both the pace at which higher-performing hardware becomes available and its price. CL2QCD is an OpenCL based implementation of LQCD using Wilson fermions that was developed within this thesis. It operates on GPUs by all major vendors as well as on central processing units (CPUs). On the AMD Radeon HD 7970 it provides the fastest double-precision D kernel for a single GPU, achieving 120GFLOPS. D - the most compute intensive kernel in LQCD simulations - is commonly used to compare LQCD platforms. This performance is enabled by an in-depth analysis of optimization techniques for bandwidth-limited codes on GPUs. Further, analysis of the communication between GPU and CPU, as well as between multiple GPUs, enables high-performance Krylov space solvers and linear scaling to multiple GPUs within a single system. LQCD

  11. Energy- and cost-efficient lattice-QCD computations using graphics processing units

    International Nuclear Information System (INIS)

    Bach, Matthias

    2014-01-01

    Quarks and gluons are the building blocks of all hadronic matter, like protons and neutrons. Their interaction is described by Quantum Chromodynamics (QCD), a theory under test by large scale experiments like the Large Hadron Collider (LHC) at CERN and in the future at the Facility for Antiproton and Ion Research (FAIR) at GSI. However, perturbative methods can only be applied to QCD for high energies. Studies from first principles are possible via a discretization onto an Euclidean space-time grid. This discretization of QCD is called Lattice QCD (LQCD) and is the only ab-initio option outside of the high-energy regime. LQCD is extremely compute and memory intensive. In particular, it is by definition always bandwidth limited. Thus - despite the complexity of LQCD applications - it led to the development of several specialized compute platforms and influenced the development of others. However, in recent years General-Purpose computation on Graphics Processing Units (GPGPU) came up as a new means for parallel computing. Contrary to machines traditionally used for LQCD, graphics processing units (GPUs) are a massmarket product. This promises advantages in both the pace at which higher-performing hardware becomes available and its price. CL2QCD is an OpenCL based implementation of LQCD using Wilson fermions that was developed within this thesis. It operates on GPUs by all major vendors as well as on central processing units (CPUs). On the AMD Radeon HD 7970 it provides the fastest double-precision D kernel for a single GPU, achieving 120GFLOPS. D - the most compute intensive kernel in LQCD simulations - is commonly used to compare LQCD platforms. This performance is enabled by an in-depth analysis of optimization techniques for bandwidth-limited codes on GPUs. Further, analysis of the communication between GPU and CPU, as well as between multiple GPUs, enables high-performance Krylov space solvers and linear scaling to multiple GPUs within a single system. LQCD

  12. A Short Review of the Theory of Hard Exclusive Processes

    International Nuclear Information System (INIS)

    Wallon, S.

    2012-01-01

    We first present an introduction to the theory of hard exclusive processes. We then illustrate this theory by a few selected examples. The last part is devoted to the most recent developments in the asymptotical energy limit. (author)

  13. A method of analyzing the scaling violation of inclusive spectra in hard processes

    International Nuclear Information System (INIS)

    Furmanski, W.; Petronzio, R.

    1982-01-01

    The analytic solution of the evolution equations in QCD is given in the form of a series of Laguerre polynomials in the variable y = ln(1/x). The Laguerre series converges very quickly and it can be truncated after few terms with a reasonable accuracy. Also high precision calculations are possible since the coefficients of the series are given by simple recurrence formulae. The method works both for non-singlet and for singlet spectra and it can be applied to any hard process. The inclusion of higher order effects is immediate. The Laguerre technique provides a natural framework for extracting from the data the input quark and gluon distributions without any prejudices concerning their particular analytic form. (orig.)

  14. QCD collinear factorization, its extensions and the partonic distributions

    OpenAIRE

    Szymanowski, Lech

    2012-01-01

    I review the basics of the collinear factorization theorem applied primarily to deep inelastic scattering (DIS) involving forward parton distributions (PDFs) and the extensions of this theorem for exclusive processes probing non-forward parton distributions (GPDs), the generalized distribution amplitudes (GDAs) and the transition distribution amplitudes (TDAs). These QCD factorization theorem is an important tool in the description of hard processes in QCD. Whenever valid, it permits to repre...

  15. Inclusive hard processes in photon-photon and photon-proton interactions

    OpenAIRE

    Glasman, Claudia

    1999-01-01

    Measurements of jet, prompt photon, high-pT hadron and heavy quark production in photon-induced processes provide tests of QCD and are sensitive to the photon parton densities. A review of the latest experimental results in photon-photon and photon-proton interactions is presented. Next-to-leading-order QCD calculations for these measurements are discussed.

  16. Dispersion representations for hard exclusive processes. Beyond the born approximation

    International Nuclear Information System (INIS)

    Diehl, M.; Ivanov, D.Yu.

    2007-07-01

    Several hard exclusive scattering processes admit a description in terms of generalized parton distributions and perturbative hard-scattering kernels. Both the physical amplitude and the hard-scattering kernels fulfill dispersion relations. We give a detailed investigation of their consistency at all orders in perturbation theory. The results shed light on the information about generalized parton distributions that can be extracted from the real and imaginary parts of exclusive amplitudes. They also provide a practical consistency check for models of these distributions in which Lorentz invariance is not exactly satisfied. (orig.)

  17. Spin correlations in the Drell–Yan process, parton entanglement, and other unconventional QCD effects

    Energy Technology Data Exchange (ETDEWEB)

    Nachtmann, O., E-mail: O.Nachtmann@thphys.uni-heidelberg.de

    2014-11-15

    We review ideas on the structure of the QCD vacuum which had served as motivation for the discussion of various non-standard QCD effects in high-energy reactions in articles from 1984 to 1995. These effects include, in particular, transverse-momentum and spin correlations in the Drell–Yan process and soft photon production in hadron–hadron collisions. We discuss the relation of the approach introduced in the above-mentioned articles to the approach, developed later, using transverse-momentum-dependent parton distributions (TDMs). The latter approach is a special case of our more general one which allows for parton entanglement in high-energy reactions. We discuss signatures of parton entanglement in the Drell–Yan reaction. Also for Higgs-boson production in pp collisions via gluon–gluon annihilation effects of entanglement of the two gluons are discussed and are found to be potentially important. These effects can be looked for in the current LHC experiments. In our opinion studying parton-entanglement effects in high-energy reactions is, on the one hand, very worthwhile by itself and, on the other hand, it allows to perform quantitative tests of standard factorisation assumptions. Clearly, the experimental observation of parton-entanglement effects in the Drell–Yan reaction and/or in Higgs-boson production would have a great impact on our understanding how QCD works in high-energy collisions.

  18. Space-time description of hard processes

    International Nuclear Information System (INIS)

    Ioffe, B.L.; Khoze, V.A.; Lipatov, L.N.

    1984-01-01

    The authors show that the interaction in deep inelastic scattering processes occurs mainly in a region near the light cone. It is concluded that in all cases studied, the scaling behaviour of the structure functions corresponds to the same light cone singularities of the coordinate functions as in the case of scattering on a free spin-1/2 fermion (or, perhaps, on a spinless boson). (Auth.)

  19. Novel QCD Phenomena at Electron-Proton Colliders

    International Nuclear Information System (INIS)

    Brodsky, S

    2008-01-01

    I discuss several novel phenomenological features of QCD which are observable in deep inelastic lepton-nucleon and lepton-nucleus scattering. Initial- and final-state interactions from gluon exchange, normally neglected in the parton model, have a profound effect on QCD hard-scattering reactions, leading to leading-twist single-spin asymmetries, the diffractive contribution to deep inelastic scattering, and the breakdown of the pQCD Lam-Tung relation in Drell-Yan reactions. Leading-twist diffractive processes in turn lead to nuclear shadowing and non-universal antishadowing--physics not incorporated in the light-front wavefunctions of the nucleus computed in isolation

  20. Exclusive processes: Tests of coherent QCD phenomena and nucleon substructure at CEBAF

    International Nuclear Information System (INIS)

    Brodsky, S.J.

    1994-07-01

    Measurements of exclusive processes such as electroproduction, photoproduction, and Compton scattering are among the most sensitive probes of proton structure and coherent phenomena in quantum chromodynamics. The continuous electron beam at CEBAF, upgraded in laboratory energy to 10--12 GeV, will allow a systematic study of exclusive, semi-inclusive, and inclusive reactions in a kinematic range well-tuned to the study of fundamental nucleon and nuclear substructure. I also discuss the potential at CEBAF for studying novel QCD phenomena at the charm production threshold, including the possible production of nuclear-bound quarkonium

  1. Exclusive two-photon processes: Tests of QCD at the amplitude level

    International Nuclear Information System (INIS)

    Brodsky, S.J.

    1992-07-01

    Exclusive two-photon processes at large momentum transfer, particularly Compton scattering γp→γp and its crossed-channel reactions γγ→ bar pp and bar pp→γγ, can provide definitive information on the bound-state distributions of quarks in hadrons at the amplitude level. Recent theoretical work has shown that QCD predictions based on the factorization of long and short distance physics are already applicable at momentum transfers of order of a few GeV

  2. On Maximal Hard-Core Thinnings of Stationary Particle Processes

    Science.gov (United States)

    Hirsch, Christian; Last, Günter

    2018-02-01

    The present paper studies existence and distributional uniqueness of subclasses of stationary hard-core particle systems arising as thinnings of stationary particle processes. These subclasses are defined by natural maximality criteria. We investigate two specific criteria, one related to the intensity of the hard-core particle process, the other one being a local optimality criterion on the level of realizations. In fact, the criteria are equivalent under suitable moment conditions. We show that stationary hard-core thinnings satisfying such criteria exist and are frequently distributionally unique. More precisely, distributional uniqueness holds in subcritical and barely supercritical regimes of continuum percolation. Additionally, based on the analysis of a specific example, we argue that fluctuations in grain sizes can play an important role for establishing distributional uniqueness at high intensities. Finally, we provide a family of algorithmically constructible approximations whose volume fractions are arbitrarily close to the maximum.

  3. Process for altering the colour of hard stones

    International Nuclear Information System (INIS)

    Samoilovich, M.I.; Shaposhniko, A.A.; Turinge, A.P.; Vakhidov, S.A.; Nurullaev, Ergash.

    1981-01-01

    Process for altering the colour of hard stones and articles made with such stones, used in the jewellery trade, consisting in treating the hard stones in a neutron reactor and gamma particles accompanying them, whereby the treatment is performed with fast neutrons of at least 0.5 MeV, at integral doses of 5x10 15 to 1x10 18 neutrons/cm 2 , and gamma radiations, at integral doses of 5x10 6 to 1x10 9 R, at temperatures under 300 0 C [fr

  4. Quantum field kinetics of QCD quark-gluon transport theory for light-cone dominated processes

    CERN Document Server

    Kinder-Geiger, Klaus

    1996-01-01

    A quantum kinetic formalism is developed to study the dynamical interplay of quantum and statistical-kinetic properties of non-equilibrium multi-parton systems produced in high-energy QCD processes. The approach provides the means to follow the quantum dynamics in both space-time and energy-momentum, starting from an arbitrary initial configuration of high-momentum quarks and gluons. Using a generalized functional integral representation and adopting the `closed-time-path' Green function techniques, a self-consistent set of equations of motions is obtained: a Ginzburg-Landau equation for a possible color background field, and Dyson-Schwinger equations for the 2-point functions of the gluon and quark fields. By exploiting the `two-scale nature' of light-cone dominated QCD processes, i.e. the separation between the quantum scale that specifies the range of short-distance quantum fluctuations, and the kinetic scale that characterizes the range of statistical binary inter- actions, the quantum-field equations of ...

  5. Search for QCD Instanton-Induced Processes in Deep-Inelastic Scattering at HERA

    CERN Document Server

    Adloff, C.; Andrieu, B.; Anthonis, T.; Astvatsatourov, A.; Babaev, A.; Bahr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Becker, J.; Beckingham, M.; Beglarian, A.; Behnke, O.; Beier, C.; Belousov, A.; Berger, C.; Berndt, T.; Bizot, J.C.; Bohme, J.; Boudry, V.; Braunschweig, W.; Brisson, V.; Broker, H.B.; Brown, D.P.; Bruckner, W.; Bruncko, D.; Busser, F.W.; Bunyatyan, A.; Burrage, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Carli, T.; Caron, S.; Cassol-Brunner, F.; Clarke, D.; Collard, C.; Contreras, J.G.; Coppens, Y.R.; Coughlan, J.A.; Cousinou, M.C.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; Davidsson, M.; Delcourt, B.; Delerue, N.; Demirchyan, R.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dingfelder, J.; Dixon, P.; Dodonov, V.; Dowell, J.D.; Droutskoi, A.; Dubak, A.; Duprel, C.; Eckerlin, Guenter; Eckstein, D.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Ferron, S.; Fleischer, M.; Fleischmann, P.; Fleming, Y.H.; Flugge, G.; Fomenko, A.; Foresti, I.; Formanek, J.; Franke, G.; Frising, G.; Gabathuler, E.; Gabathuler, K.; Garvey, J.; Gassner, J.; Gayler, Joerg; Gerhards, R.; Gerlich, C.; Ghazaryan, Samvel; Goerlich, L.; Gogitidze, N.; Grab, C.; Grabski, V.; Grassler, H.; Greenshaw, T.; Grindhammer, Guenter; Hadig, T.; Haidt, D.; Hajduk, L.; Haller, J.; Haynes, W.J.; Heinemann, B.; Heinzelmann, G.; Henderson, R.C.W.; Hengstmann, S.; Henschel, H.; Heremans, R.; Herrera, G.; Herynek, I.; Hildebrandt, M.; Hilgers, M.; Hiller, K.H.; Hladky, J.; Hoting, P.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Hurling, S.; Ibbotson, M.; Issever, C .; Jacquet, M.; Jaffre, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, C.; Johnson, D.P.; Jones, M.A.S.; Jung, H.; Kant, D.; Kapichine, M.; Karlsson, M.; Karschnick, O.; Keil, F.; Keller, N.; Kennedy, J.; Kenyon, I.R.; Kermiche, S.; Kiesling, Christian M.; Kjellberg, P.; Klein, M.; Kleinwort, C.; Kluge, T.; Knies, G.; Koblitz, B.; Kolya, S.D.; Korbel, V.; Kostka, P.; Kotelnikov, S.K.; Koutouev, R.; Koutov, A.; Kroseberg, J.; Kruger, K.; Kuhr, T.; Kurca, T.; Lamb, D.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Laycock, P.; Lebailly, E.; Lebedev, A.; Leissner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; Lindstroem, M.; List, B.; Lobodzinska, E.; Lobodzinski, B.; Loginov, A.; Loktionova, N.; Lubimov, V.; Luders, S.; Luke, D.; Lytkin, L.; Malden, N.; Malinovski, E.; Malinovski, I.; Mangano, S.; Maracek, R.; Marage, P.; Marks, J.; Marshall, R.; Martyn, H.U.; Martyniak, J.; Maxfield, S.J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, J.; Meyer, P.O.; Mikocki, S.; Milstead, D.; Mohrdieck, S.; Mondragon, M.N.; Moreau, F.; Morozov, A.; Morris, J.V.; Muller, K.; Murin, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, T.; Nellen, G.; Newman, Paul R.; Niebergall, F.; Niebuhr, C.; Nix, O.; Nowak, G.; Olsson, J.E.; Ozerov, D.; Panassik, V.; Pascaud, C.; Patel, G.D.; Peez, M.; Perez, E.; Petrukhin, A.; Phillips, J.P.; Pitzl, D.; Poschl, R.; Potachnikova, I.; Povh, B.; Radel, G.; Rauschenberger, J.; Reimer, P.; Reisert, B.; Reyna, D.; Risler, C.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rusakov, S.; Rybicki, K.; Sankey, D.P.C.; Schatzel, S.; Scheins, J.; Schilling, F.P.; Schleper, P.; Schmidt, D.; Schmidt, S.; Schmitt, S.; Schneider, M.; Schoeffel, L.; Schoning, A.; Schorner, T.; Schroder, V.; Schultz-Coulon, H.C.; Schwanenberger, C.; Sedlak, K.; Sefkow, F.; Chekelian, V.; Sheviakov, I.; Shtarkov, L.N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, Arnd E.; Spitzer, H.; Stamen, R.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Swart, M.; Tchetchelnitski, S.; Thompson, Graham; Thompson, P.D.; Tobien, N.; Tomasz, F.; Traynor, D.; Truoel, Peter; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Turney, J.E.; Tzamariudaki, E.; Udluft, S.; Uraev, A.; Urban, Marcel; Usik, A.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vassiliev, S.; Vazdik, Y.; Vest, A.; Vichnevski, A.; Wacker, K.; Wagner, J.; Wallny, R.; Waugh, B.; Weber, G.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; White, G.; Wiesand, S.; Wilksen, T.; Winde, M.; Winter, G.G.; Wissing, C.; Wobisch, M.; Woehrling, E.E.; Wunsch, E.; Wyatt, A.C.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zomer, F.; zur Nedden, M.

    2002-01-01

    Signals of QCD instanton-induced processes are searched for in deep-inelastic scattering (DIS) at the electron-proton collider HERA in a kinematic region defined by the Bjorken-scaling variables x > 10^(-3), 0.1 < y < 0.6 and photon virtualities 10 <= Q^2 < 100GeV^2. Several observables characterising hadronic final state properties of QCD instanton-induced events are exploited to identify a potentially instanton-enriched domain. While an excess of events with instanton-like topology over the expectation of the standard DIS background is observed it can not be claimed to be significant given the uncertainty of the simulation. Upper limits on the cross-section for instanton-induced processes of between 60pb and 1000pb are set dependent on the kinematic domain considered. The data do not exclude the cross-section predicted by instanton perturbation theory for small instanton sizes. At large instanton sizes a naive extrapolation of instanton perturbation theory yields a cross-section in the range of ...

  6. CO II laser free-form processing of hard tissue

    Science.gov (United States)

    Werner, Martin; Klasing, Manfred; Ivanenko, Mikhail; Harbecke, Daniela; Steigerwald, Hendrik; Hering, Peter

    2007-07-01

    Drilling and surface processing of bone and tooth tissue belongs to standard medical procedures (bores and embeddings for implants, trepanation etc.). Small circular bores can be generally quickly produced with mechanical drills. However problems arise at angled drilling, the need to execute drilling procedures without damaging of sensitive soft tissue structures underneath the bone or the attempt to mill small non-circular cavities in hard tissue with high precision. We present investigations on laser hard tissue "milling", which can be advantageous for solving these problems. The processing of bone is done with a CO II laser (10.6 μm) with pulse durations of 50 - 100 μs, combined with a PC-controlled fast galvanic laser beam scanner and a fine water-spray, which helps keeping the ablation process effective and without thermal side-effects. Laser "milling" of non-circular cavities with 1 - 4 mm width and about 10 mm depth can be especially interesting for dental implantology. In ex-vivo investigations we found conditions for fast laser processing of these cavities without thermal damage and with minimised tapering. It included the exploration of different filling patterns (concentric rings, crosshatch, parallel lines, etc.), definition of maximal pulse duration, repetition rate and laser power, and optimal water spray position. The optimised results give evidence for the applicability of pulsed CO II lasers for biologically tolerable effective processing of deep cavities in hard tissue.

  7. Novel QCD Phenomenology

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins

    2011-08-12

    I review a number of topics where conventional wisdom in hadron physics has been challenged. For example, hadrons can be produced at large transverse momentum directly within a hard higher-twist QCD subprocess, rather than from jet fragmentation. Such 'direct' processes can explain the deviations from perturbative QCD predictions in measurements of inclusive hadron cross sections at fixed x{sub T} = 2p{sub T}/{radical}s, as well as the 'baryon anomaly', the anomalously large proton-to-pion ratio seen in high centrality heavy ion collisions. Initial-state and final-state interactions of the struck quark, the soft-gluon rescattering associated with its Wilson line, lead to Bjorken-scaling single-spin asymmetries, diffractive deep inelastic scattering, the breakdown of the Lam-Tung relation in Drell-Yan reactions, as well as nuclear shadowing and antishadowing. The Gribov-Glauber theory predicts that antishadowing of nuclear structure functions is not universal, but instead depends on the flavor quantum numbers of each quark and antiquark, thus explaining the anomalous nuclear dependence measured in deep-inelastic neutrino scattering. Since shadowing and antishadowing arise from the physics of leading-twist diffractive deep inelastic scattering, one cannot attribute such phenomena to the structure of the nucleus itself. It is thus important to distinguish 'static' structure functions, the probability distributions computed from the square of the target light-front wavefunctions, versus 'dynamical' structure functions which include the effects of the final-state rescattering of the struck quark. The importance of the J = 0 photon-quark QCD contact interaction in deeply virtual Compton scattering is also emphasized. The scheme-independent BLM method for setting the renormalization scale is discussed. Eliminating the renormalization scale ambiguity greatly improves the precision of QCD predictions and increases the sensitivity of

  8. Fully NLO Parton Shower in QCD

    International Nuclear Information System (INIS)

    Skrzypek, M.; Jadach, S.; Slawinska, M.; Gituliar, O.; Kusina, A.; Placzek, W.

    2011-01-01

    The project of constructing a complete NLO-level Parton Shower Monte Carlo for the QCD processes developed in IFJ PAN in Krakow is reviewed. Four issues are discussed: (1) the extension of the standard inclusive collinear factorization into a new, fully exclusive scheme; (2) reconstruction of the LO Parton Shower in the new scheme; (3) inclusion of the exclusive NLO corrections into the hard process and (4) inclusion of the exclusive NLO corrections into the evolution (ladder) part. (authors)

  9. One-loop QCD and Higgs bosons to partons processes using six-dimensional helicity and generalized unitarity

    International Nuclear Information System (INIS)

    Davies, Scott

    2011-01-01

    We combine the six-dimensional helicity formalism of Cheung and O'Connell with D-dimensional generalized unitarity to obtain a new formalism for computing one-loop amplitudes in dimensionally regularized QCD. With this procedure, we simultaneously obtain the pieces that are constructible from four-dimensional unitarity cuts and the rational pieces that are missed by them, while retaining a helicity formalism. We illustrate the procedure using four- and five-point one-loop amplitudes in QCD, including examples with external fermions. We also demonstrate the technique's effectiveness in next-to-leading order QCD corrections to Higgs processes by computing the next-to-leading order correction to the Higgs plus three positive-helicity gluons amplitude in the large top-quark mass limit.

  10. Quantum field kinetics of QCD: Quark-gluon transport theory for light-cone-dominated processes

    International Nuclear Information System (INIS)

    Geiger, K.

    1996-01-01

    A quantum-kinetic formalism is developed to study the dynamical interplay of quantum and statistical-kinetic properties of nonequilibrium multiparton systems produced in high-energy QCD processes. The approach provides the means to follow the quantum dynamics in both space-time and energy-momentum, starting from an arbitrary initial configuration of high-momentum quarks and gluons. Using a generalized functional integral representation and adopting the open-quote open-quote closed-time-path close-quote close-quote Green function techniques, a self-consistent set of equations of motions is obtained: a Ginzburg-Landau equation for a possible color background field, and Dyson-Schwinger equations for the two-point functions of the gluon and quark fields. By exploiting the open-quote open-quote two-scale nature close-quote close-quote of light-cone-dominated QCD processes, i.e., the separation between the quantum scale that specifies the range of short-distance quantum fluctuations, and the kinetic scale that characterizes the range of statistical binary interactions, the quantum field equations of motion are converted into a corresponding set of open-quote open-quote renormalization equations close-quote close-quote and open-quote open-quote transport equations.close-quote close-quote The former describe renormalization and dissipation effects through the evolution of the spectral density of individual, dressed partons, whereas the latter determine the statistical occurrence of scattering processes among these dressed partons. The renormalization equations and the transport equations are coupled, and, hence, must be solved self-consistently. This amounts to evolving the multiparton system, from a specified initial configuration, in time and full seven-dimensional phase space, constrained by the Heisenberg uncertainty principle. (Abstract Truncated)

  11. Recent QCD results from ATLAS

    CERN Document Server

    Meyer, C; The ATLAS collaboration

    2014-01-01

    The ATLAS collaboration has performed studies of a wide range of QCD phenomena, from soft particle to hard photon and jet production. Recent soft-QCD measurements include studies of underlying event and vector meson production. Differential measurements of inclusive and dijet production provide stringent tests of high-order QCD predictions and provide input for determination of parton density functions. Measurements of isolated inclusive and di-photons cross sections for high transverse momentum photons test theoretical predictions of perturbative QCD and constrain parton density functions. An overview of these results is given.

  12. Eco-efficient and high performance hard chrome process

    Energy Technology Data Exchange (ETDEWEB)

    Negre, P. [Protection des Metaux, Montreuil (France)

    2001-07-01

    Clean manufacturing processes that can minimize effects on the environment are discussed using electrolytic hard chromium-plating as an example. The goal of the research proposal described in this paper is to develop processes from a new and non-toxic electrolytic solution that would allow for harder, thick coatings of chromium that is more resistant to corrosion than traditional coatings and without the carcinogenic effects of hexavalent chromium. The process, as envisaged, will combine the advantages of chromium plating processes based on non-toxic compounds already available, the result primarily of the chemical formulation of the solutions for chromium plating on which the microstructure and the capacity of the structural hardening of the coatings depend. The paper provides an overview of the project, estimates person year and time requirements (225 person-years and 3.5 years) and provides a list of participating partners.

  13. QCD Dual

    DEFF Research Database (Denmark)

    Sannino, Francesco

    2009-01-01

    We uncover a novel solution of the 't Hooft anomaly matching conditions for QCD. Interestingly in the perturbative regime the new gauge theory, if interpreted as a possible QCD dual, predicts the critical number of flavors above which QCD in the nonperturbative regime, develops an infrared stable...

  14. CP violation induced by the double resonance for pure annihilation decay process in perturbative QCD

    Energy Technology Data Exchange (ETDEWEB)

    Lue, Gang; Li, Sheng-Tao; Wang, Yu-Ting [Henan University of Technology, College of Science, Zhengzhou (China); Lu, Ye [Guangxi Normal University, Department of Physics, Guilin (China)

    2017-08-15

    In a perturbative QCD approach we study the direct CP violation in the pure annihilation decay process of anti B{sup 0}{sub s} → π{sup +}π{sup -}π{sup +}π{sup -} induced by the ρ and ω double resonance effect. Generally, the CP violation is small in the pure annihilation type decay process. However, we find that the CP violation can be enhanced by double ρ-ω interference when the invariant masses of the π{sup +}π{sup -} pairs are in the vicinity of the ω resonance. For the decay process of anti B{sup 0}{sub s} → π{sup +}π{sup -}π{sup +}π{sup -}, the CP violation can reach A{sub CP}(anti B{sup 0}{sub s} → π{sup +}π{sup -}π{sup +}π{sup -}) = 27.20{sup +0.05+0.28+7.13}{sub -0.15-0.31-6.11}%. (orig.)

  15. Experimental tests of QCD

    International Nuclear Information System (INIS)

    Hansl-Kozanecka, T.

    1992-01-01

    The phenomenological aspects of Quantum Chromodynamics (QCD) are examined which are relevant for lepton-hadron, electron-positron and hadron-hadron collisions. In deep inelastic scattering the virtual γ or W/Z is used as a probe of the nucleon structure. The strong coupling constant (α s ) measurements via deep inelastic scattering and e + e - annihilation are discussed. Parton-parton collisions (e.g., hard hadron-hadron collisions) are examined as the third regime for QCD tests. (K.A.) 122 refs., 84 figs., 4 tabs

  16. Apparatus and process for deposition of hard carbon films

    Science.gov (United States)

    Nyaiesh, Ali R.; Garwin, Edward L.

    1989-01-03

    A process and an apparatus for depositing thin, amorphous carbon films having extreme hardness on a substrate is described. An enclosed chamber maintained at less than atmospheric pressure houses the substrate and plasma producing elements. A first electrode is comprised of a cavity enclosed within an RF coil which excites the plasma. A substrate located on a second electrode is excited by radio frequency power applied to the substrate. A magnetic field confines the plasma produced by the first electrode to the area away from the walls of the chamber and focuses the plasma onto the substrate thereby yielding film deposits having higher purity and having more rapid buildup than other methods of the prior art.

  17. Hard scattering in γp interactions

    International Nuclear Information System (INIS)

    Ahmed, T.; Andreev, V.; Andrieu, B.

    1992-10-01

    We report on the investigation of the final state in interactions of quasi-real photons with protons. The data were taken with the H1 detector at the HERA ep collider. Evidence for hard interactions is seen in both single particle spectra and jet formation. The data can best be described by inclusion of resolved photon processes as predicted by QCD. (orig.)

  18. Multiplicity and Underlying Event in ALICE: as measurements and as tools to probe QCD arXiv

    CERN Document Server

    INSPIRE-00361691

    With the high collision energies at the LHC, the contributions to particle production from hard-QCD processes increase, but it remains dominated by soft-QCD processes. Such processes challenge the theoretical models, since they are described by non-perturbative phenomenology. A selection of the most recent ALICE measurements of charged-particle multiplicities and the Underlying Event will be presented, focusing on model comparisons. A summary of the current understanding of soft-QCD processes will be discussed, evaluating possible ways to further constrain theory.

  19. Light-cone quantization and QCD phenomenology

    International Nuclear Information System (INIS)

    Brodsky, S.J.; Robertson, D.G.

    1995-01-01

    In principle, quantum chromodynamics provides a fundamental description of hadronic and nuclear structure and dynamics in terms of their elementary quark and gluon degrees of freedom. In practice, the direct application of QCD to reactions involving the structure of hadrons is extremely complex because of the interplay of nonperturbative effects such as color confinement and multi-quark coherence. A crucial tool in analyzing such phenomena is the use of relativistic light-cone quantum mechanics and Fock state methods to provide tractable and consistent treatments of relativistic many-body systems. In this article we present an overview of this formalism applied to QCD, focusing in particular on applications to the final states in deep inelastic lepton scattering that will be relevant for the proposed European Laboratory for Electrons (ELFE), HERMES, HERA, SLAC, and CEBAF. We begin with a brief introduction to light-cone field theory, stressing how it many allow the derivation of a constituent picture, analogous to the constituent quark model, from QCD. We then discuss several applications of the light-cone Fock state formalism to QCD phenomenology. The Fock state representation includes all quantum fluctuations of the hadron wavefunction, including far off-shell configurations such as intrinsic charm and, in the case of nuclei, hidden color. In some applications, such as exclusive processes at large momentum transfer, one can make first-principle predictions using factorization theorems which separate the hard perturbative dynamics from the nonpertubative physics associated with hadron binding. The Fock state components of the hadron with small transverse size, which dominate hard exclusive reactions, have small color dipole moments and thus diminished hadronic interactions. Thus QCD predicts minimal absorptive corrections, i.e., color transparency for quasi-elastic exclusive reactions in nuclear targets at large momentum transfer

  20. Components of QCD

    International Nuclear Information System (INIS)

    Sivers, D.

    1979-10-01

    Some aspects of a simple strategy for testing the validity of QCD perturbation theory are examined. The importance of explicit evaluation of higher-order contributions is illustrated by considering Z 0 decays. The recent progress toward understanding exclusive processes in QCD is discussed and some simple examples are given of how to isolate and test the separate components of the perturbation expansion in a hypothetical series of jet experiments

  1. Conformal Symmetry as a Template for QCD

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S

    2004-08-04

    Conformal symmetry is broken in physical QCD; nevertheless, one can use conformal symmetry as a template, systematically correcting for its nonzero {beta} function as well as higher-twist effects. For example, commensurate scale relations which relate QCD observables to each other, such as the generalized Crewther relation, have no renormalization scale or scheme ambiguity and retain a convergent perturbative structure which reflects the underlying conformal symmetry of the classical theory. The ''conformal correspondence principle'' also dictates the form of the expansion basis for hadronic distribution amplitudes. The AdS/CFT correspondence connecting superstring theory to superconformal gauge theory has important implications for hadron phenomenology in the conformal limit, including an all-orders demonstration of counting rules for hard exclusive processes as well as determining essential aspects of hadronic light-front wavefunctions. Theoretical and phenomenological evidence is now accumulating that QCD couplings based on physical observables such as {tau} decay become constant at small virtuality; i.e., effective charges develop an infrared fixed point in contradiction to the usual assumption of singular growth in the infrared. The near-constant behavior of effective couplings also suggests that QCD can be approximated as a conformal theory even at relatively small momentum transfer. The importance of using an analytic effective charge such as the pinch scheme for unifying the electroweak and strong couplings and forces is also emphasized.

  2. Conformal Symmetry as a Template for QCD

    International Nuclear Information System (INIS)

    Brodsky, S

    2004-01-01

    Conformal symmetry is broken in physical QCD; nevertheless, one can use conformal symmetry as a template, systematically correcting for its nonzero β function as well as higher-twist effects. For example, commensurate scale relations which relate QCD observables to each other, such as the generalized Crewther relation, have no renormalization scale or scheme ambiguity and retain a convergent perturbative structure which reflects the underlying conformal symmetry of the classical theory. The ''conformal correspondence principle'' also dictates the form of the expansion basis for hadronic distribution amplitudes. The AdS/CFT correspondence connecting superstring theory to superconformal gauge theory has important implications for hadron phenomenology in the conformal limit, including an all-orders demonstration of counting rules for hard exclusive processes as well as determining essential aspects of hadronic light-front wavefunctions. Theoretical and phenomenological evidence is now accumulating that QCD couplings based on physical observables such as τ decay become constant at small virtuality; i.e., effective charges develop an infrared fixed point in contradiction to the usual assumption of singular growth in the infrared. The near-constant behavior of effective couplings also suggests that QCD can be approximated as a conformal theory even at relatively small momentum transfer. The importance of using an analytic effective charge such as the pinch scheme for unifying the electroweak and strong couplings and forces is also emphasized

  3. Future directions for QCD

    International Nuclear Information System (INIS)

    Bjorken, J.D.

    1996-10-01

    New directions for exploring QCD at future high-energy colliders are sketched. These include jets within jets. BFKL dynamics, soft and hard diffraction, searches for disoriented chiral condensate, and doing a better job on minimum bias physics. The new experimental opportunities include electron-ion collisions at HERA, a new collider detector at the C0 region of the TeVatron, and the FELIX initiative at the LHC

  4. Hard Coat Layers by PE-CVD Process for the Top Surface of Touch Panel

    International Nuclear Information System (INIS)

    Okunishi, T; Sato, N; Yazawa, K

    2013-01-01

    In order to protect surface from damages, the high pencil hardness and the high abrasion resistance are required for the hard coat layers on polyethylene telephthalate (PET) films for the application of touch panel surface. We have already found that the UV-curing-hard-coat-polymer (UHP) coated PET films show the poor abrasion resistance, while they have the high pencil hardness. It reveals that the abrasion resistance of hard coat layers of the UHP is not simply dependent on the pencil hardness. In this work, we have studied to improve the abrasion resistance of SiOC films as hard coat layers, which were formed by PE-CVD process on UHP coated PET. The abrasion resistance was evaluated by Taber abrasion test. PE-CVD hard coat layers which formed on UHP coater PET films have showed the better abrasion resistance and have the possibility of substitution to the thin glass sheets for touch panel application.

  5. Mean associative multiplicities in deep inelastic processes

    International Nuclear Information System (INIS)

    Dzhaparidze, G.Sh.; Kiselev, A.V.; Petrov, V.A.

    1981-01-01

    The associative hadron multiplicities in deep inelastic and Drell--Yan processes are studied. In particular the mean multiplicities in different hard processes in QCD are found to be determined by the mean multiplicity in parton jet [ru

  6. Transport at ''NLO'' in hot QCD

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    The study of QCD kinetics is driven by a vast array of the experimental measurements of transport at the LHC, ranging from heavy quark energy loss, jet suppression, and hydrodynamics. I first review the fundamental elements of QCD kinetic theory, i.e. plasma screening, 2to2 scattering, and medium modified collinear bremsstrahlung. Then I will summarize recent progress in calculating these elements and their interplay at "NLO" -- "NLO" refers to an order $\\sqrt{\\alpha_s}$ correction to the plasma processes arising from the statistical fluctuations of soft gluons. These "NLO" calculations suggest a computational strategy where the influence of the Debye sector on the real time dynamics of the hard lightlike modes can be incorporated into a few medium coefficients (such as the drag coefficient and $\\hat{q}$), which can be simulated with a Euclidean 3D dimensionally reduced theory.

  7. Stochastic processes and the non-perturbative structure of the QCD vacuum

    International Nuclear Information System (INIS)

    Vilela Mendes, R.

    1992-01-01

    Based on a local Gaussian evaluation of the functional integral representation, a method is developed to obtain ground state functionals. The method is applied to the gluon sector of QCD. For the leading term in the ground state functional, stochastic techniques are used to check consistency of the quantum theory, finiteness of the mass gap and the scaling relation in the continuum limit. The functional also implies strong chromomagnetic fluctuations which constrain the propagators in the fermion sector. (orig.)

  8. Hard Diffraction - from Blois 1985 to 2005

    Energy Technology Data Exchange (ETDEWEB)

    Gunnar, Ingelman [Uppsala Univ., High Energy Physics (Sweden)

    2005-07-01

    The idea of diffractive processes with a hard scale involved, to resolve the underlying parton dynamics, was presented at the first Blois conference in 1985 and experimentally verified a few years later. Today hard diffraction is an attractive research field with high-quality data and new theoretical models. The trend from Regge-based pomeron models to QCD-based parton level models has given insights on QCD dynamics involving perturbative gluon exchange mechanisms. In the new QCD-based models, the pomeron is not part of the proton wave function, but diffraction is an effect of the scattering process. Models based on interactions with a colour background field provide an interesting approach which avoids conceptual problems of pomeron-based models, such as the pomeron flux, and provide a basis for common theoretical framework for all final states, diffractive gap events as well as non-diffractive events. Finally, the new process of gaps between jets provides strong evidence for the BFKL dynamics as predicted since long by QCD, but so far hard to establish experimentally.

  9. Form factors and QCD in spacelike and timelike region

    International Nuclear Information System (INIS)

    A.P. Bakulev; A.V. Radyushkin; N.G. Stefanis

    2000-01-01

    The authors analyze the basic hard exclusive processes: πγ * γ-transition, pion and nucleon electromagnetic form factors, and discuss the analytic continuation of QCD formulas from the spacelike q 2 2 > 0 of the relevant momentum transfers. They describe the construction of the timelike version of the coupling constant α s . They show that due to the analytic continuation of the collinear logarithms each eigenfunction of the evolution equation acquires a phase factor and investigate the resulting interference effects which are shown to be very small. They found no sources for the K-factor-type enhancements in the perturbative QCD contribution to the hadronic form factors. To study the soft part of the pion electromagnetic form factor, they use a QCD sum rule inspired model and show that there are non-canceling Sudakov double logarithms which result in a K-factor-type enhancement in the timelike region

  10. Form factors and QCD in spacelike and timelike regions

    International Nuclear Information System (INIS)

    Bakulev, A. P.; Radyushkin, A. V.; Stefanis, N. G.

    2000-01-01

    We analyze the basic hard exclusive processes, the πγ * γ-transition and the pion and nucleon electromagnetic form factors, and discuss the analytic continuation of QCD formulas from the spacelike q 2 2 >0 of the relevant momentum transfers. We describe the construction of the timelike version of the coupling constant α s . We show that due to the analytic continuation of the collinear logarithms, each eigenfunction of the evolution equation acquires a phase factor and investigate the resulting interference effects which are shown to be very small. We find no sources for the K-factor-type enhancements in the perturbative QCD contribution to the hadronic form factors. To study the soft part of the pion electromagnetic form factor, we use a QCD sum rule inspired model and show that there are noncanceling Sudakov double logarithms which result in a K-factor-type enhancement in the timelike region

  11. Experimental application of QCD antennas

    International Nuclear Information System (INIS)

    Bobrovskyi, Sergei

    2010-02-01

    A serious problem in searches for new physics at the LHC is the rejection of QCD induced multijet events. In this thesis the formalism of QCD antenna variables based on the SPHEL approximation of QCD matrix elements is applied for the rst time on experimentally reconstructed jets in order to discriminate QCD from supersymmetric processes. The new observables provide additional information with respect to traditional event shape variables. Albeit correlated with experimentally measured missing transverse energy, the variables can be used to improve the signal to background ratio. (orig.)

  12. Experimental application of QCD antennas

    Energy Technology Data Exchange (ETDEWEB)

    Bobrovskyi, Sergei

    2010-02-15

    A serious problem in searches for new physics at the LHC is the rejection of QCD induced multijet events. In this thesis the formalism of QCD antenna variables based on the SPHEL approximation of QCD matrix elements is applied for the rst time on experimentally reconstructed jets in order to discriminate QCD from supersymmetric processes. The new observables provide additional information with respect to traditional event shape variables. Albeit correlated with experimentally measured missing transverse energy, the variables can be used to improve the signal to background ratio. (orig.)

  13. Threshold resummation and higher order effects in QCD

    International Nuclear Information System (INIS)

    Ringer, Felix Maximilian

    2015-01-01

    Quantum chromodynamics (QCD) is a quantum field theory that describes the strong interactions between quarks and gluons, the building blocks of all hadrons. Thanks to the experimental progress over the past decades, there has been an ever-growing need for QCD precision calculations for scattering processes involving hadrons. For processes at large momentum transfer, perturbative QCD offers a systematic approach for obtaining precise predictions. This approach relies on two key concepts: the asymptotic freedom of QCD and factorization. In a perturbative calculation at higher orders, the infrared cancellation between virtual and real emission diagrams generally leaves behind logarithmic contributions. In many observables relevant for hadronic scattering these logarithms are associated with a kinematic threshold and are hence known as ''threshold logarithms''. They become large when the available phase space for real gluon emission shrinks. In order to obtain a reliable prediction from QCD, the threshold logarithms need to be taken into account to all orders in the strong coupling constant, a procedure known as ''threshold resummation''. The main focus of my PhD thesis is on studies of QCD threshold resummation effects beyond the next-to-leading logarithmic order. Here we primarily consider the production of hadron pairs in hadronic collisions as an example. In addition, we also consider hadronic jet production, which is particularly interesting for the phenomenology at the LHC. For both processes, we fully take into account the non-trivial QCD color structure of the underlying partonic hard- scattering cross sections. We find that threshold resummation leads to sizable numerical effects in the kinematic regimes relevant for comparisons to experimental data.

  14. QCD corrections for two jet production in photon-photon collisions

    International Nuclear Information System (INIS)

    Gastmans, R.; Berends, F.A.; Kunszt, Z.

    1980-09-01

    We present the calculation of the first order QCD corrections to the process γγ → q anti q, including virtual gluons and bremsstrahlung of soft and hard collinear gluons. The obtained cross section is then used to calculate the αsub(s) corrections to the process e + e - → e + e - + 2 jets. The numerical importance of hard acollinear gluons is also discussed. (orig.)

  15. Lattice QCD

    International Nuclear Information System (INIS)

    Hasenfratz, P.

    1983-01-01

    The author presents a general introduction to lattice gauge theories and discusses non-perturbative methods in the gauge sector. He then shows how the lattice works in obtaining the string tension in SU(2). Lattice QCD at finite physical temperature is discussed. Universality tests in SU(2) lattice QCD are presented. SU(3) pure gauge theory is briefly dealt with. Finally, fermions on the lattice are considered. (Auth.)

  16. Opportunities, Challenges, and Fantasies in Lattice QCD

    OpenAIRE

    Wilczek, Frank

    2002-01-01

    Some important problems in quantitative QCD will certainly yield to hard work and adequate investment of resources, others appear difficult but may be accessible, and still others will require essentially new ideas. Here I identify several examples in each class.

  17. Processed Apple Product Marketing Analysis: Hard Cider and Apple Wine

    OpenAIRE

    Rowles, Kristin

    2000-01-01

    Hard cider and apple wine offer new value-added marketing opportunities to the apple industry. Both products are situated in rapidly growing categories of the beverage industry. The development of effective marketing strategies for these products requires an understanding of the forces driving competition in these markets. This paper provides background information to support competitive analysis and strategy development. Development of these markets will be positive for the apple industry, b...

  18. Electron dosimetry in irradiation processing with rad-hard diodes

    International Nuclear Information System (INIS)

    Santos, Thais Cavalheri dos

    2012-01-01

    This work had the aim of the development of dosimetric systems based on Si special diodes, resistant to radiation damage to online monitoring of irradiation processing using 1.5 MeV electrons energy and for relative dosimetry and clinical electron beam scanning within an energy range of 6 MeV up to 21 MeV. The diodes used were produced by Float Zone standard (FZ), Magnetic Czochralski (MCz) and epitaxy growth (EPI) methods. In order to use the diodes as detectors, they were fixed on alumina base to allow the connection of the polarization electrodes and the signals extraction. After the diode assembly on the base, each one was housed in a black acrylic probe with aluminized Mylar® window and LEMO® connector. With the devices operating in photovoltaic mode, the integration of the current signals as a function of irradiation time allowed obtain the charge produced in the sensitive volume of each diode irradiated. The electron accelerator used for high doses irradiation was the DC 1500/25/4 JOB 188 of the 1.5 MeV installed at the Radiation Technology Center of the IPEN/CNEN-SP. The current profile as function of exposure time, the response repeatability, the sensitivity as function of absorbed dose and the dose response curve were studied for each device. In comparison to FZ diode, we observed a greater decrease in the sensitivity for MCz diode, and good repeatability in both cases. Also, the increasing of the charge with the absorbed dose was well fitted by a second order polynomial function. In the EPI diode characterization, this one exhibited repeatability better than CTA dosimeters applied routinely in radiation processing. The above results indicate the potential use of these radiation hardness Si diodes in online dosimetry to high doses applications. For low doses irradiation were used the linear accelerators KD2 and Primus, both manufactured by Siemens and located at Sirio-Libanes Hospital. The diodes responses were evaluated for electron beams within the

  19. Higher-twist effects in QCD, deep inelastic scattering, and the Drell-Yan process

    International Nuclear Information System (INIS)

    Berger, E.L.; Stanford Univ., CA

    1980-01-01

    Inclusion of specific effects associated with constituent binding in hadronic wave functions is shown to lead to important non-scaling, non-factorizing 1/Q 2 contributions to cross sections for semi-inclusive deep-inelastic scattering, the Drell-Yan process, and other hard scattering reactions. These 1/Q 2 higher-twist terms are predicted to be dominant in well defined kinematic regions such as large x and/or large z. The provide angular distributions typical of longitudinally polarized virtual photons and W's, including sin 2 theta terms in meson induced Drell-Yan processes and in e + e - → πX, as well as unusual (1-γ) terms in deep-inelastic scattering. Calculations are also presented of the quark structure functions of the pion qsub(π)(x,Q 2 ) and for the quark to pion fragmentation function Dsub(π)(z,Q 2 ). Predictions are made for the azimuthal angle dependence of the cross sections for πN → μ anti μX and IN → l'πX. (orig.)

  20. Higher twist effects in QCD description of light meson exclusive formfactors

    International Nuclear Information System (INIS)

    Gorskij, A.S.

    1987-01-01

    The general approach to a quantitative description of higher twist effects in hard exclusive processes in QCD is proposed. The consistent calculations in coordinate space and the choice of special gauges for quantum and classical gluon fields are essential ingradients of this method. The self consistent system of twist three wave functions for π-meson has been built

  1. 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

  2. Materials and Manufacturing Processing; Special Issue on Hard Carbon Films

    Science.gov (United States)

    1993-01-01

    AZ 85721 G. SMOLIK, P.O. Box 1625, Idaho National Engineering Laboratory, Idaho Falls, ID 83415 J.B. TERRELL, Reynolds Metals Company, P.O. Box 27003 ...18%Si alloy using inserts of ISO SPGN120308 and HEHN532FN. The damage to diamond films after cutting was examined by SEM and micro-laser Raman...uncoated cemented carbide insert corresponding to ISO K10 grade and sintered diamond insert were also used. Milling a hard carbon under dry condition The

  3. Target costing as an element of the hard coal extraction cost planning process

    Directory of Open Access Journals (Sweden)

    Katarzyna Segeth-Boniecka

    2017-09-01

    Full Text Available Target costing as an element of the hard coal extraction cost planning process Striving for the efficiency of activities is of great significance in the management of hard coal extractive enterprises, which are constantly subjected to the process of restructuring. Effective cost management is an important condition of the increase in the efficiency of the researched business entities’ activity. One of the tools whose basic objective is conscious influencing cost levels is target costing. The aim of this article is to analyse the conditions of implementing target costing in the planning of hard coal extraction costs in hard coal mines in Poland. The subject area raises a topical and important problem of the scope of solutions concerning cost analysis in hard coal mines in Poland, which has not been thoroughly researched yet. To achieve the abovementioned aim, the theoretical works of the subject area have been referenced. The mine management process is difficult and requires the application of best suited and most modern tools, including those used in the planning process of hard coal extraction costs in order to support the economic efficiency of mining operations. The use of the target costing concept in the planning of hard coal mine operations aims to support the decision-making process, so as to achieve a specified level of economic efficiency of the operations carried out in a territorially designated site of hard coal extraction.

  4. Study of hard processes in the ALICE experiment

    CERN Document Server

    Vajzer, Michal; Bielcikova, Jana

    2015-01-01

    Jets are collimated sprays of particles resulting from fragmentation of associated hard scattered partons. They are measured in different types of collisions at different energies to test perturbative quantum chromodynamic calculations and are used to study the hard scattering, fragmentation, hadronisation and other properties of partons. These properties studied in simple systems such as proton-proton collisions, serve as a baseline to investigate their modifications by hot and dense nuclear matter created in high energy heavy-ion collisions. This thesis presents analysis of data from minimum bias proton-proton collisions at centre of mass energy of 2.76 and 7 TeV collected using the ALICE detector system at the LHC is presented with jet transverse momenta in range from 20 GeV/c to 100 GeV/c. Reconstruction of the inclusive jet cross-section from charged tracks at midrapidity is done using standard modern anti-k$_T$ and k$_T$ algorithms with underlying event subtraction and correction for detector effects vi...

  5. QCD Structure of Nuclear Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Granados, Carlos [Florida Intl Univ., Miami, FL (United States)

    2011-05-25

    This dissertation investigated selected processes involving baryons and nuclei in hard scattering reactions. Through these processes, this work explored the constituent structure of baryons and the mechanisms through which the interactions between these constituents ultimately control the selected reactions. First, hard nucleon-nucleon elastic scattering was studied considering the quark exchange (QE) between the nucleons to be the dominant mechanism of interaction in the constituent picture. It was found that an angular asymmetry exhibited by proton-neutron (pn) elastic scattering data is explained within this framework if a quark-diquark picture dominates the nucleon's structure instead of a more traditional SU(6) model. The latter yields an asymmetry around 90 deg center of mass scattering with a sign opposite to what is experimentally observed. The second process is the hard breakup by a photon of a nucleon-nucleon system in light nuclei. Proton-proton (pp) and pn breakup in 3He, and double Δ-isobars production in deuteron breakup were analyzed in the hard rescattering model (HRM), which in conjunction with the QE mechanism provides a QCD description of the reaction. Cross sections for both channels in 3He photodisintegration were computed without the need of a fitting parameter. The results presented here for pp breakup show excellent agreement with recent experimental data. In double Δ-isobars production in deuteron breakup, HRM angular distributions for the two double Δ channels were compared to the pn channel and to each other. An important prediction from this study is that the Δ++ Δ- channel consistently dominates Δ+Δ0, which is in contrast with models that unlike the HRM consider a double Δ system in the initial state of the interaction. For such models both channels should have the same strength.

  6. EFFECT OF ENDOSPERM HARDNESS ON AN ETHANOL PROCESS USING A GRANULAR STARCH HYDROLYZING ENZYME

    Energy Technology Data Exchange (ETDEWEB)

    Wang, P; W Liu, D B; Johnston, K D; Rausch, S J; Schmidt, M E; Tumbleson, V Singh

    2010-01-01

    Granular starch hydrolyzing enzymes (GSHE) can hydrolyze starch at low temperature (32°C). The dry grind process using GSHE (GSH process) has fewer unit operations and no changes in process conditions (pH 4.0 and 32°C) compared to the conventional process because it dispenses with the cooking and liquefaction step. In this study, the effects of endosperm hardness, protease, urea, and GSHE levels on GSH process were evaluated. Ground corn, soft endosperm, and hard endosperm were processed using two GSHE levels (0.1 and 0.4 mL per 100 g ground material) and four treatments of protease and urea addition. Soft and hard endosperm materials were obtained by grinding and sifting flaking grits from a dry milling pilot plant; classifications were confirmed using scanning electron microscopy. During 72 h of simultaneous granular starch hydrolysis and fermentation (GSHF), ethanol and glucose profiles were determined using HPLC. Soft endosperm resulted in higher final ethanol concentrations compared to ground corn or hard endosperm. Addition of urea increased final ethanol concentrations for soft and hard endosperm. Protease addition increased ethanol concentrations and fermentation rates for soft endosperm, hard endosperm, and ground corn. The effect of protease addition on ethanol concentrations and fermentation rates was most predominant for soft endosperm, less for hard endosperm, and least for ground corn. Samples (soft endosperm, hard endosperm, or corn) with protease resulted in higher (1.0% to 10.5% v/v) ethanol concentration compared to samples with urea. The GSH process with protease requires little or no urea addition. For fermentation of soft endosperm, GSHE dose can be reduced. Due to nutrients (lipids, minerals, and soluble proteins) present in corn that enhance yeast growth, ground corn fermented faster at the beginning than hard and soft endosperm.

  7. From notes to chords in QCD

    International Nuclear Information System (INIS)

    Wilczek, F.

    1998-01-01

    After a very brief overview recollecting the 'classic' parts of QCD, that is its application to describe hard processes and static properties of hadrons, I survey recent work - some very recent - on QCD at non-zero temperature and density. At finite temperature and zero density there is a compelling theoretical framework allowing us to predict highly specific, non-trivial dependence of the phase structure on the number of flavors and colors. Several aspects have been rigorously, and successfully, tested against massive numerical realizations of the microscopic theory. The theoretical description of high density is nowhere near as mature, but some intriguing possibilities have been put forward. The color/flavor locked state recently proposed for three flavors has many remarkable features connected to its basic symmetry structure, notably including chiral symmetry re-breaking and the existence (unlike for two flavors) of a gauge invariant order parameter. I survey potential applications to heavy ion collisions, astrophysics, and cosmology. A noteworthy possibility is that stellar explosions are powered by release of QCD latent heat. (orig.)

  8. Modeling of the flow stress for AISI H13 Tool Steel during Hard Machining Processes

    Science.gov (United States)

    Umbrello, Domenico; Rizzuti, Stefania; Outeiro, José C.; Shivpuri, Rajiv

    2007-04-01

    In general, the flow stress models used in computer simulation of machining processes are a function of effective strain, effective strain rate and temperature developed during the cutting process. However, these models do not adequately describe the material behavior in hard machining, where a range of material hardness between 45 and 60 HRC are used. Thus, depending on the specific material hardness different material models must be used in modeling the cutting process. This paper describes the development of a hardness-based flow stress and fracture models for the AISI H13 tool steel, which can be applied for range of material hardness mentioned above. These models were implemented in a non-isothermal viscoplastic numerical model to simulate the machining process for AISI H13 with various hardness values and applying different cutting regime parameters. Predicted results are validated by comparing them with experimental results found in the literature. They are found to predict reasonably well the cutting forces as well as the change in chip morphology from continuous to segmented chip as the material hardness change.

  9. Modeling of the flow stress for AISI H13 Tool Steel during Hard Machining Processes

    International Nuclear Information System (INIS)

    Umbrello, Domenico; Rizzuti, Stefania; Outeiro, Jose C.; Shivpuri, Rajiv

    2007-01-01

    In general, the flow stress models used in computer simulation of machining processes are a function of effective strain, effective strain rate and temperature developed during the cutting process. However, these models do not adequately describe the material behavior in hard machining, where a range of material hardness between 45 and 60 HRC are used. Thus, depending on the specific material hardness different material models must be used in modeling the cutting process. This paper describes the development of a hardness-based flow stress and fracture models for the AISI H13 tool steel, which can be applied for range of material hardness mentioned above. These models were implemented in a non-isothermal viscoplastic numerical model to simulate the machining process for AISI H13 with various hardness values and applying different cutting regime parameters. Predicted results are validated by comparing them with experimental results found in the literature. They are found to predict reasonably well the cutting forces as well as the change in chip morphology from continuous to segmented chip as the material hardness change

  10. Strong Bisimilarity and Regularity of Basic Parallel Processes is PSPACE-Hard

    DEFF Research Database (Denmark)

    Srba, Jirí

    2002-01-01

    We show that the problem of checking whether two processes definable in the syntax of Basic Parallel Processes (BPP) are strongly bisimilar is PSPACE-hard. We also demonstrate that there is a polynomial time reduction from the strong bisimilarity checking problem of regular BPP to the strong...... regularity (finiteness) checking of BPP. This implies that strong regularity of BPP is also PSPACE-hard....

  11. A study on the interplay between perturbative QCD and CSS/TMD formalism in SIDIS processes

    Energy Technology Data Exchange (ETDEWEB)

    Boglione, M. [Univ. di Torino, Torino (Italy); INFN, Torino (Italy); Gonzalez Hernandez, J. O. [INFN, Torino (Italy); Melis, S. [Univ. di Torino, Torino (Italy); Prokudin, A. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2015-02-16

    We study the Semi-Inclusive Deep Inelastic Scattering (SIDIS) cross section as a function of the transverse momentum, qT. In order to describe it over a wide region of qT, soft gluon resummation has to be performed. Here we will use the original Collins-Soper-Sterman (CSS) formalism; however, the same procedure would hold within the improved Transverse Momentum Dependent (TMD) framework. We study the matching between the region where fixed order perturbative QCD can successfully be applied and the region where soft gluon resummation is necessary. We find that the commonly used prescription of matching through the so-called Y-factor cannot be applied in the SIDIS kinematical configurations we examine. In particular, the non-perturbative component of the resummed cross section turns out to play a crucial role and should not be overlooked even at relatively high energies. As a result, the perturbative expansion of the resummed cross section in the matching region is not as reliable as it is usually believed and its treatment requires special attention.

  12. Search for QCD-instanton-induced processes in deep inelastic scattering at HERA

    International Nuclear Information System (INIS)

    Sievers, M.

    2000-07-01

    A limit on the QCD instanton induced cross section has been determined using the data recorded by the ZEUS detector during the year 1997, with a total integrated luminosity of 26 pb -1 . Deep inelastic scattering events were selected, requiring Q 2 > 75 GeV 2 and x > 10 -3 . Cuts to enrich the instanton fraction (final cuts) have been devised: They are the jet transverse momentum, the reconstructed Q '2 , the transverse energy, the mass and the multiplicity of the instanton candidate. The best strategy to determine a limit on fraction of the instanton candidates among the events after the final cuts has turned out to be a fit to the sphericity distributions. The upper limit at 95% confidence level of the fraction of instanton events in the DIS sample, including systematic errors, is f lim,Hrw = 12% for the Herwig Monte Carlo program. Using the Ariadne Monte Carlo program yields a limit of f lim,Ari = 8.2%. These limits have to be compared to the value predicted by theory (QCDINS 1.6) of: f = 6.2% A second, independent, method relying on the best strategy of cuts was not as sensitive and gave weaker limits. (orig.)

  13. On relation between distribution functions in hard and soft processes

    International Nuclear Information System (INIS)

    Kisselev, A.V.; Petrov, V.A.

    1992-10-01

    It is shown that in the particle-exchange model the hadron-hadron scattering amplitude admits parton-like representation with the distribution functions coinciding with those extracted from deep inelastic processes. (author). 13 refs

  14. Weak-interacting holographic QCD

    International Nuclear Information System (INIS)

    Gazit, D.; Yee, H.-U.

    2008-06-01

    We propose a simple prescription for including low-energy weak-interactions into the frame- work of holographic QCD, based on the standard AdS/CFT dictionary of double-trace deformations. As our proposal enables us to calculate various electro-weak observables involving strongly coupled QCD, it opens a new perspective on phenomenological applications of holographic QCD. We illustrate efficiency and usefulness of our method by performing a few exemplar calculations; neutron beta decay, charged pion weak decay, and meson-nucleon parity non-conserving (PNC) couplings. The idea is general enough to be implemented in both Sakai-Sugimoto as well as Hard/Soft Wall models. (author)

  15. Vector meson dominance and pointlike coupling of the photon in soft and hard processes

    International Nuclear Information System (INIS)

    Paul, E.

    1990-05-01

    Recent experimental results on photoproduction of hadrons probe the nature of the interacting photon over a wide kinematical range from soft to hard processes. Single inclusive spectra and energy flows of the final state charged particles are well described by assuming that photon production data are built up by an incoherent superposition of a soft Vector-Meson-Dominance component and a hard pointlike photon component. (orig.)

  16. QCD and Hadron Physics

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; Deshpande, Abhay L.; Gao, Haiyan; McKeown, Robert D.; Meyer, Curtis A.; Meziani, Zein-Eddine; Milner, Richard G.; Qiu, Jianwei; Richards, David G.; Roberts, Craig D.

    2015-02-26

    This White Paper presents the recommendations and scientific conclusions from the Town Meeting on QCD and Hadronic Physics that took place in the period 13-15 September 2014 at Temple University as part of the NSAC 2014 Long Range Planning process. The meeting was held in coordination with the Town Meeting on Phases of QCD and included a full day of joint plenary sessions of the two meetings. The goals of the meeting were to report and highlight progress in hadron physics in the seven years since the 2007 Long Range Plan (LRP07), and present a vision for the future by identifying the key questions and plausible paths to solutions which should define the next decade. The introductory summary details the recommendations and their supporting rationales, as determined at the Town Meeting on QCD and Hadron Physics, and the endorsements that were voted upon. The larger document is organized as follows. Section 2 highlights major progress since the 2007 LRP. It is followed, in Section 3, by a brief overview of the physics program planned for the immediate future. Finally, Section 4 provides an overview of the physics motivations and goals associated with the next QCD frontier: the Electron-Ion-Collider.

  17. Conformal Aspects of QCD

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S

    2003-11-19

    Theoretical and phenomenological evidence is now accumulating that the QCD coupling becomes constant at small virtuality; i.e., {alpha}{sub s}(Q{sup 2}) develops an infrared fixed point in contradiction to the usual assumption of singular growth in the infrared. For example, the hadronic decays of the {tau} lepton can be used to determine the effective charge {alpha}{sub {tau}}(m{sub {tau}{prime}}{sup 2}) for a hypothetical {tau}-lepton with mass in the range 0 < m{sub {tau}{prime}} < m{sub {tau}}. The {tau} decay data at low mass scales indicates that the effective charge freezes at a value of s = m{sub {tau}{prime}}{sup 2} of order 1 GeV{sup 2} with a magnitude {alpha}{sub {tau}} {approx} 0.9 {+-} 0.1. The near-constant behavior of effective couplings suggests that QCD can be approximated as a conformal theory even at relatively small momentum transfer and why there are no significant running coupling corrections to quark counting rules for exclusive processes. The AdS/CFT correspondence of large N{sub c} supergravity theory in higher-dimensional anti-de Sitter space with supersymmetric QCD in 4-dimensional space-time also has interesting implications for hadron phenomenology in the conformal limit, including an all-orders demonstration of counting rules for exclusive processes and light-front wavefunctions. The utility of light-front quantization and light-front Fock wavefunctions for analyzing nonperturbative QCD and representing the dynamics of QCD bound states is also discussed.

  18. New Perspectives for Hadron Phenomenology:The Effects of Final-State Interactions and Near-Conformal Effective QCD Couplings

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S

    2003-10-24

    The effective QCD charge extracted from {tau} decay is remarkably constant at small momenta, implying the near-conformal behavior of hadronic interactions at small momentum transfer. The correspondence of large-N{sub c} supergravity theory in higher-dimensional anti-de Sitter spaces with gauge theory in physical space-time also has interesting implications for hadron phenomenology in the conformal limit, such as constituent counting rules for hard exclusive processes. The utility of light-front quantization and lightfront Fock wavefunctions for analyzing such phenomena and representing the dynamics of QCD bound states is reviewed. I also discuss the novel effects of initial- and final-state interactions in hard QCD inclusive processes, including Bjorken-scaling single-spin asymmetries and the leading-twist diffractive and shadowing contributions to deep inelastic lepton-proton scattering.

  19. QCD Results from ATLAS and CMS

    CERN Document Server

    Leyton, M; The ATLAS collaboration

    2014-01-01

    The ATLAS and CMS collaborations have performed a wide range of studies of QCD phenomena, from soft particle to hard photon and jet production. Recent soft-­QCD measurements include studies of the underlying event, double parton interactions and vector meson production. Differential measurements of inclusive and dijet production provide stringent tests of high­-order QCD predictions and provide input for the determination of parton density functions. Measurements of isolated, inclusive and di­-photon cross sections for high-pT photons test various theoretical predictions and further constrain PDFs. An overview of these results is given.


  20. Dual constituent-exchange dynamics in soft and hard hadronic processes

    International Nuclear Information System (INIS)

    Akkelin, S.V.; Kobylinskij, N.A.; Martynov, E.S.; Shelest, V.P.

    1987-01-01

    A possibility to match the dual theory of soft hadronic processes to the dimensional counting rules for hard processes has been studied. This aim is shown to be attained within the framework of the dual analytical model under certain conditions on the shape and parameters of the Regge trajectories

  1. Dual dynamics of constituent interchange in soft and hard hadronic processes

    International Nuclear Information System (INIS)

    Akkelin, S.V.; Kobylinskii, N.A.; Martynov, E.S.; Shelest, V.P.

    1987-01-01

    The possibility of combining the dual theory of soft hadronic processes with the rules of dimensional counting for hard processes is investigated. It is shown that this is achieved in the framework of a dual analytic model with certain conditions on the form and parameters of the Regge trajectories

  2. Strong Bisimilarity and Regularity of Basic Parallel Processes is PSPACE-Hard

    DEFF Research Database (Denmark)

    Srba, Jirí

    2002-01-01

    We show that the problem of checking whether two processes definable in the syntax of Basic Parallel Processes (BPP) are strongly bisimilar is PSPACE-hard. We also demonstrate that there is a polynomial time reduction from the strong bisimilarity checking problem of regular BPP to the strong...

  3. 13. international QCD conference (QCD 06)

    International Nuclear Information System (INIS)

    2006-01-01

    This conference was organized around 5 sessions: 1) quantum chromodynamics (QCD) at colliders, 2) CP-violation, Kaon decays and Chiral symmetry, 3) perturbative QCD, 4) physics of light and heavy hadrons, 5) confinement, thermodynamics QCD and axion searches. This document gathers only the slides of the presentations

  4. 13. international QCD conference (QCD 06)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    This conference was organized around 5 sessions: 1) quantum chromodynamics (QCD) at colliders, 2) CP-violation, Kaon decays and Chiral symmetry, 3) perturbative QCD, 4) physics of light and heavy hadrons, 5) confinement, thermodynamics QCD and axion searches. This document gathers only the slides of the presentations.

  5. Research on Melt Degassing Processes of High Conductivity Hard Drawn Aluminum Wire

    Science.gov (United States)

    Xu, Xuexia; Feng, Yanting; Wang, Qing; Li, Wenbin; Fan, Hui; Wang, Yong; Li, Guowei; Zhang, Daoqian

    2018-03-01

    Degassing effects of ultrasonic and vacuum processes on high conductivity hard drawn aluminum melt were studied. Results showed that the degassing efficiency improved with the increase of ultrasonic power within certain range, stabilizing at 70% with 240W. For vacuum degassing process, hydrogen content of aluminum melt decreased with the loading time and was linear with logarithm of vacuum degree. Comparison of degassing effects of ultrasonic, vacuum, vacuum-ultrasonic degassing process showed that vacuum-ultrasonic process presented optimal effect.

  6. Micromanufacturing Of Hard To Machine Materials By Physical And Chemical Ablation Processes

    International Nuclear Information System (INIS)

    Schubert, A.; Edelmann, J.; Gross, S.; Meichsner, G.; Wolf, N.; Schneider, J.; Zeidler, H.; Hackert, M.

    2011-01-01

    Miniaturization leads to high requirements to the applied manufacturing processes especially in respect to the used hard to machine materials and the aims of structure size and geometrical accuracy. Traditional manufacturing processes reach their limits here. One alternative for these provide thermal and chemical ablation processes. These processes are applied for the production of different microstructures in different materials like hardened steel, carbides and ceramics especially for medical engineering and tribological applications.

  7. QCD@LHC International Conference

    CERN Document Server

    2016-01-01

    The particle physics groups of UZH and ETH will host the QCD@LHC2016 conference (22.8.-26.8., UZH downtown campus), which is part of an annual conference series bringing together theorists and experimentalists working on hard scattering processes at the CERN LHC, ranging from precision studies of Standard Model processes to searches for new particles and phenomena. The format of the conference is a combination of plenary review talks and parallel sessions, with the latter providing a particularly good opportunity for junior researchers to present their results. The conference will take place shortly after the release of the new data taken by the LHC in sping 2016 at a collision energy of 13TeV, expected to more than double the currently available data set. It will be one of the first opportunities to discuss these data in a broader context, and we expect the conference to become a very lively forum at the interface of phenomenology and experiment.

  8. Transverse nucleon structure and diagnostics of hard parton-parton processes at LHC

    Energy Technology Data Exchange (ETDEWEB)

    L. Frankfurt, M. Strikman, C. Weiss

    2011-03-01

    We propose a new method to determine at what transverse momenta particle production in high-energy pp collisions is governed by hard parton-parton processes. Using information on the transverse spatial distribution of partons obtained from hard exclusive processes in ep/\\gamma p scattering, we evaluate the impact parameter distribution of pp collisions with a hard parton-parton process as a function of p_T of the produced parton (jet). We find that the average pp impact parameters in such events depend very weakly on p_T in the range 2 < p_T < few 100 GeV, while they are much smaller than those in minimum-bias inelastic collisions. The impact parameters in turn govern the observable transverse multiplicity in such events (in the direction perpendicular to the trigger particle or jet). Measuring the transverse multiplicity as a function of p_T thus provides an effective tool for determining the minimum p_T for which a given trigger particle originates from a hard parton-parton process.

  9. Effect of raw materials and hardening process on hardness of manually forged knife

    Science.gov (United States)

    Balkhaya, Suwarno

    2017-06-01

    Knives are normally made by forging process either using a machine or traditional method by means of hammering process. This present work was conducted to study the effects of steel raw materials and hardening process on the hardness of manually forged knives. The knife samples were made by traditional hammering (forging) process done by local blacksmith. Afterward, the samples were heat treated with two different hardening procedures, the first was based on the blacksmith procedure and the second was systematically done at the laboratory. The forging was done in the temperature ranged between 900-950°C, while the final temperature ranged between 650-675°C. The results showed that knives made of spring steel and heat treated in simulated condition at the laboratory obtained higher level of hardness, i.e. 62 HRC. In general, knives heat treated by local blacksmith had lower level of hardness that those obtained from simulated condition. Therefore, we concluded that the traditional knife quality in term of hardness can be improved by optimizing the heat treatment schedule.

  10. The automation of the "making safe" process in South African hard-rock underground mine

    CSIR Research Space (South Africa)

    Teleka, SR

    2011-07-01

    Full Text Available In South African hard-rock mines, best practice dictates that the hanging-walls be inspected after blasting. This process is known as ‘making safe’ and although intended to save lives, it is laborious and subjective. Pressure is placed on the barrer...

  11. Synergy of modeling processes in the area of soft and hard modeling

    Directory of Open Access Journals (Sweden)

    Sika Robert

    2017-01-01

    Full Text Available High complexity of production processes results in more frequent use of computer systems for their modeling and simulation. Process modeling helps to find optimal solution, verify some assumptions before implementation and eliminate errors. In practice, modeling of production processes concerns two areas: hard modeling (based on differential equations of mathematical physics and soft (based on existing data. In the paper the possibility of synergistic connection of these two approaches was indicated: it means hard modeling support based on the tools used in soft modeling. It aims at significant reducing the time in order to obtain final results with the use of hard modeling. Some test were carried out in the Calibrate module of NovaFlow&Solid (NF&S simulation system in the frame of thermal analysis (ATAS-cup. The authors tested output values forecasting in NF&S system (solidification time on the basis of variable parameters of the thermal model (heat conduction, specific heat, density. Collected data was used as an input to prepare soft model with the use of MLP (Multi-Layer Perceptron neural network regression model. The approach described above enable to reduce the time of production process modeling with use of hard modeling and should encourage production companies to use it.

  12. Topics in perturbative QCD beyond the leading order

    International Nuclear Information System (INIS)

    Buras, A.J.

    1979-08-01

    The basic structure of QCD formulae for various inclusive and semi-inclusive processes is presented. Next to leading order QCD corrections to inclusive deep-inelastic scattering are discussed in some detail. The methods for calculations of QCD corrections (leading, next to leading) to semi-inclusive processes are outlined. Some results of these calculations are discussed. 58 references

  13. Transition from reversible to irreversible magnetic exchange-spring processes in antiferromagnetically exchange-coupled hard/soft/hard trilayer structures

    International Nuclear Information System (INIS)

    Wang Xiguang; Guo Guanghua; Zhang Guangfu

    2011-01-01

    The demagnetization processes of antiferromagnetically exchange-coupled hard/soft/hard trilayer structures have been studied based on the discrete one-dimensional atomic chain model and the linear partial domain-wall model. It is found that, when the magnetic anisotropy of soft layer is taken into account, the changes of the soft layer thickness and the interfacial exchange coupling strength may lead a transition of demagnetization process in soft layer from the reversible to the irreversible magnetic exchange-spring process. For the trilayer structures with very thin soft layer, the demagnetization process exhibits typical reversible exchange-spring behavior. However, as the thickness of soft layer is increased, there is a crossover point t c , after which the process becomes irreversible. Similarly, there is also a critical interfacial exchange coupling constant A sh c , above which the exchange-spring process is reversible. When A sh sh c , the irreversible exchange-spring process is achieved. The phase diagram of reversible and irreversible exchange-spring processes is mapped in the plane of the interfacial exchange coupling A sh and soft layer thickness N s . - Research highlights: → A differing magnetic exchange-spring process is found in antiferromagnetically exchange-coupled hard/soft/hard trilayers if the magnetic anisotropy of the soft layers is taken into account. → The change of the soft layer thickness may lead to a transition of demagnetization process in soft layer from the reversible to the irreversible exchange-spring process. → The change of the soft-hard interfacial exchange coupling strength may lead a transition of demagnetization process in soft layer from the reversible to the irreversible exchange-spring process. → The phase diagram of reversible and irreversible exchange-spring processes is mapped in the plane of the interfacial exchange coupling and soft layer thickness.

  14. Restricted conformal invariance in QCD and its predictive power for virtual two-photon processes

    CERN Document Server

    Müller, D

    1998-01-01

    The conformal algebra provides powerful constraints, which guarantee that renormalized conformally covariant operators exist in the hypothetical conformal limit of the theory, where the $\\beta$-function vanishes. Thus, in this limit also the conformally covariant operator product expansion on the light cone holds true. This operator product expansion has predictive power for two-photon processes in the generalized Bjorken region. Only the Wilson coefficients and the anomalous dimensions that are known from deep inelastic scattering are required for the prediction of all other two-photon processes in terms of the process-dependent off-diagonal expectation values of conformal operators. It is checked that the next-to-leading order calculations for the flavour non-singlet meson transition form factors are consistent with the corrections to the corresponding Wilson coefficients in deep inelasitic scattering.

  15. Formulae and figures for basic two-body QCD processes in ep interaction

    International Nuclear Information System (INIS)

    Tymieniecka, T.; Warsaw Univ.; Zarnecki, A.F.

    1992-10-01

    A compilation of some useful formulae is given for basic 2→2 processes involving quarks, gluons and photons. The formulae are illustrated by evaluation of some partonic cross sections, parton luminosities and ep cross sections at HERA and LEPxLHC energies. (orig.)

  16. Hardness and microstructure homogeneity of pure copper processed by accumulative back extrusion

    International Nuclear Information System (INIS)

    Bazaz, B.; Zarei-Hanzaki, A.; Fatemi-Varzaneh, S.M.

    2013-01-01

    The present work deals with the microstructure evolution of a pure copper processed by a new severe plastic deformation method. A set of pure copper (99.99%) work-pieces with coarse-grained microstructures was processed by accumulative back extrusion (ABE) method at room temperature. The optical and scanning electron microscopy (SEM) and hardness measurements were utilized to study the microstructural evolution and hardness homogeneity. The results indicated that ABE is a capable process to provide a homogenous grain refined microstructure in pure copper. The observed grain refinement was discussed relying on the occurrence of dynamic restoration processes. The analysis of microstructure and hardness showed outstanding homogeneity improvement throughout the work-pieces as the consecutive ABE passes were applied. The homogeneity improvement was attributed to the propagation of the shear bands and also the heavily deformed regions. A reversing route was also applied in the ABE processing to investigate its effect on the development of microstructural homogeneity. Comparing to the conventional route, the application of the reversing route was found to yield better homogeneity after less passes of the process.

  17. Search for QCD instanton-induced processes at HERA in the high-Q.sup.2./sup. domain

    Czech Academy of Sciences Publication Activity Database

    Andreev, V.; Baghdasaryan, A.; Begzsuren, K.; Cvach, Jaroslav; Ferencei, Jozef; Hladký, Jan; Reimer, Petr

    2016-01-01

    Roč. 76, č. 7 (2016), 1-16, č. článku 381. ISSN 1434-6044 R&D Projects: GA MŠk LG14033 Institutional support: RVO:68378271 ; RVO:61389005 Keywords : deep-inelastic scattering * neutral currents * instantons * QCD Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 5.331, year: 2016

  18. Soft gluons and superleading logarithms in QCD

    CERN Document Server

    Forshaw, J R

    2009-01-01

    After a brief introduction to the physics of soft gluons in QCD we present a surprising prediction. Dijet production in hadron-hadron collisions provides the paradigm, i.e. h_1 +h_2 \\to jj+X. In particular, we look at the case where there is a restriction placed on the emission of any further jets in the region in between the primary (highest p_T) dijets. Logarithms in the ratio of the jet scale to the veto scale can be summed to all orders in the strong coupling. Surprisingly, factorization of collinear emissions fails at scales above the veto scale and triggers the appearance of double logarithms in the hard sub-process. The effect appears first at fourth order relative to the leading order prediction and is subleading in the number of colours.

  19. The impact of the manufacturing process on the hardness and sensory properties of milk chocolate

    Directory of Open Access Journals (Sweden)

    Zarić Danica B.

    2012-01-01

    Full Text Available The aim of this paper was to examine the impact of the manufacturing process on the textural characteristics and sensory properties of milk chocolate. The research was conducted on the samples of chocolate produced in a ball mill during 30, 60 and 90 minutes of refining, each of them being pre-crystallized at 26, 28 and 30°C. A chocolate mass of identical ingredient composition was also produced using a standard manufacturing process at the same pre-crystallization temperatures. Chocolate hardness was examined using a piece of equipment called Texture Analyser, measuring the stress intensity which leads to chocolate crushing. Sensory analysis was performed using the point scoring method. The new manufacturing process, i.e. the manufacturing of chocolate in a ball mill improves sensory properties and hardness of milk chocolate. [Projekat Ministarstva nauke Republike Srbije, br. TR 31014

  20. QCD condensates in ADS/QCD

    DEFF Research Database (Denmark)

    Bechi, Jacopo

    2009-01-01

    This paper focuses on some issues about condensates and renormalization in AdS/QCD models. In particular we consider the consistency of the AdS/QCD approach for scale dependent quantities as the chiral condensate questioned in some recent papers and the 4D meaning of the 5D cosmological constant...... in a model in which the QCD is dual to a 5D gravity theory. We will be able to give some arguments that the cosmological constant is related to the QCD gluon condensate....

  1. Processing and properties of mechanically alloyed sintered steels with hard inclusions

    International Nuclear Information System (INIS)

    Gutsfeld, C.

    1991-10-01

    The aim of this work was the development of mechanically alloyed sintered steels with inert hard inclusions and their characterisation concerning the mechanical properties and the sliding wear behaviour. For this material concept the hard materials NbC, TiC, TiN and Al 2 O 3 were chosen with volume contents upto 20%. Mechanical alloying of the raw powders is a necessary prerequisit for an extreme fine and homogeneous microstructure and good mechanical and wear properties. Through a connecting powder annealing a conventional powder metallurgical processing with cold pressing and sintering is possible. For the consolidation pressureless liquid phase sintering initiated through phosphorus contents of 0,6% is suitable. Because of the strong hampering of grain growth through the included hard particles sintering densities upto 99% TD are possible with extreme fine microstructures. The mechanical properties can be varied in wide ranges. So tensile strengths of 1150 MPa, elongations at fracture of 17%, hardness of over 800 HV and fatigue strengths of 370 MPa have been reached. Throughout HIP or sinter forging the mechanical properties can be improved furthermore. (orig.) [de

  2. Structure changes in steels and hard metal induced by nanosecond and femtosecond laser processing

    Science.gov (United States)

    Dumitru, Gabriel; Romano, Valerio; Weber, Heinz P.; Haefke, Henry; Gerbig, Yvonne; Sentis, Marc L.; Hermann, Joerg; Bruneau, Sebastien

    2003-11-01

    Investigations on the occurrence of structure and hardness changes (for two sorts of steel and for a hard metal substrate) in the immediate vicinity of laser induced craters are presented in this work. Experiments with femtosecond pulses were performed in air with a Ti:sapphire laser (800 nm, 100 fs) at mean fluences of 2, 5 and 10 J/cm2. Series of microcraters were induced with 100 to 5,000 laser pulses per hole. Experiments with similar fluences, but 10 to 40 pules per hole, were performed on the same materials using a Nd:YAG delivering 100 ns pulese. After laser irradiation, cuts were made through the processed samples and the changes occurred in the crystalline structure of the target materials were evidenced by metallographical analysis of the resulting cross-sections. Hardness measurements were performed in points situated in the immediate vicinity of the laser-induced pores. Affected zones in the material surrounding laser induced pores were always found in the ns-regime, however with different properties for various laser parameters. In the fs-regime, zones of modified materials were also found and in such zones a significant hardness increasing was evidenced; the limit of the low fluences regime, where no structure changes occurred, was found to be slightly above 2 J/cm2.

  3. Process and devices of detection of hard electromagnetic or particle radiations using a superconducting element

    International Nuclear Information System (INIS)

    Drukier, A.K.; Valette, Claude; Waysand, Georges.

    1975-01-01

    The invention relates to processes and systems for the detection of hard electromagnetic or particle radiations and the sensors fitted to these systems. 'Hard radiations' means those whose energy is greater than a variable threshold, depending on the applications, but always more than 5 keV. The use of these sensors and the associated systems can therefore be envisaged in radiography and also in emission gammagraphy in the biological, anatomic and medical fields. In these processes, in order to detect a photon or a radiation particle, use is made of the transition phenomenon of a homogeneous grain of superconducting material of the first kind, from the metastable superconducting state to the normal state, under the effect of a photoelectron ejected by the impact of the photon or of the particle on the grain of superconducting material [fr

  4. One-loop corrections to the process e+e-→tt including hard bremsstrahlung

    International Nuclear Information System (INIS)

    Fleischer, J.; Riemann, T.; Werthenbach, A.; Leike, A.

    2002-03-01

    Radiative corrections to the process e + e - → t anti t are calculated in one-loop approximation of the Standard Model. There exist results from several groups. This talk provides further comparisons of the complete electroweak contributions, including hard bremsstrahlung. The excellent final agreement of the different groups allows to continue by working on a code for an event generator for TESLA and an extension to e + e - → 6 fermions. (orig.)

  5. Non destructive evaluation of residual stresses in welding and hard-surfacing processes

    International Nuclear Information System (INIS)

    Suarez, J.C.; Fernandez, L.M.; Cruz, C.; Aragon, B.; Merino, F.

    1995-01-01

    In this paper transversal and longitudinal stress profiles in welding and hard-surfacing by welding processes are presented. The stresses were measured by RMS of Barkhausen signal. In this work it is shown that in each case the level of stresses is strongly dependent on the number of weld beads of surfacing layers deposited. The subsequent deposition of new weld beads or surfacing layers produces a stress-relieving effect

  6. Seven topics in perturbative QCD

    International Nuclear Information System (INIS)

    Buras, A.J.

    1980-09-01

    The following topics of perturbative QCD are discussed: (1) deep inelastic scattering; (2) higher order corrections to e + e - annihilation, to photon structure functions and to quarkonia decays; (3) higher order corrections to fragmentation functions and to various semi-inclusive processes; (4) higher twist contributions; (5) exclusive processes; (6) transverse momentum effects; (7) jet and photon physics

  7. Hard Probes in Heavy-Ion Physics

    CERN Document Server

    Renk, Thorsten

    2012-01-01

    The aim of ultrarelativistic heavy ion physics is to study collectivity and thermodynamics of Quantum Chromodynamics (QCD) by creating a transient small volume of matter with extreme density and temperature. There is experimental evidence that most of the particles created in such a collision form indeed a thermalized system characterized by collective response to pressure gradients. However, a numerically small subset of high transverse momentum ($P_T$) processes takes place independent of the bulk, with the outgoing partons subsequently propagating through the bulk medium. Understanding the modification of such 'hard probes' by the bulk medium is an important part of the efforts to determine the properties of hot and dense QCD matter. In this paper, current developments are reviewed.

  8. QCD in hadron-hadron collisions

    International Nuclear Information System (INIS)

    Albrow, M.

    1997-03-01

    Quantum Chromodynamics provides a good description of many aspects of high energy hadron-hadron collisions, and this will be described, along with some aspects that are not yet understood in QCD. Topics include high E T jet production, direct photon, W, Z and heavy flavor production, rapidity gaps and hard diffraction

  9. Multiparton interactions and multiparton distributions in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Markus

    2011-11-15

    After a brief recapitulation of the general interest of parton densities, we discuss multiple hard interactions and multiparton distributions. We report on recent theoretical progress in their QCD description, on outstanding conceptual problems and on possibilities to use multiparton distributions as a laboratory to test and improve our understanding of hadron structure. (orig.)

  10. Multiparton interactions and multiparton distributions in QCD

    International Nuclear Information System (INIS)

    Diehl, Markus

    2011-11-01

    After a brief recapitulation of the general interest of parton densities, we discuss multiple hard interactions and multiparton distributions. We report on recent theoretical progress in their QCD description, on outstanding conceptual problems and on possibilities to use multiparton distributions as a laboratory to test and improve our understanding of hadron structure. (orig.)

  11. QCD: color or glow

    International Nuclear Information System (INIS)

    Reya, E.

    1982-01-01

    The some of motivations for color and the numerous qualitative successes of QCD are presented. Non-leading higher order contributions to the (x, Q 2 )-dependence of scaling violations of non-singlet and singlet structure functions are discussed, especially non-perturbative correction to deep inelastic processes such as higher twist contributions. Finally the topic of how to account theoretically for the existence of free fractionally charged particles by concentrating mainly on spontaneously breaking SU(3) color is presented. (M.F.W.)

  12. γγ → M{sup +}M{sup -}(M = π, K) processes with twist-3 corrections in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Cong [Southwest University, School of Physical Science and Technology, Chongqing (China); Chinese Academy of Sciences, State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Beijing (China); Zhou, Ming-Zhen; Chen, Hong [Southwest University, School of Physical Science and Technology, Chongqing (China)

    2017-04-15

    We study the γγ → M{sup +}M{sup -}(M = π, K) processes with the contributions from the two-particle twist-2 and twist-3 distribution amplitudes of pion and kaon mesons on BHL prescription in the standard hard-scattering approach. The results show that the contributions from twist-3 parts are actually not power suppressed compared with the leading-twist contributions in the low energy region. The cross sections with twist-3 corrections agree well with the experimental data in the two-photon center-of-mass energy W > 2.8 GeV and we also predict the cross section ratio σ{sub 0}(K{sup +}K{sup -})/σ{sub 0}(π{sup +}π{sup -}), which is compatible with the experimental data from TPC and Belle. (orig.)

  13. Magnetic Field Effects on CaCO3 Precipitation Process in Hard Water

    Directory of Open Access Journals (Sweden)

    Nelson Saksono

    2010-10-01

    Full Text Available Magnetic treatment is applied as physical water treatment for scale prevention especially CaCO3, from hard water in piping equipment by reducing its hardness.Na2CO3 and CaCl2 solution sample was used in to investigate the magnetic fields influence on the formation of particle of CaCO3. By changing the strength of magnetic fields, exposure time and concentration of samples solution, this study presents quantitative results of total scale deposit, total precipitated CaCO3 and morphology of the deposit. This research was run by comparing magnetically and non-magnetically treated  samples. The results showed an increase of deposits formation rate and total number of precipitated CaCO3 of magnetically treated samples. The increase of concentration solution sample will also raised the deposit under magnetic  field. Microscope images showed a greater number but smaller size of CaCO3 deposits form in magnetically treated samples, and aggregation during the processes. X-ray diffraction (XRD analysis showed that magnetically samples were dominated by calcite. But, there was a significant decrease of calcite’s peak intensities from magnetized  samples that indicated the decrease of the amount of calcite and an increase of total amorphous of deposits. This result  showed that magnetization of hard water leaded to the decreasing of ion Ca2+ due to the increasing of total CaCO3 precipitation process.

  14. Microstructure and hardness performance of AA6061 aluminium composite using friction stir processing

    Science.gov (United States)

    Marini, C. D.; Fatchurrohman, N.

    2018-04-01

    Rice husk ash (RHA) is an industrial waste that has become a potential reinforced material for aluminium matrix composite (AMCs) due to low cost and abundantly available resources. Friction stir processing (FSP) has been introduced as a method to modify surface properties of the metal and alloy including theirs composite as well. The present work reports the production and characterization of AA6061 and AA6061/5 vol% RHA using FSP using parameters rotation speed 1000 rpm and traversed speed 25 mm/min. The microstructure was studied using optical microscopy (OM). A homogenous dispersion of RHA particles was obtained in the composite. No agglomeration or segregation was observed. The produced composite exhibited a fine grain structure. An improvement in hardness profile was observed as AA6061/5 vol% RHA improves in hardness compared to FSPed of AA6061 without reinforcement.

  15. Hard and soft processes in small p/sub T/ inclusive reactions

    Energy Technology Data Exchange (ETDEWEB)

    Kanki, T [Osaka Univ., Toyonaka (Japan). Coll. of General Education; Okamoto, Y; Ryang, S

    1977-12-01

    Small p/sub T/ inclusive single-hadron spectra in high-energy hadron-hadron collisions are discussed in view of the two-component structure; each component corresponds to the contribution from the incoherent hard process or the coherent soft process among the partons. The clustered parton model, where each constituent quark is considered a cluster of the partons, gives the theoretical basis and certain regularities for both components. The various experimental spectra are shown to be well described by the two-component formula with these regularities. It is also argued that the CIM approach to small p sub(T) shows some disagreement with the data.

  16. QCD and string theories

    International Nuclear Information System (INIS)

    Cohen-Tannoudji, G.

    1990-01-01

    This paper is devoted to a review of the connections between quantumchromodynamics (QCD) and string theories. One reviews the phenomenological models leading to string pictures in non perturbative QCD and the string effects, related to soft gluon coherence, which arise in perturbative QCD. One tries to build a string theory which goes to QCD at the zero slope limit. A specific model, based on superstring theories is shown to agree with QCD four point amplitudes at the Born approximation and with one loop corrections. One shows how this approach can provide a theoretical framework to account for the phenomenological property of parton-hadron duality

  17. QCD and hadronic strings

    International Nuclear Information System (INIS)

    Cohen-Tannoudji, G.

    1989-01-01

    This series of lectures is devoted to review ot he connections between QCD and string theories. One reviews the phenomenological models leading to string pictures in non perturbative QCD and the string effects, related to soft gluon coherence, which arise in perturbative QCD. One tries to build a string theory which goes to QCD at the zero slope limit. A specific model, based on superstring theories is shown to agree with QCD four point amplitudes at the Born approximation and with one loop corrections. One shows how this approach can provide a theoretical framework to account for the phenomenological property of parton-hadron duality.(author)

  18. A theoretical overview on single hard diffraction

    International Nuclear Information System (INIS)

    Wuesthoff, M.

    1996-01-01

    The concept of the Pomeron structure function and its application in Single Hard Diffraction at hadron colliders and in diffractive Deep Inelastic Scattering is critically reviewed. Some alternative approaches are briefly surveyed with a focus on QCD inspired models

  19. Light-Front QCD

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.

    2004-11-30

    In these lectures, I survey a number of applications of light-front methods to hadron and nuclear physics phenomenology and dynamics, including light-front statistical physics. Light-front Fock-state wavefunctions provide a frame-independent representation of hadrons in terms of their fundamental quark and gluon degrees of freedom. Nonperturbative methods for computing LFWFs in QCD are discussed, including string/gauge duality which predicts the power-law fall-off at high momentum transfer of light-front Fock-state hadronic wavefunctions with an arbitrary number of constituents and orbital angular momentum. The AdS/CFT correspondence has important implications for hadron phenomenology in the conformal limit, including an all-orders derivation of counting rules for exclusive processes. One can also compute the hadronic spectrum of near-conformal QCD assuming a truncated AdS/CFT space. Given the LFWFs, one can compute form factors, heavy hadron decay amplitudes, hadron distribution amplitudes, and the generalized parton distributions underlying deeply virtual Compton scattering. The quantum fluctuations represented by the light-front Fock expansion leads to novel QCD phenomena such as color transparency, intrinsic heavy quark distributions, diffractive dissociation, and hidden-color components of nuclear wavefunctions. A new test of hidden color in deuteron photodisintegration is proposed. The origin of leading-twist phenomena such as the diffractive component of deep inelastic scattering, single-spin asymmetries, nuclear shadowing and antishadowing is also discussed; these phenomena cannot be described by light-front wavefunctions of the target computed in isolation. Part of the anomalous NuTeV results for the weak mixing angle {theta}{sub W} could be due to the non-universality of nuclear antishadowing for charged and neutral currents.

  20. Effect of ion nitridation process on hardness and the corrosion resistance of biomaterials

    International Nuclear Information System (INIS)

    Wirjoadi; Lely Susita; Bambang Siswanto; Sudjatmoko

    2012-01-01

    Ion nitriding process has been performed on metal biomaterials to improve their mechanical properties of materials, particularly to increase hardness and corrosion resistance. This metallic biomaterials used for artificial bone or a prosthetic graft and used as devices of orthopedic biomaterials are usually of 316L SS metal-type and Ti-6Al-4V alloy. The purpose of this study is to research the development and utilization of ion nitridation method in order to get iron and titanium nitride thin films on the metallic biomaterials for artificial bone that has wear resistance and corrosion resistance is better. Microhardness of the samples was measured using a microhardness tester, optimum hardness of SS 316L samples are about 582 VHN, this was obtained at the nitriding temperature of 500 °C, the nitriding time of 3 hours and the nitrogen gas pressure of 1.6 mbar, while optimum hardness of Ti-6Al-4V alloy is 764 VHN, this was obtained at the nitriding temperature of 500 °C, the nitriding time of 4 hours and the nitrogen gas pressure of 1.6 mbar. The hardness value of SS 316L sample and Ti-6Al-4V alloy increase to 143% and 153%, if compared with standard samples. The optimum corrosion resistance at temperature of 350 °C for SS 316L and Ti-6Al-4V are 260,12 and 110,49 μA/cm 2 or corrosion rate are 29,866 and 15,189 mpy, respectively. (author)

  1. The influence of milling-burnishing successive and simultaneous processes on the material hardness

    Science.gov (United States)

    Grigoraş, C. C.; Brabie, G.; Chirita, B.

    2016-08-01

    Recent developments in the field of bio-engineering allow the use of magnesium alloys as a substitute for medical implants. The issue with such alloys is the degradation rate witch has to be improved in order to provide the necessary support for the entire duration of the bone fraction healing. For improving the bone shielding heat treatment does not represent a solution, but chemical and/or mechanical do. One mechanical process that has excellent result is burnishing, but this process is difficult to be implemented on a milling machine. Therefore, it was necessary that a new tool and tool holder to be developed, that allow the simultaneous process to take place. A high-pressure hydraulic roller burnishing tool with a special tool holder was used on a CNC milling machine. The material used for this study is magnesium alloy AZ31B-F, and one of the main purposes was to improve the material hardness (HV). The milling-burnishing parameters that where varied are the speed and feed, burnishing pressure and depth, type of process (successive or simultaneous), machining direction and the material hardness after milling. The results were analyzed as percentage improvement between the milling and burnishing measured values.

  2. Hard diffraction and small-x

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    In the United States, phrases such as ''small-x evolution'', ''the BFKL Pomeron'', ''deep-inelastic rapiditygap events'' and ''hard-diffraction'' do not generate the same intensity of discussion amongst high-energy physicists that they do in Europe. However, for three days in the fall such discussion filled the air at Fermilab. The ''2nd Workshop on Small-x and Diffractive Physics at the Tevatron'' was a review of the rapid theoretical and experimental progress taking place in this field. Although Quantum Chromo-dynamics (QCD) has been established as the theory of strong interactions for twenty years, as yet neither perturbative high-energy calculations nor low-energy non-perturbative techniques have been successfully extended to the mixture of high energy and low transverse momenta which characterize traditional ''soft'' diffractive processes. The simplest soft diffractive process is elastic scattering. In this case it is easiest to accept that there is an exchanged ''pomeron'', which can be pictured as a virtual entity with no electric charge or strong charge (colour), perhaps like an excitation of the vacuum. The same pomeron is expected to appear in all diffractive processes. Understanding the pomeron in QCD is a fundamental theoretical and experimental challenge. In the last two or three years the ''frontier'' in this challenging area of QCD has been pushed back significantly in both theory and experiment. Progress has been achieved by studying the evolution of hard collisions to relatively smaller constituent momenta (small x) and by studying ''hard'' diffractive collisions containing simultaneous signatures of diffraction and hard perturbative processes. The hard processes have included high transverse momentum jet production, deep inelastic lepton scattering, and (most recently) W

  3. Peripheral processes 2 → 3 and 2 → 4 in QED and QCD in p-p-bar high-energy collisions

    International Nuclear Information System (INIS)

    Ahmadov, A. I.; Bystritskiy, Yu. M.; Kuraev, E. A.

    2011-01-01

    Differential cross sections of processes with high-energy p(-p)p collisions—creation of a scalar, a pseudoscalar and a lepton pair—are considered in the Weizsacker-Williams approximation in QED in the QCD framework, processes with conversion of the initial proton (antiproton) to fermionic jets accompanied with one gluon jet and the state of two gluons and a quark-antiquark pair (without a rapidity gap) are considered in the framework of the effective Regge action of Lipatov’s theory. The process of creation of a Higgs boson accompanied with two fermionic jets is considered. The azimuthal correlation in the process of two gluon jets separated by a rapidity gap is investigated. The gluon Reggeization effects are taken into account. Some distributions are illustrated by numerical calculations.

  4. Hard production of exotic hybrid mesons

    Energy Technology Data Exchange (ETDEWEB)

    Anikin, I.; Teryaev, O.V. [Bogoliubov Lab. of Theoretical Physics, JINR, Dubna (Russian Federation); Pire, B.; Anikin, I. [Ecole Polytechnique, CPHT, 91 - Palaiseau (France); Szymanowski, I. [Soltan Institute for Nuclear Studies, Warsaw (Poland); Liege Univ. (Belgium); Anikin, I.; Wallon, S. [Paris-11 Univ., Lab. de Physique Theorique, 91 - Orsay (France)

    2005-07-01

    Exotic hybrid mesons H, with quantum numbers J{sup PC} = 1{sup -+} may be copiously produced in the hard exclusive processes {gamma}{sup *}(Q{sup 2}){gamma} {yields} H and {gamma}{sup *}(Q{sup 2})P(p) {yields} HP(p') because they have a leading twist distribution amplitude with a sizable coupling constant f{sub H}, which may be estimated through QCD sum rules. The reaction rates scale in the same way as the corresponding rates for usual mesons. (authors)

  5. The quark-recombination model and correlations between hard and soft hadronic processes

    International Nuclear Information System (INIS)

    Ranft, J.

    1978-07-01

    Proceeding from the fact that quark and gluon recombination models make definite predictions for correlations between hard and soft processes, the following experiments are briefly discussed: (i) correlations between deep inelastic antineutrino-proton scattering and particle production in the proton fragmentation region, (ii) correlations between massive lepton pairs and particles produced in the fragmentation regions, and (iii) correlations between large transverse momentum particles and leading protons. In order to present the large transverse momentum - leading proton correlation, a divided correlation function similar to that used for studying short-range correlations of low transverse momentum particles is defined

  6. A Radiation-Hard Analog Memory In The AVLSI-RA Process

    International Nuclear Information System (INIS)

    Britton, C.L. Jr.; Wintenberg, A.L.; Read, K.F.; Simpson, M.L.; Young, G.R.; Clonts, L.G.; Kennedy, E.J.; Smith, R.S.; Swann, B.K.; Musser, J.A.

    1995-01-01

    A radiation hardened analog memory for an Interpolating Pad Camber has been designed at Oak Ridge National Laboratory and fabricated by Harris Semiconductor in the AVLSI-RA CMOS process. The goal was to develop a rad-hard analog pipeline that would deliver approximately 9-bit performance, a readout settling time of 500ns following read enable, an input and output dynamic range of +/-2.25V, a corrected rms pedestal of approximately 5mV or less, and a power dissipation of less than 10mW/channel. The pre- and post-radiation measurements to 5MRad are presented

  7. Studies of semi-inclusive and hard exclusive processes at Jlab

    International Nuclear Information System (INIS)

    Harutyun Avagyan

    2008-01-01

    The main goal of experiments proposed for the CLAS12 detector in conjunction with the 12-GeV CEBAF accelerator is the study of the nucleon through hard exclusive, semi-inclusive, and inclusive processes. This will provide new insights into nucleon dynamics at the elementary quark and gluon level. In this contribution we provide an overview of ongoing studies of the structure of nucleon in terms of quark and gluon degrees of freedom and future physics program planned with CLAS and CLAS12

  8. Jets and QCD

    International Nuclear Information System (INIS)

    Ali, A.; Kramer, G.

    2010-12-01

    The observation of quark and gluon jets has played a crucial role in establishing Quantum Chromodynamics [QCD] as the theory of the strong interactions within the Standard Model of particle physics. The jets, narrowly collimated bundles of hadrons, reflect configurations of quarks and gluons at short distances. Thus, by analysing energy and angular distributions of the jets experimentally, the properties of the basic constituents of matter and the strong forces acting between them can be explored. In this review we summarise the properties of quark and gluon jets and the impact of their observation on Quantum Chromodynamics, primarily the discovery of the gluons as the carriers of the strong force. Focusing on these basic points, jets in e + e - collisions will be in the foreground of the discussion. In addition we will delineate the role of jets as tools for exploring other particle aspects in ep and pp/p anti p collisions - quark and gluon densities in protons, measurements of the QCD coupling, fundamental 2-2 quark/gluon scattering processes, but also the impact of jet decays of top quarks, and W ± ,Z bosons on the electroweak sector. The presentation to a large extent is formulated in a non-technical language with the intent to recall the significant steps historically and convey the significance of this field also to communities beyond high energy physics. (orig.)

  9. Jets and QCD

    Energy Technology Data Exchange (ETDEWEB)

    Ali, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kramer, G. [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik

    2010-12-15

    The observation of quark and gluon jets has played a crucial role in establishing Quantum Chromodynamics [QCD] as the theory of the strong interactions within the Standard Model of particle physics. The jets, narrowly collimated bundles of hadrons, reflect configurations of quarks and gluons at short distances. Thus, by analysing energy and angular distributions of the jets experimentally, the properties of the basic constituents of matter and the strong forces acting between them can be explored. In this review we summarise the properties of quark and gluon jets and the impact of their observation on Quantum Chromodynamics, primarily the discovery of the gluons as the carriers of the strong force. Focusing on these basic points, jets in e{sup +}e{sup -} collisions will be in the foreground of the discussion. In addition we will delineate the role of jets as tools for exploring other particle aspects in ep and pp/p anti p collisions - quark and gluon densities in protons, measurements of the QCD coupling, fundamental 2-2 quark/gluon scattering processes, but also the impact of jet decays of top quarks, and W{sup {+-}},Z bosons on the electroweak sector. The presentation to a large extent is formulated in a non-technical language with the intent to recall the significant steps historically and convey the significance of this field also to communities beyond high energy physics. (orig.)

  10. A Demonstrator Analog Signal Processing Circuit in a Radiation Hard SOI-CMOS Technology

    CERN Multimedia

    2002-01-01

    % RD-9 A Demonstrator Analog Signal Processing Circuit in a Radiation Hard SOI-CMOS Technology \\\\ \\\\Radiation hardened SOI-CMOS (Silicon-On-Insulator, Complementary Metal-Oxide- \\linebreak Semiconductor planar microelectronic circuit technology) was a likely candidate technology for mixed analog-digital signal processing electronics in experiments at the future high luminosity hadron colliders. We have studied the analog characteristics of circuit designs realized in the Thomson TCS radiation hard technologies HSOI3-HD. The feature size of this technology was 1.2 $\\mu$m. We have irradiated several devices up to 25~Mrad and 3.10$^{14}$ neutrons cm$^{-2}$. Gain, noise characteristics and speed have been measured. Irradiation introduces a degradation which in the interesting bandwidth of 0.01~MHz~-~1~MHz is less than 40\\%. \\\\ \\\\Some specific SOI phenomena have been studied in detail, like the influence on the noise spectrum of series resistence in the thin silicon film that constitutes the body of the transistor...

  11. Dual QCD and phase transition in early universe

    International Nuclear Information System (INIS)

    Ranjan, Akhilesh; Raina, P.K.; Nandan, Hemwati

    2009-01-01

    The quantum chromodynamics (QCD) vacuum with condensed monopoles/ dyons (i.e., a dual Ginzburg- Landau (DGL) type model of QCD or dual QCD) has been quite successful to describe the large-distance behavior of QCD vacuum. Further, such DGL theory of QCD at finite temperature is also found to be useful in studying the phase transition process as believed to occur in early universe. In the present article, we have used the DGL theory of QCD with dyons to study the hadronisation in early universe. The effective potential at finite temperature is calculated. The notions of the phase transition in the background of the dyonically condensed QCD vacuum has been investigated by calculating the critical temperature in view of the temperature dependent couplings

  12. Calculating hadronic properties in strong QCD

    International Nuclear Information System (INIS)

    Pennington, M.R.

    1996-01-01

    This talk gives a brief review of the progress that has been made in calculating the properties of hadrons in strong QCD. In keeping with this meeting I will concentrate on those properties that can be studied with electromagnetic probes. Though perturbative QCD is highly successful, it only applies in a limited kinematic regime, where hard scattering occur, and the quarks move in the interaction region as if they are free, pointlike objects. However, the bulk of strong interactions are governed by the long distance regime, where the strong interaction is strong. It is this regime of length scales of the order of a Fermi, that determines the spectrum of light hadrons and their properties. The calculation of these properties requires an understanding of non-perturbative QCD, of confinement and chiral symmetry breaking. (author)

  13. Effect of process parameters on hardness, temperature profile and solidification of different layers processed by direct metal laser sintering (DMLS)

    International Nuclear Information System (INIS)

    Ahmed, Sazzad Hossain; Mian, Ahsan; Srinivasan, Raghavan

    2016-01-01

    In DMLS process objects are fabricated layer by layer from powdered material by melting induced by a controlled laser beam. Metallic powder melts and solidifies to form a single layer. Solidification map during layer formation is an important route to characterize micro-structure and grain morphology of sintered layer. Generally, solidification leads to columnar, equiaxed or mixture of these two types grain morphology depending on solidification rate and thermal gradient. Eutectic or dendritic structure can be formed in fully equiaxed zone. This dendritic growth has a large effect on material properties. Smaller dendrites generally increase ductility of the layer. Thus, materials can be designed by creating desired grain morphology in certain regions using DMLS process. To accomplish this, hardness, temperature distribution, thermal gradient and solidification cooling rate in processed layers will be studied under change of process variables by using finite element analysis, with specific application to Ti-6Al-4V.

  14. Effect of process parameters on hardness, temperature profile and solidification of different layers processed by direct metal laser sintering (DMLS)

    Science.gov (United States)

    Ahmed, Sazzad Hossain; Mian, Ahsan; Srinivasan, Raghavan

    2016-07-01

    In DMLS process objects are fabricated layer by layer from powdered material by melting induced by a controlled laser beam. Metallic powder melts and solidifies to form a single layer. Solidification map during layer formation is an important route to characterize micro-structure and grain morphology of sintered layer. Generally, solidification leads to columnar, equiaxed or mixture of these two types grain morphology depending on solidification rate and thermal gradient. Eutectic or dendritic structure can be formed in fully equiaxed zone. This dendritic growth has a large effect on material properties. Smaller dendrites generally increase ductility of the layer. Thus, materials can be designed by creating desired grain morphology in certain regions using DMLS process. To accomplish this, hardness, temperature distribution, thermal gradient and solidification cooling rate in processed layers will be studied under change of process variables by using finite element analysis, with specific application to Ti-6Al-4V.

  15. Effect of process parameters on hardness, temperature profile and solidification of different layers processed by direct metal laser sintering (DMLS)

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Sazzad Hossain; Mian, Ahsan, E-mail: ahsan.mian@wright.edu; Srinivasan, Raghavan [Department of Mechanical and Materials Engineering, Wright State University, Dayton, Ohio 45435 (United States)

    2016-07-12

    In DMLS process objects are fabricated layer by layer from powdered material by melting induced by a controlled laser beam. Metallic powder melts and solidifies to form a single layer. Solidification map during layer formation is an important route to characterize micro-structure and grain morphology of sintered layer. Generally, solidification leads to columnar, equiaxed or mixture of these two types grain morphology depending on solidification rate and thermal gradient. Eutectic or dendritic structure can be formed in fully equiaxed zone. This dendritic growth has a large effect on material properties. Smaller dendrites generally increase ductility of the layer. Thus, materials can be designed by creating desired grain morphology in certain regions using DMLS process. To accomplish this, hardness, temperature distribution, thermal gradient and solidification cooling rate in processed layers will be studied under change of process variables by using finite element analysis, with specific application to Ti-6Al-4V.

  16. Dynamical effects of QCD vacuum structure

    International Nuclear Information System (INIS)

    Ferreira, Erasmo

    1994-01-01

    The role of the QCD vacuum structure in the determination of the properties of states and processes occurring in the confinement regime of QCD is reviewed. The finite range of the vacuum correlations is discussed, and an analytical form is suggested for the correlation functions. The role of the vacuum quantum numbers in the phenomenology of high-energy scattering is reviewed. The vacuum correlation model of non-perturbative QCD is mentioned as a bridge between the fundamental theory and the description of the experiments. (author). 13 refs., 1 fig

  17. QCD are we ready for the LHC?

    CERN Multimedia

    CERN. Geneva

    2006-01-01

    The LHC energy regime poses a serious challenge to our capability of predicting QCD reactions to the level of accuracy necessary for a successful programme of searches for physics beyond the Standard Model. In these lectures, I'll introduce basic concepts in QCD, and present techniques based on perturbation theory, such as fixed-order and resummed computations, and Monte Carlo simulations. I'll discuss applications of these techniques to hadron-hadron processes, concentrating on recent trends in perturbative QCD aimed at improving our understanding of LHC phenomenology.

  18. Effect of cure cycle on curing process and hardness for epoxy resin

    Directory of Open Access Journals (Sweden)

    2009-09-01

    Full Text Available A 3-dimensional finite element model is developed to simulate and analyze the temperature and degree of cure field of epoxy casting part during cure process. The present model based on general finite element software ABAQUS is verified by literature example and experimental data. The numerical results show good agreement with literature example and measured data, and are even more accurate than the simulation of literature. After modeling successfully, the influence of temperature cure cycle ramps have on the temperature and degree of cure gradient is investigated. Moreover, the effect of non-uniform temperature and degree of cure field within epoxy casting part on hardness is demonstrated. The present model provides an accurate and novel method that allows further insight into the process of cure for epoxy resin.

  19. Reliability evaluation of hard disk drive failures based on counting processes

    International Nuclear Information System (INIS)

    Ye, Zhi-Sheng; Xie, Min; Tang, Loon-Ching

    2013-01-01

    Reliability assessment for hard disk drives (HDDs) is important yet difficult for manufacturers. Motivated by the fact that the particle accumulation in the HDDs, which accounts for most HDD catastrophic failures, is contributed from the internal and external sources, a counting process with two arrival sources is proposed to model the particle cumulative process in HDDs. This model successfully explains the collapse of traditional ALT approaches for accelerated life test data. Parameter estimation and hypothesis tests for the model are developed and illustrated with real data from a HDD test. A simulation study is conducted to examine the accuracy of large sample normal approximations that are used to test existence of the internal and external sources.

  20. Enhancing the Hardness of Sintered SS 17-4PH Using Nitriding Process for Bracket Orthodontic Application

    Science.gov (United States)

    Suharno, B.; Supriadi, S.; Ayuningtyas, S. T.; Widjaya, T.; Baek, E. R.

    2018-01-01

    Brackets orthodontic create teeth movement by applying force from wire to bracket then transferred to teeth. However, emergence of friction between brackets and wires reduces load for teeth movement towards desired area. In order to overcome these problem, surface treatment like nitriding chosen as a process which could escalate efficiency of transferred force by improving material hardness since hard materials have low friction levels. This work investigated nitriding treatment to form nitride layer which affecting hardness of sintered SS 17-4PH. The nitride layers produced after nitriding process at various temperature i.e. 470°C, 500°C, 530°C with 8hr holding time under 50% NH3 atmosphere. Optical metallography was conducted to compare microstructure of base and surface metal while the increasing of surface hardness then observed using vickers microhardness tester. Hardened surface layer was obtained after gaseous nitriding process because of nitride layer that contains Fe4N, CrN and Fe-αN formed. Hardness layers can achieved value 1051 HV associated with varies thickness from 53 to 119 μm. The presence of a precipitation process occurring in conjunction with nitriding process can lead to a decrease in hardness due to nitrogen content diminishing in solid solution phase. This problem causes weakening of nitrogen expansion in martensite lattice.

  1. Work Hard / Play Hard

    OpenAIRE

    Burrows, J.; Johnson, V.; Henckel, D.

    2016-01-01

    Work Hard / Play Hard was a participatory performance/workshop or CPD experience hosted by interdisciplinary arts atelier WeAreCodeX, in association with AntiUniversity.org. As a socially/economically engaged arts practice, Work Hard / Play Hard challenged employees/players to get playful, or go to work. 'The game changes you, you never change the game'. Employee PLAYER A 'The faster the better.' Employer PLAYER B

  2. First tests of a novel radiation hard CMOS sensor process for Depleted Monolithic Active Pixel Sensors

    Science.gov (United States)

    Pernegger, H.; Bates, R.; Buttar, C.; Dalla, M.; van Hoorne, J. W.; Kugathasan, T.; Maneuski, D.; Musa, L.; Riedler, P.; Riegel, C.; Sbarra, C.; Schaefer, D.; Schioppa, E. J.; Snoeys, W.

    2017-06-01

    The upgrade of the ATLAS [1] tracking detector for the High-Luminosity Large Hadron Collider (LHC) at CERN requires novel radiation hard silicon sensor technologies. Significant effort has been put into the development of monolithic CMOS sensors but it has been a challenge to combine a low capacitance of the sensing node with full depletion of the sensitive layer. Low capacitance brings low analog power. Depletion of the sensitive layer causes the signal charge to be collected by drift sufficiently fast to separate hits from consecutive bunch crossings (25 ns at the LHC) and to avoid losing the charge by trapping. This paper focuses on the characterization of charge collection properties and detection efficiency of prototype sensors originally designed in the framework of the ALICE Inner Tracking System (ITS) upgrade [2]. The prototypes are fabricated both in the standard TowerJazz 180nm CMOS imager process [3] and in an innovative modification of this process developed in collaboration with the foundry, aimed to fully deplete the sensitive epitaxial layer and enhance the tolerance to non-ionizing energy loss. Sensors fabricated in standard and modified process variants were characterized using radioactive sources, focused X-ray beam and test beams before and after irradiation. Contrary to sensors manufactured in the standard process, sensors from the modified process remain fully functional even after a dose of 1015neq/cm2, which is the the expected NIEL radiation fluence for the outer pixel layers in the future ATLAS Inner Tracker (ITk) [4].

  3. Recent QCD results from ATLAS at the LHC

    CERN Document Server

    Keoshkerian, H; The ATLAS collaboration

    2014-01-01

    The ATLAS collaboration has performed studies of a wide range of QCD phenomena, from soft particle to hard photon and jet production. Recent soft-QCD measurements include studies of underlying event, vector meson production. Differential measurements of inclusive and dijet production provide stringent tests of high-order QCD predictions and provide input for determination of parton density functions. Measurements of isolated inclusive and di-photons cross sections for high p_T photons test various theoretical predictions and constrain parton density functions. An overview of these results is given.



  4. QCD roadshow rolls on

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1979-10-15

    Is quantum chromodynamics (QCD) the ultimate theory of hadronic phenomena? Or, put more sceptically, can one tell QCD from a hole in the ground? This is the title of a new theory roadshow, which after a successful premiere at CERN went on to attract a large audience at Erice, Sicily, during the recent international school of subnuclear physics.

  5. QCD and nuclei

    International Nuclear Information System (INIS)

    Simonov, Yu.A.

    1989-01-01

    To apply QCD to nuclear physics one needs methods of long-distance QCD. A new method, method of Confining Background Fields, CBF, which incorporates confinement, is presented with applications to heavy and light quarks, both in mesons and baryons. Spin-dependent forces are calculated for light and heavy quarks. The quark potential model in some limiting case is derived. 25 refs

  6. QCD roadshow rolls on

    International Nuclear Information System (INIS)

    Anon.

    1979-01-01

    Is quantum chromodynamics (QCD) the ultimate theory of hadronic phenomena? Or, put more sceptically, can one tell QCD from a hole in the ground? This is the title of a new theory roadshow, which after a successful premiere at CERN went on to attract a large audience at Erice, Sicily, during the recent international school of subnuclear physics

  7. Challenges for QCD theory: some personal reflections

    International Nuclear Information System (INIS)

    Sjöstrand, T

    2013-01-01

    At the LHC all processes are QCD ones, whether ‘signal’ or ‘background’. In this review the frontiers of current QCD research are addressed, towards increased understanding, improved calculational precision, and role in potential future discoveries. Issues raised include: - the limits of perturbative QCD calculations and parton distribution usage,; - the nature of multiparton interactions,; - the impact of colour reconnection on physical observables,; - the need for progress on hadronization modelling,; - the improvements of parton showers and their combination with the matrix-element description,; - the use of QCD concepts in Beyond-the-Standard-Model scenarios and; - the key position of event generators and other software in the successful exploration of LHC physics. On the way, several questions are posed, where further studies are needed. (paper)

  8. QCD on the light cone

    International Nuclear Information System (INIS)

    Brodsky, S.J.

    1992-09-01

    The quantization of gauge theory at fixed light-cone time τ = t - z/c provides new perspectives for solving non-perturbative problems in quantum chromodynamics. The light-cone Fock state expansion provides both a precise definition of the relativistic wavefunctions of hadrons as bound-states of quarks and gluons and a general calculus for predicting QCD processes at the amplitude level. Applications to exclusive processes and weak decay amplitudes are discussed. The problem of computing the hadronic spectrum and the corresponding light-cone wavefunctions of QCD in one space and one time dimension has been successfully reduced to the diagonalization of a discrete representation of the light-cone Hamiltonian. The problems confronting the solution of gauge theories in 3 + 1 dimensions in the light-cone quantization formalism,, including zero modes and non-perturbative renormalization, are reviewed

  9. Economic Assessment for Recycling Critical Metals From Hard Disk Drives Using a Comprehensive Recovery Process

    Science.gov (United States)

    Nguyen, Ruby Thuy; Diaz, Luis A.; Imholte, D. Devin; Lister, Tedd E.

    2017-09-01

    Since the 2011 price spike of rare earth elements (REEs), research on permanent magnet recycling has blossomed globally in an attempt to reduce future REE criticality. Hard disk drives (HDDs) have emerged as one feasible feedstock for recovering valuable REEs such as praseodymium, neodymium, and dysprosium. Nevertheless, current processes for recycling electronic waste only focus on certain metals as a result of feedstock and metal price uncertainties. In addition, there is a perception that recycling REEs is unprofitable. To shed some light on the economic viability of REE recycling from U.S. HDDs, this article combines techno-economic information of an electro-hydrometallurgical process with end-of-life HDD availability in a simulation model. The results showed that adding REE recovery to an HDD base and precious metal recovery process was profitable given current prices. Recovered REEs from U.S. HDDs could meet up to 5.2% rest-of-world (excluding China) neodymium magnet demand. Feedstock, aluminum, and gold prices are key factors to recycling profitability. REEs contributed 13% to the co-recycling profit.

  10. First tests of a novel radiation hard CMOS sensor process for Depleted Monolithic Active Pixel Sensors

    International Nuclear Information System (INIS)

    Pernegger, H.; Hoorne, J.W. van; Kugathasan, T.; Musa, L.; Riedler, P.; Riegel, C.; Schaefer, D.; Schioppa, E.J.; Snoeys, W.; Bates, R.; Buttar, C.; Maneuski, D.; Dalla, M.; Sbarra, C.

    2017-01-01

    The upgrade of the ATLAS [1] tracking detector for the High-Luminosity Large Hadron Collider (LHC) at CERN requires novel radiation hard silicon sensor technologies. Significant effort has been put into the development of monolithic CMOS sensors but it has been a challenge to combine a low capacitance of the sensing node with full depletion of the sensitive layer. Low capacitance brings low analog power. Depletion of the sensitive layer causes the signal charge to be collected by drift sufficiently fast to separate hits from consecutive bunch crossings (25 ns at the LHC) and to avoid losing the charge by trapping. This paper focuses on the characterization of charge collection properties and detection efficiency of prototype sensors originally designed in the framework of the ALICE Inner Tracking System (ITS) upgrade [2]. The prototypes are fabricated both in the standard TowerJazz 180nm CMOS imager process [3] and in an innovative modification of this process developed in collaboration with the foundry, aimed to fully deplete the sensitive epitaxial layer and enhance the tolerance to non-ionizing energy loss. Sensors fabricated in standard and modified process variants were characterized using radioactive sources, focused X-ray beam and test beams before and after irradiation. Contrary to sensors manufactured in the standard process, sensors from the modified process remain fully functional even after a dose of 10"1"5 n _e_q/cm"2, which is the the expected NIEL radiation fluence for the outer pixel layers in the future ATLAS Inner Tracker (ITk) [4].

  11. Examinations of the process of hard coal and biomass blend combustion in OEA (oxygen enriched atmosphere)

    International Nuclear Information System (INIS)

    Pawlak-Kruczek, Halina; Ostrycharczyk, Michał; Czerep, Michał; Baranowski, Marcin; Zgóra, Jacek

    2015-01-01

    The benefits of oxygen enrichment have been demonstrated in a variety of industrial combustion applications, but to date no implementation of oxygen enrichment in boilers has been reported, primarily due to their already high thermal efficiencies and a very large scale of such systems, which require significant amounts of oxygen. But recently, oxygen combustion in boilers has become one of the CCS technologies which can be an effective tool for reducing greenhouse gases emissions, and oxygen enriched combustion is suitable for low-calorific fuels, including biomass. This paper analyses the use of oxygen enrichment in a furnace for co-firing of different kinds of biomass with hard coal in terms of emission and burnout impact (LOI). As a part of this research, the effect of injection oxygen mode and total oxygen concentration on the flue gas emission (SO_2, NO_x) and burnout from co-firing of straw and wooden biomass in different proportions (20% and 40%) with hard coal were studied. The co-firing tests were carried out in an isothermal flow reactor. One of the benefits from the OEA (oxygen enriched atmosphere) technology is more effective separation of CO_2 owing to the higher CO_2 concentration in the flue gas. The additional advantage of the OEA combustion technology in comparison with oxy-fuel combustion is that the OEA process needs lower O_2 purities and therefore it is cost-effective. Experimental tests on co-firing of 20% straw-hard coal blend were conducted in oxygen enriched (up to 25 and 30%) atmospheres with three variants of O_2 injection modes. NO_x, SO_2 emissions and burnout for the various atmospheres in the combustion chamber were studied. Moreover, co-firing tests were performed with 40% share of wooden biomass to examine the effect of the biomass share and a type on emission of NO_x and SO_2 in OEA. The two O_2 injection modes were investigated. In each case, the emission of SO_2 increases alongside an increase of oxygen concentration in

  12. Hard scattering and a diffractive trigger

    International Nuclear Information System (INIS)

    Berger, E.L.; Collins, J.C.; Soper, D.E.; Sterman, G.

    1986-02-01

    Conclusions concerning the properties of hard scattering in diffractively produced systems are summarized. One motivation for studying diffractive hard scattering is to investigate the interface between Regge theory and perturbative QCD. Another is to see whether diffractive triggering can result in an improvement in the signal-to-background ratio of measurements of production of very heavy quarks. 5 refs

  13. The QCD/SM working group: Summary report

    International Nuclear Information System (INIS)

    Giele, W.

    2004-01-01

    Quantum Chromo-Dynamics (QCD), and more generally the physics of the Standard Model (SM), enter in many ways in high energy processes at TeV Colliders, and especially in hadron colliders (the Tevatron at Fermilab and the forthcoming LHC at CERN), First of all, at hadron colliders, QCD controls the parton luminosity, which rules the production rates of any particle or system with large invariant mass and/or large transverse momentum. Accurate predictions for any signal of possible ''New Physics'' sought at hadron colliders, as well as the corresponding backgrounds, require an improvement in the control of uncertainties on the determination of PDF and of the propagation of these uncertainties in the predictions. Furthermore, to fully exploit these new types of PDF with uncertainties, uniform tools (computer interfaces, standardization of the PDF evolution codes used by the various groups fitting PDF's) need to be proposed and developed. The dynamics of colour also affects, both in normalization and shape, various observables of the signals of any possible ''New Physics'' sought at the TeV scale, such as, e.g. the production rate, or the distributions in transverse momentum of the Higgs boson. Last, but not least, QCD governs many backgrounds to the searches for this ''New Physics''. Large and important QCD corrections may come from extra hard parton emission (and the corresponding virtual corrections), involving multi-leg and/or multi-loop amplitudes. This requires complex higher order calculations, and new methods have to be designed to compute the required multi-legs and/or multi-loop corrections in a tractable form. In the case of semi-inclusive observables, logarithmically enhanced contributions coming from multiple soft and collinear gluon emission require sophisticated QCD resummation techniques. Resummation is a catch-all name for efforts to extend the predictive power of QCD by summing the large logarithmic corrections to all orders in perturbation theory. In

  14. The QCD/SM working group: Summary report

    Energy Technology Data Exchange (ETDEWEB)

    W. Giele et al.

    2004-01-12

    Quantum Chromo-Dynamics (QCD), and more generally the physics of the Standard Model (SM), enter in many ways in high energy processes at TeV Colliders, and especially in hadron colliders (the Tevatron at Fermilab and the forthcoming LHC at CERN), First of all, at hadron colliders, QCD controls the parton luminosity, which rules the production rates of any particle or system with large invariant mass and/or large transverse momentum. Accurate predictions for any signal of possible ''New Physics'' sought at hadron colliders, as well as the corresponding backgrounds, require an improvement in the control of uncertainties on the determination of PDF and of the propagation of these uncertainties in the predictions. Furthermore, to fully exploit these new types of PDF with uncertainties, uniform tools (computer interfaces, standardization of the PDF evolution codes used by the various groups fitting PDF's) need to be proposed and developed. The dynamics of colour also affects, both in normalization and shape, various observables of the signals of any possible ''New Physics'' sought at the TeV scale, such as, e.g. the production rate, or the distributions in transverse momentum of the Higgs boson. Last, but not least, QCD governs many backgrounds to the searches for this ''New Physics''. Large and important QCD corrections may come from extra hard parton emission (and the corresponding virtual corrections), involving multi-leg and/or multi-loop amplitudes. This requires complex higher order calculations, and new methods have to be designed to compute the required multi-legs and/or multi-loop corrections in a tractable form. In the case of semi-inclusive observables, logarithmically enhanced contributions coming from multiple soft and collinear gluon emission require sophisticated QCD resummation techniques. Resummation is a catch-all name for efforts to extend the predictive power of QCD by summing the large

  15. Process optimization for ultrasonic vibration assisted polishing of micro-structured surfaces on super hard material

    Science.gov (United States)

    Sun, Zhiyuan; Guo, Bing; Rao, Zhimin; Zhao, Qingliang

    2014-08-01

    In consideration of the excellent property of SiC, the ground micro-structured surface quality is hard to meet the requirement - consequently the ultrasonic vibration assisted polishing (UVAP) of micro-structures of molds is proposed in this paper. Through the orthogonal experiment, the parameters of UVAP of micro-structures were optimized. The experimental results show that, abrasive polishing process, the effect of the workpiece feed rate on the surface roughness (Ra), groove tip radius (R) and material removal rate (MRR) of micro-structures is significant. While, the UVAP, the most significant effect factor for Ra, R and MRR is the ultrasonic amplitude of the ultrasonic vibration. In addition, within the scope of the polishing process parameters selected by preliminary experiments, ultrasonic amplitude of 2.5μm, polishing force of 0.5N, workpiece feed rate of 5 mm·min-1, polishing wheel rotational speed of 50rpm, polishing time of 35min, abrasive size of 100nm and the polishing liquid concentration of 15% is the best technology of UVAP of micro-structures. Under the optimal parameters, the ground traces on the micro-structured surface were removed efficiently and the integrity of the edges of the micro-structure after grinding was maintained efficiently.

  16. Drell-Yan diffraction: breakdown of QCD factorization

    International Nuclear Information System (INIS)

    Pasechnik, R.S.; Kopeliovich, B.Z.

    2011-01-01

    We consider the diffractive Drell-Yan process in proton-(anti)proton collisions at high energies in the color dipole approach. The calculations are performed at forward rapidities of the leptonic pair. The effect of eikonalization of the universal ''bare'' dipole-target elastic amplitude in the saturation regime takes into account the principal part of the gap survival probability. We present predictions for the total and differential cross sections of the single-diffractive lepton-pair production at RHIC and LHC energies. We analyze implications of the QCD factorization breakdown in the diffractive Drell-Yan process, which is caused by a specific interplay of the soft and hard interactions, resulting in rather unusual properties of the corresponding observables. (orig.)

  17. Exotic hybrid mesons in hard electroproduction

    International Nuclear Information System (INIS)

    Anikin, I.V.; Pire, B.; Szymanowski, L.; Teryaev, O.V.; Wallon, S.

    2005-01-01

    We estimate the sizeable cross section for deep exclusive electroproduction of an exotic J PC =1 -+ hybrid meson in the Bjorken regime. The production amplitude scales like the one for usual meson electroproduction, i.e., as 1/Q 2 . This is due to the nonvanishing leading twist distribution amplitude for the hybrid meson, which may be normalized thanks to its relation to the energy-momentum tensor and to the QCD sum rules technique. The hard amplitude is considered up to next-to-leading order in α S and we explore the consequences of fixing the renormalization scale ambiguity through the Brodsky-Lepage-Mackenzie (BLM) procedure. We study the particular case where the hybrid meson decays through a πη meson pair. We discuss the πη generalized distribution amplitude and then calculate the production amplitude for this process. We propose a forward-backward asymmetry in the production of π and η mesons as a signal for the hybrid meson production. We briefly comment on hybrid electroproduction at very high energy, in the diffractive limit where a QCD Odderon exchange mechanism should dominate. The conclusion of our study is that hard electroproduction is a promising way to study exotic hybrid mesons, in particular, at JLAB, HERA (HERMES), or CERN (Compass)

  18. Gravitational waves generated from the cosmological QCD phase transition within AdS/QCD

    Directory of Open Access Journals (Sweden)

    M. Ahmadvand

    2017-09-01

    Full Text Available We study the gravitational waves produced by the collision of the bubbles as a probe for the cosmological first order QCD phase transition, considering heavy static quarks. Using AdS/QCD and the correspondence between a first order Hawking–Page phase transition and confinement–deconfinement phase transition, we find the spectrum and the strain amplitude of the gravitational wave within the hard and soft wall models. We postulate the duration of the phase transition corresponds to the evaporation time of the black hole in the five dimensional dual gravity space, and thereby obtain a bound on the string length in the space and correspondingly on the duration of the QCD phase transition. We also show that IPTA and SKA detectors will be able to detect these gravitational waves, which can be an evidence for the first order deconfinement transition.

  19. Baryon physics in holographic QCD

    Directory of Open Access Journals (Sweden)

    Alex Pomarol

    2009-03-01

    Full Text Available In a simple holographic model for QCD in which the Chern–Simons term is incorporated to take into account the QCD chiral anomaly, we show that baryons arise as stable solitons which are the 5D analogs of 4D skyrmions. Contrary to 4D skyrmions and previously considered holographic scenarios, these solitons have sizes larger than the inverse cut-off of the model, and therefore they are predictable within our effective field theory approach. We perform a numerical determination of several static properties of the nucleons and find a satisfactory agreement with data. We also calculate the amplitudes of “anomalous” processes induced by the Chern–Simons term in the meson sector, such as ω→πγ and ω→3π. A combined fit to baryonic and mesonic observables leads to an agreement with experiments within 16%.

  20. Excited QCD 2017

    CERN Document Server

    2017-01-01

    This edition is the ninth in a series of workshops that had been previously organised in Poland (2009), Slovakia (2010 and 2015), France (2011), Portugal (2012 and 2016) and Bosnia and Herzegovina (2013 and 2014). In the year 2017 the workshop goes to the beautiful Sintra near Lisbon, Portugal. The workshop covers diverse aspects of QCD: (i) QCD at low energies: excited hadrons, new resonances, glueballs, multiquarks. (ii) QCD at high temperatures and large densities: heavy-ion collisions, jets, diffraction, hadronisation, quark-gluon plasma, holography, colour-glass condensate, compact stars, applications to astrophysics.

  1. Predictive Lattice QCD

    International Nuclear Information System (INIS)

    Kronfeld, Andreas

    2005-01-01

    Quantum chromodynamics (QCD) is the quantum field theory describing the strong interactions of quarks bound inside hadrons. It is marvelous theory, which works (mathematically) at all distance scales. Indeed, for thirty years, theorists have known how to calculate short-distance properties of QCD, thanks to the (Nobel-worthy) idea of asymptotic freedom. More recently, numerical techniques applied to the strong-coupling regime of QCD have enabled us to compute long-distance bound-state properties. In this colloquium, we review these achievements and show how the new-found methods of calculation will influence high-energy physics.

  2. DESY: QCD workshop

    International Nuclear Information System (INIS)

    Ingelman, Gunnar

    1994-01-01

    The traditional annual DESY Theory Workshop highlights a topical theory sector. The most recent was under the motto 'Quantum Chromo-Dynamics' - QCD, the field theory of quarks and gluons. The organizers had arranged a programme covering most aspects of current QCD research. This time the workshop was followed by a topical meeting on 'QCD at HERA' to look at the electron-proton scattering experiments now in operation at DESY's new HERA collider

  3. QED, QCD en pratique

    OpenAIRE

    Aurenche , P; Guillet , J.-Ph; Pilon , E

    2016-01-01

    3rd cycle; Ces notes sont une introduction à l'application de l'électrodynamique quantique (QED) et de la chromodynamiques quantique (QCD) aux réactions de diffusion à hautes énergies. Le premier thème abordé est celui des divergences ultraviolettes et de la renormalisation à une boucle, avec comme conséquence pour QCD la liberté asymptotique. Le deuxième thème est celui des divergences infrarouges et colinéaires qui dans QCD sont traitées dans le cadre du modèle des partons avec l'introducti...

  4. Aspects of perturbative QCD in Monte Carlo shower models

    International Nuclear Information System (INIS)

    Gottschalk, T.D.

    1986-01-01

    The perturbative QCD content of Monte Carlo models for high energy hadron-hadron scattering is examined. Particular attention is given to the recently developed backwards evolution formalism for initial state parton showers, and the merging of parton shower evolution with hard scattering cross sections. Shower estimates of K-factors are discussed, and a simple scheme is presented for incorporating 2 → QCD cross sections into shower model calculations without double counting. Additional issues in the development of hard scattering Monte Carlo models are summarized. 69 references, 20 figures

  5. Angular distribution of Drell-Yan process at hadron colliders to NLO-QCD in models of TeV scale gravity

    International Nuclear Information System (INIS)

    Mathews, Prakash; Ravindran, V.

    2006-01-01

    In TeV scale gravity models, for dilepton production at hadron colliders, we present the NLO-QCD corrections for the double differential cross section in the invariant mass and scattering angle. For both ADD and RS models, the quantitative impact of QCD corrections for extra dimension searches at LHC and Tevatron are investigated. We present the K-factors for both ADD and RS models at LHC and Tevatron. Inclusion of QCD corrections to NLO stabilises the cross section with respect to scale variations

  6. Studies of the process of an unsteady formation of hard nitride coatings in an arc plasma flow

    International Nuclear Information System (INIS)

    Zake, M.

    1996-01-01

    The kinetic studies of an unsteady formation of hard ZrN and TiN coatings on the surface of metallic (Zr, Ti) samples in an Ar-N plasma flow are carried out. The obtained result is that at the initial stage of an unsteady heating of titanium samples nitrogen atoms penetrate into metal lattice and form interstitial compounds of hard nitrogen solutions in α-phase of Ti. This process is followed by a growth of thin surface layers of titanium nitrides with subsequent changes of surface radiance of exposed samples. Unsteady formation of ZrN is a similar two-stage process which includes the ZrN film growth and formation of a α-hard solution with subsequent changes of total normal emissivity of the surface. (author). 1 ref., 1 fig

  7. NN wave function at small distances and hard bremsstrahlung in the process pp→ppγ

    International Nuclear Information System (INIS)

    Neudatchin, V. G.; Khokhlov, N. A.; Shirokov, A. M.; Knyr, V. A.

    1997-01-01

    Various possibilities of studying the NN wave function at small distances--and in particular, quark degrees of freedom in the NN system--are discussed. It is shown that there is such a possibility at moderate energies--namely, hard bremsstrahlung in the process pp→ppγ at proton-beam energies in the range 350-450 MeV permits distinguishing between the pp wave function with nodes in S and P waves that corresponds to the Moscow potential of NN interaction from functions obtained with repulsive-core mesonic potentials. In the regions where photon energies in the c.m.s. are maximal (forward and backward photon emission angles in the laboratory frame), the pp→ppγ cross section calculated with the Moscow potential has maxima at which it is approximately five times larger than the analogous cross section calculated with repulsive-core mesonic potentials. The coordinate-representation formalism of the theory of bremsstrahlung is expounded

  8. QCD and hadron structure

    International Nuclear Information System (INIS)

    Kaplan, D.B.

    1995-01-01

    I give a brief and selective overview of QCD as it pertains to determining hadron structure, and the relevant directions in this field for nuclear theory. This document is intended to start discussion about priorities, not end it

  9. ATLAS soft QCD results

    CERN Document Server

    Sykora, Tomas; The ATLAS collaboration

    2018-01-01

    Recent results of soft QCD measurements performed by the ATLAS collaboration are reported. The measurements include total, elastic and inelastic cross sections, inclusive spectra, underlying event and particle correlations in p-p and p-Pb collisions.

  10. Gluonium spectrum in QCD

    International Nuclear Information System (INIS)

    Dominguez, C.A.

    1987-02-01

    The scalar (0 ++ ) and the tensor (2 ++ ) gluonium spectrum is analyzed in the framework of QCD sum rules. Stable eigenvalue solutions, consistent with duality and low energy theorems, are obtained for the mass and width of these glueballs. (orig.)

  11. Resonances in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, Matthias F. M.; Lange, Jens Sören; Pennington, Michael; Bettoni, Diego; Brambilla, Nora; Crede, Volker; Eidelman, Simon; Gillitzer, Albrecht; Gradl, Wolfgang; Lang, Christian B.; Metag, Volker; Nakano, Takashi; Nieves, Juan; Neubert, Sebastian; Oka, Makoto; Olsen, Stephen L.; Pappagallo, Marco; Paul, Stephan; Pelizäus, Marc; Pilloni, Alessandro; Prencipe, Elisabetta; Ritman, Jim; Ryan, Sinead; Thoma, Ulrike; Uwer, Ulrich; Weise, Wolfram

    2016-04-01

    We report on the EMMI Rapid Reaction Task Force meeting 'Resonances in QCD', which took place at GSI October 12-14, 2015 (Fig.~1). A group of 26 people met to discuss the physics of resonances in QCD. The aim of the meeting was defined by the following three key questions; what is needed to understand the physics of resonances in QCD?; where does QCD lead us to expect resonances with exotic quantum numbers?; and what experimental efforts are required to arrive at a coherent picture? For light mesons and baryons only those with up, down and strange quark content were considered. For heavy-light and heavy-heavy meson systems, those with charm quarks were the focus.This document summarizes the discussions by the participants, which in turn led to the coherent conclusions we present here.

  12. Perturbative QCD and jets

    International Nuclear Information System (INIS)

    Mueller, A.H.

    1986-03-01

    A brief review of some of the recent progress in perturbative QCD is given (heavy quark production, small-x physics, minijets and related topics, classical simulations in high energy reactions, coherence and the string effect)

  13. Computers for Lattice QCD

    International Nuclear Information System (INIS)

    Christ, Norman H

    2000-01-01

    The architecture and capabilities of the computers currently in use for large-scale lattice QCD calculations are described and compared. Based on this present experience, possible future directions are discussed

  14. Wide Temperature Rad-Hard ASIC for Process Control of a Fuel Cell System, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Ridgetop Group developed a top-level design of a rad-hard application-specific integrated circuit (ASIC) for spacecraft power management that is functional over a...

  15. QCD at finite temperature

    International Nuclear Information System (INIS)

    Kikkawa, Keiji

    1983-01-01

    The varidity of the perturbation method in the high temperature QCD is discussed. The skeleton expansion method takes account of plasmon effects and eliminates the electric infrared singularity but not the magnetic one. A possibility of eliminating the latter, which was recently proposed, is examined by a gauge invariant skeleton expansion. The magnetic singularity is unable to be eliminated by the perturbation method. This implies that some non-perturbative approaches must be incorporated in the high temperature QCD. (author)

  16. Aspects of QCD factorization

    International Nuclear Information System (INIS)

    Neubert, Matthias

    2001-01-01

    The QCD factorization approach provides the theoretical basis for a systematic analysis of nonleptonic decay amplitudes of B mesons in the heavy-quark limit. After recalling the basic ideas underlying this formalism, several tests of QCD factorization in the decays B→D (*) L, B→K * γ, and B→πK, ππ are discussed. It is then illustrated how factorization can be used to obtain new constraints on the parameters of the unitarity triangle

  17. Color ordering in QCD

    OpenAIRE

    Schuster, Theodor

    2013-01-01

    We derive color decompositions of arbitrary tree and one-loop QCD amplitudes into color ordered objects called primitive amplitudes. Furthermore, we derive general fermion flip and reversion identities spanning the null space among the primitive amplitudes and use them to prove that all color ordered tree amplitudes of massless QCD can be written as linear combinations of color ordered tree amplitudes of $\\mathcal{N}=4$ super Yang-Mills theory.

  18. QCD for Collider Physics

    OpenAIRE

    Skands, Peter

    2011-01-01

    These lectures are directed at a level suitable for graduate students in experimental and theoretical High Energy Physics. They are intended to give an introduction to the theory and phenomenology of quantum chromodynamics (QCD) as it is used in collider physics applications. The aim is to bring the reader to a level where informed decisions can be made concerning different approaches and their uncertainties. The material is divided into four main areas: 1) fundamentals, 2) perturbative QCD, ...

  19. A comparison between rad-hard float zone silicon diodes as gamma dosimeter in radiation processing

    International Nuclear Information System (INIS)

    Camargo, Fábio de; Gonçalves, Josemary A.C.; Bueno, Carmen C.

    2017-01-01

    In this work, we report on the results obtained with rad-hard Standard Float Zone (STFZ) and Diffused Oxygenated Float Zone (DOFZ) silicon diodes in radiation processing dosimetry. The dosimetric probes were designed to operate in the direct current mode, as on-line radiation dosimeter. The irradiation of the samples was performed using a 60 Co source with a dose rate of almost 2.4 kGy/h. The current response of each diode was measured as a function of the exposure time in steps from 5 kGy up to 50 kGy to achieve a total absorbed dose of 275 kGy. In this dose range it is observed a significant decrease in the photocurrent generated in both devices due to gamma radiation defects produced in their active volumes. To mitigate this effect, the samples were pre-irradiated with 60 Co gamma rays at 700 kGy. Despite of being less sensitive, these devices presented stable and reproducible current signals with a relative sensitivity decrease of about 19% within the whole range of dose studied. The dose-response curves of the pre-irradiated diodes showed quadratic behavior with correlation coefficient higher than 0.9999 for total absorbed dose up to 275 kGy. The comparison of the FZ and DOFZ responses evidenced that the latter was slightly superior to the first. However, it is important to note that all pre-irradiated diodes can be used as gamma dosimeters in radiation processing applications. (author)

  20. A comparison between rad-hard float zone silicon diodes as gamma dosimeter in radiation processing

    Energy Technology Data Exchange (ETDEWEB)

    Camargo, Fábio de [Amazônia Azul Tecnologias de Defesa S.A. (AMAZUL), São Paulo, SP (Brazil); Gonçalves, Josemary A.C.; Bueno, Carmen C., E-mail: dcamargo@gmail.com, E-mail: ccbueno@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil)

    2017-07-01

    In this work, we report on the results obtained with rad-hard Standard Float Zone (STFZ) and Diffused Oxygenated Float Zone (DOFZ) silicon diodes in radiation processing dosimetry. The dosimetric probes were designed to operate in the direct current mode, as on-line radiation dosimeter. The irradiation of the samples was performed using a {sup 60}Co source with a dose rate of almost 2.4 kGy/h. The current response of each diode was measured as a function of the exposure time in steps from 5 kGy up to 50 kGy to achieve a total absorbed dose of 275 kGy. In this dose range it is observed a significant decrease in the photocurrent generated in both devices due to gamma radiation defects produced in their active volumes. To mitigate this effect, the samples were pre-irradiated with {sup 60}Co gamma rays at 700 kGy. Despite of being less sensitive, these devices presented stable and reproducible current signals with a relative sensitivity decrease of about 19% within the whole range of dose studied. The dose-response curves of the pre-irradiated diodes showed quadratic behavior with correlation coefficient higher than 0.9999 for total absorbed dose up to 275 kGy. The comparison of the FZ and DOFZ responses evidenced that the latter was slightly superior to the first. However, it is important to note that all pre-irradiated diodes can be used as gamma dosimeters in radiation processing applications. (author)

  1. Microstructures, hardness and bioactivity of hydroxyapatite coatings deposited by direct laser melting process

    International Nuclear Information System (INIS)

    Tlotleng, Monnamme; Akinlabi, Esther; Shukla, Mukul; Pityana, Sisa

    2014-01-01

    Hydroxyapatite (HAP) coatings on bioinert metals such as Ti–6Al–4V are necessary for biomedical applications. Together, HAP and Ti–6Al–4V are biocompatible and bioactive. The challenges of depositing HAP on Ti–6Al–4V with traditional thermal spraying techniques are well founded. In this paper, HAP was coated on Ti–6Al–4V using direct laser melting (DLM) process. This process, unlike the traditional coating processes, is able to achieve coatings with good metallurgical bonding and little dilution. The microstructural and mechanical properties, chemical composition and bio-activities of the produced coatings were studied with optical microscopy, scanning electron microscope equipped with energy dispersive X-ray spectroscopy, and Vickers hardness machine, and by immersion test in Hanks' solution. The results showed that the choice of the laser power has much influence on the evolving microstructure, the mechanical properties and the retainment of HAP on the surface of the coating. Also, the choice of laser power of 750 W led to no dilution. The microhardness results inferred a strong intermetallic–ceramic interfacial bonding; which meant that the 750 W coating could survive long in service. Also, the coating was softer at the surface and stronger in the heat affected zones. Hence, this process parameter setting can be considered as an optimal setting. The soak tests revealed that the surface of the coating had unmelted crystals of HAP. The CaP ratio conducted on the soaked coating was 2.00 which corresponded to tetra calcium phosphate. This coating seems attractive for metallic implant applications. - Highlights: • Characteristics of HAP coatings produced on Ti-6Al-4V achieved with direct laser melting are reported. • Optimal process parameters necessary to achieve biocompatible coating are reported. • The SEM micrograph of the soaked HAP coating revealed partially melted crystals of HAP. • The HAP coating was retained at the surface of

  2. Microstructures, hardness and bioactivity of hydroxyapatite coatings deposited by direct laser melting process

    Energy Technology Data Exchange (ETDEWEB)

    Tlotleng, Monnamme, E-mail: MTlotleng@csir.co.za [Laser Materials Processing Group, National Laser Center CSIR, Pretoria 0001 (South Africa); Department of Mechanical Engineering Science, University of Johannesburg, Auckland Park, Kingsway Campus, Johannesburg 2006 (South Africa); Akinlabi, Esther [Department of Mechanical Engineering Science, University of Johannesburg, Auckland Park, Kingsway Campus, Johannesburg 2006 (South Africa); Shukla, Mukul [Department of Mechanical Engineering Technology, University of Johannesburg, Doornfontein Campus, Johannesburg 2006 (South Africa); Department of Mechanical Engineering, MNNIT, Allahabad, UP 211004 (India); Pityana, Sisa [Laser Materials Processing Group, National Laser Center CSIR, Pretoria 0001 (South Africa); Department of Chemical and Metallurgical Engineering, Tshwane University of Technology, Pretoria 0001 (South Africa)

    2014-10-01

    Hydroxyapatite (HAP) coatings on bioinert metals such as Ti–6Al–4V are necessary for biomedical applications. Together, HAP and Ti–6Al–4V are biocompatible and bioactive. The challenges of depositing HAP on Ti–6Al–4V with traditional thermal spraying techniques are well founded. In this paper, HAP was coated on Ti–6Al–4V using direct laser melting (DLM) process. This process, unlike the traditional coating processes, is able to achieve coatings with good metallurgical bonding and little dilution. The microstructural and mechanical properties, chemical composition and bio-activities of the produced coatings were studied with optical microscopy, scanning electron microscope equipped with energy dispersive X-ray spectroscopy, and Vickers hardness machine, and by immersion test in Hanks' solution. The results showed that the choice of the laser power has much influence on the evolving microstructure, the mechanical properties and the retainment of HAP on the surface of the coating. Also, the choice of laser power of 750 W led to no dilution. The microhardness results inferred a strong intermetallic–ceramic interfacial bonding; which meant that the 750 W coating could survive long in service. Also, the coating was softer at the surface and stronger in the heat affected zones. Hence, this process parameter setting can be considered as an optimal setting. The soak tests revealed that the surface of the coating had unmelted crystals of HAP. The CaP ratio conducted on the soaked coating was 2.00 which corresponded to tetra calcium phosphate. This coating seems attractive for metallic implant applications. - Highlights: • Characteristics of HAP coatings produced on Ti-6Al-4V achieved with direct laser melting are reported. • Optimal process parameters necessary to achieve biocompatible coating are reported. • The SEM micrograph of the soaked HAP coating revealed partially melted crystals of HAP. • The HAP coating was retained at the surface of

  3. Radiation hardness of CMOS monolithic active pixel sensors manufactured in a 0.18 μm CMOS process

    Energy Technology Data Exchange (ETDEWEB)

    Linnik, Benjamin [Goethe-Universitaet Frankfurt (Germany); Collaboration: CBM-MVD-Collaboration

    2015-07-01

    CMOS Monolithic Active Pixels Sensors (MAPS) are considered as the technology of choice for various vertex detectors in particle and heavy-ion physics including the STAR HFT, the upgrade of the ALICE ITS, the future ILC detectors and the CBM experiment at FAIR. To match the requirements of those detectors, their hardness to radiation is being improved, among others in a joined research activity of the Goethe University Frankfurt and the IPHC Strasbourg. It was assumed that combining an improved high resistivity (1-8 kΩcm) sensitive medium with the features of a 0.18 μm CMOS process, is suited to reach substantial improvements in terms of radiation hardness as compared to earlier sensor designs. This strategy was tested with a novel generation of sensor prototypes named MIMOSA-32 and MIMOSA-34. We show results on the radiation hardness of those sensors and discuss its impact on the design of future vertex detectors.

  4. Four-jet production at LHC and Tevatron in QCD

    International Nuclear Information System (INIS)

    Blok, B.; Dokshitzer, Yu.; Frankfurt, L.; Strikman, M.

    2011-01-01

    We demonstrate that in the back-to-back kinematics the production of four jets in the collision of two partons is suppressed in the leading log approximation of pQCD, compared to the E-circumflex hard processes involving the collision of four partons. We derive the basic equation for four-jet production in QCD in terms of the convolution of generalized two-parton distributions of colliding hadrons in the momentum space representation. Our derivation leads to geometrical approach in the impact parameter space close to that suggested within the parton model and used before to describe the four-jet production. We develop the independent parton approximation to the light-cone wave function of the proton. Comparison with the CDF and D0 data shows that the independent parton approximation to the light-cone wave function of the proton is insufficient to explain the data. We argue that the data indicate the presence of significant multiparton correlations in the light-cone wave functions of colliding protons.

  5. Soft QCD at the CMS and ATLAS experiments

    CERN Document Server

    Veres, Gabor

    2016-01-01

    A short overview of some of the recent results on soft QCD processes at the LHC will be presented from the ATLAS and CMS experiments. The discussion will proceed starting from the most inclusive to the more differential and rare phenomena. New results include total inelastic cross section measurements; studies of minimum bias collisions (charged particle $\\eta$ and $p_T$ distributions and two-particle correlations in high-multiplicity events); features of the underlying event (multiplicity and $\\Sigma p_T$ distributions in the presence of a high-$p_T$ track, jet, Z boson or $t\\overline{t}$ pair); minijets characterizing the transition between the soft and hard QCD regimes; dijets with a rapidity gap (as a signature of color-singlet exchange); M\\uller-Navelet dijets and their angular decorrelations (as an attempt to search for signs of the BFKL evolution and deviations from DGLAP); and finally, Double Parton Scattering (DPS) studies using various final states (4-jet events, $\\gamma$ + 3 jets, 2 b-jets and 2 je...

  6. Interplay of soft and hard processes and hadron $p_{T}$ spectra in p A and AA collisions

    CERN Document Server

    Enke, Wang; 10.1103/PhysRevC.64.034901

    2001-01-01

    Motivated by a schematic model of multiple parton scattering within the Glauber formalism, the transverse momentum spectra in pA and AA collisions are analyzed in terms of a nuclear modification factor with respect to pp collisions. The existing data at the CERN Super Proton Synchrotron energies are shown to be consistent with the picture of Glauber multiple scattering in which the interplay between soft and hard processes and the effect of absorptive processes lead to nontrivial nuclear modification of the particle spectra. Relative to the additive model of incoherent hard scattering, the spectra are enhanced at large p/sub T/ (hard) by multiple scattering while suppressed at low p/sub T/ (soft) by absorptive correction with the transition occurring at around a scale p/sub 0/~1-2 GeV/c that separates soft and hard processes. Around the same scale, the p/sub T / spectra in pp collisions also change from an exponential form at low p/sub T/ to a power-law behavior at high p/sub T/. At very large p/sub T/>>p/sub...

  7. Hard electronics; Hard electronics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    Hard material technologies were surveyed to establish the hard electronic technology which offers superior characteristics under hard operational or environmental conditions as compared with conventional Si devices. The following technologies were separately surveyed: (1) The device and integration technologies of wide gap hard semiconductors such as SiC, diamond and nitride, (2) The technology of hard semiconductor devices for vacuum micro- electronics technology, and (3) The technology of hard new material devices for oxides. The formation technology of oxide thin films made remarkable progress after discovery of oxide superconductor materials, resulting in development of an atomic layer growth method and mist deposition method. This leading research is expected to solve such issues difficult to be easily realized by current Si technology as high-power, high-frequency and low-loss devices in power electronics, high temperature-proof and radiation-proof devices in ultimate electronics, and high-speed and dense- integrated devices in information electronics. 432 refs., 136 figs., 15 tabs.

  8. THE EFFICIENCY OF ELECTROCOAGULATION PROCESS USING ALUMINUM ELECTRODES IN REMOVAL OF HARDNESS FROM WATER

    Directory of Open Access Journals (Sweden)

    M. Malakootian ، N. Yousefi

    2009-04-01

    Full Text Available There are various techniques for removal of water hardness each with its own special advantages and disadvantages. Electrochemical or electrocoagulation method due to its simplicity has gained a great attention and is used for removal of various ions and organic matters. The aim of the present study was to investigate the efficiency of this technique in removal of water hardness under different conditions. This experimental study was performed using a pilot plant. The applied pilot was comprised of a reservoir containing aluminum sheet electrodes. The electrodes were connected as monopolar and a power supply was used for supplying direct electrical current. Drinking water of Kerman (southeast of Iran was used in the experiments. The efficiency of the system in three different pH, voltages and time intervals were determined. Results showed the efficiency of 95.6% for electrocoagulation technique in hardness removal. pH and electrical potential had direct effect on hardness removal in a way that the highest efficiency rate was obtained in pH=10.1, potential difference of 20 volt and detention time of 60 minutes. Considering the obtained efficiency in the present study, electrocoagulation technique may be suggested as an effective alternative technique in hardness removal.

  9. Jet formation and interference in a thin QCD medium

    CERN Document Server

    Casalderrey-Solana, Jorge; Tywoniuk, Konrad

    2016-11-29

    In heavy-ion collisions, an abundant production of high-energy QCD jets allows to study how these multiparticle sprays are modified as they pass through the quark-gluon plasma. In order to shed new light on this process, we compute the inclusive two-gluon rate off a hard quark propagating through a color deconfined medium at first order in medium opacity. We explicitly impose an energy ordering of the two emitted gluons, such that the "hard" gluon can be thought of as belonging to the jet substructure while the other is a "soft" emission (which can be collinear or medium-induced). Our analysis focusses on two specific limits that clarify the modification of the additional angle- and formation time-ordering of splittings. In one limit, the formation time of the "hard" gluon is short compared to the "soft" gluon formation time, leading to a probabilistic formula for production of and subsequent radiation off a quark-gluon antenna. In the other limit, the ordering of formation is reverted, which automatically le...

  10. Observation of hard processes in rapidity gap events in {gamma}p interactions at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, T.; Aid, S.; Andreev, V.; Andrieu, B.; Appuhn, R.D.; Arpagaus, M.; Babaev, A.; Baehr, J.; Ban, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Barth, M.; Bassler, U.; Beck, H.P.; Behrend, H.J.; Belousov, A.; Berger, C.; Bergstein, H.; Bernardi, G.; Bernet, R.; Bertrand-Coremans, G.; Besancon, M.; Beyer, R.; Biddulph, P.; Bizot, J.C.; Blobel, V.; Borras, K.; Botterweck, F.; Boudry, V.; Braemer, A.; Brasse, F.; Braunschweig, W.; Brisson, V.; Bruncko, D.; Brune, C.; Buchholz, R.; Buengener, L.; Buerger, J.; Buesser, F.W.; Buniatian, A.; Burke, S.; Buschhorn, G.; Campbell, A.J.; Carli, T.; Charles, F.; Clarke, D.; Clegg, A.B.; Clerbaux, B.; Colombo, M.; Contreras, J.G.; Coughlan, J.A.; Courau, A.; Coutures, C.; Cozzika, G.; Criegee, L.; Cussans, D.G.; Cvach, J.; Dagoret, S.; Dainton, J.B.; Danilov, M.; Dau, W.D.; Daum, K.; David, M.; Deffur, E.; Delcourt, B.; Del Buono, L.; De Roeck, A.; De Wolf, E.A.; Di Nezza, P.; Dollfus, C.; Dowell, J.D.; Dreis, H.B.; Droutskoi, V.; Duboc, J.; Duellmann, D.; Duenger, O.; Duhm, H.; Ebert, J.; Ebert, T.R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Ehrlichmann, H.; Eichenberger, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellison, R.J.; Elsen, E.; Erdmann, M.; Erdmann, W.; Evrard, E.; Favart, L.; Fedotov, A.; Feeken, D.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Fleischer, M.; Flieser, M.; Fluegge, G.; Fomenko, A.; Fominykh, B.; Forbush, M.; Formanek, J.; Foster, J.M.; Franke, G.; Fretwurst, E.; Gabathuler, E.; Gabathuler, K.; Gamerdinger, K.; Garvey, J.; Gayler, J.; Gebauer, M.; Gellrich, A.; Genzel, H.; Gerhards, R.; Goerlach, U.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goldner, D.; Gonzalez-Pineiro, B.; Goodall, A.M.; Gorelov, I.; Goritchev, P.; Grab, C.; Graessler, H.; Graessler, R.; Greenshaw, T.; Grindhammer, G.; Gruber, A.; Gruber, C.; Haack, J.; Haidt, D.; Hajduk, L.; Hamon, O.; Hampel, M.; Hanlon, E.M.; Hapke, M.; Haynes, W.J.; Heatherington, J.; Heinzelmann, G.; Henderson, R.C.W.; H1 Collaboration

    1995-02-06

    Events with no hadronic energy flow in a large interval of pseudo-rapidity in the proton direction are observed in photon-proton interactions at an average centre of mass energy left angle {radical}(s{sub {gamma}p}) right angle of 200 GeV. These events are interpreted as photon diffractive dissociation. Evidence for hard scattering in photon diffractive dissociation is demonstrated using inclusive single particle spectra, thrust as a function of transverse energy, and the observation of jet production. The data can be described by a Monte Carlo calculation including hard photon-pomeron scattering. ((orig.))

  11. Hadronic and nuclear interactions in QCD

    International Nuclear Information System (INIS)

    1982-01-01

    Despite the evidence that QCD - or something close to it - gives a correct description of the structure of hadrons and their interactions, it seems paradoxical that the theory has thus far had very little impact in nuclear physics. One reason for this is that the application of QCD to distances larger than 1 fm involves coherent, non-perturbative dynamics which is beyond present calculational techniques. For example, in QCD the nuclear force can evidently be ascribed to quark interchange and gluon exchange processes. These, however, are as complicated to analyze from a fundamental point of view as is the analogous covalent bond in molecular physics. Since a detailed description of quark-quark interactions and the structure of hadronic wavefunctions is not yet well-understood in QCD, it is evident that a quantitative first-principle description of the nuclear force will require a great deal of theoretical effort. Another reason for the limited impact of QCD in nuclear physics has been the conventional assumption that nuclear interactions can for the most part be analyzed in terms of an effective meson-nucleon field theory or potential model in isolation from the details of short distance quark and gluon structure of hadrons. These lectures, argue that this view is untenable: in fact, there is no correspondence principle which yields traditional nuclear physics as a rigorous large-distance or non-relativistic limit of QCD dynamics. On the other hand, the distinctions between standard nuclear physics dynamics and QCD at nuclear dimensions are extremely interesting and illuminating for both particle and nuclear physics

  12. Automation of one-loop QCD corrections

    CERN Document Server

    Hirschi, Valentin; Frixione, Stefano; Garzelli, Maria Vittoria; Maltoni, Fabio; Pittau, Roberto

    2011-01-01

    We present the complete automation of the computation of one-loop QCD corrections, including UV renormalization, to an arbitrary scattering process in the Standard Model. This is achieved by embedding the OPP integrand reduction technique, as implemented in CutTools, into the MadGraph framework. By interfacing the tool so constructed, which we dub MadLoop, with MadFKS, the fully automatic computation of any infrared-safe observable at the next-to-leading order in QCD is attained. We demonstrate the flexibility and the reach of our method by calculating the production rates for a variety of processes at the 7 TeV LHC.

  13. Effect of Solution Treatment Process on Hardness of Alumina Reinforced Al-9Zn Composite Produced by Squeeze Casting

    Directory of Open Access Journals (Sweden)

    Dwi Rahmalina

    2014-10-01

    Full Text Available Characteristics of aluminium matrix composites reinforced by alumina have been developed to improve mechanical properties. One of the determining factors in the development of this material is parameter of solution treatment process. This study discusses the performance of the composite matrix of Al-9Zn-6Mg-3Si reinforced by alumina powder of 5 % volume fraction. Composite are manufactured by squeeze casting process with the pressure of 20 Ton in the metal mould. To improve mechanical properties, the precipitation hardening process is conducted through variation of temperature of solution treatment of 450, 475 and 500 °C and holding time of solution treatment of 30, 60 and 90 minutes. Materials are characterized by hardness testing and microstructure observation. The results showed that the optimum condition of hardness was produced by solution treatment temperature of 500 °C and 90 minutes holding time of 86 HRB.

  14. The QCD/SM Working Group: Summary Report

    International Nuclear Information System (INIS)

    Dobbs, M.

    2004-01-01

    Among the many physics processes at TeV hadron colliders, we look most eagerly for those that display signs of the Higgs boson or of new physics. We do so however amid an abundance of processes that proceed via Standard Model (SM) and in particular Quantum Chromodynamics (QCD) interactions, and that are interesting in their own right. Good knowledge of these processes is required to help us distinguish the new from the known. Their theoretical and experimental study teaches us at the same time more about QCD/SM dynamics, and thereby enables us to further improve such distinctions. This is important because it is becoming increasingly clear that the success of finding and exploring Higgs boson physics or other New Physics at the Tevatron and LHC will depend significantly on precise understanding of QCD/SM effects for many observables. To improve predictions and deepen the study of QCD/SM signals and backgrounds was therefore the ambition for our QCD/SM working group at this Les Houches workshop. Members of the working group made significant progress towards this on a number of fronts. A variety of tools were further developed, from methods to perform higher order perturbative calculations or various types of resummation, to improvements in the modeling of underlying events and parton showers. Furthermore, various precise studies of important specific processes were conducted. A significant part of the activities in Les Houches revolved around Monte Carlo simulation of collision events. A number of contributions in this report reflect the progress made in this area. At present a large number of Monte Carlo programs exist, each written with a different purpose and employing different techniques. Discussions in Les Houches revealed the need for an accessible primer on Monte Carlo programs, featuring a listing of various codes, each with a short description, but also providing a low-level explanation of the underlying methods. This primer has now been compiled and a

  15. Phases of QCD

    Energy Technology Data Exchange (ETDEWEB)

    Roessner, Simon

    2009-04-09

    Quantum Chromodynamics (QCD) is the theory of the strong interaction within the Standard Model of elementary particles. Today's research in this area dedicates substantial resources to numeric solutions of the QCD field equations and experimental programs exploring the phases of QCD. This thesis proceeds along a complementary line - that of modelling QCD, with the aim of identifying its dominant degrees of freedom. This is possible by minimally coupling effective potentials for the Polyakov loop to Nambu-Jona-Lasinio models using temporal background fields to model chiral symmetry breaking respecting colour confinement. The fermion sign problem resulting from the minimal coupling is addressed in this work establishing a novel, systematically ordered approach. The modifications to the approximative order parameter of colour confinement, the Polyakov loop, are in direct connection with the fermion sign problem. Furthermore an effective coupling of quark densities of different flavours is induced. This mechanism, most likely also present in QCD, produces finite contributions to flavour off diagonal susceptibilities. Susceptibilities are amongst the most promising physical quantities for the experimental exploration of the phase transition at high temperatures and densities. (orig.)

  16. Phases of QCD

    International Nuclear Information System (INIS)

    Roessner, Simon

    2009-01-01

    Quantum Chromodynamics (QCD) is the theory of the strong interaction within the Standard Model of elementary particles. Today's research in this area dedicates substantial resources to numeric solutions of the QCD field equations and experimental programs exploring the phases of QCD. This thesis proceeds along a complementary line - that of modelling QCD, with the aim of identifying its dominant degrees of freedom. This is possible by minimally coupling effective potentials for the Polyakov loop to Nambu-Jona-Lasinio models using temporal background fields to model chiral symmetry breaking respecting colour confinement. The fermion sign problem resulting from the minimal coupling is addressed in this work establishing a novel, systematically ordered approach. The modifications to the approximative order parameter of colour confinement, the Polyakov loop, are in direct connection with the fermion sign problem. Furthermore an effective coupling of quark densities of different flavours is induced. This mechanism, most likely also present in QCD, produces finite contributions to flavour off diagonal susceptibilities. Susceptibilities are amongst the most promising physical quantities for the experimental exploration of the phase transition at high temperatures and densities. (orig.)

  17. Comparative of the Tribological Performance of Hydraulic Cylinders Coated by the Process of Thermal Spray HVOF and Hard Chrome Plating

    Directory of Open Access Journals (Sweden)

    R.M. Castro

    2014-03-01

    Full Text Available Due to the necessity of obtaining a surface that is resistant to wear and oxidation, hydraulic cylinders are typically coated with hard chrome through the process of electroplating process. However, this type of coating shows an increase of the area to support sealing elements, which interferes directly in the lubrication of the rod, causing damage to the seal components and bringing oil leakage. Another disadvantage in using the electroplated hard chromium process is the presence of high level hexavalent chromium Cr+6 which is not only carcinogenic, but also extremely contaminating to the environment. Currently, the alternative process of high-speed thermal spraying (HVOF - High Velocity Oxy-Fuel, uses composite materials (metal-ceramic possessing low wear rates. Research has shown that some mechanical properties are changed positively with the thermal spray process in industrial applications. It is evident that a coating based on WC has upper characteristics as: wear resistance, low friction coefficient, with respect to hard chrome coatings. These characteristics were analyzed by optical microscopy, roughness measurements and wear test.

  18. QCD machines - present and future

    International Nuclear Information System (INIS)

    Christ, N.H.

    1991-01-01

    The present status of the currently working and nearly working dedicated QCD machines is reviewed and proposals for future machines are discussed with particular emphasis on the QCD Teraflop Project in the US. (orig.)

  19. Production of high-energy substances in the process of thorough treatment of hard rocket fuel

    International Nuclear Information System (INIS)

    Shiman, L.N.; Sobolev, V.V.

    2010-01-01

    The high-energy products taken from hard rocket fuel are explored on the sensitivity to a shock, friction, electrostatic discharge, detonation impulse, vibroloads, and capsule-detonator activity. Their chemical stability, thermal stability, and other physicochemical parameters are studied. The field of a recurring effective utilization of gained octogene, ammonium, and potassium perchlorate is shown.

  20. Multi parton interactions and multi parton distributions in QCD

    International Nuclear Information System (INIS)

    Diehl, M.

    2012-01-01

    After a brief recapitulation of the general interest of parton densities, we discuss multiple hard interactions and multi parton distributions. We report on recent theoretical progress in their QCD description, on outstanding conceptual problems and on possibilities to use multi parton distributions as a laboratory to test and improve our understanding of hadron structure. (author)

  1. Heterotic Pomeron: high energy hadronic collisions in QCD

    International Nuclear Information System (INIS)

    Chung-I Tan

    1993-01-01

    A unified treatment of high energy collisions in QCD is presented. Using a probabilistic approach, both perturbative (hard) and non-perturbative (soft) components are incorporated in a consistent fashion, leading to a ''Heterotic Pomeron''. As a Regge trajectory, it is non linear, approaching 1 in the limit t → -∞. 2 tabs., 9 refs

  2. Processes and mechanisms governing hard rock cliff erosion in western Brittany, France

    Science.gov (United States)

    Laute, Katja; Letortu, Pauline; Le Dantec, Nicolas

    2017-04-01

    The evolution of rocky coasts is controlled by the interplay between subaerial, marine as well as biological processes, and the geological context. In times of ongoing climate change it is difficult to predict how these erosional landscapes will respond for example to anticipated sea-level rise or to an increase in storminess. However, it can be expected that changes in the morphodynamics of rocky coasts will have a noticeable effect on society and infrastructure. Recent studies have proven that monitoring cliff micro-seismic ground motion has been very effective in exploring both marine and atmospheric actions on coastal cliffs. But only few studies have focused so far on the effects of wave loading and water circulation (runoff, infiltration, water table variations) on cliff stability and subsequent erosion, considering the interaction between subaerial and marine processes. This project focuses on the identification and quantification of environmental controls on hard rock cliff erosion with an emphasis on discriminating the relative contributions of subaerial and marine processes. We aim at relating different sources of mechanical stress (e.g. wave loading, direct wave impact, hydrostatic pressure, thermal expansion) to cliff-scale strain (cliff-top swaying and shaking) and micro-fracturing (generation, expansion and contraction of micro-cracks) with the objective to unravel and discriminate triggering mechanisms of cliff failure. A four-month monitoring field experiment during the winter period (February-May) of 2017 is carried out at a cliff face located in Porsmilin beach (western Brittany, France). The selected cliff section is exposed to Atlantic swell from the south/southwest with a significant wave height of ca. 1.5 m on average and, reaching up to 4 m during storm events. The cliff rises ca. 20 m above the beach and is mainly formed of orthogneiss with intrusions of granodiorite. The entire cliff is highly fractured and altered, which can promote slope

  3. Next-to-leading-order QCD corrections to e+e−→H+γ

    Directory of Open Access Journals (Sweden)

    Wen-Long Sang

    2017-12-01

    Full Text Available The associated production of Higgs boson with a hard photon at lepton collider, i.e., e+e−→Hγ, is known to bear a rather small cross section in Standard Model, and can serve as a sensitive probe for the potential new physics signals. Similar to the loop-induced Higgs decay channels H→γγ,Zγ, the e+e−→Hγ process also starts at one-loop order provided that the tiny electron mass is neglected. In this work, we calculate the next-to-leading-order (NLO QCD corrections to this associated H+γ production process, which mainly stem from the gluonic dressing to the top quark loop. The QCD corrections are found to be rather modest at lower center-of-mass energy range (s<300 GeV, thus of negligible impact on Higgs factory such as CEPC. Nevertheless, when the energy is boosted to the ILC energy range (s≈400 GeV, QCD corrections may enhance the leading-order cross section by 20%. In any event, the e+e−→Hγ process has a maximal production rate σmax≈0.08 fb around s=250 GeV, thus CEPC turns out to be the best place to look for this rare Higgs production process. In the high energy limit, the effect of NLO QCD corrections become completely negligible, which can be simply attributed to the different asymptotic scaling behaviors of the LO and NLO cross sections, where the former exhibits a milder decrement ∝1/s , but the latter undergoes a much faster decrease ∝1/s2. Keywords: Standard Model, Higgs boson, QCD corrections

  4. Tests of QCD factorisation in the diffractive production of dijets in deep-inelastic scattering and photoproduction at HERA

    Science.gov (United States)

    Aktas, A.; Andreev, V.; Anthonis, T.; Antunovic, B.; Aplin, S.; Asmone, A.; Astvatsatourov, A.; Babaev, A.; Backovic, S.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Baudrand, S.; Beckingham, M.; Begzsuren, K.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, N.; Bizot, J. C.; Boenig, M.-O.; Boudry, V.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Bruncko, D.; Büsser, F. W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A. J.; Cantun Avila, K. B.; Cassol-Brunner, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Cholewa, A.; Contreras, J. G.; Coughlan, J. A.; Cozzika, G.; Cvach, J.; Dainton, J. B.; Daum, K.; de Boer, Y.; Delcourt, B.; Del Degan, M.; de Roeck, A.; de Wolf, E. A.; Diaconu, C.; Dodonov, V.; Dubak, A.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eliseev, A.; Elsen, E.; Essenov, S.; Falkewicz, A.; Faulkner, P. J. W.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Finke, L.; Fleischer, M.; Flucke, G.; Fomenko, A.; Franke, G.; Frisson, T.; Gabathuler, E.; Garutti, E.; Gayler, J.; Ghazaryan, S.; Ginzburgskaya, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gorbounov, S.; Gouzevitch, M.; Grab, C.; Greenshaw, T.; Gregori, M.; Grell, B. R.; Grindhammer, G.; Habib, S.; Haidt, D.; Hansson, M.; Heinzelmann, G.; Helebrant, C.; Henderson, R. C. W.; Henschel, H.; Herrera, G.; Hildebrandt, M.; Hiller, K. H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Hreus, T.; Hussain, S.; Jacquet, M.; Janssen, X.; Jemanov, V.; Jönsson, L.; Johnson, D. P.; Jung, A. W.; Jung, H.; Kapichine, M.; Katzy, J.; Kenyon, I. R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knies, G.; Knutsson, A.; Korbel, V.; Kostka, P.; Kraemer, M.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Krüger, K.; Landon, M. P. J.; Lange, W.; Laštovička-Medin, G.; Laycock, P.; Lebedev, A.; Leibenguth, G.; Lendermann, V.; Levonian, S.; Lindfeld, L.; Lipka, K.; Liptaj, A.; List, B.; List, J.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.-I.; Lueders, H.; Lytkin, L.; Makankine, A.; Malinovski, E.; Marage, P.; Marti, L.; Martisikova, M.; Martyn, H.-U.; Maxfield, S. J.; Mehta, A.; Meier, K.; Meyer, A. B.; Meyer, H.; Meyer, J.; Michels, V.; Mikocki, S.; Milcewicz-Mika, I.; Mladenov, D.; Mohamed, A.; Moreau, F.; Morozov, A.; Morris, J. V.; Mozer, M. U.; Müller, K.; Murín, P.; Nankov, K.; Naroska, B.; Naumann, T.; Newman, P. R.; Niebuhr, C.; Nikiforov, A.; Nowak, G.; Nowak, K.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J. E.; Osman, S.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, T.; Pascaud, C.; Patel, G. D.; Peng, H.; Perez, E.; Perez-Astudillo, D.; Perieanu, A.; Petrukhin, A.; Picuric, I.; Piec, S.; Pitzl, D.; Plačakytė, R.; Povh, B.; Prideaux, P.; Rahmat, A. J.; Raicevic, N.; Reimer, P.; Rimmer, A.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Salvaire, F.; Sankey, D. P. C.; Sauter, M.; Sauvan, E.; Schätzel, S.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schöning, A.; Schultz-Coulon, H.-C.; Sefkow, F.; Shaw-West, R. N.; Sheviakov, I.; Shtarkov, L. N.; Sloan, T.; Smiljanic, I.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, A.; Steder, M.; Stella, B.; Stiewe, J.; Stoilov, A.; Straumann, U.; Sunar, D.; Sykora, T.; Tchoulakov, V.; Thompson, G.; Thompson, P. D.; Toll, T.; Tomasz, F.; Traynor, D.; Trinh, T. N.; Truöl, P.; Tsakov, I.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, K.; Usik, A.; Utkin, D.; Valkárová, A.; Vallée, C.; van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Vinokurova, S.; Volchinski, V.; Wacker, K.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Wessels, M.; Wissing, C.; Wolf, R.; Wünsch, E.; Xella, S.; Yan, W.; Yeganov, V.; Žáček, J.; Zálešák, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zhu, Y. C.; Zimmermann, J.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.

    2007-08-01

    Measurements are presented of differential dijet cross sections in diffractive photoproduction (Q2<0.01 GeV2) and deep-inelastic scattering processes (DIS, 4QCD predictions based on diffractive parton densities previously obtained from a QCD analysis of inclusive diffractive DIS cross sections by H1. In DIS, the dijet data are well described, supporting the validity of QCD factorisation. The diffractive DIS dijet data are more sensitive to the diffractive gluon density at high fractional parton momentum than the measurements of inclusive diffractive DIS. In photoproduction, the predicted dijet cross section has to be multiplied by a factor of approximately 0.5 for both direct and resolved photon interactions to describe the measurements. The ratio of measured dijet cross section to NLO prediction in photoproduction is a factor 0.5±0.1 smaller than the same ratio in DIS. This suppression is the first clear observation of QCD hard scattering factorisation breaking at HERA. The measurements are also compared to the two soft colour neutralisation models SCI and GAL. The SCI model describes diffractive dijet production in DIS but not in photoproduction. The GAL model fails in both kinematic regions.

  5. Lattice QCD for cosmology

    International Nuclear Information System (INIS)

    Borsanyi, Sz.; Kampert, K.H.; Fodor, Z.; Forschungszentrum Juelich; Eoetvoes Univ., Budapest

    2016-06-01

    We present a full result for the equation of state (EoS) in 2+1+1 (up/down, strange and charm quarks are present) flavour lattice QCD. We extend this analysis and give the equation of state in 2+1+1+1 flavour QCD. In order to describe the evolution of the universe from temperatures several hundreds of GeV to the MeV scale we also include the known effects of the electroweak theory and give the effective degree of freedoms. As another application of lattice QCD we calculate the topological susceptibility (χ) up to the few GeV temperature region. These two results, EoS and χ, can be used to predict the dark matter axion's mass in the post-inflation scenario and/or give the relationship between the axion's mass and the universal axionic angle, which acts as a initial condition of our universe.

  6. Resonances in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, Matthias F.M., E-mail: m.lutz@gsi.de [GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Technische Universität Darmstadt, D-64289 Darmstadt (Germany); Lange, Jens Sören, E-mail: Soeren.Lange@exp2.physik.uni-giessen.de [II. Physikalisches Institut, Justus-Liebig-Universität Giessen, D-35392 Giessen (Germany); Pennington, Michael, E-mail: michaelp@jlab.org [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Bettoni, Diego [Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara, 44122 Ferrara (Italy); Brambilla, Nora [Physik Department, Technische Universität München, D-85747 Garching (Germany); Crede, Volker [Department of Physics, Florida State University, Tallahassee, FL 32306 (United States); Eidelman, Simon [Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Budker Istitute of Nuclear Physics SB RAS, Novosibirsk 630090 (Russian Federation); Gillitzer, Albrecht [Institut für Kernphysik, Forschungszentrum Jülich GmbH, D-52425 Jülich (Germany); Gradl, Wolfgang [Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55128 Mainz (Germany); Lang, Christian B. [Institut für Physik, Universität Graz, A-8010 Graz (Austria); Metag, Volker [II. Physikalisches Institut, Justus-Liebig-Universität Giessen, D-35392 Giessen (Germany); Nakano, Takashi [Research Center for Nuclear Physics, Osaka University, Osaka 567-0047 (Japan); and others

    2016-04-15

    We report on the EMMI Rapid Reaction Task Force meeting ‘Resonances in QCD’, which took place at GSI October 12–14, 2015. A group of 26 people met to discuss the physics of resonances in QCD. The aim of the meeting was defined by the following three key questions: • What is needed to understand the physics of resonances in QCD? • Where does QCD lead us to expect resonances with exotic quantum numbers? • What experimental efforts are required to arrive at a coherent picture? For light mesons and baryons only those with up, down and strange quark content were considered. For heavy–light and heavy–heavy meson systems, those with charm quarks were the focus. This document summarizes the discussions by the participants, which in turn led to the coherent conclusions we present here.

  7. Knot topology in QCD

    International Nuclear Information System (INIS)

    Zou, L.P.; Zhang, P.M.; Pak, D.G.

    2013-01-01

    We consider topological structure of classical vacuum solutions in quantum chromodynamics. Topologically non-equivalent vacuum configurations are classified by non-trivial second and third homotopy groups for coset of the color group SU(N) (N=2,3) under the action of maximal Abelian stability group. Starting with explicit vacuum knot configurations we study possible exact classical solutions. Exact analytic non-static knot solution in a simple CP 1 model in Euclidean space–time has been obtained. We construct an ansatz based on knot and monopole topological vacuum structure for searching new solutions in SU(2) and SU(3) QCD. We show that singular knot-like solutions in QCD in Minkowski space–time can be naturally obtained from knot solitons in integrable CP 1 models. A family of Skyrme type low energy effective theories of QCD admitting exact analytic solutions with non-vanishing Hopf charge is proposed

  8. Twisted mass lattice QCD

    International Nuclear Information System (INIS)

    Shindler, A.

    2007-07-01

    I review the theoretical foundations, properties as well as the simulation results obtained so far of a variant of the Wilson lattice QCD formulation: Wilson twisted mass lattice QCD. Emphasis is put on the discretization errors and on the effects of these discretization errors on the phase structure for Wilson-like fermions in the chiral limit. The possibility to use in lattice simulations different lattice actions for sea and valence quarks to ease the renormalization patterns of phenomenologically relevant local operators, is also discussed. (orig.)

  9. Phases of Holographic QCD

    International Nuclear Information System (INIS)

    Lippert, Matthew

    2009-01-01

    We investigated the Sakai-Sugimoto model of large N QCD at nonzero temperature and baryon chemical potential and in the presence of background electric and magnetic fields. We studied the holographic representation of baryons and the deconfinement, chiral-symmetry breaking, and nuclear matter phase transitions. In a background electric field, chiral-symmetry breaking corresponds to an insulator-conductor transition. A magnetic field both catalyzes chiral-symmetry breaking and generates, in the confined phase, a pseudo-scalar gradient or, in the deconfined phase, an axial current. The resulting phase diagram is in qualitative agreement with studies of hot, dense QCD.

  10. Twisted mass lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Shindler, A. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2007-07-15

    I review the theoretical foundations, properties as well as the simulation results obtained so far of a variant of the Wilson lattice QCD formulation: Wilson twisted mass lattice QCD. Emphasis is put on the discretization errors and on the effects of these discretization errors on the phase structure for Wilson-like fermions in the chiral limit. The possibility to use in lattice simulations different lattice actions for sea and valence quarks to ease the renormalization patterns of phenomenologically relevant local operators, is also discussed. (orig.)

  11. QCD and QGP: a summary

    International Nuclear Information System (INIS)

    Satz, Helmut

    1998-01-01

    The aim of high energy nuclear collisions is to study strong interaction thermodynamics in the laboratory; we want to explore colour deconfinement and the resulting new state of matter, the quark-gluon plasma. Phenomenological models have done much to form the concepts of the field, but today QCD provides the theoretical basis for our understanding of hot and dense matter and for the tools to probe it. I will therefore begin by summarizing recent results from finite temperature lattice QCD and then turn to the study of colour deconfinement using hard probes; here the recently reported anomalous J/ψ suppression represents a particularly promising signal. Similarly, the observed low mass dilepton enhancement has focussed our attention on the properties of hadrons near chiral symmetry restoration. The hadrosynthesis at freeze-out is yet another region of much present activity to be addressed in the final part of this summary. All aspects were covered here in a variety of excellent plenary talks and contributions; I hope the speakers will forgive me for concentrating on the progress in physics as I see it, rather than on individual talks. The field of high energy nuclear collisions is very many-faceted, and moreover I had to select what I could coherently summarize in the given time. I therefore also apologize to all those whose contributions to this meeting are covered insufficiently or not at all. In particular, I shall review neither the developments in astrophysics nor the search for disoriented chiral condensates, simply because of my lack of competence in these areas. (author)

  12. Explaining jet quenching with perturbative QCD alone

    CERN Document Server

    Zapp, Korinna C; Wiedemann, Urs A

    2011-01-01

    We present a new formulation of jet quenching in perturbative QCD beyond the eikonal approximation. Multiple scattering in the medium is modelled through infra-red-continued (2 -> 2) scattering matrix elements in QCD and the parton shower describing further emissions. The interplay between these processes is arranged in terms of a formation time constraint such that coherent emissions can be treated consistently. Emerging partons are hadronised by the Lund string model, tuned to describe LEP data in conjunction with the parton shower. Based on this picture we obtain a good description of the nuclear modification factor R_AA at RHIC and LHC.

  13. Resolution of ambiguities in perturbative QCD

    International Nuclear Information System (INIS)

    Nakkagawa, Hisao; Niegawa, Akira.

    1984-01-01

    In the perturbative QCD analyses of the deeply inelastic processes, the coupling constant depends on at least two mass-scales, the renormalization scale and the factorization scale. By integrating the coupled renormalization group equations with respect to these two mass-scales, the running coupling constant is defined. A perturbative approximation then introduces a new ambiguity, the integration-path dependence, into the theory. We show that the problem of this new ambiguity is resolved by imposing Stevenson's principle of minimal sensitivity. Together with the analogous analysis of the operator matrix element or the cut vertex, we can completely solve the problem of getting an unambiguous perturbative QCD prediction. (author)

  14. Parton distributions and lattice QCD calculations: A community white paper

    Science.gov (United States)

    Lin, Huey-Wen; Nocera, Emanuele R.; Olness, Fred; Orginos, Kostas; Rojo, Juan; Accardi, Alberto; Alexandrou, Constantia; Bacchetta, Alessandro; Bozzi, Giuseppe; Chen, Jiunn-Wei; Collins, Sara; Cooper-Sarkar, Amanda; Constantinou, Martha; Del Debbio, Luigi; Engelhardt, Michael; Green, Jeremy; Gupta, Rajan; Harland-Lang, Lucian A.; Ishikawa, Tomomi; Kusina, Aleksander; Liu, Keh-Fei; Liuti, Simonetta; Monahan, Christopher; Nadolsky, Pavel; Qiu, Jian-Wei; Schienbein, Ingo; Schierholz, Gerrit; Thorne, Robert S.; Vogelsang, Werner; Wittig, Hartmut; Yuan, C.-P.; Zanotti, James

    2018-05-01

    In the framework of quantum chromodynamics (QCD), parton distribution functions (PDFs) quantify how the momentum and spin of a hadron are divided among its quark and gluon constituents. Two main approaches exist to determine PDFs. The first approach, based on QCD factorization theorems, realizes a QCD analysis of a suitable set of hard-scattering measurements, often using a variety of hadronic observables. The second approach, based on first-principle operator definitions of PDFs, uses lattice QCD to compute directly some PDF-related quantities, such as their moments. Motivated by recent progress in both approaches, in this document we present an overview of lattice-QCD and global-analysis techniques used to determine unpolarized and polarized proton PDFs and their moments. We provide benchmark numbers to validate present and future lattice-QCD calculations and we illustrate how they could be used to reduce the PDF uncertainties in current unpolarized and polarized global analyses. This document represents a first step towards establishing a common language between the two communities, to foster dialogue and to further improve our knowledge of PDFs.

  15. Effect of Tip Shape of Frictional Stir Burnishing Tool on Processed Layer’s Hardness, Residual Stress and Surface Roughness

    Directory of Open Access Journals (Sweden)

    Yoshimasa Takada

    2018-01-01

    Full Text Available Friction stir burnishing (FSB is a surface-enhancement method used after machining, without the need for an additional device. The FSB process is applied on a machine that uses rotation tools (e.g., machining center or multi-tasking machine. Therefore, the FSB process can be applied immediately after the cutting process using the same machine tool. Here, we apply the FSB to the shaft materials of 0.45% C steel using a multi-tasking machine. In the FSB process, the burnishing tool rotates at a high-revolution speed. The thin surface layer is rubbed and stirred as the temperature is increased and decreased. With the FSB process, high hardness or compressive residual stress can be obtained on the surface layer. However, when we applied the FSB process using a 3 mm diameter sphere tip shape tool, the surface roughness increased substantially (Ra = 20 µm. We therefore used four types of tip shape tools to examine the effect of burnishing tool tip radius on surface roughness, hardness, residual stress in the FSB process. Results indicated that the surface roughness was lowest (Ra = 10 µm when the tip radius tool diameter was large (30 mm.

  16. QCD and collider physics

    CERN Document Server

    Stirling, William James

    1991-12-01

    1. Some basic theory. 2. Two important applications: - e+ e- annihilation (LEPSLS) ; deep inelastic scattering (HERA). 3. Other applications..., large Pt jets, W and Z, heavy quark production..., (pp- colliders). In this lecture: some basic theory. 1. QCD as a non abelian gauge field theory. 2. Asymptotic freedom. 3. Beyond leading order - renormalisation schemes. 4. MS.

  17. Renormalization of Hamiltonian QCD

    International Nuclear Information System (INIS)

    Andrasi, A.; Taylor, John C.

    2009-01-01

    We study to one-loop order the renormalization of QCD in the Coulomb gauge using the Hamiltonian formalism. Divergences occur which might require counter-terms outside the Hamiltonian formalism, but they can be cancelled by a redefinition of the Yang-Mills electric field.

  18. Phenomenology Using Lattice QCD

    Science.gov (United States)

    Gupta, R.

    2005-08-01

    This talk provides a brief summary of the status of lattice QCD calculations of the light quark masses and the kaon bag parameter BK. Precise estimates of these four fundamental parameters of the standard model, i.e., mu, md, ms and the CP violating parameter η, help constrain grand unified models and could provide a window to new physics.

  19. Scaling violation in QCD

    International Nuclear Information System (INIS)

    Furmanski, W.

    1981-08-01

    The effects of scaling violation in QCD are discussed in the perturbative scheme, based on the factorization of mass singularities in the light-like gauge. Some recent applications including the next-to-leading corrections are presented (large psub(T) scattering, numerical analysis of the leptoproduction data). A proposal is made for extending the method on the higher twist sector. (author)

  20. Hadronic laws from QCD

    International Nuclear Information System (INIS)

    Cahill, R.T.

    1992-01-01

    A review is given of progress in deriving the effective action for hadronic physics, S[π, ρ, ω, .., anti N, N, ..], from the fundamental defining action of QCD, S[anti q, q, A μ a ]. This is a problem in quantum field theory and the most success so far has been achieved using functional integral calculus (FIC) techniques. This formulates the problem as an exercise in changing the variables of integration in the functional integrals, from those of the quark and gluon fields to those of the (bare) meson and baryon fields. The appropriate variables are determined by the dynamics of QCD, and the final hadronic variables (essentially the 'normal modes' of QCD) are local fields describing the 'centre-of-mass' motion of extended bound states of quarks. The quarks are extensively dressed by the gluons, and the detailed aspects of the hidden chiral symmetry emerge naturally from the formalism. Particular attention is given to covariant integral equations which determine bare nucleon structure (i.e. in the quenched approximation). These equations, which arise from the closed double-helix diagrams of the FIC analysis, describe the baryons in terms of quark-diquark structure, in the form of Faddeev equations. This hadronisation of QCD also generates the dressing of these baryons by the pions, and the non-local πNN coupling. (orig.)

  1. Observables of QCD diffraction

    Science.gov (United States)

    Mieskolainen, Mikael; Orava, Risto

    2017-03-01

    A new combinatorial vector space measurement model is introduced for soft QCD diffraction. The model independent mathematical construction resolves experimental complications; the theoretical framework of the approach includes the Good-Walker view of diffraction, Regge phenomenology together with AGK cutting rules and random fluctuations.

  2. QCD at LEP

    CERN Document Server

    Metzger, W.J.

    2003-01-01

    Several preliminary QCD results from e+e- interactions at LEP are reported. These include studies of event shape variables, which are used to determine alpha_s and for studies of the validity of power corrections. Further, a study of color reconnection effects in 3-jet Z decays is reported.

  3. Baryons and QCD

    International Nuclear Information System (INIS)

    Nathan Isgur

    1997-01-01

    The author presents an idiosyncratic view of baryons which calls for a marriage between quark-based and hadronic models of QCD. He advocates a treatment based on valence quark plus glue dominance of hadron structure, with the sea of q pairs (in the form of virtual hadron pairs) as important corrections

  4. Anomalous couplings in WZ production beyond NLO QCD

    Energy Technology Data Exchange (ETDEWEB)

    Campanario, Francisco; Roth, Robin; Zeppenfeld, Dieter [Institute for Theoretical Physics, KIT, Karlsruhe (Germany); Sapeta, Sebastian [CERN PH-TH, Geneva (Switzerland)

    2016-07-01

    We study WZ production with anomalous couplings (AC) at anti nNLO QCD using the LoopSim method in combination with the Monte Carlo program VBFNLO. Higher order corrections to WZ production are dominated by additional hard jet radiation. Those contributions are insensitive to AC and should thus be suppressed in analyses. We do this using a dynamical jet veto based on the transverse energy of the QCD and EW final state particles. This removes jet dominated events without introducing problematic logs like a fixed p{sub T} jet veto.

  5. Hard coatings

    International Nuclear Information System (INIS)

    Dan, J.P.; Boving, H.J.; Hintermann, H.E.

    1993-01-01

    Hard, wear resistant and low friction coatings are presently produced on a world-wide basis, by different processes such as electrochemical or electroless methods, spray technologies, thermochemical, CVD and PVD. Some of the most advanced processes, especially those dedicated to thin film depositions, basically belong to CVD or PVD technologies, and will be looked at in more detail. The hard coatings mainly consist of oxides, nitrides, carbides, borides or carbon. Over the years, many processes have been developed which are variations and/or combinations of the basic CVD and PVD methods. The main difference between these two families of deposition techniques is that the CVD is an elevated temperature process (≥ 700 C), while the PVD on the contrary, is rather a low temperature process (≤ 500 C); this of course influences the choice of substrates and properties of the coating/substrate systems. Fundamental aspects of the vapor phase deposition techniques and some of their influences on coating properties will be discussed, as well as the very important interactions between deposit and substrate: diffusions, internal stress, etc. Advantages and limitations of CVD and PVD respectively will briefly be reviewed and examples of applications of the layers will be given. Parallel to the development and permanent updating of surface modification technologies, an effort was made to create novel characterisation methods. A close look will be given to the coating adherence control by means of the scratch test, at the coating hardness measurement by means of nanoindentation, at the coating wear resistance by means of a pin-on-disc tribometer, and at the surface quality evaluation by Atomic Force Microscopy (AFM). Finally, main important trends will be highlighted. (orig.)

  6. Hadron interactions at high energy in QCD

    International Nuclear Information System (INIS)

    Levin, E.M.; Ryskin, M.G.

    1988-01-01

    Well known the typical hadronic interactions at high energy are soft processes occurring at large distances where the mysterious confinement forces should be essential. Due to this fact, discussing these processes at first sight the authors are to use and really use some models that incorporate their educated guess about the confinement and utilize the QCD degrees of freedom. But really these models use the QCD terminology rather than the explicit form of the QCD interaction. Up to now the multiparticle dynamics had been the dynamics of reggeons with some detailization coming from their hypothesis about confinement. It is the Reggeon Calculus or the reggeon phenomenology that allows them to describe the main properties of exclusive and inclusive reactions at high energy in agreement with experiment. This paper discusses this problem at this Symposium in many details. However, such pure phenomenological understanding cannot satisfy all of us at the moment. The authors would like to understand the multiparticle production and other soft processes at high energy in more microscopic way using directly the form of the QCD Lagrangian

  7. Computerized micrographics in processing hard-copy records for an epidemiologic study

    International Nuclear Information System (INIS)

    Robie, D.M.; Fry, S.A.

    1983-01-01

    The availability of computers with increasing capabilities has made feasibile epidemiologic studies involving large populations such as those utilized to evaluate the health effects of occupational exposure to radiation. However, the storage and retrieval of data from the large numbers of hard-copy personnel, health physics, employment medical, historical or anecdotal documents that are the bases of such studies pose major logistics problems to investigators. The potential value of such records to epidemiologic studies depends, not only on their accuracy and completeness, but also on ease of accessibility. To address the latter problem, we are using a stand-alone user-oriented electronic filing system that records, stores, and secures hard-copy documents micrographically. This system is controlled by a computer that provides retrieval of a document image and printed copy (if desired) in less than 30 seconds from a maximum of eight fields. One thousand documents are randomly filmed and indexed on computer storage diskettes in two hours. Manual sorting and filing of the same number of documents takes over a day. At present two thousand documents can be recorded on each microfilm roll and 85,000 documents indexed on each diskette. Simultaneous searching for documents can be done using up to ten terminals while indexing is being done at the main terminal. The micrographics system provides the space-saving and security advantages of microfilm with the speed of computerized data retrieval

  8. Daily Stress, Hearing-Specific Stress and Coping: Self-Reports from Deaf or Hard of Hearing Children and Children with Auditory Processing Disorder

    Science.gov (United States)

    Eschenbeck, Heike; Gillé, Vera; Heim-Dreger, Uwe; Schock, Alexandra; Schott, Andrea

    2017-01-01

    This study evaluated stressors and coping strategies in 70 children who are deaf or hard of hearing (D/HH) or with auditory processing disorder (APD) attending Grades 5 and 6 of a school for deaf and hard-of-hearing children. Everyday general stressors and more hearing-specific stressors were examined in a hearing-specific modified stress and…

  9. QCD factorization of exclusive processes beyond leading twist: γT*→ρT impact factor with twist three accuracy

    International Nuclear Information System (INIS)

    Anikin, I.V.; Ivanov, D.Yu.; Pire, B.; Szymanowski, L.; Wallon, S.

    2010-01-01

    We describe a consistent approach to factorization of scattering amplitudes for exclusive processes beyond the leading twist approximation. The method involves the Taylor expansion of the scattering amplitude in the momentum space around the dominant light-cone direction and thus naturally introduces an appropriate set of non-perturbative correlators which encode effects not only of the lowest but also of the higher Fock states of the produced particle. The reduction of original set of correlators to a set of independent ones is achieved with the help of equations of motion and invariance of the scattering amplitude under rotation on the light cone. We compare the proposed method with the covariant method formulated in the coordinate space, based on the operator product expansion. We prove the equivalence of two proposed parametrizations of the ρ T distribution amplitudes. As a concrete application, we compute the expressions of the impact factor for the transition of virtual photon to transversally polarised ρ-meson up to the twist 3 accuracy within these two quite different methods and show that they are identical.

  10. Universality of transverse-momentum resummation and hard factors at the NNLO

    Energy Technology Data Exchange (ETDEWEB)

    Catani, Stefano [INFN, Sezione di Firenze and Dipartimento di Fisica e Astronomia, Università di Firenze, I-50019 Sesto Fiorentino, Florence (Italy); Cieri, Leandro [Dipartimento di Fisica, Università di Roma “La Sapienza” and INFN, Sezione di Roma, I-00185 Rome (Italy); Florian, Daniel de [Departamento de Física, FCEYN, Universidad de Buenos Aires, (1428) Pabellón 1 Ciudad Universitaria, Capital Federal (Argentina); Ferrera, Giancarlo [Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, I-20133 Milan (Italy); Grazzini, Massimiliano [Institut für Theoretische Physik, Universität Zürich, CH-8057 Zürich (Switzerland)

    2014-04-15

    We consider QCD radiative corrections to the production of colorless high-mass systems in hadron collisions. The logarithmically-enhanced contributions at small transverse momentum are treated to all perturbative orders by a universal resummation formula that depends on a single process-dependent hard factor. We show that the hard factor is directly related to the all-order virtual amplitude of the corresponding partonic process. The direct relation is universal (process-independent), and it is expressed by an all-order factorization formula that we explicitly evaluate up to the next-to-next-to-leading order (NNLO) in QCD perturbation theory. Once the NNLO scattering amplitude is available, the corresponding hard factor is directly determined: it controls NNLO contributions in resummed calculations at full next-to-next-to-leading logarithmic accuracy, and it can be used in applications of the q{sub T} subtraction formalism to perform fully-exclusive perturbative calculations up to NNLO. The universality structure of the hard factor and its explicit NNLO form are also extended to the related formalism of threshold resummation.

  11. Assessing accumulated hard-tissue debris using micro-computed tomography and free software for image processing and analysis.

    Science.gov (United States)

    De-Deus, Gustavo; Marins, Juliana; Neves, Aline de Almeida; Reis, Claudia; Fidel, Sandra; Versiani, Marco A; Alves, Haimon; Lopes, Ricardo Tadeu; Paciornik, Sidnei

    2014-02-01

    The accumulation of debris occurs after root canal preparation procedures specifically in fins, isthmus, irregularities, and ramifications. The aim of this study was to present a step-by-step description of a new method used to longitudinally identify, measure, and 3-dimensionally map the accumulation of hard-tissue debris inside the root canal after biomechanical preparation using free software for image processing and analysis. Three mandibular molars presenting the mesial root with a large isthmus width and a type II Vertucci's canal configuration were selected and scanned. The specimens were assigned to 1 of 3 experimental approaches: (1) 5.25% sodium hypochlorite + 17% EDTA, (2) bidistilled water, and (3) no irrigation. After root canal preparation, high-resolution scans of the teeth were accomplished, and free software packages were used to register and quantify the amount of accumulated hard-tissue debris in either canal space or isthmus areas. Canal preparation without irrigation resulted in 34.6% of its volume filled with hard-tissue debris, whereas the use of bidistilled water or NaOCl followed by EDTA showed a reduction in the percentage volume of debris to 16% and 11.3%, respectively. The closer the distance to the isthmus area was the larger the amount of accumulated debris regardless of the irrigating protocol used. Through the present method, it was possible to calculate the volume of hard-tissue debris in the isthmuses and in the root canal space. Free-software packages used for image reconstruction, registering, and analysis have shown to be promising for end-user application. Copyright © 2014. Published by Elsevier Inc.

  12. Sensitivity testing practice on pre-processing parameters in hard and soft coupled modeling

    Directory of Open Access Journals (Sweden)

    Z. Ignaszak

    2010-01-01

    Full Text Available This paper pays attention to the problem of practical applicability of coupled modeling with the use of hard and soft models types and necessity of adapted to that models data base possession. The data base tests results for cylindrical 30 mm diameter casting made of AlSi7Mg alloy were presented. In simulation tests that were applied the Calcosoft system with CAFE (Cellular Automaton Finite Element module. This module which belongs to „multiphysics” models enables structure prediction of complete casting with division of columnar and equiaxed crystals zones of -phase. Sensitivity tests of coupled model on the particular values parameters changing were made. On these basis it was determined the relations of CET (columnar-to-equaiaxed transition zone position influence. The example of virtual structure validation based on real structure with CET zone location and grain size was shown.

  13. Ultrashort pulse laser processing of hard tissue, dental restoration materials, and biocompatibles

    Science.gov (United States)

    Yousif, A.; Strassl, M.; Beer, F.; Verhagen, L.; Wittschier, M.; Wintner, E.

    2007-07-01

    During the last few years, ultra-short laser pulses have proven their potential for application in medical tissue treatment in many ways. In hard tissue ablation, their aptitude for material ablation with negligible collateral damage provides many advantages. Especially teeth representing an anatomically and physiologically very special region with less blood circulation and lower healing rates than other tissues require most careful treatment. Hence, overheating of the pulp and induction of microcracks are some of the most problematic issues in dental preparation. Up till now it was shown by many authors that the application of picosecond or femtosecond pulses allows to perform ablation with very low damaging potential also fitting to the physiological requirements indicated. Beside the short interaction time with the irradiated matter, scanning of the ultra-short pulse trains turned out to be crucial for ablating cavities of the required quality. One main reason for this can be seen in the fact that during scanning the time period between two subsequent pulses incident on the same spot is so much extended that no heat accumulation effects occur and each pulse can be treated as a first one with respect to its local impact. Extension of this advantageous technique to biocompatible materials, i.e. in this case dental restoration materials and titanium plasma-sprayed implants, is just a matter of consequence. Recently published results on composites fit well with earlier data on dental hard tissue. In case of plaque which has to be removed from implants, it turns out that removal of at least the calcified version is harder than tissue removal. Therefore, besides ultra-short lasers, also Diode and Neodymium lasers, in cw and pulsed modes, have been studied with respect to plaque removal and sterilization. The temperature increase during laser exposure has been experimentally evaluated in parallel.

  14. Scale hierarchy in high-temperature QCD

    CERN Document Server

    Akerlund, Oscar

    2013-01-01

    Because of asymptotic freedom, QCD becomes weakly interacting at high temperature: this is the reason for the transition to a deconfined phase in Yang-Mills theory at temperature $T_c$. At high temperature $T \\gg T_c$, the smallness of the running coupling $g$ induces a hierachy betwen the "hard", "soft" and "ultrasoft" energy scales $T$, $g T$ and $g^2 T$. This hierarchy allows for a very successful effective treatment where the "hard" and the "soft" modes are successively integrated out. However, it is not clear how high a temperature is necessary to achieve such a scale hierarchy. By numerical simulations, we show that the required temperatures are extremely high. Thus, the quantitative success of the effective theory down to temperatures of a few $T_c$ appears surprising a posteriori.

  15. QCD tests at CDF

    International Nuclear Information System (INIS)

    Kovacs, E.

    1996-02-01

    We present results for the inclusive jet cross section and the dijet mass distribution. The inclusive cross section and dijet mass both exhibit significant deviations from the predictions of NLO QCD for jets with E T >200 GeV, or dijet masses > 400 GeV/c 2 . We show that it is possible, within a global QCD analysis that includes the CDF inclusive jet data, to modify the gluon distribution at high x. The resulting increase in the jet cross-section predictions is 25-35%. Owing to the presence of k T smearing effects, the direct photon data does not provide as strong a constraint on the gluon distribution as previously thought. A comparison of the CDF and UA2 jet data, which have a common range in x, is plagued by theoretical and experimental uncertainties, and cannot at present confirm the CDF excess or the modified gluon distribution

  16. The QCD Effective String

    International Nuclear Information System (INIS)

    Espriu, D.

    2003-01-01

    QCD can be described in a certain kinematical regime by an effective string theory. This string must couple to background chiral fields in a chirally invariant manner, thus taking into account the true chirally non-invariant QCD vacuum. By requiring conformal symmetry of the string and the unitarity constraint on chiral fields we reconstruct the equations of motion for the latter ones. These provide a consistent background for the propagation of the string. By further requiring locality of the effective action we recover the Lagrangian of non-linear sigma model of pion interactions. The prediction is unambiguous and parameter-free. The estimated chiral structural constants of Gasser and Leutwyler fit very well the phenomenological values. (author)

  17. The Role of Diffusion Media in Nitriding Process on Surface Layers Characteristics of AISI 4140 with and without Hard Chrome Coatings

    Directory of Open Access Journals (Sweden)

    K.A. Widi

    2016-09-01

    Full Text Available The surface layer characteristics of the AISI 4140 tool steel treated by nitriding gas before and after hard chrome plating utilizing pure nitrogen diffusion media (fluidized bed reactor and the without gas (muffle reactor has been studied experimentally. The result shows that nitriding substrate with hard chrome layers has nitrogen atoms concentration almost twice greater than that without hard chrome layers. After being given a hard chrome plating, nitriding on AISI 4140 steel generally has a nitrogen concentration of up to 4 times more than the substrate without hard chrome coating. Almost the entire specimen showed the highest concentration of N atoms in the area below the surface (hardening depth of 200 to 450 µm. N atoms diffusion depth profile has a correlation with hardening depth profile, especially on the specimens layered with hard chromium. The substrate without hard chrome plating tends to have higher surface hardness than the sub-surface. The results show that the effectiveness and efficiency of the gas nitriding diffusion process can be produced without the use of gas in the muffle reactor but the specimens must be hard chromium coated first. This phenomenon can be explained by the role of the passive layer formation that works as a barrier to keeps the spreading of N atoms concentrated in sub-surface areas.

  18. Study of multiple hard-scatter processes from different p p interactions in the same ATLAS event

    CERN Document Server

    The ATLAS collaboration

    2018-01-01

    Given the large integrated luminosity and the large average pileup in the 2017 ATLAS dataset, the probability of having two leptonically decaying Z bosons originating from separate $pp$ interactions in the same LHC bunch crossing becomes non-negligible. Such events are searched for and the number observed compared with the expectation. These types of events (also for the case involving other hard scatter processes, such as W, photon or top quark production, in the same event) may cause additional backgrounds for particular physics analyses, and therefore this background must be accounted for when relevant.

  19. QCD and RHIC

    International Nuclear Information System (INIS)

    Kharzeev, D.

    2004-01-01

    In this talk I discuss recent advances in Quantum Chromo-Dynamics, in particular the progress in understanding the collective dynamics of the theory. I emphasise the significance of the RHIC program for establishing the properties of hot and dense QCD matter and for understanding the dynamics of the theory at the high parton density, strong color field frontier. Hopes and expectations for the future are discussed as well

  20. WORKSHOP QCD at 20

    International Nuclear Information System (INIS)

    Nachtmann, O.

    1992-01-01

    The modern theory of strong interactions - Quantum Chromodynamics (QCD), where quarks and gluons carrying the 'colour' quantum number play the essential role, is twenty years old. This birthday was duly celebrated at RWTH Aachen from 9-13 June, where recurring themes were - what has been achieved in the past twenty years?, where do we stand?, and what are the perspectives for the future?

  1. String dynamics in QCD

    International Nuclear Information System (INIS)

    Gervais, J.L.; Neveu, A.

    1980-01-01

    Recent works of the authors on string interpretation of the Wilson loop operators in QCD are reviewed in a self-contained fashion. Although most of the results habe already appeared in print, some new material is presented in renormalization of the Wilson loop operator and on the use of light-cone expansion to derive a linear string-like equation in light-cone formalism. (orig.)

  2. Introduction to QCD

    OpenAIRE

    Skands, Peter

    2012-01-01

    These lectures were originally given at TASI and are directed at a level suitable for graduate students in High Energy Physics. They are intended to give an introduction to the theory and phenomenology of quantum chromodynamics (QCD), focusing on collider physics applications. The aim is to bring the reader to a level where informed decisions can be made concerning different approaches and their uncertainties. The material is divided into five main areas: 1) fundamentals, 2) fixed-order pertu...

  3. The QCD Teraflops Project

    International Nuclear Information System (INIS)

    Gottlieb, S.

    1992-01-01

    Increased computer power is essential for future progress in lattice gauge theory and for other Grand challenge applications. We address the physics that can be done with a computer capable of sustaining 1 Teraflops for QCD and the technology that will make it possible to construct such a computer within the next three years. Our collaboration has proposed to build a computer based on the Thinking Machines CM5 communication network, but with nodes 10 times faster

  4. On the automation of periodic hard real-time processes: a graph-theoretical approach

    OpenAIRE

    Boode, Antoon Hendrik

    2018-01-01

    Summary In certain single-core mono-processor configurations, e.g. embedded control systems like robotic applications comprising many short processes, process context switches may consume a considerable amount of the available processing power. Reducing the number of context switches decreases the execution time and thereby increases the performance of the application. Furthermore, the end-to-end processing time suffers from the idle time of the processor, because, for example, processes have...

  5. All-loops calculation of the structure function x→0 in perturbative QCD

    International Nuclear Information System (INIS)

    Catani, S.

    1991-01-01

    We study in perturbative QCD the initial-state radiation associated to hadron processes in the semi-hard region of small x (x is the Bjorken variable). A recent analysis of the exclusive multi-gluon distributions to double (infrared and collinear) logarithmic accuracy is extended to the case of inclusive distributions, which we evaluate to single (infrared) logarithmic accuracy. Thus the resulting x→0 structure function or N→1 gluon anomalous dimension is computed to all-loops accuracy. For the inclusive distributions we are able to perform a calculation to such an accuracy by extensively using cancellations which originate from coherence of QCD radiation and the infrared regularity of real-virtual singularities. We find that the x→0 structure function satisfies the Lipatov equation. With the present study we therefore provide a new derivation of the Lipatov result in the context of hard collisions together with a fully exclusive description. We discuss the structure of the Lipatov equation in relation with the x→0 exclusive distributions previously obtained and with the Altarelli-Parisi equation valid for finite values of x. (orig.)

  6. Hadron physics from lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, Andreas [Regensburg Univ. (Germany). Inst. for Theoretical Physics

    2016-11-01

    propagate a three quark state simply three such Greens functions have to be convoluted. As we discussed, the unwanted heavy hadronic states, the so-called ''excited states'' get exponentially suppressed by the propagation in imaginary time. However, in parallel the signal of interest is also reduced, which faces any Lattice QCD practitioner with a serious optimization problem: If he chooses a very strong exponential suppression of unwanted states also the signal is lost, if he chooses a weak suppression, his signal is distorted by excited state artifacts. Therefore, many ingenious ideas were developed to improve this filtering process. One of the most efficient ones is to increase the overlap of source and sink with the hadron of interest by a process called ''smearing''. In practice, to cope with this problem, the careful analysis of many different statistical ensembles using a multitude of analysis strategies, e.g. different smearing prescriptions, is needed to obtain a realistic systematic uncertainties for all analyzed quantities. To perform such analyses for a large selection of hadronic observables was the purpose of this project. Some of these were already discussed in last years report. Therefore, we are concentrating here on some new ones. As the theoretical challenges are very similar for all of them, many applications are equally well suited for such a demonstration.

  7. Dual QCD: A review

    International Nuclear Information System (INIS)

    Baker, M.; Ball, J.S.; Zachariasen, F.

    1991-01-01

    We review the attempts to use dual (electric) vector potentials rather than the standard magnetic vector potentials to describe QCD, particularly in the infrared regime. The use of dual potentials is motivated by the fact that in classical electrodynamics, in a medium with a dielectric constant vanishing at small momenta (as is believed to be the case in QCD), electric potentials provide a far more convenient language than do magnetic potentials. To begin with, we outline attempts to construct the QCD Lagrangian in terms of dual potentials and describe the various possibilities, their shortcomings and advantages, which so far exist. We then proceed to use the most attractive (albeit consistent as a field theory only at the tree level) of these Lagrangians in a number of applications. We show that it describes a non-Abelian dual superconductor (so that it automatically confines color), derive the static quark-antiquark potential, and various temperature dependent effects, such as deconfinement and chiral symmetry breaking. (orig.)

  8. QCD: Renormalization for the practitioner

    International Nuclear Information System (INIS)

    Pascual, P.; Tarrach, R.

    1984-01-01

    These notes correspond to a GIFT (Grupo Interuniversitario de Fisica Teorica) course which was given by us in autumn 1983 at the University of Barcelona. Their main subject is renormalization in perturbative QCD and only the last chapter goes beyond perturbation theory. They are essentially self contained and their aim is to teach the student the techniques of perturbative QCD and the QCD sum rules. (orig./HSI)

  9. Open heavy flavor and other hard probes in ultra-relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Uphoff, Jan

    2013-01-01

    In this thesis hard probes are studied in the partonic transport model BAMPS (Boltzmann Approach to MultiParton Scatterings). Employing Monte Carlo techniques, this model describes the 3+1 dimensional evolution of the quark gluon plasma phase in ultra-relativistic heavy-ion collisions by propagating all particles in space and time and carrying out their collisions according to the Boltzmann equation. Since hard probes are produced in hard processes with a large momentum transfer, the value of the running coupling is small and their interactions should be describable within perturbative QCD (pQCD). This work focuses on open heavy flavor, but also addresses the suppression of light parton jets, in particular to highlight differences due to the mass. For light partons, radiative processes are the dominant contribution to their energy loss. For heavy quarks, we show that also binary interactions with a running coupling and an improved Debye screening matched to hard-thermal-loop calculations play an important role. Furthermore, the impact of the mass in radiative interactions, prominently named the dead cone effect, and the interplay with the Landau-Pomeranchuk-Migdal (LPM) effect are studied in great detail. Since the transport model BAMPS has access to all medium properties and the space time information of heavy quarks, it is the ideal tool to study the dissociation and regeneration of J/ψ mesons, which is also investigated in this thesis.

  10. Visualization of electrolyte filling process and influence of vacuum during filling for hard case prismatic lithium ion cells by neutron imaging to optimize the production process

    Science.gov (United States)

    Weydanz, W. J.; Reisenweber, H.; Gottschalk, A.; Schulz, M.; Knoche, T.; Reinhart, G.; Masuch, M.; Franke, J.; Gilles, R.

    2018-03-01

    The process of filling electrolyte into lithium ion cells is time consuming and critical to the overall battery quality. However, this process is not well understood. This is partially due to the fact, that it is hard to observe it in situ. A powerful tool for visualization of the process is neutron imaging. The filling and wetting process of the electrode stack can be clearly visualized in situ without destruction of the actual cell. The wetting of certain areas inside the electrode stack can clearly be seen when using this technique. Results showed that wetting of the electrode stack takes place in a mostly isotropic manner from the outside towards a center point of the cell at very similar speed. When the electrolyte reaches the center point, the wetting process can be considered complete. The electrode wetting is a slow but rather steady process for hard case prismatic cells. It starts with a certain speed, which is reduced over the progress of the wetting. Vacuum can assist the process and accelerate it by about a factor of two as was experimentally shown. This gives a considerable time and cost advantage for designing the production process for large-scale battery cell production.

  11. Renormalization of Extended QCD2

    International Nuclear Information System (INIS)

    Fukaya, Hidenori; Yamamura, Ryo

    2015-01-01

    Extended QCD (XQCD), proposed by Kaplan [D. B. Kaplan, arXiv:1306.5818], is an interesting reformulation of QCD with additional bosonic auxiliary fields. While its partition function is kept exactly the same as that of original QCD, XQCD naturally contains properties of low-energy hadronic models. We analyze the renormalization group flow of 2D (X)QCD, which is solvable in the limit of a large number of colors N c , to understand what kind of roles the auxiliary degrees of freedom play and how the hadronic picture emerges in the low-energy region

  12. Hadron structure from lattice QCD

    International Nuclear Information System (INIS)

    Schaefer, Andreas

    2008-01-01

    Some elements and current developments of lattice QCD are reviewed, with special emphasis on hadron structure observables. In principle, high precision experimental and lattice data provide nowadays a very detailled picture of the internal structure of hadrons. However, to relate both, a very good controle of perturbative QCD is needed in many cases. Finally chiral perturbation theory is extremely helpful to boost the precision of lattice calculations. The mutual need and benefit of all four elements: experiment, lattice QCD, perturbative QCD and chiral perturbation theory is the main topic of this review

  13. Thermal Phenomena in the Friction Process of the TG15 - Hard Anodic Coating Couple

    Directory of Open Access Journals (Sweden)

    Służałek G.

    2016-09-01

    Full Text Available The paper presents a one-dimensional model of heat conduction in a couple consisting of a cylinder made of a sliding plastic material, TG15, and a cuboid made of alloy AW 6061 coated with a hard anodic coating, where the couple is heated with the heat generated during friction. TG15 is a composite material based on polytetrafluoroethylene (PTFE with a 15% graphite filler, used for piston rings in oil-free air-compressors. Measurement of temperature in the friction zone is extremely important for the understanding and analysis of the phenomena occurring therein. It is practically impossible to introduce a temperature sensor in such a place. Therefore, the interaction taking place in such a couple was modelled using numerical methods. In order to simplify and accelerate the calculations, a one-dimensional model and constant thermophysical parameters of the materials participating in friction were adopted. To solve the proposed model, the finite difference method was used (FDM. The resultant system of equations was solved by means of an explicit scheme.

  14. Heavy-Quark Associated Production with One Hard Photon at Hadron Colliders

    Energy Technology Data Exchange (ETDEWEB)

    Hartanto, Heribertus Bayu [Florida State Univ., Tallahassee, FL (United States)

    2013-01-01

    We present the calculation of heavy-quark associated production with a hard photon at hadron colliders, namely $pp(p\\bar p) → Q\\bar Q +X$γ (for $Q=t,b$), at Next-to-Leading Order (NLO) in Quantum Chromodynamics (QCD). We study the impact of NLO QCD corrections on the total cross section and several differential distributions at both the Tevatron and the Large Hadron Collider (LHC). For $t\\bar t$γ production we observe a sizeable reduction of the renormalization and factorization scale dependence when the NLO QCD corrections are included, while for $b\\bar b$γ production a considerable scale dependence still persists at NLO in QCD. This is consistent with what emerges in similar processes involving $b$ quarks and vector bosons and we explain its origin in detail. For $b\\bar b$γ production we study both the case in which at least one $b$ jet and the case in which at least two $b$ jets are observed. We perform the $b\\bar b$γ calculation using the Four Flavor Number Scheme (4FNS) and compare the case where at least one $b$ jet is observed with the corresponding results from the Five Flavor Number Scheme (5FNS) calculation. Finally we compare our results for $p\\bar p →+b+X$γ with the Tevatron data.

  15. On the automation of periodic hard real-time processes : a graph-theoretical approach

    NARCIS (Netherlands)

    Boode, Antoon Hendrik

    2018-01-01

    Summary In certain single-core mono-processor configurations, e.g. embedded control systems like robotic applications comprising many short processes, process context switches may consume a considerable amount of the available processing power. Reducing the number of context switches decreases the

  16. Laser shock processing on microstructure and hardness of polycrystalline cubic boron nitride tools with and without nanodiamond powders

    International Nuclear Information System (INIS)

    Melookaran, Roslyn; Melaibari, Ammar; Deng, Cheng; Molian, Pal

    2012-01-01

    Highlights: ► Laser shock waves hardened polycrystalline cubic boron nitride tools by up to 15%. ► Laser shock waves can build layer-by-layer of nanodiamond to form micro-diamond tools. ► Multiple laser shocks induce significant phase transitions in cBN and nanodiamond. -- Abstract: High amplitude, short duration shock waves created by a 1064 nm, 10 ns Q-switched Nd:YAG laser were used to increase the hardness as well as build successive layers of nanodiamond on sintered polycrystalline cubic boron nitride (PcBN) tools. Multiple scans of laser shocking were applied. Scanning electron microscopy, Raman spectroscopy, Tukon microhardness tester, and optical surface profilometer were used to evaluate the microstructure, phase change, Vicker’s microhardness and surface roughness. Results indicated that laser shock processing of plain PcBN changed the binder concentration, caused phase transition from cubic to hexagonal form, increased the hardness, and almost unaffected surface roughness. Laser shock wave sintering of nanodiamond powders on PcBN resulted in deagglomeration and layer-by-layer build-up of nanoparticles for a thickness of 30 μm inferring that a novel solid freeform technique designated as “shock wave induced freeform technique (SWIFT)” is being discovered for making micro-tools. Depending on the number of multiple laser shocks, the hardness of nanodiamond compact was lower or higher than that of PcBN. It is hypothesized that nanodiamond particles could serve as crack deflectors, increasing the fracture toughness of PcBN.

  17. The rational parts of one-loop QCD amplitudes I: The general formalism

    International Nuclear Information System (INIS)

    Xiao Zhiguang; Yang Gang; Zhu Chuanjie

    2006-01-01

    A general formalism for computing only the rational parts of one-loop QCD amplitudes is developed. Starting from the Feynman integral representation of the one-loop amplitude, we use tensor reduction and recursive relations to compute the rational parts directly. Explicit formulas for the rational parts are given for all bubble and triangle integrals. Formulas are also given for box integrals up to two-mass-hard boxes which are the needed ingredients to compute up to 6-gluon QCD amplitudes. We use this method to compute explicitly the rational parts of the 5- and 6-gluon QCD amplitudes in two accompanying papers

  18. Soft Pomeron in Holographic QCD

    CERN Document Server

    Ballon-Bayona, Alfonso; Costa, Miguel S; Djurić, Marko

    2016-01-01

    We study the graviton Regge trajectory in Holographic QCD as a model for high energy scattering processes dominated by soft pomeron exchange. This is done by considering spin J fields from the closed string sector that are dual to glueball states of even spin and parity. In particular, we construct a model that governs the analytic continuation of the spin J field equation to the region of real J < 2, which includes the scattering domain of negative Maldelstam variable t. The model leads to approximately linear Regge trajectories and is compatible with the measured values of 1.08 for the intercept and 0.25 GeV$^{-2}$ for the slope of the soft pomeron. The intercept of the secondary pomeron trajectory is in the same region of the subleading trajectories, made of mesons, proposed by Donnachie and Landshoff, and should therefore be taken into account.

  19. Colour singlets in perturbative QCD

    International Nuclear Information System (INIS)

    Bassetto, A.

    1979-01-01

    In the axial gauge and at the leading log level, a definite and consistent picture seems to emerge of a parton decay into states in which many partons are found just before confinement should take place. They are grouped into colourless clusters in a number sufficient to exhaust the ''final'' state, still possessing a finite average mass. This result is peculiar of QCD, in particular of its non-abelian nature. Large transverse momenta or more generally average invariant quantities of partons are mainly due to the multiplicities involved in the branching processes. If eventually confinement would convert these clusters into hadrons (and this is of course the main issue which has still to be proven) without a large rearrangement of the colour lines, the picture we have found for colour singlets could apply to the real hadronic world. (author)

  20. Investigation on Effect of Material Hardness in High Speed CNC End Milling Process

    OpenAIRE

    Dhandapani, N. V.; Thangarasu, V. S.; Sureshkannan, G.

    2015-01-01

    This research paper analyzes the effects of material properties on surface roughness, material removal rate, and tool wear on high speed CNC end milling process with various ferrous and nonferrous materials. The challenge of material specific decision on the process parameters of spindle speed, feed rate, depth of cut, coolant flow rate, cutting tool material, and type of coating for the cutting tool for required quality and quantity of production is addressed. Generally, decision made by the...

  1. QCD: Questions, challenges, and dilemmas

    International Nuclear Information System (INIS)

    Bjorken, J.

    1996-11-01

    An introduction to some outstanding issues in QCD is presented, with emphasis on work by Diakonov and co-workers on the influence of the instanton vacuum on low-energy QCD observables. This includes the calculation of input valence-parton distributions for deep-inelastic scattering. 35 refs., 3 figs

  2. Experimental Summary Moriond QCD 2007

    CERN Document Server

    Rolandi, Gigi

    2007-01-01

    More than 90 speakers gave a presentation at this years Moriond QCD conference and more than 60 talks reported the experimental status and perspectives on Standard Model, especially QCD, search for new physics, quark spectroscopy and Heavy Ions physics. I summarize what I consider the highlights of these presentations.

  3. Nuclear properties from perturbative QCD

    International Nuclear Information System (INIS)

    Close, F.E.; Roberts, R.G.; Ross, G.G.

    1986-01-01

    Two apparently different descriptions of quark distributions in a nucleus may in fact be connected. A ''duality'' between the QCD approach and the conventional model of nucleon binding leads to nuclear properties being simply related to the anomalous dimensions of QCD. (orig.)

  4. Quarklei: nuclear physics from QCD

    International Nuclear Information System (INIS)

    Goldman, T.

    1985-01-01

    The difficulties posed for nuclear physics by either recognizing or ignoring QCD, are discussed. A QCD model for nuclei is described. A crude approximation is shown to qualitatively reproduce saturation of nuclear binding energies and the EMC effect. The model is applied seriously to small nuclei, and to hypernuclei

  5. Composite operators in QCD

    International Nuclear Information System (INIS)

    Sonoda, Hidenori

    1992-01-01

    We give a formula for the derivatives of a correlation function of composite operators with respect to the parameters (i.e. the strong fine structure constant and the quark mass) of QCD in four- dimensional euclidean space. The formula is given as spatial integration of the operator conjugate to a parameter. The operator product of a composite operator and a conjugate operator has an unintegrable part, and the formula requires divergent subtractions. By imposing consistency conditions we drive a relation between the anomalous dimensions of the composite operators and the unintegrable part of the operator product coefficients. (orig.)

  6. Process optimization and properties of magnetically hard cobalt carbide nanoparticles via modified polyol method

    International Nuclear Information System (INIS)

    Zamanpour, Mehdi; Bennett, Steven P.; Majidi, Leily; Chen, Yajie; Harris, Vincent G.

    2015-01-01

    Highlights: • High-coercivity cobalt carbides were synthesized by polyol method. • No rare earth elements were used during synthesis process. • Process parameters (reaction temperature, precursors’ concentrations, surfactants and reaction duration) were studied/optimized. • Process was scaled-up to synthesis more than 5 g powders per batch. - Abstract: Cobalt carbide magnetic nanoparticles were successfully synthesized via a modified polyol process without using a rare-earth catalyst during the synthesis process. The present results show admixtures of Co 2 C and Co 3 C phases possessing magnetization values exceeding 47 emu/g and coercivity values exceeding 2.3 kOe at room temperature. Moreover, these experiments have illuminated the important role of the reaction temperature, hydroxyl ion concentrations and the reaction duration on the crystallographic structure and magnetic properties of the nanoparticles. The crystallographic structure and particle size of the Co x C nanoparticles were characterized by X-ray diffractometry and scanning electron microscopy. Vibrating sample magnetometry was used to determine magnetic properties. Scale-up of synthesis to more than 5 g per batch was demonstrated with no significant degradation of magnetic properties

  7. Process optimization and properties of magnetically hard cobalt carbide nanoparticles via modified polyol method

    Energy Technology Data Exchange (ETDEWEB)

    Zamanpour, Mehdi; Bennett, Steven P. [Center for Microwave Magnetic Materials and Integrated Circuits (CM3IC), Northeastern University, Boston, MA 02115 (United States); Majidi, Leily [Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA 02115 (United States); Chen, Yajie [Center for Microwave Magnetic Materials and Integrated Circuits (CM3IC), Northeastern University, Boston, MA 02115 (United States); Harris, Vincent G. [Center for Microwave Magnetic Materials and Integrated Circuits (CM3IC), Northeastern University, Boston, MA 02115 (United States); Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115 (United States)

    2015-03-15

    Highlights: • High-coercivity cobalt carbides were synthesized by polyol method. • No rare earth elements were used during synthesis process. • Process parameters (reaction temperature, precursors’ concentrations, surfactants and reaction duration) were studied/optimized. • Process was scaled-up to synthesis more than 5 g powders per batch. - Abstract: Cobalt carbide magnetic nanoparticles were successfully synthesized via a modified polyol process without using a rare-earth catalyst during the synthesis process. The present results show admixtures of Co{sub 2}C and Co{sub 3}C phases possessing magnetization values exceeding 47 emu/g and coercivity values exceeding 2.3 kOe at room temperature. Moreover, these experiments have illuminated the important role of the reaction temperature, hydroxyl ion concentrations and the reaction duration on the crystallographic structure and magnetic properties of the nanoparticles. The crystallographic structure and particle size of the Co{sub x}C nanoparticles were characterized by X-ray diffractometry and scanning electron microscopy. Vibrating sample magnetometry was used to determine magnetic properties. Scale-up of synthesis to more than 5 g per batch was demonstrated with no significant degradation of magnetic properties.

  8. Hard scattering contribution to particle production in high energy heavy-ion collisions

    International Nuclear Information System (INIS)

    Pareek, Pooja; Mishra, Aditya Nath; Sahoo, Pragati; Sahoo, Raghunath

    2014-01-01

    Global observables like the multiplicity of produced charged particles and transverse energy, are the key observables used to characterize the properties of the matter created in heavy-ion collisions. In order to study the dependence of the charged particle density on colliding system, center of mass energy and collision centrality, there have been measurements starting few GeV to TeV energies at LHC. There is a need to understand the particle production contribution coming from the QCD hard processes, which scale with number of binary nucleon-nucleon collisions, N coll and soft processes scaling with number of participant nucleons, N part

  9. Effect of cutting temperature on hardness of SiC and diamond in the nano-cutting process of monocrystalline silicon

    Science.gov (United States)

    Wang, Jiachun; Li, Yuntao; Liu, Xiaoxuan; Lv, Maoqiang

    2016-10-01

    In the process of cutting silicon by natural diamond tools, groove wear happens on the flank face of cutting tool frequently.Scholars believe that one of the wear reasons is mechanical scratching effect by hard particles like SiC. To reveal the mechanical scratching mechanism, it is essential to study changes in the mechanical properties of hard particles and diamond, especially the effect of cutting temperature on hardness of diamond and hard particles. Molecular dynamics (MD) model that contact-zone temperature between tool and workpiece was calculated by dividing zone while nano-cutting monocrystalline silicon was established, cutting temperature values in different regions were computed as the simulation was carried out.On this basis, the models of molecular dynamics simulation of SiC and diamond were established separately with setting the initial temperature to room temperature. The laws of length change of C-C bond and Si-C bond varing with increase of simulation temperature were studied. And drawing on predecessors' research on theoretical calculation of hardness of covalent crystals and the relationship between crystal valence electron density and bond length, the curves that the hardness of diamond and SiC varing with bond length were obtained. The effect of temperature on the hardness was calculated. Results show that, local cutting temperature can reach 1300K.The rise in cutting temperature leaded to a decrease in the diamond local atomic clusters hardness,SiC local atomic clusters hardness increased. As the cutting temperature was more than 1100K,diamond began to soften, the local clusters hardness was less than that of SiC.

  10. Hard Hats, Octopuses and Rubber Boots- Operational Managers in Building Processes

    DEFF Research Database (Denmark)

    Koch, Christian

    2004-01-01

    This paper discusses Operation management (OM) in the production of buildings. It is initially contended that OM needs to be improved, from a theoretical and practical perspective. Departing from a criticism of present modeling and management of processes it is suggested to develop an understanding...... of the steps and interdependencies in the process. The field study shows a vast amount of interruptions in operational managers work at the building site. The site managers studied typically worked with four main activities and were interrupted some 126 times during a workday. The prime reason...

  11. Academic Training: QCD: are we ready for the LHC

    CERN Multimedia

    2006-01-01

    2006-2007 ACADEMIC TRAINING PROGRAMME LECTURE SERIES 4, 5, 6, 7 December, from 11:00 to 12:00 4, 5, 6 December - Main Auditorium, bldg. 500, 7 December - TH Auditorium, bldg. 4 - 3-006 QCD: are we ready for the LHC S. FRIXIONE / INFN, Genoa, Italy The LHC energy regime poses a serious challenge to our capability of predicting QCD reactions to the level of accuracy necessary for a successful programme of searches for physics beyond the Standard Model. In these lectures, I'll introduce basic concepts in QCD, and present techniques based on perturbation theory, such as fixed-order and resummed computations, and Monte Carlo simulations. I'll discuss applications of these techniques to hadron-hadron processes, concentrating on recent trends in perturbative QCD aimed at improving our understanding of LHC phenomenology.

  12. NNLO corrections for LHC processes

    CERN Document Server

    Caola, Fabrizio

    2015-01-01

    To fully profit from the remarkable achievements of the experimental program at the LHC, very precise theoretical predictions for signal and background processes are required. In this contribution, I will review some of the recent progress in fully exclusive next-to-next-toleading-order (NNLO) QCD computations. As an example of the phenomenological relevance of these results, I will present LHC predictions for t-channel single-top production and Higgs boson production in association with one hard jet.

  13. The three-gluon vertex of QCD

    International Nuclear Information System (INIS)

    Koller, K.; Zerwas, P.M.; Walsh, T.F.

    1978-12-01

    We show how the Q 2 evolution of gluon jets can be used to provide indirect but strong evidence for the 3 gluon vertex of QCD. We propose looking for this evolution in the QantiQ → 3G → hadrons decay of successive 1 3 S 1 quarkonium states. The results apply to other processes if G jets can be isolated. (orig.) [de

  14. Soft QCD at CMS and ATLAS

    CERN Document Server

    Starovoitov, Pavel; The ATLAS collaboration

    2018-01-01

    A short overview of the recent soft QCD results from the ATLAS and CMS collaborations is presented. The inelastic cross section measurement by CMS at 13 TeV is summarised. The contribution of the diffractive processes to the very forward photon spectra studied by ATLAS and LHCf is discussed. The ATLAS measurements of the exclusive two-photon production of the muon pairs is presented and compared to the previous ATLAS and CMS results.

  15. Analysis of hard exclusive scattering processes of the HERMES recoil experiment

    International Nuclear Information System (INIS)

    Brodski, Irina

    2014-11-01

    Deeply virtual Compton Scattering (DVCS), ep → epγ is the simplest reaction giving indication of generalized parton distributions (GPD) of the nucleon. The DVCS process has the same final state as the Bethe-Heitler process (BH). For this reason the access is taken not through the cross-sections directly but through asymmetries between DVCS events depending on charge and polarization of the 27.6 GeV beam. For the first time the azimuthal asymmetry amplitudes according the charge of the lepton beam are extracted using a kinematically complete reconstruction method at the HERMES experiment. The recoil detector installed in 2006 allows the reconstruction of recoiling protons that completes the measurements of the forward detector to cover almost the complete angle range around the vertex. This approach allows suppressing the background processes by almost a complete magnitude compared to the traditional method using only the information of the forward spectrometer. The analysis of the asymmetries was carried out at different values of the kinematic variables t c' x B and Q 2 to investigate the dependence of these variables. This work pushes the limits of the readability of data and shows which periods have been found to be unstable in the data acquisition. It points out the impact of this finding to previous HERMES publications.

  16. Investigation on Effect of Material Hardness in High Speed CNC End Milling Process

    Directory of Open Access Journals (Sweden)

    N. V. Dhandapani

    2015-01-01

    Full Text Available This research paper analyzes the effects of material properties on surface roughness, material removal rate, and tool wear on high speed CNC end milling process with various ferrous and nonferrous materials. The challenge of material specific decision on the process parameters of spindle speed, feed rate, depth of cut, coolant flow rate, cutting tool material, and type of coating for the cutting tool for required quality and quantity of production is addressed. Generally, decision made by the operator on floor is based on suggested values of the tool manufacturer or by trial and error method. This paper describes effect of various parameters on the surface roughness characteristics of the precision machining part. The prediction method suggested is based on various experimental analysis of parameters in different compositions of input conditions which would benefit the industry on standardization of high speed CNC end milling processes. The results show a basis for selection of parameters to get better results of surface roughness values as predicted by the case study results.

  17. Investigation on Effect of Material Hardness in High Speed CNC End Milling Process.

    Science.gov (United States)

    Dhandapani, N V; Thangarasu, V S; Sureshkannan, G

    2015-01-01

    This research paper analyzes the effects of material properties on surface roughness, material removal rate, and tool wear on high speed CNC end milling process with various ferrous and nonferrous materials. The challenge of material specific decision on the process parameters of spindle speed, feed rate, depth of cut, coolant flow rate, cutting tool material, and type of coating for the cutting tool for required quality and quantity of production is addressed. Generally, decision made by the operator on floor is based on suggested values of the tool manufacturer or by trial and error method. This paper describes effect of various parameters on the surface roughness characteristics of the precision machining part. The prediction method suggested is based on various experimental analysis of parameters in different compositions of input conditions which would benefit the industry on standardization of high speed CNC end milling processes. The results show a basis for selection of parameters to get better results of surface roughness values as predicted by the case study results.

  18. Massively Parallel QCD

    International Nuclear Information System (INIS)

    Soltz, R; Vranas, P; Blumrich, M; Chen, D; Gara, A; Giampap, M; Heidelberger, P; Salapura, V; Sexton, J; Bhanot, G

    2007-01-01

    The theory of the strong nuclear force, Quantum Chromodynamics (QCD), can be numerically simulated from first principles on massively-parallel supercomputers using the method of Lattice Gauge Theory. We describe the special programming requirements of lattice QCD (LQCD) as well as the optimal supercomputer hardware architectures that it suggests. We demonstrate these methods on the BlueGene massively-parallel supercomputer and argue that LQCD and the BlueGene architecture are a natural match. This can be traced to the simple fact that LQCD is a regular lattice discretization of space into lattice sites while the BlueGene supercomputer is a discretization of space into compute nodes, and that both are constrained by requirements of locality. This simple relation is both technologically important and theoretically intriguing. The main result of this paper is the speedup of LQCD using up to 131,072 CPUs on the largest BlueGene/L supercomputer. The speedup is perfect with sustained performance of about 20% of peak. This corresponds to a maximum of 70.5 sustained TFlop/s. At these speeds LQCD and BlueGene are poised to produce the next generation of strong interaction physics theoretical results

  19. Unraveling the Structure of Hadrons with Effective Field Theories of QCD

    International Nuclear Information System (INIS)

    Iain Stewart

    2004-01-01

    Effective Field theory is a powerful framework based on controlled expansions for problems with a natural separation of energy scales. This technique is particularly important for QCD, the theory of strong interactions, due to the vast diversity of phenomena that it describes. Stewart and collaborators have invented a new class of effective theories that can be used in processes with energetic hadrons. These Soft-Collinear Effective Theories provide a unified framework for describing hadronic processes which involve hard probes or the release of a large amount of energy. Many interesting issues about hadronic physics can be addressed with the soft-collinear effective theory. Examples include the size and shape of hadronic form factors, the universality of hadronic distribution functions for a plethora of processes, and the importance of subleading corrections at intermediate energy scales. Effective field theories allow these issues to be addressed using only the underlying symmetries and scales in QCD. Understanding these issues also has a direct impact on other areas of physics, such as on devising clean methods for the measurement of CP violation in the decay of B-mesons. Current progress on the soft-collinear effective theory and related methods is discussed in this report

  20. On a possible test of the hard-Pomeron theory

    International Nuclear Information System (INIS)

    Ioffe, B.L.

    1992-01-01

    In the last few years there have been discussions of the fact that the Pomeron-the Regge pole responsible for high-energy scattering-has in reality a double role: a soft Pomeron built of multiperipheral hadron exchange and a hard Pomeron described by gluon exchanges in QCD. Recently, Bjorken emphasized the need to distinguish these two forms of the Pomeron. The question arises of whether it is possible to distinguish the hard and soft Pomeron experimentally. According to the hard-Pomeron concept, the hadron-hadron total cross section is determined by the imaginary part of the forward scattering amplitude corresponding to two-gluon exchange with ladder corrections. This mechanism dominates in the case of scattering of particles built from heavy quarks (a good example is γγ scattering) and also in the case of virtual-particle scattering (for example, virtual photons, where quark pairs must also be included in the ladder). These processes are hard (γ virt γ virt scattering) or impossible (γγ scattering) to observe experimentally. Bjorken suggested another process whose cross section is determined by hard-Pomeron exchange - double diffractional hadron-hadron (e.g., pp) scattering at high energies with jet production in the projectile and target fragmentation regions. If the momentum transfer from the projectile to the target is in the intermediate region, |t|∼1 GeV, and events are selected with a rapidity gap in the rapidity distribution of produced particles between the two fragmentation regions, then, according to Bjorken, a process determined by the hard Pomeron will be observed. The author addresses this proposal

  1. Process for carbonizing hard-to-heat bituminous material like shale

    Energy Technology Data Exchange (ETDEWEB)

    Nagel, K

    1921-11-29

    A process is described for carbonizing bituminous material, like shale, with the production of sufficient heat for carbonization by burning a part of the bitumen itself by means of a gas stream going in a circuit, to which oxygen in regulated amounts is admitted. It is characterized by the fact that the gas stream already cooled for detarring before its re-entrance into the carbonization chamber is mixed in the inlet channels with an amount of oxygen (air or other free oxygen containing gases), that without sintering or melting of the residue it is burned and the carbonization is carried out evenly.

  2. Radiation hardness evaluation of the commercial 150 nm CMOS process using 60Co source

    International Nuclear Information System (INIS)

    Carna, M; Havranek, M; Hejtmanek, M; Janoska, Z; Marcisovsky, M; Neue, G; Tomasek, L; Vrba, V

    2014-01-01

    We present a study of radiation effects on MOSFET transistors irradiated with a 60 Co source to a total absorbed dose of 1.5 Mrad. The transistor test structures were manufactured using a commercial 150 nm CMOS process and are composed of transistors of different types (NMOS and PMOS), dimensions and insulation from the bulk material by means of deep n-wells. We have observed a degradation of electrical characteristics of both PMOS and NMOS transistors, namely a large increase of the leakage current of the NMOS transistors after irradiation

  3. Ionization processes in the Fe 27 region of hot iron plasma in the field of hard gamma radiation

    International Nuclear Information System (INIS)

    Illarionov, A.F.

    1989-01-01

    A highly ionized hot plasma of an iron 26 56 Fe-type heavy element in the field of hard ionizing gamma-ray radiation is considered. The processes of ionization and recombination are discussed for a plasma consisting of the fully ionized Fe 27 and the hydrogen-like Fe 26 ions of iron in the case of large optical depth of the plasma with respect to the photoionization by gamma-ray quanta. The self-ionization process of a hot plasma with the temperature kT ≅ I (I being the ionization potential), due to the production of the own ionizing gamma-ray quanta, by the free-free (ff) and recombination (fb) radiation mechanisms, is investigated. It is noted that in the stationary situation the process of self-ionization of a hot plasma imposes the restriction upon the plasma temperature, kT<1.5 I. It is shown that the ionization of heavy-ion plasma by the impact of thermal electrons is dominating over the processes of ff- and fb-selfionization of plasma only by the large concentration of hydrogen-like iron at the periphery of the region of fully ionized iron Fe 27

  4. QCD Factorizations in Exclusive γ*γ*→ρL0ρL0

    International Nuclear Information System (INIS)

    Pire, B.; Segond, M.; Szymanowski, L.; Wallon, S.

    2008-01-01

    The exclusive process e + e - →e + e - ρ L 0 ρ L 0 allows to study various dynamics and factorization properties of perturbative QCD. At moderate energy, we demonstrate how collinearQCD factorization emerges, involving either generalized distribution amplitudes (GDA) or transition distribution amplitudes (TDA). At higher energies, in the Regge limit of QCD, we show that it offers a promising probe of the BFKL resummation effects to be studied at ILC

  5. Hard rock tunnel boring machine penetration test as an indicator of chipping process efficiency

    Directory of Open Access Journals (Sweden)

    M.C. Villeneuve

    2017-08-01

    Full Text Available The transition from grinding to chipping can be observed in tunnel boring machine (TBM penetration test data by plotting the penetration rate (distance/revolution against the net cutter thrust (force per cutter over the full range of penetration rates in the test. Correlating penetration test data to the geological and geomechanical characteristics of rock masses through which a penetration test is conducted provides the ability to reveal the efficiency of the chipping process in response to changing geological conditions. Penetration test data can also be used to identify stress-induced tunnel face instability. This research shows that the strength of the rock is an important parameter for controlling how much net cutter thrust is required to transition from grinding to chipping. It also shows that the geological characteristics of a rock will determine how efficient chipping occurs once it has begun. In particular, geological characteristics that lead to efficient fracture propagation, such as fabric and mica contents, will lead to efficient chipping. These findings will enable a better correlation between TBM performance and geological conditions for use in TBM design, as a basis for contractual payments where penetration rate dominates the excavation cycle and in further academic investigations into the TBM excavation process.

  6. Calculation of hadronic part of photon structure function in QCD

    International Nuclear Information System (INIS)

    Gorskij, A.S.; Ioffe, B.L.; Oganesyan, A.G.; Khodzhamiryan, A.Yu.

    1989-01-01

    The photon structure function in QCD in the intermediate region of the Bjorken variable 0.2 2 /2pq, where q 2 is the hard photon virtuality, p is the soft photon momentum) is calculated. It is shown that without introduction of fitting parameters the experimental data can be described in the range 3GeV 2 ≤Q 2 2 /Q 2 =-q 2 /not taking account for the leading logarithmic corrections. It is demonstrated that the corrections proportional to μ ν 2 > to the hard photon scattering amplitude on the longitudinal soft photon and to the Callan-Gross relation vanish. 16 refs.; 6 figs

  7. Radiation hard pixel sensors using high-resistive wafers in a 150 nm CMOS processing line

    Science.gov (United States)

    Pohl, D.-L.; Hemperek, T.; Caicedo, I.; Gonella, L.; Hügging, F.; Janssen, J.; Krüger, H.; Macchiolo, A.; Owtscharenko, N.; Vigani, L.; Wermes, N.

    2017-06-01

    Pixel sensors using 8'' CMOS processing technology have been designed and characterized offering the benefits of industrial sensor fabrication, including large wafers, high throughput and yield, as well as low cost. The pixel sensors are produced using a 150 nm CMOS technology offered by LFoundry in Avezzano. The technology provides multiple metal and polysilicon layers, as well as metal-insulator-metal capacitors that can be employed for AC-coupling and redistribution layers. Several prototypes were fabricated and are characterized with minimum ionizing particles before and after irradiation to fluences up to 1.1 × 1015 neq cm-2. The CMOS-fabricated sensors perform equally well as standard pixel sensors in terms of noise and hit detection efficiency. AC-coupled sensors even reach 100% hit efficiency in a 3.2 GeV electron beam before irradiation.

  8. Hard is Normal: Military Families' Transitions Within the Process of Deployment.

    Science.gov (United States)

    Yablonsky, Abigail M; Barbero, Edie Devers; Richardson, Jeanita W

    2016-02-01

    US military deployments have become more frequent and lengthier in duration since 2003. Over half of US military members are married, and many also have children. The authors sought to understand the process of deployment from the perspective of the military family. After a thorough search of the literature, 21 primary research reports of 19 studies with an aggregate sample of 874 were analyzed using qualitative metasynthesis. The deployment process was experienced in four temporal domains. The military family as a whole shared the pre-deployment transition: all family members felt uncertain about the future, needed to complete tasks to "get ready" for deployment, and experienced a sense of distancing in preparation for the upcoming separation. The AD member went through the deployment transition independently, needing to "stay engaged" with the military mission, building a surrogate family and simultaneously trying to maintain connection with the family at home. In parallel, the home front family was going through a transposement transition, moving forward as an altered family unit, taking on new roles and responsibilities, and trying to simultaneously connect with the deployed member and find support from other military families. In post-deployment, the family went through the "reintegration" transition together, managing expectations, and readjusting family roles, all needing understanding and appreciation for their sacrifices during the recent separation. Effective family communication was important for military family well-being after deployment but unexpectedly challenging for many. Clinical, research, and policy recommendations are discussed. © 2015 Wiley Periodicals, Inc. This article has been contributed to by a US Government employee and her work is in the public domain in the USA.

  9. Separation of mercury in industrial processes of Polish hard steam coals cleaning

    Directory of Open Access Journals (Sweden)

    Wierzchowski Krzysztof

    2016-01-01

    Full Text Available Coal use is regarded as one of main sources of anthropogenic propagation of mercury in the environment. The coal cleaning is listed among methods of the mercury emission reduction. The article concerns the statistical assessment of mercury separation between coal cleaning products. Two industrial processes employed in the Polish coal preparation plants are analysed: coal cleaning in heavy media vessels and coal cleaning in jigs. It was found that the arithmetic mean mercury content in coarse and medium coal size fractions for clean coal from heavy media vessels, amounts 68.9 μg/kg, and most of the results lay below the mean value, while for rejects it amounts 95.5 μg/kg. It means that it is for around 25 μg/kg greater than in the clean coal. The arithmetic mean mercury content in raw coal smalls amounts around 118 mg/kg. The cleaning of smalls in jigs results in clean coal and steam coal blends characterized by mean mercury content 96.8 μg/kg and rejects with mean mercury content 184.5 μg/kg.

  10. Heavy flavor production in QCD

    International Nuclear Information System (INIS)

    Hoyer, P.

    1989-01-01

    In this paper a brief survey is given of the status of heavy quark hadroproduction in QCD. The next-to-leading order calculation allows an estimate of the theoretical uncertainties to be made. They are manageable for top, but considerable for charm. The data on charm continues to show an excess of events at large x F , compared to QCD expectations. This may be linked to the measured anomalous A-dependence of the cross section on nuclear targets, also present at large x F . QCD models for the diffractive production of heavy quarks remain to be tested experimentally

  11. Non-perturbative QCD correlation functions

    Energy Technology Data Exchange (ETDEWEB)

    Cyrol, Anton Konrad

    2017-11-27

    Functional methods provide access to the non-perturbative regime of quantum chromo- dynamics. Hence, they allow investigating confinement and chiral symmetry breaking. In this dissertation, correlation functions of Yang-Mills theory and unquenched two-flavor QCD are computed from the functional renormalization group. Employing a self-consistent vertex expansion of the effective action, Yang-Mills correlation functions are obtained in four as well as in three spacetime dimensions. To this end, confinement and Slavnov-Taylor identities are discussed. Our numerical results show very good agreement with corresponding lattice results. Next, unquenched two-flavor QCD is considered where it is shown that the unquenched two-flavor gluon propagator is insensitive to the pion mass. Furthermore, the necessity for consistent truncations is emphasized. Finally, correlation functions of finite-temperature Yang-Mills theory are computed in a truncation that includes the splitting of the gluon field into directions that are transverse and longitudinal to the heat bath. In particular, it includes the splitting of the three- and four-gluon vertices. The obtained gluon propagator allows to extract a Debye screening mass that coincides with the hard thermal loop screening mass at high temperatures, but is meaningful also at temperatures below the phase transition temperature.

  12. Hard electroproduction of hybrid mesons

    International Nuclear Information System (INIS)

    Anikin, I.V.; LPT Universite Paris-Sud, Orsay; Szymanowski, L.; Teryaev, O.V.; ); Wallon, S.

    2005-01-01

    We estimate the sizeable cross section for deep exclusive electroproduction of an exotic J PC = 1 -+ hybrid meson in the Bjorken regime. The production amplitude scales like the one for usual meson electroproduction, i.e. as 1/Q 2 . This is due to the non-vanishing leading twist distribution amplitude for the hybrid meson, which may be normalized thanks to its relation to the energy momentum tensor and to the QCD sum rules technique. The hard amplitude is considered up to next-to-leading order in as and we explore the consequences of fixing the renormalization scale ambiguity through the BLM procedure. (author)

  13. Datagrids for lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Buechner, O. [Zentralinstitut fuer Angewandte Mathematik ZAM, 52425 Juelich (Germany); Ernst, M. [Deutsches Elektronen-Synchrotron DESY, 22603 Hamburg (Germany); Jansen, K. [John von Neumann-Institut fuer Computing NIC/DESY, 15738 Zeuthen (Germany); Lippert, Th. [Zentralinstitut fuer Angewandte Mathematik ZAM, 52425 Juelich (Germany); Melkumyan, D. [Deutsches Elektronen-Synchrotron DESY, 15738 Zeuthen (Germany); Orth, B. [Zentralinstitut fuer Angewandte Mathematik ZAM, 52425 Juelich (Germany); Pleiter, D. [John von Neumann-Institut fuer Computing NIC/DESY, 15738 Zeuthen (Germany)]. E-mail: dirk.pleiter@desy.de; Stueben, H. [Konrad-Zuse-Institut fuer Informationstechnik ZIB, 14195 Berlin (Germany); Wegner, P. [Deutsches Elektronen-Synchrotron DESY, 15738 Zeuthen (Germany); Wollny, S. [Konrad-Zuse-Institut fuer Informationstechnik ZIB, 14195 Berlin (Germany)

    2006-04-01

    As the need for computing resources to carry out numerical simulations of Quantum Chromodynamics (QCD) formulated on a lattice has increased significantly, efficient use of the generated data has become a major concern. To improve on this, groups plan to share their configurations on a worldwide level within the International Lattice DataGrid (ILDG). Doing so requires standardized description of the configurations, standards on binary file formats and common middleware interfaces. We describe the requirements and problems, and discuss solutions. Furthermore, an overview is given on the implementation of the LatFor DataGrid [http://www-zeuthen.desy.de/latfor/ldg], a France/German/Italian grid that will be one of the regional grids within the ILDG grid-of-grids concept.

  14. Vacuum structure and QCD

    International Nuclear Information System (INIS)

    Gross, D.

    1979-01-01

    An overview of QCD is given, and some of the dynamical issues that arise in attempts to solve this theory are discussed. In particular, attention is focused on the problems that appear in attempts to discuss the structure of low-lying hadrons, e.g. nucleons, on the basis of a color gauge theory of quarks. The picture of hadronic structure developed by Callan, Dashen, and Gross is reviewed; this picture maintains that it presents the qualitative features of hadronic structure emerging in a direct way from first principles. Finally, the relevance of the emerging understanding of the structure of hadrons to the question of what hadronic matter (nuclear or quark matter) might look like at high densities is discussed

  15. Monte-Carlo Simulation of Hard Probes in Heavy-Ion Collisions

    International Nuclear Information System (INIS)

    Schenke, Bjoern; Jeon, Sangyong; Gale, Charles

    2011-01-01

    Results from the Modular Algorithm for Relativistic Treatment of heavy IoN Interactions (MARTINI) are presented. This comprehensive event generator for the hard and penetrating probes in high energy nucleus-nucleus collisions employs a time evolution model for the soft background, PYTHIA 8.1 and the McGill-AMY parton evolution scheme including radiative as well as elastic processes. It generates full event configurations in the high p T region, taking into account thermal QCD and QED effects as well as effects of the evolving medium.

  16. International Meeting: Excited QCD 2014

    CERN Document Server

    Giacosa, Francesco; Malek, Magdalena; Marinkovic, Marina; Parganlija, Denis

    2014-01-01

    Excited QCD 2014 will take place on the beautiful Bjelasnica mountain located in the vicinity of the Bosnian capital Sarajevo. Bjelasnica was a venue of the XIV Winter Olympic Games and it is situated only 30 kilometers from Sarajevo International Airport. The workshop program will start on February 2 and finish on February 8, 2014, with scientific lectures taking place from February 3 to 7. Workshop participants will be accomodated in Hotel Marsal, only couple of minutes by foot from the Olympic ski slopes. ABOUT THE WORKSHOP This edition is the sixth in a series of workshops that were previously organised in Poland, Slovakia, France and Portugal. Following the succesful meeting in 2013, the Workshop is returning to Sarajevo Olympic mountains in 2014, exactly thirty years after the Games. The workshop covers diverse aspects of QCD: (i) QCD at low energies: excited hadrons, glueballs, multiquarks. (ii) QCD at high temperatures and large densities: heavy-ion collisions, jets, diffraction, hadronisation, quark-...

  17. Developments in perturbative QCD? challenges from collider physics

    Energy Technology Data Exchange (ETDEWEB)

    Zeppenfeld, Dieter [Valencia Univ. (Spain). Dept. de Fisica Teorica]. E-mail: dieter@phenom.physics.wisc.edu

    1996-07-01

    The search for new phenomena at hadron colliders requires a good understanding of QCD processes. The analysis of multi-jet signatures in the top quark search at the Tevatron is one example, forward jet tagging and rapidity gap techniques in the analysis of weak boson scattering events at the LH C will be another important application. These topics are discussed in the context of multi-parton/multi-jet QCD processes. Also described are some of the calculation tools, like amplitude techniques and automatic code generation for tree level processes. (author)

  18. Developments in perturbative QCD? challenges from collider physics

    International Nuclear Information System (INIS)

    Zeppenfeld, Dieter

    1996-01-01

    The search for new phenomena at hadron colliders requires a good understanding of QCD processes. The analysis of multi-jet signatures in the top quark search at the Tevatron is one example, forward jet tagging and rapidity gap techniques in the analysis of weak boson scattering events at the LH C will be another important application. These topics are discussed in the context of multi-parton/multi-jet QCD processes. Also described are some of the calculation tools, like amplitude techniques and automatic code generation for tree level processes. (author)

  19. Gauge invariant sub-structures of tree-level double-emission exact QCD spin amplitudes

    CERN Document Server

    Van Hameren, A

    2009-01-01

    In this note we discuss possible separations of exact, massive, tree-level spin amplitudes into gauge invariant parts. We concentrate our attention on processes involving two quarks entering a color- neutral current and, thanks to the QCD interactions, two extra external gluons. We will search for forms compatible with parton shower languages, without applying approximations or restrictions on phase space regions. Special emphasis will be put on the isolation of parts necessary for the construction of evolution kernels for individual splittings and to some degree for the running coupling constant as well. Our aim is to better understand the environment necessary to optimally match hard matrix elements with partons shower algorithms. To avoid complications and ambiguities related to regularization schemes, we ignore, at this point, virtual corrections. Our representation is quite universal: any color-neutral current can be used, in particular our approach is not restricted to vector currents only.

  20. QCD parton showers and NLO EW corrections to Drell-Yan

    CERN Document Server

    Richardson, P; Sapronov, A A; Seymour, M H; Skands, P Z

    2012-01-01

    We report on the implementation of an interface between the SANC generator framework for Drell-Yan hard processes, which includes next-to-leading order electroweak (NLO EW) corrections, and the Herwig++ and Pythia8 QCD parton shower Monte Carlos. A special aspect of this implementation is that the initial-state shower evolution in both shower generators has been augmented to handle the case of an incoming photon-in-a-proton, diagrams for which appear at the NLO EW level. The difference between shower algorithms leads to residual differences in the relative corrections of 2-3% in the p_T(mu) distributions at p_T(mu)>~50 GeV (where the NLO EW correction itself is of order 10%).

  1. Self-similarity of hard cumulative processes in fixed target experiment for BES-II at STAR

    International Nuclear Information System (INIS)

    Tokarev, M.V.; Aparin, A.A.; Zborovsky, I.

    2014-01-01

    Search for signatures of phase transition in Au + Au collisions is in the heart of the heavy ion program at RHIC. Systematic study of particle production over a wide range of collision energy revealed new phenomena such as the nuclear suppression effect expressed by nuclear modification factor, the constituent quark number scaling for elliptic flow, the 'ridge effect' in - fluctuations, etc. To determine the phase boundaries and location of the critical point of nuclear matter, the Beam Energy Scan (BES-I) program at RHIC has been suggested and performed by STAR and PHENIX Collaborations. The obtained results have shown that the program (BES-II) should be continued. In this paper a proposal to use hard cumulative processes in BES Phase-II program is outlined. Selection of the cumulative events is assumed to enrich data sample by a new type of collisions characterized by higher energy density and more compressed matter. This would allow finding clearer signatures of phase transition, location of a critical point and studying extreme conditions in heavy ion collisions.

  2. Long-Term Reliability of a Hard-Switched Boost Power Processing Unit Utilizing SiC Power MOSFETs

    Science.gov (United States)

    Ikpe, Stanley A.; Lauenstein, Jean-Marie; Carr, Gregory A.; Hunter, Don; Ludwig, Lawrence L.; Wood, William; Iannello, Christopher J.; Del Castillo, Linda Y.; Fitzpatrick, Fred D.; Mojarradi, Mohammad M.; hide

    2016-01-01

    Silicon carbide (SiC) power devices have demonstrated many performance advantages over their silicon (Si) counterparts. As the inherent material limitations of Si devices are being swiftly realized, wide-band-gap (WBG) materials such as SiC have become increasingly attractive for high power applications. In particular, SiC power metal oxide semiconductor field effect transistors' (MOSFETs) high breakdown field tolerance, superior thermal conductivity and low-resistivity drift regions make these devices an excellent candidate for power dense, low loss, high frequency switching applications in extreme environment conditions. In this paper, a novel power processing unit (PPU) architecture is proposed utilizing commercially available 4H-SiC power MOSFETs from CREE Inc. A multiphase straight boost converter topology is implemented to supply up to 10 kilowatts full-scale. High Temperature Gate Bias (HTGB) and High Temperature Reverse Bias (HTRB) characterization is performed to evaluate the long-term reliability of both the gate oxide and the body diode of the SiC components. Finally, susceptibility of the CREE SiC MOSFETs to damaging effects from heavy-ion radiation representative of the on-orbit galactic cosmic ray environment are explored. The results provide the baseline performance metrics of operation as well as demonstrate the feasibility of a hard-switched PPU in harsh environments.

  3. Fabrication of a metallic roll stamp with low internal stress and high hardness for large area display applications by a pulse reverse current electroforming process

    International Nuclear Information System (INIS)

    Kim, Joongeok; Han, Jungjin; Kim, Taekyung; Kang, Shinill

    2014-01-01

    With the increasing demand for large scale micro/nano components in the fields of display, energy and electrical devices, etc, the establishment of a roll imprinting process has become a priority. The fabrication of a roll stamp with high dimensional accuracy and uniformity is one of the key issues in the roll imprinting process, because the roll stamp determines the properties of the replicated micro/nano structures. In this study, a method to fabricate a metallic roll stamp with low internal stress, high flatness, and high hardness was proposed by a pulse reverse current (PRC) electroforming process. The effects of PRC electroforming processes on the internal stress, hardness, and grain size of the electroformed stamp were examined, and the optimum process conditions were suggested. As a practical example of the proposed method, various micro-patterns for electronic circuits were fabricated via the roll imprinting process using a PRC electroformed stamp. (paper)

  4. Lattice QCD at finite temperature with Wilson fermions

    International Nuclear Information System (INIS)

    Pinke, Christopher

    2014-01-01

    The subatomic world is governed by the strong interactions of quarks and gluons, described by Quantum Chromodynamics (QCD). Quarks experience confinement into colour-less objects, i.e. they can not be observed as free particles. Under extreme conditions such as high temperature or high density, this constraint softens and a transition to a phase where quarks and gluons are quasi-free particles (Quark-Gluon-Plasma) can occur. This environment resembles the conditions prevailing during the early stages of the universe shortly after the Big Bang. The phase diagram of QCD is under investigation in current and future collider experiments, for example at the Large Hadron Collider (LHC) or at the Facility for Antiproton and Ion Research (FAIR). Due to the strength of the strong interactions in the energy regime of interest, analytic methods can not be applied rigorously. The only tool to study QCD from first principles is given by simulations of its discretised version, Lattice QCD (LQCD). These simulations are in the high-performance computing area, hence, the numerical aspects of LQCD are a vital part in this field of research. In recent years, Graphic Processing Units (GPUs) have been incorporated in these simulations as they are a standard tool for general purpose calculations today. In the course of this thesis, the LQCD application CL 2 QCD has been developed, which allows for simulations on GPUs as well as on traditional CPUs, as it is based on OpenCL. CL 2 QCD constitutes the first application for Wilson type fermions in OpenCL. It provides excellent performance and has been applied in physics studies presented in this thesis. The investigation of the QCD phase diagram is hampered by the notorious sign-problem, which restricts current simulation algorithms to small values of the chemical potential. Theoretically, studying unphysical parameter ranges allows for constraints on the phase diagram. Of utmost importance is the clarification of the order of the finite

  5. Chiral models of low energy QCD

    International Nuclear Information System (INIS)

    Ripka, G.

    1993-01-01

    Two processes may be distinguished when a hadron propagates in a dense baryonic medium. The polarization of the medium and the change in the quark structure of the hadron. The polarization of the medium is better described in terms of colorless mesons and nucleons while the intrinsic change of the hadron is better described by quark models. It is shown how to couple the two processes. The scaling of effective Lagrangians, is related to changes in the quark constituent masses, based on the QCD scale anomaly. (author) 62 refs

  6. QCD teraflops computer

    International Nuclear Information System (INIS)

    Negele, J.W.

    1993-01-01

    Architectural enhancements are described to increase the performance of the arithmetic accelerator and memory of the nodes in the CM-5 for QCD and a broad range of general problems while maintaining compatibility with existing software, compilers, communications network and I/O subsystems. A factor of 10 increase in performance is obtained by increasing the number of floating point processors by a factor of 4, extending the vector instruction set for dual execution of single-precision arithmetic, and increasing the clock rate from 32 to 40 MHz. The required memory bandwidth is obtained by using synchronous DRAMs and 4 floating point processors are packaged into a multichip module which occupies the same area as a present processor package. The proposed 2048 node machine will provide 2.6 Teraflops peak, 0.5 - 1.5 Teraflops sustained on lattices of 32 2 x 64 - 128 3 x 256, will have 256 Gigabytes of memory, 1 Terabyte of disk, an estimated cost of approximately $40 million, and can be built in 2.5 years. (orig.)

  7. Induced QCD I: theory

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, Bastian B. [Institute for Theoretical Physics, Goethe-University of Frankfurt,60438 Frankfurt (Germany); Institute for Theoretical Physics, University of Regensburg,93040 Regensburg (Germany); Lohmayer, Robert; Wettig, Tilo [Institute for Theoretical Physics, University of Regensburg,93040 Regensburg (Germany)

    2016-11-14

    We explore an alternative discretization of continuum SU(N{sub c}) Yang-Mills theory on a Euclidean spacetime lattice, originally introduced by Budzcies and Zirnbauer. In this discretization the self-interactions of the gauge field are induced by a path integral over N{sub b} auxiliary boson fields, which are coupled linearly to the gauge field. The main progress compared to earlier approaches is that N{sub b} can be as small as N{sub c}. In the present paper we (i) extend the proof that the continuum limit of the new discretization reproduces Yang-Mills theory in two dimensions from gauge group U(N{sub c}) to SU(N{sub c}), (ii) derive refined bounds on N{sub b} for non-integer values, and (iii) perform a perturbative calculation to match the bare parameter of the induced gauge theory to the standard lattice coupling. In follow-up papers we will present numerical evidence in support of the conjecture that the induced gauge theory reproduces Yang-Mills theory also in three and four dimensions, and explore the possibility to integrate out the gauge fields to arrive at a dual formulation of lattice QCD.

  8. Probing QCD in low energy anti pp collisions

    International Nuclear Information System (INIS)

    Brodsky, S.J.

    1986-06-01

    A number of exclusive and inclusive antiproton reactions are discussed which could provide useful constraints or test novel features of quantum chromodynamics in the intermediate momentum transfer domain involving both perturbative and non-perturbative dynamics. High momentum transfer reactions are briefly reviewed. Inclusive antiproton reactions and the QCD critical length, QCD predictions for proton-antiproton exclusive processes, and studies of the Compton amplitude in proton-antiproton annihilation are covered. Testing hadron helicity conservation in heavy quark resonance is discussed. Also covered are heavy hadron pair production in proton-antiproton exclusive interactions, exclusive nuclear reactions, and quasi-exclusive nuclear processes

  9. Progress on double-logarithmic large-x and small-x resummations for (semi-)inclusive hard processes

    International Nuclear Information System (INIS)

    Vogt, A.; Kom, C.H.; Lo Presti, N.A.; Soar, G.; Vermaseren, J.A.M.; Yeats, K.

    2012-12-01

    Over the past few years considerable progress has been made on the resummation of double-logarithmically enhanced threshold (large-x) and high-energy (small-x) higher-order contributions to the splitting functions for parton and fragmentation distributions and to the coefficient functions for inclusive deep-inelastic scattering and semi-inclusive e + e - annihilation. We present an overview of the methods which allow, in many cases, to derive the coefficients of the highest three logarithms at all orders in the strong coupling from next-to-next-to-leading order results in massless perturbative QCD. Some representative analytical and numerical results are shown, and the present limitations of these resummations are discussed.

  10. Progress on double-logarithmic large-x and small-x resummations for (semi-)inclusive hard processes

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, A.; Kom, C.H.; Lo Presti, N.A.; Soar, G. [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences; Almasy, A.A.; Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Vermaseren, J.A.M. [NIKHEF Theory Group, Amsterdam (Netherlands); Yeats, K. [Simon Fraser Univ., Burnaby, BC (Canada). Dept. of Mathematics

    2012-12-15

    Over the past few years considerable progress has been made on the resummation of double-logarithmically enhanced threshold (large-x) and high-energy (small-x) higher-order contributions to the splitting functions for parton and fragmentation distributions and to the coefficient functions for inclusive deep-inelastic scattering and semi-inclusive e{sup +}e{sup -} annihilation. We present an overview of the methods which allow, in many cases, to derive the coefficients of the highest three logarithms at all orders in the strong coupling from next-to-next-to-leading order results in massless perturbative QCD. Some representative analytical and numerical results are shown, and the present limitations of these resummations are discussed.

  11. QCD Jets and particle correlations in heavy-ion collisions

    CERN Document Server

    Nguyen, Matthew

    2017-01-01

    Measurements of jets and particle correlations in nucleus-nucleus collisions are intended to probe QCD interactions in the high temperature phase, where matter is understood to behave as a quark-gluon plasma. Two probes are reviewed: jets which are used to study the energy loss of hard-scattered partons in this medium and particle correlations which are used to understand collective effects of the bulk matter. Whereas collisions of lighter systems, namely proton-ion and proton-proton, initially served primarily as control experiments, certain (but not all) effects first observed in nucleus-nucleus collisions have proven to be pervasive in these systems. Comparative measurements in these three systems have broadened our understanding of many-body QCD phenomena, and raised new questions. This talk reviewed these recent developments.

  12. Soft and hard pomerons: Is there a distinction?

    International Nuclear Information System (INIS)

    Bjorken, J.D.

    1991-07-01

    One of the big unsolved problems of QCD remains the problem of the Pomeron: what is the relation of high energy elastic and diffractive phenomena to the underlying theory? This is not a subject in which I have actively worked. But my interest in it has in this year increased greatly. The reason has to do with ideas for experimentation at SSC/LHC which either directly address the problem or which require the understanding of strong-interaction diffractive phenomena as backgrounds for discovery-physics processes involving electroweak boson exchanges. I will in this talk omit these motivations, which can be found elsewhere, and instead concentrate on some personal veiwpoints regarding the Pomeron which may or may not be conventional. The main question has to do with the distinction between the original, old-fashioned ''soft'' Pomeron of the 1960s, built out of multiperipheral hadron-exchanges, and the more modern perturbative-QCD ''hard'' Pomeron, built out of multiperipheral gluon exchanges. The perspective I offer comes mainly from two sources: one is heavy-flavor physics, and the other is the Manohar-Georgi view of constituent quark physics. 27 refs., 5 figs

  13. Determination of s(x) and anti s(x) from a global QCD analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zomer, F

    1999-10-01

    A new global QCD analysis of DIS data is presented. The {nu}Fe and {nu}-bar Fe differential cross-section data are included to constrain the strange component of the nucleon sea. As a result we found a hard strangeness at high-x and some evidence for an asymmetry between xs(x) and xs-bar(x). (author)

  14. Insight into subdecimeter fracturing processes during hydraulic fracture experiment in Äspö hard rock laboratory, Sweden

    Science.gov (United States)

    Kwiatek, Grzegorz; Martínez-Garzón, Patricia; Plenkers, Katrin; Leonhardt, Maria; Zang, Arno; Dresen, Georg; Bohnhoff, Marco

    2017-04-01

    We analyze the nano- and picoseismicity recorded during a hydraulic fracturing in-situ experiment performed in Äspö Hard Rock Laboratory, Sweden. The fracturing experiment included six fracture stages driven by three different water injection schemes (continuous, progressive and pulse pressurization) and was performed inside a 28 m long, horizontal borehole located at 410 m depth. The fracturing process was monitored with two different seismic networks covering a wide frequency band between 0.01 Hz and 100000 Hz and included broadband seismometers, geophones, high-frequency accelerometers and acoustic emission sensors. The combined seismic network allowed for detection and detailed analysis of seismicity with moment magnitudes MW<-4 (source sizes approx. on cm scale) that occurred solely during the hydraulic fracturing and refracturing stages. We relocated the seismicity catalog using the double-difference technique and calculated the source parameters (seismic moment, source size, stress drop, focal mechanism and seismic moment tensors). The physical characteristics of induced seismicity are compared to the stimulation parameters and to the formation parameters of the site. The seismic activity varies significantly depending on stimulation strategy with conventional, continuous stimulation being the most seismogenic. We find a systematic spatio-temporal migration of microseismic events (propagation away and towards wellbore injection interval) and temporal transitions in source mechanisms (opening - shearing - collapse) both being controlled by changes in fluid injection pressure. The derived focal mechanism parameters are in accordance with the local stress field orientation, and signify the reactivation of pre-existing rock flaws. The seismicity follows statistical and source scaling relations observed at different scales elsewhere, however, at an extremely low level of seismic efficiency.

  15. Hard breakup of the deuteron into two Δ isobars

    International Nuclear Information System (INIS)

    Granados, Carlos G.; Sargsian, Misak M.

    2011-01-01

    We study high-energy photodisintegration of the deuteron into two Δ isobars at large center of mass angles within the QCD hard rescattering model (HRM). According to the HRM, the process develops in three main steps: the photon knocks a quark from one of the nucleons in the deuteron; the struck quark rescatters off a quark from the other nucleon sharing the high energy of the photon; then the energetic quarks recombine into two outgoing baryons which have large transverse momenta. Within the HRM, the cross section is expressed through the amplitude of pn→ΔΔ scattering which we evaluated based on the quark-interchange model of hard hadronic scattering. Calculations show that the angular distribution and the strength of the photodisintegration is mainly determined by the properties of the pn→ΔΔ scattering. We predict that the cross section of the deuteron breakup to Δ ++ Δ - is 4-5 times larger than that of the breakup to the Δ + Δ 0 channel. Also, the angular distributions for these two channels are markedly different. These can be compared with the predictions based on the assumption that two hard Δ isobars are the result of the disintegration of the preexisting ΔΔ components of the deuteron wave function. In this case, one expects the angular distributions and cross sections of the breakup in both Δ ++ Δ - and Δ + Δ 0 channels to be similar.

  16. Analytic continuation in perturbative QCD

    International Nuclear Information System (INIS)

    Caprini, Irinel

    2002-01-01

    We discuss some attempts to improve standard perturbative expansion in QCD by using the analytic continuation in the momentum and the Borel complex planes. We first analyse the momentum-plane analyticity properties of the Borel-summed Green functions in perturbative QCD and the connection between the Landau singularities and the infrared renormalons. By using the analytic continuation in the Borel complex plane, we propose a new perturbative series replacing the standard expansion in powers of the normalized coupling constant a. The new expansion functions have branch point and essential singularities at the origin of the complex a-plane and divergent Taylor expansions in powers of a. On the other hand the modified expansion of the QCD correlators is convergent under rather conservative conditions. (author)

  17. Quantum chromodynamics (QCD) and collider physics

    International Nuclear Information System (INIS)

    Ellis, R.K.; Stirling, W.J.

    1990-01-01

    This report discusses: fundamentals of perturbative QCD; QCD in e + e - → hadrons; deep inelastic scattering and parton distributions; the QCD parton model in hadron-hadron collisions; large p T jet production in hadron-hadron collisions; the production of vector bosons in hadronic collisions; and the production of heavy quarks

  18. Theoretical summary talk of QCD 2002

    International Nuclear Information System (INIS)

    Basu, Rahul

    2003-01-01

    This is a summary of the talks on QCD, not including QCD at finite temperature or density (which are discussed elsewhere) presented at the QCD 2002 meeting held at IIT, Kanpur. I have attempted to give only an overview of the talks since the details may be found in the individual contributions. (author)

  19. Modeling the thermodynamics of QCD

    Energy Technology Data Exchange (ETDEWEB)

    Hell, Thomas

    2010-07-26

    Strongly interacting (QCD) matter is expected to exhibit a multifaceted phase structure: a hadron gas at low temperatures, a quark-gluon plasma at very high temperatures, nuclear matter in the low-temperature and high-density region, color superconductors at asymptotically high densities. Most of the conjectured phases cannot yet be scrutinized by experiments. Much of the present picture - particularly concerning the intermediate temperature and density area of the phase diagram of QCD matter - is based on model calculations. Further insights come from Lattice-QCD computations. The present thesis elaborates a nonlocal covariant extension of the Nambu and Jona-Lasinio (NJL) model with built-in constraints from the running coupling of QCD at high-momentum and instanton physics at low-momentum scales. We present this model for two and three quark flavors (in the latter case paying particular attention to the axial anomaly). At finite temperatures and densities, gluon dynamics is incorporated through a gluonic background field, expressed in terms of the Polyakov loop (P). The thermodynamics of this nonlocal PNJL model accounts for both chiral and deconfinement transitions. We obtain results in mean-field approximation and beyond, including additional pionic and kaonic contributions to the chiral condensate, the pressure and other thermodynamic quantities. Finally, the nonlocal PNJL model is applied to the finite-density region of the QCD phase diagram; for three quark flavors we investigate, in particular, the dependence of the critical point appearing in the models on the axial anomaly. The thesis closes with a derivation of the nonlocal PNJL model from first principles of QCD. (orig.)

  20. Quantity of selected probiotic cultures in semi-hard cheese with low-cooking curd during the maturation process.

    Science.gov (United States)

    Lovayová, Viera; Dudriková, E; Rimárová, K; Siegfried, L

    2015-08-01

    The work studies the survival of added selected probiotic bacteria Lactobacillus acidophilus (S1), Lactobacillus casei (S2), and Lactobacillus plantarum96 (S3) in semi-hard cheese with low-cooking curd during the maturation process. Cheeses were made according to the standard procedure (Polyfood SI 050 device). Probiotic lactobacilli strains Lactobacillus acidophilus (S1), Lactobacillus casei (S2), and Lactobacillus plantarum96 (S3) used in this study were added into the milk before the renneting process. The manufactured cheeses were matured for 6 months at the temperature of 10 °C. Cheese samples were taken for pH and titratable acidity measurements, lactobacilli enumeration, and chemical analysis at 30, 60, 90, 120, 150 and 180 days of maturation. At the end of the experiment (180 days) the cheese samples were analyzed also for the amount of lactic acid and protein contents. Initial numbers of lactobacilli inoculated into the milk (10(8) CFU mL(-1)) decreased during the first 2 weeks of maturation and reached from 2.15 10(7) CFU g(-1) in S1 cheese to 4.32 10(7) CFU g(-1) in S3 cheese. The number of Lactobacillus acidophilus strain bacteria at the beginning of the maturation period was 2.47.10(7) CFU g(-1) and declined until day 120 of maturation to the number of 0.45 10(6) CFU g(-1). In the last month of the experiment day 180 the viable cell numbers started to rise up to the final number of 0.41 10(7) CFU g(-1). The numbers of Lactobacillus plantarum96 varied around 10(8) CFU g(-1) during the whole period of the experiment. According to our results it was detected that in all experimental cheeses, the used probiotic lactobacilli reached the values above 10(6) CFU g(-1). Thus the legislated and therapeutic minimum limits set for the products containing probiotic bacteria for human diet were fulfilled.

  1. Fermion determinants in lattice QCD

    International Nuclear Information System (INIS)

    Johnson, Christopher Andrew

    2001-01-01

    The main topic of this thesis concerns efficient algorithms for the calculation of determinants of the kind of matrix typically encountered in lattice QCD. In particular an efficient method for calculating the fermion determinant is described. Such a calculation is useful to illustrate the effects of light dynamical (virtual) quarks. The methods employed in this thesis are stochastic methods, based on the Lanczos algorithm, which is used for the solution of large, sparse matrix problems via a partial tridiagonalisation of the matrix. Here an implementation is explored which requires less exhaustive treatment of the matrix than previous Lanczos methods. This technique exploits the analogy between the Lanczos tridiagonalisation algorithm and Gaussian quadrature in order to calculate the fermion determinant. A technique for determining a number of the eigenvalues of the matrix is also presented. A demonstration is then given of how one can improve upon this estimate considerably using variance reduction techniques, reducing the variance by a factor of order 100 with a further, equal amount of work. The variance reduction method is a two-stage process, involving a Chebyshev approximation to the quantity in question and then the subtraction of traceless operators. The method is applied to the fermion determinant for non-perturbatively improved Wilson fermions on a 16 3 x 32 lattice. It is also applicable to a wider class of matrix operators. Finally we discuss how dynamical quark effects may be simulated in a Monte Carlo process with an effective partitioning of low and high eigenmodes. This may be done via selective updating of a trial configuration which highlights the physically relevant effects of light quark modes. (author)

  2. Recent QCD results from CDF

    International Nuclear Information System (INIS)

    Yun, J.C.

    1990-01-01

    In this paper we report recent QCD analysis with the new data taken from CDF detector. CDF recorded an integrated luminosity of 4.4 nb -1 during the 1988--1989 run at center of mass system (CMS) energy of 1.8 TeV. The major topics of this report are inclusive jet, dijet, trijet and direct photon analysis. These measurements are compared of QCD predictions. For the inclusive jet an dijet analysis, tests of quark compositeness are emphasized. 11 refs., 6 figs

  3. The supercritical pomeron in QCD

    International Nuclear Information System (INIS)

    White, A. R.

    1998-01-01

    Deep-inelastic diffractive scaling violations have provided fundamental insight into the QCD pomeron, suggesting a single gluon inner structure rather than that of a perturbative two-gluon bound state. This talk outlines a derivation of a high-energy, transverse momentum cut-off, confining solution of QCD. The pomeron, in first approximation, is a single reggeized gluon plus a ''wee parton'' component that compensates for the color and particle properties of the gluon. This solution corresponds to a super-critical phase of Reggeon Field Theory

  4. Simulating QCD at finite density

    CERN Document Server

    de Forcrand, Philippe

    2009-01-01

    In this review, I recall the nature and the inevitability of the "sign problem" which plagues attempts to simulate lattice QCD at finite baryon density. I present the main approaches used to circumvent the sign problem at small chemical potential. I sketch how one can predict analytically the severity of the sign problem, as well as the numerically accessible range of baryon densities. I review progress towards the determination of the pseudo-critical temperature T_c(mu), and towards the identification of a possible QCD critical point. Some promising advances with non-standard approaches are reviewed.

  5. The first lap in QCD

    International Nuclear Information System (INIS)

    Close, F.E.

    1980-07-01

    The idea that quantum chromodynamics is Nature's choice for the theory of quark interactions and that desirable phenomena, such as quark confinement, are consequences of it are considered. The lecture is presented under the headings: (1) Why do we believe that quarks have colour. (2) A rapid summary of the parton model in deep inelastic scattering. (3) Non Abelian theories: the vertices. (4) Hyperfine splitting of hadrons: more evidence for colour. (5) Renormalisation. (6) Alpha(Q 2 ). (7) The renormalisation group equations. (8) QCD, the renormalisation group equation and deep inelastic data. (9) Higher order corrections in QCD. (U.K.)

  6. Neutron star structure from QCD

    CERN Document Server

    Fraga, Eduardo S; Vuorinen, Aleksi

    2016-01-01

    In this review article, we argue that our current understanding of the thermodynamic properties of cold QCD matter, originating from first principles calculations at high and low densities, can be used to efficiently constrain the macroscopic properties of neutron stars. In particular, we demonstrate that combining state-of-the-art results from Chiral Effective Theory and perturbative QCD with the current bounds on neutron star masses, the Equation of State of neutron star matter can be obtained to an accuracy better than 30% at all densities.

  7. 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

  8. Lattice QCD: Status and Prospect

    International Nuclear Information System (INIS)

    Ukawa, Akira

    2006-01-01

    A brief review is given of the current status and near-future prospect of lattice QCD studies of the Standard Model. After summarizing a bit of history, we describe current attempts toward inclusion of dynamical up, down and strange quarks. Recent results on the light hadron mass spectrum as well as those on the heavy quark quantities are described. Recent work on lattice pentaquark search is summarized. We touch upon the PACS-CS Project for building our next machine for lattice QCD, and conclude with a summary of computer situation and the physics possibilities over the next several years

  9. Hadron scattering, resonances, and QCD

    Science.gov (United States)

    Briceño, R. A.

    2016-11-01

    The non-perturbative nature of quantum chromodynamics (QCD) has historically left a gap in our understanding of the connection between the fundamental theory of the strong interactions and the rich structure of experimentally observed phenomena. For the simplest properties of stable hadrons, this is now circumvented with the use of lattice QCD (LQCD). In this talk I discuss a path towards a rigorous determination of few-hadron observables from LQCD. I illustrate the power of the methodology by presenting recently determined scattering amplitudes in the light-meson sector and their resonance content.

  10. Archeology and evolution of QCD

    CERN Document Server

    De Rújula, A.

    2017-01-01

    These are excerpts from the closing talk at the "XIIth Conference on Quark Confinement and the Hadron Spectrum", which took place last Summer in Thessaloniki --an excellent place to enjoy an interest in archeology. A more complete personal view of the early days of QCD and the rest of the Standard Model is given in [1]. Here I discuss a few of the points which --to my judgement-- illustrate well the QCD evolution (in time), both from a scientific and a sociological point of view.

  11. The generalized scheme-independent Crewther relation in QCD

    Science.gov (United States)

    Shen, Jian-Ming; Wu, Xing-Gang; Ma, Yang; Brodsky, Stanley J.

    2017-07-01

    The Principle of Maximal Conformality (PMC) provides a systematic way to set the renormalization scales order-by-order for any perturbative QCD calculable processes. The resulting predictions are independent of the choice of renormalization scheme, a requirement of renormalization group invariance. The Crewther relation, which was originally derived as a consequence of conformally invariant field theory, provides a remarkable connection between two observables when the β function vanishes: one can show that the product of the Bjorken sum rule for spin-dependent deep inelastic lepton-nucleon scattering times the Adler function, defined from the cross section for electron-positron annihilation into hadrons, has no pQCD radiative corrections. The ;Generalized Crewther Relation; relates these two observables for physical QCD with nonzero β function; specifically, it connects the non-singlet Adler function (Dns) to the Bjorken sum rule coefficient for polarized deep-inelastic electron scattering (CBjp) at leading twist. A scheme-dependent ΔCSB-term appears in the analysis in order to compensate for the conformal symmetry breaking (CSB) terms from perturbative QCD. In conventional analyses, this normally leads to unphysical dependence in both the choice of the renormalization scheme and the choice of the initial scale at any finite order. However, by applying PMC scale-setting, we can fix the scales of the QCD coupling unambiguously at every order of pQCD. The result is that both Dns and the inverse coefficient CBjp-1 have identical pQCD coefficients, which also exactly match the coefficients of the corresponding conformal theory. Thus one obtains a new generalized Crewther relation for QCD which connects two effective charges, αˆd (Q) =∑i≥1 αˆg1 i (Qi), at their respective physical scales. This identity is independent of the choice of the renormalization scheme at any finite order, and the dependence on the choice of the initial scale is negligible. Similar

  12. The gauge-independent QCD effective charge

    International Nuclear Information System (INIS)

    Watson, N.J.

    1999-01-01

    It is shown how the QCD concept of a gauge-, scale-and scheme-independent one-loop effective charge can be extended directly at the diagrammatic level to QCD, thus justifying explicitly the 'naive non-abelialization' prescription used in renormalon calculus. It is first argued that, for one-shell external fields and at the strictly one-loop level, the required gluon self-energy-like function is precisely that obtained from S-matrix elements via the pinch technique. The generalization of the pinch technique to explicitly off-shell processes is then introduced. It is shown how, as a result of a fundamental cancellation among conventional perturbation theory diagrams encoded in the QCD Ward identities, the pinch technique one-loop gluon self-energy iΠ μν ab (q) remains gauge-independent and universal regardless of the fact that the 'external' fields in the given process are off-shell. This demonstration involves a simple technique enabling the isolation in a arbitrary gauge, of iΠ μν ab (q) from subclasses of up to several hundreds diagrams at once. Furthermore, it is shown how this one-loop cancellation mechanism iterates for the subclasses of n-loop diagrams containing implicitly the Dyson chains of n-loop self energies iΠ μν ab (q). The gauge cancellation required for the Dyson summation of iΠ μν ab (q) is thus demonstrated explicitly in the class of ghost-free gauges for all orders n. (authors)

  13. Electroweak Higgs production with HiggsPO at NLO QCD

    International Nuclear Information System (INIS)

    Greljo, Admir; Isidori, Gino; Zhang, Hantian; Lindert, Jonas M.; Marzocca, David

    2017-01-01

    We present the HiggsPO UFO model for Monte Carlo event generation of electroweak VH and VBF Higgs production processes at NLO in QCD in the formalism of Higgs pseudo-observables (PO). We illustrate the use of this tool by studying the QCD corrections, matched to a parton shower, for several benchmark points in the Higgs PO parameter space. We find that, while being sizable and thus important to be considered in realistic experimental analyses, the QCD higher-order corrections largely factorize. As an additional finding, based on the NLO results, we advocate to consider 2D distributions of the two-jet azimuthal-angle difference and the leading jet p T for new physics searches in VBF Higgs production. The HiggsPO UFO model is publicly available. (orig.)

  14. Electroweak Higgs production with HiggsPO at NLO QCD

    Science.gov (United States)

    Greljo, Admir; Isidori, Gino; Lindert, Jonas M.; Marzocca, David; Zhang, Hantian

    2017-12-01

    We present the HiggsPO UFO model for Monte Carlo event generation of electroweak VH and VBF Higgs production processes at NLO in QCD in the formalism of Higgs pseudo-observables (PO). We illustrate the use of this tool by studying the QCD corrections, matched to a parton shower, for several benchmark points in the Higgs PO parameter space. We find that, while being sizable and thus important to be considered in realistic experimental analyses, the QCD higher-order corrections largely factorize. As an additional finding, based on the NLO results, we advocate to consider 2D distributions of the two-jet azimuthal-angle difference and the leading jet p_T for new physics searches in VBF Higgs production. The HiggsPO UFO model is publicly available.

  15. Electroweak Higgs production with HiggsPO at NLO QCD

    Energy Technology Data Exchange (ETDEWEB)

    Greljo, Admir [Universitaet Zuerich, Physik-Institut, Zurich (Switzerland); Johannes Gutenberg-Universitaet Mainz, PRISMA Cluster of Excellence and Mainz Institute for Theoretical Physics, Mainz (Germany); University of Sarajevo, Faculty of Science, Sarajevo (Bosnia and Herzegovina); Isidori, Gino; Zhang, Hantian [Universitaet Zuerich, Physik-Institut, Zurich (Switzerland); Lindert, Jonas M. [Durham University, Department of Physics, Institute for Particle Physics Phenomenology, Durham (United Kingdom); Marzocca, David [Universitaet Zuerich, Physik-Institut, Zurich (Switzerland); INFN, Sezione di Trieste(Italy); SISSA, Trieste (Italy)

    2017-12-15

    We present the HiggsPO UFO model for Monte Carlo event generation of electroweak VH and VBF Higgs production processes at NLO in QCD in the formalism of Higgs pseudo-observables (PO). We illustrate the use of this tool by studying the QCD corrections, matched to a parton shower, for several benchmark points in the Higgs PO parameter space. We find that, while being sizable and thus important to be considered in realistic experimental analyses, the QCD higher-order corrections largely factorize. As an additional finding, based on the NLO results, we advocate to consider 2D distributions of the two-jet azimuthal-angle difference and the leading jet p{sub T} for new physics searches in VBF Higgs production. The HiggsPO UFO model is publicly available. (orig.)

  16. The dual description of long-distance QCD (Dual QCD)

    International Nuclear Information System (INIS)

    Baker, M.

    1990-01-01

    We construct and solve a local field theory which describes in terms of dual variables a system having an A μ propagator behaving like M 2 /q 4 in the infrared and discuss how this theory can be used as a starting point for describing long-distance QCD. 3 refs

  17. Consistent Perturbative Fixed Point Calculations in QCD and Supersymmetric QCD

    DEFF Research Database (Denmark)

    Ryttov, Thomas A.

    2016-01-01

    order by order in $\\Delta_f$. We then compute $\\gamma_*$ through $O(\\Delta_f^2)$ for supersymmetric QCD in the $\\overline{\\text{DR}}$ scheme and find that it matches the exact known result. We find that $\\gamma_*$ is astonishingly well described in perturbation theory already at the few loops level...

  18. Effects of carbon nanotube content and annealing temperature on the hardness of CNT reinforced aluminum nanocomposites processed by the high pressure torsion technique

    Energy Technology Data Exchange (ETDEWEB)

    Phuong, Doan Dinh, E-mail: phuongdd@ims.vast.ac.vn [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Str., Cau Giay Distr., Hanoi (Viet Nam); Trinh, Pham Van; An, Nguyen Van; Luan, Nguyen Van; Minh, Phan Ngoc [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Str., Cau Giay Distr., Hanoi (Viet Nam); Khisamov, Rinat Kh.; Nazarov, Konstantin S.; Zubairov, Linar R.; Mulyukov, Radik R.; Nazarov, Ayrat A. [Institute for Metals Superplasticity Problems, Russian Academy of Sciences 39, Stepan Khalturin Str., Ufa 450001 (Russian Federation)

    2014-11-15

    Highlights: • CNT/Al nanocomposites were consolidated by HIP and subsequently processed by the high pressure torsion technique. • High pressure torsion processing was unable to break apart or disperse the CNT agglomerates persisted in powder preparation. • HPT-processed CNT/Al nanocomposites exhibited secondary hardening during annealing at temperatures below 150 °C. - Abstract: In this paper, the microstructure and hardness of CNT reinforced aluminium (CNT/Al) nanocomposites prepared by the advanced powder metallurgy method and subsequently processed by the high pressure torsion (HPT) technique are studied. The effects of CNT content and annealing temperature on the hardness of the nanocomposites are investigated. The results show that annealing materials at temperatures below 150 °C leads to secondary hardening, while annealing at higher temperatures soften the nanocomposites. HPT-processed CNT/Al nanocomposites with 1.5 wt.% of CNTs are shown to have the highest hardness in comparison with other composites containing CNTs from 0 up to 2 wt.%. Microstructures, CNT distribution and the phase composition of CNT/Al nanocomposites are investigated by transmission and scanning electron microscopy and X-ray diffraction techniques.

  19. Hard Quasi-real Photo-production of Charged Hadrons at COMPASS energies

    CERN Document Server

    Morréale, Astrid

    2011-01-01

    The Common Muon Proton Apparatus for Structure and Spectroscopy (COMPASS) at CERN with its use of beams of naturally polarized muons scattered of a polarized deuteron target, provides an environment of hard scattering between quasi-real photons and partons. Hard hadron quasi-real photo-production with polarized initial states is sensitive to the polarized gluon distribution $\\Delta$G through $\\gamma$-gluon($g$) direct channels as well as $q$-$g$ resolved processes. Comparisons of unpolarized differential cross section measurements to next-to-leading order (NLO) pQCD calculations are essential to develop our understanding of proton-proton and lepton-nucleon scattering at varying center of mass energies. These measurements are important to asses the applicability of NLO pQCD in interpreting polarized processes. In this talk we will discuss unidentified charged separated hadron production at low $Q^{2}$ (Q$^{2}1.0\\,GeV/c$). $$ spectra of charged hadrons at $Q^{2}>1 GeV^{2}/c^{2}$ will also be discussed.

  20. Valence QCD: Connecting QCD to the quark model

    International Nuclear Information System (INIS)

    Liu, K.F.; Dong, S.J.; Draper, T.; Sloan, J.; Leinweber, D.; Woloshyn, R.M.

    1999-01-01

    A valence QCD theory is developed to study the valence quark properties of hadrons. To keep only the valence degrees of freedom, the pair creation through the Z graphs is deleted in the connected insertions, whereas the sea quarks are eliminated in the disconnected insertions. This is achieved with a new 'valence QCD' Lagrangian where the action in the time direction is modified so that the particle and antiparticle decouple. It is shown in this valence version of QCD that the ratios of isovector to isoscalar matrix elements (e.g., F A /D A and F S /D S ratios) in the nucleon reproduce the SU(6) quark model predictions in a lattice QCD calculation. We also consider how the hadron masses are affected on the lattice and discover new insights into the origin of dynamical mass generation. It is found that, within statistical errors, the nucleon and the Δ become degenerate for the quark masses we have studied (ranging from 1 to 4 times the strange mass). The π and ρ become nearly degenerate in this range. It is shown that valence QCD has the C, P, T symmetries. The lattice version is reflection positive. It also has the vector and axial symmetries. The latter leads to a modified partially conserved axial Ward identity. As a result, the theory has a U(2N F ) symmetry in the particle-antiparticle space. Through lattice simulation, it appears that this is dynamically broken down to U q (N F )xU bar q (N F ). Furthermore, the lattice simulation reveals spin degeneracy in the hadron masses and various matrix elements. This leads to an approximate U q (2N F )xU bar q (2N F ) symmetry which is the basis for the valence quark model. In addition, we find that the masses of N, Δ,ρ,π,a 1 , and a 0 all drop precipitously compared to their counterparts in the quenched QCD calculation. This is interpreted as due to the disappearance of the 'constituent' quark mass which is dynamically generated through tadpole diagrams. The origin of the hyperfine splitting in the baryon is

  1. QCD and short-range nuclear phenomena

    International Nuclear Information System (INIS)

    Frankfurt, L.L.; Strikman, M.I.

    1981-01-01

    In terms of pertubative QCD we estimate the shape of the high-momentum tail of the nucleus wave function. We derive QCD predictions for the yield of leading particles in nucleus fragmentation processes. The predicted yield is much larger than the expectations of the quark counting rules. Obtained formulae are in reasonable agreement with the momentum and angular dependence of cumulative particle production. We derive general expressions for deep inelastic lepton-nucleus scattering using the LSZ representation for the amplitude and use it to calculate the scaling violation in high Q 2 near threshold eD scattering at x >= 1. It is shown that the existence of few-nucleon correlations explains the large cross section of the deep inelastic process e + 3 He → e +... and leads to a larger effect for heavier nuclei. We demonstrate that the observed features of ν(anti ν) + A → μsup(+-) + backward proton + X data indicate the dominance of few-nucleon correlations in the nucleus wave function over average field configurations at momenta > 0.4 GeV/c. Implications of these data for the magnitude of smearing in deep inelastic processes are also considered. (orig.)

  2. Hard photoproduction of multiparticle hadronic final states

    International Nuclear Information System (INIS)

    Paul, E.

    1992-02-01

    Recent results from fixed-target experiments on the photoproduction of hadrons have shown that pointlike photon interaction processes of lowest order in QCD can be studied. These are the flavour-dependent γg-fusion process which is the keyprocess to explore the gluon structure function of the nucleon at small x g and the QCD-Compton process which is a tool to study gluon fragmentation. The status of experimental results and comparison to QCD prediction is reviewed. The γg-fusion process will be measured in ep scatterings with almost real photons at HERA photon energies (equivalent to up to 50 TeV in the rest frame of the proton) down to x g > or approx. 10 -4 . Resolved (partonlike) photon interactions are predicted to be measurable at these high energies, too. (orig.)

  3. Exotic hybrid mesons in hard electroproduction

    CERN Document Server

    Anikin, I V; Szymanowski, L; Teryaev, O V; Wallon, S

    2005-01-01

    We estimate the sizeable cross section for deep exclusive electroproduction of an exotic $J^{PC}=1^{-+}$ hybrid meson in the Bjorken regime. The production amplitude scales like the one for usual meson electroproduction, i.e. as $1/Q^2$. This is due to the non-vanishing leading twist distribution amplitude for the hybrid meson, which may be normalized thanks to its relation to the energy momentum tensor and to the QCD sum rules technique. The hard amplitude is considered up to next-to-leading order in $\\alpha_{S}$ and we explore the consequences of fixing the renormalization scale ambiguity through the BLM procedure. We study the particular case where the hybrid meson decays through a $\\pi\\eta $ meson pair. We discuss the $\\pi\\eta$ generalized distribution amplitude and then calculate the production amplitude for this process. We propose a forward-backward asymmetry in the production of $\\pi$ and $\\eta$ mesons as a signal for the hybrid meson production. We briefly comment on hybrid electroproduction at very ...

  4. The search for QCD exotica

    International Nuclear Information System (INIS)

    Dzierba, A.R.

    1995-01-01

    One of the open questions in non-perturbative QCD has to do with the existence of meson states predicted by the theory other than qq states. These include four-quark states (q 2 q 2 or molecules like KK), states of pure glue (glueballs: gg or ggg) and mixed or hybrid states (qqg). The prima facie candidate for a non-qq state would be one possessing exotic quantum numbers, J PC , not consistent with a qq combination. Examples include J PC =0 +- , 0-- , -+ ,hor-ellipsis Remarkably, states with exotic quantum numbers have not been found despite intensive searches. The case for a possible sighting of an exotic J Jc = 1 -+ state decaying into ηπ O , made a few years ago, seems to be dissolving. Yet, the evidence for non-qq states is clearly present. Conventional qq nonets are over-subscribed, states have been found with decay modes or production characteristics peculiar for qq. The experimental lesson we have learned is that information from a number of complementary processes must be brought together in order to understand the meson spectrum. Information has come from e + e - ,γγ, γγ, and pp collisions, from vector meson decays and from peripheral and central hadroproduction. This talk will review the status of the experimental search. I will especially point out how new technology is being brought to bear on the re-visit of the light quark sector. New instrumentation allows for sophisticated and selective triggers. The recent explosion in computing power allows us to analyze data with unprecedented statistics. Preliminary results from a recently completed, ultra-high statistics experiment using the Multiparticle Spectrometer at Brookhaven Lab will be presented. I will also describe the extension of the search to CEBAF, where an approved experiment there will study the sub-structure of scalar mesons via the radiative decays of the ER meson

  5. Current issues in perturbative QCD

    International Nuclear Information System (INIS)

    Hinchliffe, I.

    1994-12-01

    This review talk discusses some issues of active research in perturbative QCD. The following topics are discussed: (1) current value of αs; (2) heavy quark production in hadron collisions; (3) production of Ψ and Υ in p anti p collisions; (4) prompt photon production; (5) small-x and related phenomena; and (6) particle multiplicity in heavy quark jets

  6. New results in perturbative QCD

    International Nuclear Information System (INIS)

    Ellis, R.K.

    1986-01-01

    Three topics in perturbative QCD important for Super-collider physics are reviewed. The topics are: 1. (2 → 2) jet phenomena calculated in O(αs 3 ). 2. New techniques for the calculation of tree graphs. 3. Color coherence in jet phenomena. 31 references, 6 figures

  7. Reggeon interactions in perturbative QCD

    International Nuclear Information System (INIS)

    Kirschner, R.

    1994-08-01

    We study the pairwise interaction of reggeized gluons and quarks in the Regge limit of perturbative QCD. The interactions are represented as integral kernels in the transverse momentum space and as operators in the impact parameter space. We observe conformal symmetry and holomorphic factorization in all cases. (orig.)

  8. LHC physics: challenges for QCD

    OpenAIRE

    Frixione, S.

    2003-01-01

    I review the status of the comparisons between a few measurements at hadronic colliders and perturbative QCD predictions, which emphasize the need for improving the current computations. Such improvements will be mandatory for a satisfactory understanding of high-energy collisions at the LHC

  9. An overview of lattice QCD

    International Nuclear Information System (INIS)

    Woloshyn, R.M.

    1988-03-01

    The basic concepts of the Lagrangian formulation of lattice field theory are discussed. The Wilson and staggered schemes for dealing with fermions on the lattice are described. Some recent results for hadron masses and vector and axial vector current matrix elements in lattice QCD are reviewed. (Author) (118 refs., 16 figs.)

  10. Two flavor QCD and Confinement

    DEFF Research Database (Denmark)

    D'Elia, M.; Di Giacomo, A.; Pica, Claudio

    2005-01-01

    We argue that the order of the chiral transition for N_f=2 is a sensitive probe of the QCD vacuum, in particular of the mechanism of color confinement. A strategy is developed to investigate the order of the transition by use of finite size scaling analysis. An in-depth numerical investigation is...

  11. Multiplicity distributions in QCD cascades

    International Nuclear Information System (INIS)

    Gustafson, G.

    1992-03-01

    Multiplicity distributions for hadrons and for jets are studied in QCD parton cascades. The colour dipole formalism is used and earlier results in the double log approximation are generalized to include terms which are suppressed by colour factors or factors of ln s. The result is a set of coupled differential equations, together with appropriate boundary conditions

  12. Chiral symmetry in perturbative QCD

    International Nuclear Information System (INIS)

    Trueman, T.L.

    1979-04-01

    The chiral symmetry of quantum chromodynamics with massless quarks is unbroken in perturbation theory. Dimensional regularization is used. The ratio of the vector and axial vector renormalization constante is shown to be independent of the renormalization mass. The general results are explicitly verified to fourth order in g, the QCD coupling constant

  13. Beyond QCD: Why and How

    International Nuclear Information System (INIS)

    Preparata, G.

    1983-01-01

    In this paper the necessity of going beyond Quantum chromodynamics is argued, and a new theory of Isotropic Chromodynamics (ICD) is introduced. The basic theoretical notions behind QCD--quarks, colors, and gauge theory are retained, but the conclusion that QCD must be the theory of hadrions is questioned. Two points of QCD are reviewed, gluons (including glueballs), and asymptotic freedom. It is suggested that much of this theory is wishful thinking. Beyond QCD, aspects which are puzzling in hadrodynamics are well understood in two-dimensional gauge theories (confinement, freedom at short distances etc). Anisotropic chromodynamics is proposed in the attempt to conjugate the basic pillars of hadrodynamics with the peculiar characteristics of two-dimensional gauge dynamics. In order to construct a gauge dynamics for the color field which is isomorphic to a two-dimensional gauge-theory base space must be enlarged to a seven dimension space-time structure, to be called Anisotropic Space-Time (AST). The ideas and present achievements of ICD are then reviewed

  14. A classical primer for QCD

    International Nuclear Information System (INIS)

    Moriyasu, K.

    1981-01-01

    A basic primer for QCD is presented using a semiclassical approach to the colour Maxwell equations. The non-Abelian nature of colour symmetry and the violation of superposition by colour fields is compared with QED. A simple discussion of asymptotic freedom is also presented. (author)

  15. Bc→BP,BV Decays with the QCD Factorization Approach

    International Nuclear Information System (INIS)

    Chang, Qin; Wang, Na; Sun, Junfeng; Yang, Yueling

    2015-01-01

    We studied the nonleptonic B c →BP, BV decays with the QCD factorization approach. It is found that the Cabibbo favored processes of B c →B s π, B s ρ, B u K - are the promising decay channels with branching ratio larger than 1%, which should be observed earlier by the LHCb collaboration

  16. Renormalization and applications of baryon distribution amplitudes QCD

    Energy Technology Data Exchange (ETDEWEB)

    Rohrwild, Juergen Holger

    2009-07-17

    Higher-twist effects are relevant for precision calculations of hard exclusive reactions. Furthermore, they reveal fine details of the hadron structure. In this work we construct an operator basis for arbitrary twist respecting the conformal symmetry of QCD (which is realized on 1-loop level). Using this basis the 1-loop renormalization kernels of twist 4 are constructed for baryon operators. The full spectrum of anomalous dimensions and the multiplicatively renormalizable operators is obtained. As an application of these results the radiative N{sup *}(1535) decay is discussed. Employing light-cone sum rule, the transition form factors can be directly related to the N{sup *} distribution amplitudes. (orig.)

  17. Renormalization and applications of baryon distribution amplitudes in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Rohrwild, Juergen Holger

    2009-07-17

    Higher-twist effects are relevant for precision calculations of hard exclusive reactions. Furthermore, they reveal fine details of the hadron structure. In this work we construct an operator basis for arbitrary twist respecting the conformal symmetry of QCD (which is realized on 1-loop level). Using this basis the 1-loop renormalization kernels of twist 4 are constructed for baryon operators. The full spectrum of anomalous dimensions and the multiplicatively renormalizable operators is obtained. As an application of these results the radiative N{sup *}(1535) decay is discussed. Employing light-cone sum rule, the transition form factors can be directly related to the N* distribution amplitudes. (orig.)

  18. QCD threshold corrections for gluino pair production at hadron colliders

    Energy Technology Data Exchange (ETDEWEB)

    Langenfeld, Ulrich [Wuerzburg Univ. (Germany); Moch, Sven-Olaf; Pfoh, Torsten [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2012-11-15

    We present the complete threshold enhanced predictions in QCD for the total cross section of gluino pair production at hadron colliders at next-to-next-to-leading order. Thanks to the computation of the required one-loop hard matching coefficients our results are accurate to the next-to-next-to-leading logarithm. In a brief phenomenological study we provide predictions for the total hadronic cross sections at the LHC and we discuss the uncertainties arising from scale variations and the parton distribution functions.

  19. Renormalization and applications of baryon distribution amplitudes in QCD

    International Nuclear Information System (INIS)

    Rohrwild, Juergen Holger

    2009-01-01

    Higher-twist effects are relevant for precision calculations of hard exclusive reactions. Furthermore, they reveal fine details of the hadron structure. In this work we construct an operator basis for arbitrary twist respecting the conformal symmetry of QCD (which is realized on 1-loop level). Using this basis the 1-loop renormalization kernels of twist 4 are constructed for baryon operators. The full spectrum of anomalous dimensions and the multiplicatively renormalizable operators is obtained. As an application of these results the radiative N * (1535) decay is discussed. Employing light-cone sum rule, the transition form factors can be directly related to the N* distribution amplitudes. (orig.)

  20. Renormalization and applications of baryon distribution amplitudes QCD

    International Nuclear Information System (INIS)

    Rohrwild, Juergen Holger

    2009-01-01

    Higher-twist effects are relevant for precision calculations of hard exclusive reactions. Furthermore, they reveal fine details of the hadron structure. In this work we construct an operator basis for arbitrary twist respecting the conformal symmetry of QCD (which is realized on 1-loop level). Using this basis the 1-loop renormalization kernels of twist 4 are constructed for baryon operators. The full spectrum of anomalous dimensions and the multiplicatively renormalizable operators is obtained. As an application of these results the radiative N * (1535) decay is discussed. Employing light-cone sum rule, the transition form factors can be directly related to the N * distribution amplitudes. (orig.)

  1. Investigation of the effect of nanoclay and processing parameters on the tensile strength and hardness of injection molded Acrylonitrile Butadiene Styrene–organoclay nanocomposites

    International Nuclear Information System (INIS)

    Mamaghani Shishavan, Sajjad; Azdast, Taher; Rash Ahmadi, Samrand

    2014-01-01

    Highlights: • Development of polymer/clay nanocomposites. • Compatibility of ABS and montmorillonite nanoclay and composition capability of them. • Effect of nanoclay content and process parameters on the mechanical properties of nanocomposite. • Analyzing the distribution of nanoclay layers using XRD test. • Dependency of tensile strength and hardness to the nanoclay content and processing conditions. - Abstract: Polymer–clay nanocomposites have attracted considerable interest over recent years due to their dramatic improved mechanical properties. In the present study, compatibility of Acrylonitrile Butadiene Styrene (ABS) and organically modified montmorillonite nanoclay (Cloisite 30B) and composition capability of them are investigated. Polymethylmethacrylate (PMMA) in varying amount (0, 2, and 4 wt%) is used as the compatibilizer. In order to produce nanocomposite parts, the material is first compounded using a twin-screw extruder and then injected into a mold. The effect of the nanoclay percentage and processing parameters on the tensile strength and hardness of nanocomposite parts is also explored using Taguchi Design of Experiments method. Nanoclay content (in three levels: 0, 2 and 4 wt%), melt temperature (in three levels: 190, 200 and 210 °C), holding pressure (in three levels: 80, 105 and 130 MPa) and holding pressure time (in three levels: 1, 2.5 and 4 s) are considered as the variable parameters. Moreover, distribution of nanoclay layers is analyzed using Wide Angle X-ray Diffraction (XRD) test. XRD results displayed that with the presence of PMMA, nanoclay in ABS matrix is compounded in more exfoliated and less intercalated dispersion mode. Adding PMMA also leads to a remarkable increase in the fluidity of the melt during injection molding process. Results also illustrated that nanocomposites with medium loading level (i.e. 2%) of nanoclay have the highest tensile strength, while the highest hardness number belongs to nanocomposites with

  2. The Emergence of Hadrons from QCD Color

    Science.gov (United States)

    Brooks, William; Color Dynamics in Cold Matter (CDCM) Collaboration

    2015-10-01

    The formation of hadrons from energetic quarks, the dynamical enforcement of QCD confinement, is not well understood at a fundamental level. In Deep Inelastic Scattering, modifications of the distributions of identified hadrons emerging from nuclei of different sizes reveal a rich variety of spatial and temporal characteristics of the hadronization process, including its dependence on spin, flavor, energy, and hadron mass and structure. The EIC will feature a wide range of kinematics, allowing a complete investigation of medium-induced gluon bremsstrahlung by the propagating quarks, leading to partonic energy loss. This fundamental process, which is also at the heart of jet quenching in heavy ion collisions, can be studied for light and heavy quarks at the EIC through observables quantifying hadron ``attenuation'' for a variety of hadron species. Transverse momentum broadening of hadrons, which is sensitive to the nuclear gluonic field, will also be accessible, and can be used to test our understanding from pQCD of how this quantity evolves with pathlength, as well as its connection to partonic energy loss. The evolution of the forming hadrons in the medium will shed new light on the dynamical origins of the forces between hadrons, and thus ultimately on the nuclear force. Supported by the Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) of Chile.

  3. QCD-instantons at LHC. Theoretical aspects

    International Nuclear Information System (INIS)

    Petermann, M.

    2007-06-01

    Instantons are nonperturbative, topologically nontrivial field configurations, which occur in every nonabelian gauge theory. They can be understood as tunneling processes between topologically distinct vacua. Although being a basic theoretical aspect of the Standard Model, a direct experimental verification of instanton processes is still lacking. In this thesis the general discovery potential for QCD-instantons at the LHC is studied in detail by means of instanton perturbation theory. In this context the close correspondence between the leading instanton induced processes at HERA and at LHC becomes important. Essential aspects and differences to deep inelastic scattering can already be revealed by studying the simplest process. Based on these results inclusive cross sections are calculated including the emission of final state gluons. Compared to deep inelastic scattering, a large enhancement of the cross section is found. (orig.)

  4. Decay constants in soft wall AdS/QCD revisited

    Energy Technology Data Exchange (ETDEWEB)

    Braga, Nelson R.F., E-mail: braga@if.ufrj.br [Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, RJ 21941-972 (Brazil); Diles, Saulo, E-mail: smdiles@if.ufrj.br [Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, RJ 21941-972 (Brazil); Contreras, M.A. Martin, E-mail: ma.martin41@uniandes.edu.co [High Energy Group, Department of Physics, Universidad de los Andes, Carrera 1, No 18A-10, Bloque Ip, ZIP 111711, Bogotá (Colombia)

    2016-12-10

    Phenomenological AdS/QCD models, like hard wall and soft wall, provide hadronic mass spectra in reasonable consistency with experimental and (or) lattice results. These simple models are inspired in the AdS/CFT correspondence and assume that gauge/gravity duality holds in a scenario where conformal invariance is broken through the introduction of an energy scale. Another important property of hadrons: the decay constant, can also be obtained from these models. However, a consistent formulation of an AdS/QCD model that reproduces the observed behavior of decay constants of vector meson excited states is still lacking. In particular: for radially excited states of heavy vector mesons, the experimental data lead to decay constants that decrease with the radial excitation level. We show here that a modified framework of soft wall AdS/QCD involving an additional dimensionfull parameter, associated with an ultraviolet energy scale, provides decay constants decreasing with radial excitation level. In this version of the soft wall model the two point function of gauge theory operators is calculated at a finite position of the anti-de Sitter space radial coordinate.

  5. A comparative approach for the investigation of biological information processing: An examination of the structure and function of computer hard drives and DNA

    Science.gov (United States)

    2010-01-01

    Background The robust storage, updating and utilization of information are necessary for the maintenance and perpetuation of dynamic systems. These systems can exist as constructs of metal-oxide semiconductors and silicon, as in a digital computer, or in the "wetware" of organic compounds, proteins and nucleic acids that make up biological organisms. We propose that there are essential functional properties of centralized information-processing systems; for digital computers these properties reside in the computer's hard drive, and for eukaryotic cells they are manifest in the DNA and associated structures. Methods Presented herein is a descriptive framework that compares DNA and its associated proteins and sub-nuclear structure with the structure and function of the computer hard drive. We identify four essential properties of information for a centralized storage and processing system: (1) orthogonal uniqueness, (2) low level formatting, (3) high level formatting and (4) translation of stored to usable form. The corresponding aspects of the DNA complex and a computer hard drive are categorized using this classification. This is intended to demonstrate a functional equivalence between the components of the two systems, and thus the systems themselves. Results Both the DNA complex and the computer hard drive contain components that fulfill the essential properties of a centralized information storage and processing system. The functional equivalence of these components provides insight into both the design process of engineered systems and the evolved solutions addressing similar system requirements. However, there are points where the comparison breaks down, particularly when there are externally imposed information-organizing structures on the computer hard drive. A specific example of this is the imposition of the File Allocation Table (FAT) during high level formatting of the computer hard drive and the subsequent loading of an operating system (OS). Biological

  6. A comparative approach for the investigation of biological information processing: an examination of the structure and function of computer hard drives and DNA.

    Science.gov (United States)

    D'Onofrio, David J; An, Gary

    2010-01-21

    The robust storage, updating and utilization of information are necessary for the maintenance and perpetuation of dynamic systems. These systems can exist as constructs of metal-oxide semiconductors and silicon, as in a digital computer, or in the "wetware" of organic compounds, proteins and nucleic acids that make up biological organisms. We propose that there are essential functional properties of centralized information-processing systems; for digital computers these properties reside in the computer's hard drive, and for eukaryotic cells they are manifest in the DNA and associated structures. Presented herein is a descriptive framework that compares DNA and its associated proteins and sub-nuclear structure with the structure and function of the computer hard drive. We identify four essential properties of information for a centralized storage and processing system: (1) orthogonal uniqueness, (2) low level formatting, (3) high level formatting and (4) translation of stored to usable form. The corresponding aspects of the DNA complex and a computer hard drive are categorized using this classification. This is intended to demonstrate a functional equivalence between the components of the two systems, and thus the systems themselves. Both the DNA complex and the computer hard drive contain components that fulfill the essential properties of a centralized information storage and processing system. The functional equivalence of these components provides insight into both the design process of engineered systems and the evolved solutions addressing similar system requirements. However, there are points where the comparison breaks down, particularly when there are externally imposed information-organizing structures on the computer hard drive. A specific example of this is the imposition of the File Allocation Table (FAT) during high level formatting of the computer hard drive and the subsequent loading of an operating system (OS). Biological systems do not have an

  7. A comparative approach for the investigation of biological information processing: An examination of the structure and function of computer hard drives and DNA

    Directory of Open Access Journals (Sweden)

    D'Onofrio David J

    2010-01-01

    Full Text Available Abstract Background The robust storage, updating and utilization of information are necessary for the maintenance and perpetuation of dynamic systems. These systems can exist as constructs of metal-oxide semiconductors and silicon, as in a digital computer, or in the "wetware" of organic compounds, proteins and nucleic acids that make up biological organisms. We propose that there are essential functional properties of centralized information-processing systems; for digital computers these properties reside in the computer's hard drive, and for eukaryotic cells they are manifest in the DNA and associated structures. Methods Presented herein is a descriptive framework that compares DNA and its associated proteins and sub-nuclear structure with the structure and function of the computer hard drive. We identify four essential properties of information for a centralized storage and processing system: (1 orthogonal uniqueness, (2 low level formatting, (3 high level formatting and (4 translation of stored to usable form. The corresponding aspects of the DNA complex and a computer hard drive are categorized using this classification. This is intended to demonstrate a functional equivalence between the components of the two systems, and thus the systems themselves. Results Both the DNA complex and the computer hard drive contain components that fulfill the essential properties of a centralized information storage and processing system. The functional equivalence of these components provides insight into both the design process of engineered systems and the evolved solutions addressing similar system requirements. However, there are points where the comparison breaks down, particularly when there are externally imposed information-organizing structures on the computer hard drive. A specific example of this is the imposition of the File Allocation Table (FAT during high level formatting of the computer hard drive and the subsequent loading of an operating

  8. Hard coal; Steinkohle

    Energy Technology Data Exchange (ETDEWEB)

    Loo, Kai van de; Sitte, Andreas-Peter [Gesamtverband Steinkohle e.V., Herne (Germany)

    2013-04-01

    The year 2012 benefited from a growth of the consumption of hard coal at the national level as well as at the international level. Worldwide, the hard coal still is the number one energy source for power generation. This leads to an increasing demand for power plant coal. In this year, the conversion of hard coal into electricity also increases in this year. In contrast to this, the demand for coking coal as well as for coke of the steel industry is still declining depending on the market conditions. The enhanced utilization of coal for the domestic power generation is due to the reduction of the nuclear power from a relatively bad year for wind power as well as reduced import prices and low CO{sub 2} prices. Both justify a significant price advantage for coal in comparison to the utilisation of natural gas in power plants. This was mainly due to the price erosion of the inexpensive US coal which partly was replaced by the expansion of shale gas on the domestic market. As a result of this, the inexpensive US coal looked for an outlet for sales in Europe. The domestic hard coal has continued the process of adaptation and phase-out as scheduled. Two further hard coal mines were decommissioned in the year 2012. RAG Aktiengesellschaft (Herne, Federal Republic of Germany) running the hard coal mining in this country begins with the preparations for the activities after the time of mining.

  9. Azimuthal decorrelation between leptons in the Drell-Yan process as a probe of infrared QCD Phenomenology, predictions and measurement of a novel collider observable using perturbative resummation techniques

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00337682; Dasgupta, Mrinal

    This thesis presents phenomenological studies of a state-of-the-art NNLL+NLO theoretical calculation of a novel collider observable known as 'phi star'. In these studies the 'phi star' observable, a measure of azimuthal decorrelation, is applied directly to the leptons in the production of massive lepton pairs in hadron collisions (the Drell-Yan process). This provides an alternate measure of the recoil of the massive vector boson (Z/gamma) against initial state QCD radiation, but with distinct experimental advantages over the traditional boson transverse momentum. Attention is focused on the small-'phi star' regime (the quasi-back-to-back regime) where the infrared dynamics of soft/collinear gluon emissions become important. These phenomenological studies are followed up with the presentation of a measurement of 'phi star' in 'Z to mu mu' events using 20.3 fb^-1 of collision data collected by the ATLAS experiment in 2012. Finally, studies directly related to the ATLAS absolute luminosity calibration by the v...

  10. Standard hardness conversion tables for metals relationship among brinell hardness, vickers hardness, rockwell hardness, superficial hardness, knoop hardness, and scleroscope hardness

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 Conversion Table 1 presents data in the Rockwell C hardness range on the relationship among Brinell hardness, Vickers hardness, Rockwell hardness, Rockwell superficial hardness, Knoop hardness, and Scleroscope hardness of non-austenitic steels including carbon, alloy, and tool steels in the as-forged, annealed, normalized, and quenched and tempered conditions provided that they are homogeneous. 1.2 Conversion Table 2 presents data in the Rockwell B hardness range on the relationship among Brinell hardness, Vickers hardness, Rockwell hardness, Rockwell superficial hardness, Knoop hardness, and Scleroscope hardness of non-austenitic steels including carbon, alloy, and tool steels in the as-forged, annealed, normalized, and quenched and tempered conditions provided that they are homogeneous. 1.3 Conversion Table 3 presents data on the relationship among Brinell hardness, Vickers hardness, Rockwell hardness, Rockwell superficial hardness, and Knoop hardness of nickel and high-nickel alloys (nickel content o...

  11. Precision probes of QCD at high energies

    Science.gov (United States)

    Alioli, Simone; Farina, Marco; Pappadopulo, Duccio; Ruderman, Joshua T.

    2017-07-01

    New physics, that is too heavy to be produced directly, can leave measurable imprints on the tails of kinematic distributions at the LHC. We use energetic QCD processes to perform novel measurements of the Standard Model (SM) Effective Field Theory. We show that the dijet invariant mass spectrum, and the inclusive jet transverse momentum spectrum, are sensitive to a dimension 6 operator that modifies the gluon propagator at high energies. The dominant effect is constructive or destructive interference with SM jet production. We compare differential next-to-leading order predictions from POWHEG to public 7 TeV jet data, including scale, PDF, and experimental uncertainties and their respective correlations. We constrain a New Physics (NP) scale of 3.5 TeV with current data. We project the reach of future 13 and 100 TeV measurements, which we estimate to be sensitive to NP scales of 8 and 60 TeV, respectively. As an application, we apply our bounds to constrain heavy vector octet colorons that couple to the QCD current. We project that effective operators will surpass bump hunts, in terms of coloron mass reach, even for sequential couplings.

  12. Pion form factor in QCD at intermediate momentum transfers

    Science.gov (United States)

    Braun, V. M.; Khodjamirian, A.; Maul, M.

    2000-04-01

    We present a quantitative analysis of the electromagnetic pion form factor in the light-cone sum rule approach, including radiative corrections and higher-twist effects. The comparison to the existing data favors the asymptotic profile of the pion distribution amplitude and allows us to estimate the deviation: [∫du/uφπ(u)]/[∫du/uφasπ(u)]=1.1+/-0.1 at the scale of 1 GeV. Special attention is paid to the precise definition and interplay of soft and hard contributions at intermediate momentum transfer, and to the matching of the sum rule to the perturbative QCD prediction. We observe a strong numerical cancellation between the soft (end-point) contribution and power-suppressed hard contributions of higher twist, so that the total nonperturbative correction to the usual PQCD result turns out to be of the order of 30% for Q2~1 GeV2.

  13. QCD on the connection machine

    International Nuclear Information System (INIS)

    Gupta, R.

    1990-01-01

    In this talk I give a brief introduction to the standard model of particle interactions and illustrate why analytical methods fail to solve QCD. I then give some details of our implementation of the high performance QCD code on the CM2 and highlight the important lessons learned. The sustained speed of the code at the time of this conference is 5.2 Gigaflops (scaled to a full 64K machine). Since this is a conference dedicated to computing in the 21st century, I will tailor my expectations (somewhat idiosyncratic) of the physics objectives to reflect what we will be able to do in 10 years time, extrapolating from where we stand today. This work is being done under a joint LANL-TMC collaboration consisting of C. Baillie, R. Brickner, D. Daniel, G. Kilcup, L. Johnson, A. Patel. S. Sharpe and myself. 5 refs

  14. Innovations in lattice QCD algorithms

    International Nuclear Information System (INIS)

    Orginos, Konstantinos

    2006-01-01

    Lattice QCD calculations demand a substantial amount of computing power in order to achieve the high precision results needed to better understand the nature of strong interactions, assist experiment to discover new physics, and predict the behavior of a diverse set of physical systems ranging from the proton itself to astrophysical objects such as neutron stars. However, computer power alone is clearly not enough to tackle the calculations we need to be doing today. A steady stream of recent algorithmic developments has made an important impact on the kinds of calculations we can currently perform. In this talk I am reviewing these algorithms and their impact on the nature of lattice QCD calculations performed today

  15. Dijet production in diffractive deep-inelastic scattering in next-to-next-to-leading order QCD arXiv

    CERN Document Server

    Britzger, D.; Gehrmann, T.; Huss, A.; Niehues, J.; Žlebčík, R.

    Hard processes in diffractive deep-inelastic scattering can be described by a factorisation into parton-level subprocesses and diffractive parton distributions. In this framework, cross sections for inclusive dijet production in diffractive deep-inelastic electron-proton scattering (DIS) are computed to next-to-next-to-leading order (NNLO) QCD accuracy and compared to a comprehensive selection of data. Predictions for the total cross sections, 39 single-differential and four double-differential distributions for six measurements at HERA by the H1 and ZEUS collaborations are calculated. In the studied kinematical range, the NNLO corrections are found to be sizeable and positive. The NNLO predictions typically exceed the data, while the kinematical shape of the data is described better at NNLO than at next-to-leading order (NLO). A significant reduction of the scale uncertainty is achieved in comparison to NLO predictions. Our results use the currently available NLO diffractive parton distributions, and the dis...

  16. Testing QCD with current algebra

    International Nuclear Information System (INIS)

    Leutwyler, H.

    1984-01-01

    Spontaneously broken chiral symmetry fixes the low energy structure of QCD to a large extent. I show how to determine the Green's functions to first nonleading order in a simultaneous expansion in powers of the momenta and of the u- and d-quark masses. In particular, I discuss the corrections of order M π 2 to the low energy theorems for ππ scattering. 19 refs., 1 tab. (author)

  17. Lattice gauge theory for QCD

    International Nuclear Information System (INIS)

    DeGrand, T.

    1997-01-01

    These lectures provide an introduction to lattice methods for nonperturbative studies of Quantum Chromodynamics. Lecture 1: Basic techniques for QCD and results for hadron spectroscopy using the simplest discretizations; lecture 2: Improved actions--what they are and how well they work; lecture 3: SLAC physics from the lattice-structure functions, the mass of the glueball, heavy quarks and α s (M z ), and B-anti B mixing. 67 refs., 36 figs

  18. Scale setting in lattice QCD

    International Nuclear Information System (INIS)

    Sommer, Rainer

    2014-02-01

    The principles of scale setting in lattice QCD as well as the advantages and disadvantages of various commonly used scales are discussed. After listing criteria for good scales, I concentrate on the main presently used ones with an emphasis on scales derived from the Yang-Mills gradient flow. For these I discuss discretisation errors, statistical precision and mass effects. A short review on numerical results also brings me to an unpleasant disagreement which remains to be explained.

  19. The status of perturbative QCD

    International Nuclear Information System (INIS)

    Ellis, R.K.

    1988-10-01

    The advances in perturbative QCD are reviewed. The status of determinations of the coupling constant α/sub S/ and the parton distribution functions is presented. New theoretical results on the spin dependent structure functions of the proton are also reviewed. The theoretical description of the production of vector bosons, jets and heavy quarks is outlined with special emphasis on new results. Expected rates for top quark production at hadronic colliders are presented. 111 refs., 8 figs

  20. Hadronic τ decays and QCD

    International Nuclear Information System (INIS)

    Davier, M.

    1999-12-01

    Hadronic decays of the τ lepton provide a clean source to study hadron dynamics in an energy regime dominated by resonances, with the interesting information captured in the spectral functions. Recent results on exclusive channels are reviewed. Inclusive spectral functions are the basis for QCD analyses, delivering an accurate determination of the strong coupling constant and quantitative information on nonperturbative contributions. Strange decays yield a determination of the strange quark mass. (author)

  1. Lattice gauge theory for QCD

    Energy Technology Data Exchange (ETDEWEB)

    DeGrand, T. [Univ. of Colorado, Boulder, CO (United States). Dept. of Physics

    1997-06-01

    These lectures provide an introduction to lattice methods for nonperturbative studies of Quantum Chromodynamics. Lecture 1: Basic techniques for QCD and results for hadron spectroscopy using the simplest discretizations; lecture 2: Improved actions--what they are and how well they work; lecture 3: SLAC physics from the lattice-structure functions, the mass of the glueball, heavy quarks and {alpha}{sub s} (M{sub z}), and B-{anti B} mixing. 67 refs., 36 figs.

  2. Nucleon structure from lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Dinter, Simon

    2012-11-13

    In this thesis we compute within lattice QCD observables related to the structure of the nucleon. One part of this thesis is concerned with moments of parton distribution functions (PDFs). Those moments are essential elements for the understanding of nucleon structure and can be extracted from a global analysis of deep inelastic scattering experiments. On the theoretical side they can be computed non-perturbatively by means of lattice QCD. However, since the time lattice calculations of moments of PDFs are available, there is a tension between these lattice calculations and the results from a global analysis of experimental data. We examine whether systematic effects are responsible for this tension, and study particularly intensively the effects of excited states by a dedicated high precision computation. Moreover, we carry out a first computation with four dynamical flavors. Another aspect of this thesis is a feasibility study of a lattice QCD computation of the scalar quark content of the nucleon, which is an important element in the cross-section of a heavy particle with the nucleon mediated by a scalar particle (e.g. Higgs particle) and can therefore have an impact on Dark Matter searches. Existing lattice QCD calculations of this quantity usually have a large error and thus a low significance for phenomenological applications. We use a variance-reduction technique for quark-disconnected diagrams to obtain a precise result. Furthermore, we introduce a new stochastic method for the calculation of connected 3-point correlation functions, which are needed to compute nucleon structure observables, as an alternative to the usual sequential propagator method. In an explorative study we check whether this new method is competitive to the standard one. We use Wilson twisted mass fermions at maximal twist in all our calculations, such that all observables considered here have only O(a{sup 2}) discretization effects.

  3. ADS/CFT and QCD

    International Nuclear Information System (INIS)

    Brodsky, Stanley J.; de Teramond, Guy F.

    2007-01-01

    The AdS/CFT correspondence between string theory in AdS space and conformal .eld theories in physical spacetime leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. Although QCD is not conformally invariant, one can nevertheless use the mathematical representation of the conformal group in five-dimensional anti-de Sitter space to construct a first approximation to the theory. The AdS/CFT correspondence also provides insights into the inherently non-perturbative aspects of QCD, such as the orbital and radial spectra of hadrons and the form of hadronic wavefunctions. In particular, we show that there is an exact correspondence between the fifth-dimensional coordinate of AdS space z and a specific impact variable ζ which measures the separation of the quark and gluonic constituents within the hadron in ordinary space-time. This connection allows one to compute the analytic form of the frame-independent light-front wavefunctions, the fundamental entities which encode hadron properties and allow the computation of decay constants, form factors, and other exclusive scattering amplitudes. New relativistic lightfront equations in ordinary space-time are found which reproduce the results obtained using the 5-dimensional theory. The effective light-front equations possess remarkable algebraic structures and integrability properties. Since they are complete and orthonormal, the AdS/CFT model wavefunctions can also be used as a basis for the diagonalization of the full light-front QCD Hamiltonian, thus systematically improving the AdS/CFT approximation

  4. Hadronic {tau} decays and QCD

    Energy Technology Data Exchange (ETDEWEB)

    Davier, M

    1999-12-01

    Hadronic decays of the {tau} lepton provide a clean source to study hadron dynamics in an energy regime dominated by resonances, with the interesting information captured in the spectral functions. Recent results on exclusive channels are reviewed. Inclusive spectral functions are the basis for QCD analyses, delivering an accurate determination of the strong coupling constant and quantitative information on nonperturbative contributions. Strange decays yield a determination of the strange quark mass. (author)

  5. Nucleon structure from lattice QCD

    International Nuclear Information System (INIS)

    Dinter, Simon

    2012-01-01

    In this thesis we compute within lattice QCD observables related to the structure of the nucleon. One part of this thesis is concerned with moments of parton distribution functions (PDFs). Those moments are essential elements for the understanding of nucleon structure and can be extracted from a global analysis of deep inelastic scattering experiments. On the theoretical side they can be computed non-perturbatively by means of lattice QCD. However, since the time lattice calculations of moments of PDFs are available, there is a tension between these lattice calculations and the results from a global analysis of experimental data. We examine whether systematic effects are responsible for this tension, and study particularly intensively the effects of excited states by a dedicated high precision computation. Moreover, we carry out a first computation with four dynamical flavors. Another aspect of this thesis is a feasibility study of a lattice QCD computation of the scalar quark content of the nucleon, which is an important element in the cross-section of a heavy particle with the nucleon mediated by a scalar particle (e.g. Higgs particle) and can therefore have an impact on Dark Matter searches. Existing lattice QCD calculations of this quantity usually have a large error and thus a low significance for phenomenological applications. We use a variance-reduction technique for quark-disconnected diagrams to obtain a precise result. Furthermore, we introduce a new stochastic method for the calculation of connected 3-point correlation functions, which are needed to compute nucleon structure observables, as an alternative to the usual sequential propagator method. In an explorative study we check whether this new method is competitive to the standard one. We use Wilson twisted mass fermions at maximal twist in all our calculations, such that all observables considered here have only O(a 2 ) discretization effects.

  6. Scale setting in lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Sommer, Rainer [DESY, Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2014-02-15

    The principles of scale setting in lattice QCD as well as the advantages and disadvantages of various commonly used scales are discussed. After listing criteria for good scales, I concentrate on the main presently used ones with an emphasis on scales derived from the Yang-Mills gradient flow. For these I discuss discretisation errors, statistical precision and mass effects. A short review on numerical results also brings me to an unpleasant disagreement which remains to be explained.

  7. QCD contributions to vacuum polarization

    International Nuclear Information System (INIS)

    Reinders, L.J.; Rubinstein, H.R.; Yazaki, S.

    1980-01-01

    We have computed to lowest non-trivial order the perturbative and non-perturbative contributions to the vacuum polarization from all currents up to and including spin 2 ++ . These expressions are important, for example to evaluate QCD sum rules for heavy and light quark systems as shown by Shifman, Vainshtein and Zakharov. Most of the known ones are verified, one slightly changed, and many new ones are displayed. (orig.)

  8. Perturbative QCD at finite temperature

    International Nuclear Information System (INIS)

    Altherr, T.

    1989-03-01

    We discuss an application of finite temperature QCD to lepton-pair production in a quark-gluon plasma. The perturbative calculation is performed within the realtime formalism. After cancellation of infrared and mass singularities, the corrections at O (α s ) are found to be very small in the region where the mass of the Drell-Yan pair is much larger than the temperature of the plasma. Interesting effects, however, appear at the annihilation threshold of the thermalized quarks

  9. Tests of QCD using jets, bosons plus jets, and top quark production at colliders

    CERN Document Server

    Cossutti, Fabio

    2017-01-01

    Quantum Chromodynamics (QCD) is actively studied at present collidersusing several physics signatures as probes. Results from measurementsdone at LHC, but also from the legacy analyses of Tevatron and HERAdata, are discussed. Jets are the main tool for such investigation, asexperimental evidence for emission of gluons or quark production inQCD-dominated processes. Jet production in multijet events or inassociation with vector bosons is discussed. The investigation of theproduction of heavy quarks, and in particular of the top quark, is ofspecial importance both for the physics implications in the search fornew phenomena and for its unique characteristics from the QCD point ofview.

  10. Perturbative corrections to B → D form factors in QCD

    Science.gov (United States)

    Wang, Yu-Ming; Wei, Yan-Bing; Shen, Yue-Long; Lü, Cai-Dian

    2017-06-01

    We compute perturbative QCD corrections to B → D form factors at leading power in Λ/ m b , at large hadronic recoil, from the light-cone sum rules (LCSR) with B-meson distribution amplitudes in HQET. QCD factorization for the vacuum-to- B-meson correlation function with an interpolating current for the D-meson is demonstrated explicitly at one loop with the power counting scheme {m}_c˜ O(√{Λ {m}_b}) . The jet functions encoding information of the hard-collinear dynamics in the above-mentioned correlation function are complicated by the appearance of an additional hard-collinear scale m c , compared to the counterparts entering the factorization formula of the vacuum-to- B-meson correction function for the construction of B → π from factors. Inspecting the next-to-leading-logarithmic sum rules for the form factors of B → Dℓν indicates that perturbative corrections to the hard-collinear functions are more profound than that for the hard functions, with the default theory inputs, in the physical kinematic region. We further compute the subleading power correction induced by the three-particle quark-gluon distribution amplitudes of the B-meson at tree level employing the background gluon field approach. The LCSR predictions for the semileptonic B → Dℓν form factors are then extrapolated to the entire kinematic region with the z-series parametrization. Phenomenological implications of our determinations for the form factors f BD +,0 ( q 2) are explored by investigating the (differential) branching fractions and the R( D) ratio of B → Dℓν and by determining the CKM matrix element |V cb | from the total decay rate of B → Dμν μ .

  11. Applications of QCD

    International Nuclear Information System (INIS)

    Landshoff, P.V.

    1983-01-01

    The author describes the application of quantum chromodynamics to deep inelastic lepton scattering, the Drell-Yan process, e + e - -annihilation, #betta##betta#-physics, large psub(T) processes, and wide angle quark-quark scattering. Furthermore higher order terms are considered. (HSI)

  12. Factorization in QCD in Feynman gauge

    International Nuclear Information System (INIS)

    Tucci, R.R.

    1985-01-01

    We present a mass divergence power counting technique for QCD in the Feynman gauge. For the process γ/sup */ → qq, we find the leading regions of integration and show that single diagrams are at worst logarithmically divergent. Using the Weyl representation facilities the γ matrix manipulations necessary for power counting and adds much physical insight. We prove Ward type identities which are needed in the proof of factorization of the Drill Yan process. Previous treatments prove them only for an axial gauge, and the proofs are diagrammatic in nature. We, on the other hand, establish the identities for the Feynman gauge and through symmetry considerations at the Lagrangian level. The strategy is to first derive exact results in a background field gauge and then to show that to leading order in the mass divergences the background field gauge results can be used in the Feynman gauge

  13. Investigation on the effect of Friction Stir Processing Parameters on Micro-structure and Micro-hardness of Rice Husk Ash reinforced Al6061 Metal Matrix Composites

    Science.gov (United States)

    Fatchurrohman, N.; Farhana, N.; Marini, C. D.

    2018-03-01

    Friction stir processing (FSP) is an alternative way to produce the surface composites of aluminium alloy in order to modify the microstructure and improve the mechanical properties. In this experiment, Al6061 aluminium alloy has been chosen to be used as the matrix base plate for the FSP. Al606 has potential for the use in advanced application but it has low wear resistance. While, the reinforced used was rice husk ash (RHA) in order to produce surface composites which increased the micro hardness of the plate composites. The Al6061 was stirred individually and with 5 weight % of RHA at three different tool rotational speeds of 800 rpm, 1000 rpm and 1200 rpm. After running the FSP, the result in the distribution of particles and the micro hardness of the specimens were identified. The result showed that Al6061 plate with the existing 5 weight % of RHA reinforced at the highest of tool rotational speeds of 1200rpm has the best distribution of particles and the highest result in average of micro hardness with 80Hv.

  14. Reggeons in pQCD

    International Nuclear Information System (INIS)

    Griffiths, S.

    1999-06-01

    We consider the description of deep inelastic scattering by perturbative quantum chromo dynamics in the Regge-limit, specifically via the Reggeization of fundamental particles (gluons and quarks) and the description of processes by integro-differential equations such as the BFKL equation. We review the Reggeization of the gluon via Feynman diagrams in the leading-log approximation and then extend this to an original demonstration of the quark's Reggeization. In analogy to the hard Pomeron's description in terms of Reggeized gluons we consider the ρ-meson's trajectory in terms of the exchange of Reggeized quarks and derive the evolution equation describing this. The solutions of this equation, both analytic and numeric, are then looked at in some detail, and we demonstrate how the low-x behaviour is enhanced. We then make modifications to include a running coupling constant and massive propagators, and investigate the effects that these have on the asymptotics of the ρ-trajectory. (author)

  15. Topology in dynamical lattice QCD simulations

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, Florian

    2012-08-20

    Lattice simulations of Quantum Chromodynamics (QCD), the quantum field theory which describes the interaction between quarks and gluons, have reached a point were contact to experimental data can be made. The underlying mechanisms, like chiral symmetry breaking or the confinement of quarks, are however still not understood. This thesis focuses on topological structures in the QCD vacuum. Those are not only mathematically interesting but also closely related to chiral symmetry and confinement. We consider methods to identify these objects in lattice QCD simulations. Based on this, we explore the structures resulting from different discretizations and investigate the effect of a very strong electromagnetic field on the QCD vacuum.

  16. Topology in dynamical lattice QCD simulations

    International Nuclear Information System (INIS)

    Gruber, Florian

    2012-01-01

    Lattice simulations of Quantum Chromodynamics (QCD), the quantum field theory which describes the interaction between quarks and gluons, have reached a point were contact to experimental data can be made. The underlying mechanisms, like chiral symmetry breaking or the confinement of quarks, are however still not understood. This thesis focuses on topological structures in the QCD vacuum. Those are not only mathematically interesting but also closely related to chiral symmetry and confinement. We consider methods to identify these objects in lattice QCD simulations. Based on this, we explore the structures resulting from different discretizations and investigate the effect of a very strong electromagnetic field on the QCD vacuum.

  17. Academic training: QCD: are we ready for the LHC

    CERN Multimedia

    2006-01-01

    2006-2007 ACADEMIC TRAINING PROGRAMME LECTURE SERIES 4, 5, 6, 7 December, from 11:00 to 12:00 4, 5, 6 December - Main Auditorium, bldg. 500, 7 December - TH Auditorium, bldg. 4 - 3-006 QCD: are we ready for the LHC S. FRIXIONE / INFN, Genoa, Italy The LHC energy regime poses a serious challenge to our capability of predicting QCD reactions to the level of accuracy necessary for a successful programme of searches for physics beyond the Standard Model. In these lectures, I'll introduce basic concepts in QCD, and present techniques based on perturbation theory, such as fixed-order and resummed computations, and Monte Carlo simulations. I'll discuss applications of these techniques to hadron-hadron processes, concentrating on recent trends in perturbative QCD aimed at improving our understanding of LHC phenomenology. ENSEIGNEMENT ACADEMIQUE ACADEMIC TRAINING Françoise Benz 73127 academic.training@cern.ch If you wish to participate in one of the following courses, please tell to your supervisor and apply ...

  18. Disconnected Diagrams in Lattice QCD

    Science.gov (United States)

    Gambhir, Arjun Singh

    In this work, we present state-of-the-art numerical methods and their applications for computing a particular class of observables using lattice quantum chromodynamics (Lattice QCD), a discretized version of the fundamental theory of quarks and gluons. These observables require calculating so called "disconnected diagrams" and are important for understanding many aspects of hadron structure, such as the strange content of the proton. We begin by introducing the reader to the key concepts of Lattice QCD and rigorously define the meaning of disconnected diagrams through an example of the Wick contractions of the nucleon. Subsequently, the calculation of observables requiring disconnected diagrams is posed as the computationally challenging problem of finding the trace of the inverse of an incredibly large, sparse matrix. This is followed by a brief primer of numerical sparse matrix techniques that overviews broadly used methods in Lattice QCD and builds the background for the novel algorithm presented in this work. We then introduce singular value deflation as a method to improve convergence of trace estimation and analyze its effects on matrices from a variety of fields, including chemical transport modeling, magnetohydrodynamics, and QCD. Finally, we apply this method to compute observables such as the strange axial charge of the proton and strange sigma terms in light nuclei. The work in this thesis is innovative for four reasons. First, we analyze the effects of deflation with a model that makes qualitative predictions about its effectiveness, taking only the singular value spectrum as input, and compare deflated variance with different types of trace estimator noise. Second, the synergy between probing methods and deflation is investigated both experimentally and theoretically. Third, we use the synergistic combination of deflation and a graph coloring algorithm known as hierarchical probing to conduct a lattice calculation of light disconnected matrix elements

  19. Disconnected Diagrams in Lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Gambhir, Arjun [College of William and Mary, Williamsburg, VA (United States)

    2017-08-01

    In this work, we present state-of-the-art numerical methods and their applications for computing a particular class of observables using lattice quantum chromodynamics (Lattice QCD), a discretized version of the fundamental theory of quarks and gluons. These observables require calculating so called \\disconnected diagrams" and are important for understanding many aspects of hadron structure, such as the strange content of the proton. We begin by introducing the reader to the key concepts of Lattice QCD and rigorously define the meaning of disconnected diagrams through an example of the Wick contractions of the nucleon. Subsequently, the calculation of observables requiring disconnected diagrams is posed as the computationally challenging problem of finding the trace of the inverse of an incredibly large, sparse matrix. This is followed by a brief primer of numerical sparse matrix techniques that overviews broadly used methods in Lattice QCD and builds the background for the novel algorithm presented in this work. We then introduce singular value deflation as a method to improve convergence of trace estimation and analyze its effects on matrices from a variety of fields, including chemical transport modeling, magnetohydrodynamics, and QCD. Finally, we apply this method to compute observables such as the strange axial charge of the proton and strange sigma terms in light nuclei. The work in this thesis is innovative for four reasons. First, we analyze the effects of deflation with a model that makes qualitative predictions about its effectiveness, taking only the singular value spectrum as input, and compare deflated variance with different types of trace estimator noise. Second, the synergy between probing methods and deflation is investigated both experimentally and theoretically. Third, we use the synergistic combination of deflation and a graph coloring algorithm known as hierarchical probing to conduct a lattice calculation of light disconnected matrix elements

  20. A Case Study of Engaging Hard-to-Reach Participants in the Research Process: Community Advisors on Research Design and Strategies (CARDS)®.

    Science.gov (United States)

    Kaiser, Betty L; Thomas, Gay R; Bowers, Barbara J

    2017-02-01

    Lack of diversity among study participants in clinical research limits progress in eliminating health disparities. The engagement of lay stakeholders, such as patient or community advisory boards (CABs), has the potential to increase recruitment and retention of underrepresented groups by providing a structure for gathering feedback on research plans and materials from this target population. However, many CABs intentionally recruit prominent stakeholders who are connected to or comfortable with research and academia and thus may not accurately represent the perspectives of underrepresented groups who have been labeled hard-to-reach, including racial minorities and low-income or low-literacy populations. We developed a partnership between the University of Wisconsin-Madison School of Nursing and two community centers to deliberately engage hard-to-reach people in two lay advisory groups, the Community Advisors on Research Design and Strategies (CARDS)®. Community center staff recruited the CARDS from center programs, including parenting and childcare programs, women's support groups, food pantries, and senior meal programs. The CARDS model differs from other CABs in its participants, processes, and outcomes. Since 2010, the CARDS have met monthly with nurses and other researchers, helping them understand how research processes and the language, tone, appearance, and organization of research materials can discourage people from enrolling in clinical studies. We have successfully used the CARDS model to bring hard-to-reach populations into the research process and have sustained their participation. The model represents a promising strategy for increasing the diversity of participants in clinical research. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  1. Behavioral Health Providers for Persons Who Are Deaf, Deafblind, or Hard-of-Hearing: A National Survey of the Structural and Process Domains of Care.

    Science.gov (United States)

    Nolan, Beth A D; Mathos, Kimberly; Fusco, Laura E; Post, Edward P

    2015-01-01

    Research suggests higher prevalence of mental health problems for those with hearing problems than in the general population. Despite barriers, mental health services for persons who are deaf and hard-of-hearing (HOH) have developed to meet the cultural and communication needs of this population. The authors conducted a national survey of mental health service providers to persons who are deaf, deafblind, or HOH, to learn about their structural and process domains of care. Results indicate that services for persons who are deaf, deafblind, or HOH are inadequate for consumers with serious mental illness. Results also uncovered unique pathways to care and practitioners.

  2. Effect of Mo addition on the microstructure and hardness of ultrafine-grained Ni alloys processed by a combination of cryorolling and high-pressure torsion

    Energy Technology Data Exchange (ETDEWEB)

    Kapoor, Garima [Department of Materials Physics, Eötvös Loránd University, P.O.B. 32, Budapest H-1518 (Hungary); Huang, Yi [Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO171BJ (United Kingdom); Sarma, V. Subramanya [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Langdon, Terence G. [Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO171BJ (United Kingdom); Gubicza, Jenő, E-mail: jeno.gubicza@ttk.elte.hu [Department of Materials Physics, Eötvös Loránd University, P.O.B. 32, Budapest H-1518 (Hungary)

    2017-03-14

    An investigation was conducted to examine the effect of molybdenum (Mo) content on the grain size, lattice defect structure and hardness of nickel (Ni) processed by severe plastic deformation (SPD). The SPD processing was applied to Ni samples with low (~0.3 at%) and high (~5 at%) Mo concentrations by a consecutive application of cryorolling and high-pressure torsion (HPT). The grain size and the dislocation density were determined by scanning electron microscopy and X-ray line profile analysis, respectively. In addition, the hardness values in the centers, half-radius and peripheries of the HPT-processed disks were determined after ½, 5 and 20 turns. The results show the higher Mo content yields a dislocation density about two times larger and a grain size about 30% smaller. The smallest value of the grain size was ~125 nm and the highest measured dislocation density was ~60×10{sup 14} m{sup −2} for Ni-5% Mo. For the higher Mo concentration, the dislocation arrangement parameter was larger indicating a less clustered dislocation structure due to the hindering effect of Mo on the rearrangement of dislocations into low energy configurations. The results show there is a good correlation between the dislocation density and the yield strength using the Taylor equation. The α parameter in this equation is slightly lower for the higher Mo concentration in accordance with the less clustered dislocation structure.

  3. Charm production and QCD analysis at HERA and LHC

    International Nuclear Information System (INIS)

    Zenaiev, Oleksandr

    2015-03-01

    In this thesis the study of charm production in ep and pp collisions is presented. The heavy-quark masses provide a hard scale, allowing the application of perturbative QCD. A measurement of D + -meson production in deep inelastic scattering with the ZEUS detector at HERA is presented. The analysis was performed using a data sample with an integrated luminosity of 354 pb -1 . Differential cross sections were measured as a function of virtuality Q 2 , inelasticity y, transverse momentum and pseudorapidity of the D + mesons. Lifetime information was used to reduce the combinatorial background significantly. Next-to-leading-order QCD predictions in the fixed-flavour-number scheme were compared to the data. This measurement was combined with other H1 and ZEUS measurements of charm production. The combination was performed at inclusive level for the reduced charm cross sections, which were obtained from the measured visible cross sections, extrapolated to the full phase space using the shape of the theoretical predictions in the fixed-flavour-number scheme. The combination method accounts for the correlations of the systematic uncertainties among the different datasets, thus allowing cross calibration of different measurements. The combined charm data were compared to QCD predictions in various heavy-flavour schemes and used together with the inclusive production data at HERA as input for QCD analyses to determine the charm running mass in the MS renormalisation scheme and the optimal values of the charm-quark mass parameters in other heavy-flavour schemes. An additional combination of the H1 and ZEUS D *+ visible cross sections was performed to provide the combined cross sections without theory-related uncertainties from the extrapolation procedure. This combination also provides differential cross sections as a function of the D *+ kinematic variables. Next-to-leading-order QCD predictions in the fixed-flavour-number scheme were compared to the combined D *+ cross

  4. Higher order QCD corrections in exclusive charmless B decays

    International Nuclear Information System (INIS)

    Bell, G.

    2006-10-01

    We discuss exclusive charmless B decays within the Standard Model of particle physics. These decays play a central role in the on-going process to constrain the parameters of the CKM matrix and to clarify the nature of CP violation. In order to exploit the rich source of data that is currently being collected at the experiments, a systematic theoretical treatment of the complicated hadronic dynamics is strongly desired. QCD Factorization represents a model-independent framework to compute hadronic matrix elements from first principles. It is based on a power expansion in Λ QCD /m b and allows for the systematic implementation of perturbative corrections. In particular, we consider hadronic two-body decays as B → ππ and perform a conceptual analysis of heavy-to-light form factors which encode the strong interaction effects in semi-leptonic decays as B → πlν. Concerning the hadronic decays we compute NNLO QCD corrections which are particularly important with respect to strong interaction phases and hence direct CP asymmetries. On the technical level, we perform a 2-loop calculation which is based on an automatized reduction algorithm and apply sophisticated techniques for the calculation of loop-integrals. We indeed find that the considered quantities are well-defined as predicted by QCD Factorization, which is the result of a highly complicated subtraction procedure. We present results for the imaginary part of the topological tree amplitudes and observe that the considered corrections are substantial. The calculation of the real part of the amplitudes is far more complicated and we present a preliminary result which is based on certain simplifications. Our calculation is one part of the full NNLO analysis of nonleptonic B decays within QCD Factorization which is currently pursued by various groups. In our conceptual analysis of the QCD dynamics in heavy-to-light transitions we consider form factors between non-relativistic bound states which can be

  5. Higher order QCD corrections in exclusive charmless B decays

    Energy Technology Data Exchange (ETDEWEB)

    Bell, G.

    2006-10-15

    We discuss exclusive charmless B decays within the Standard Model of particle physics. These decays play a central role in the on-going process to constrain the parameters of the CKM matrix and to clarify the nature of CP violation. In order to exploit the rich source of data that is currently being collected at the experiments, a systematic theoretical treatment of the complicated hadronic dynamics is strongly desired. QCD Factorization represents a model-independent framework to compute hadronic matrix elements from first principles. It is based on a power expansion in {lambda}{sub QCD}/m{sub b} and allows for the systematic implementation of perturbative corrections. In particular, we consider hadronic two-body decays as B {yields} {pi}{pi} and perform a conceptual analysis of heavy-to-light form factors which encode the strong interaction effects in semi-leptonic decays as B {yields} {pi}l{nu}. Concerning the hadronic decays we compute NNLO QCD corrections which are particularly important with respect to strong interaction phases and hence direct CP asymmetries. On the technical level, we perform a 2-loop calculation which is based on an automatized reduction algorithm and apply sophisticated techniques for the calculation of loop-integrals. We indeed find that the considered quantities are well-defined as predicted by QCD Factorization, which is the result of a highly complicated subtraction procedure. We present results for the imaginary part of the topological tree amplitudes and observe that the considered corrections are substantial. The calculation of the real part of the amplitudes is far more complicated and we present a preliminary result which is based on certain simplifications. Our calculation is one part of the full NNLO analysis of nonleptonic B decays within QCD Factorization which is currently pursued by various groups. In our conceptual analysis of the QCD dynamics in heavy-to-light transitions we consider form factors between non

  6. Probing QCD with the ATLAS Detector

    CERN Document Server

    Kulchitsky, Yuri; The ATLAS collaboration

    2018-01-01

    Perturbative QCD calculations at next-to-next-to leading order (NNLO) are available for many processes since several years and can be rigorously tested with a large variety of final states. In this talk, we present the latest results from the ATLAS collaboration involving jets, dijets, photons in association with heavy flavors and vector bosons in association with jets, measured at center of mass energies of 8 and 13 TeV. All measured cross-sections are compared to state-of-the art theory predictions. Moreover, we present two measurements of dijet energy correlations allowing to test the renormalization group equation and to extract the strong coupling constant. The talk concludes with the latest results of jet-substructure studies at 13 TeV, in particular the measurement of the jet soft-drop mass.

  7. Separation of soft and collinear infrared limits of QCD squared matrix elements

    CERN Document Server

    Nagy, Zoltan; Trócsányi, Z L; Trocsanyi, Zoltan; Somogyi, Gabor; Trocsanyi, Zoltan

    2007-01-01

    We present a simple way of separating the overlap between the soft and collinear factorization formulae of QCD squared matrix elements. We check its validity explicitly for single and double unresolved emissions of tree-level processes. The new method makes possible the definition of helicity-dependent subtraction terms for regularizing the real contributions in computing radiative corrections to QCD jet cross sections. This implies application of Monte Carlo helicity summation in computing higher order corrections.

  8. Processes with large Psub(T) in the quantum chromodynamics

    International Nuclear Information System (INIS)

    Slepchenko, L.A.

    1981-01-01

    Necessary data on deep inelastic processes and processes of hard collision of hadrons and their interpretation in QCD are stated. Low of power reduction of exclusive and inclusive cross sections at large transverse momenta, electromagnetic and inelastic (structural functions) formfactors of hadrons have been discussed. When searching for a method of taking account of QCD effects scaling disturbance was considered. It is shown that for the large transverse momenta the deep inelastic l-h scatterina is represented as the scattering with a compound system (hadron) in the pulse approximation. In an assumption of a parton model obtained was a hadron cross section calculated through a renormalized structural parton function was obtained. Proof of the factorization in the principal logarithmic approximation of QCD has been obtained by means of a quark-gluon diagram technique. The cross section of the hadron reaction in the factorized form, which is analogous to the l-h scattering, has been calculated. It is shown that a) the diagram summing with the gluon emission generates the scaling disturbance in renormalized structural functions (SF) of quarks and gluons and a running coupling constant arises simultaneously; b) the disturbance character of the Bjorken scaling of SF is the same as in the deep inelasic lepton scattering. QCD problems which can not be solved within the framework of the perturbation theory, are discussed. The evolution of SF describing the bound state of a hadron and the hadron light cone have been studied. Radiation corrections arising in two-loop and higher approximations have been evaluated. QCD corrections for point-similar power asymptotes of processes with high energies and transfers of momenta have been studied on the example of the inclusive production of quark and gluon jets. Rules of the quark counting of anomalous dimensionalities of QCD have been obtained. It is concluded that the considered limit of the inclusive cross sections is close to

  9. The gauge-independent QCD effective charge

    International Nuclear Information System (INIS)

    Watson, N.J.

    1997-01-01

    It is shown how the QED concept of a gauge-, scale- and scheme-independent one-loop effective charge can be extended directly at the diagrammatic level to QCD, thus justifying explicitly the ''naive non-abelianization'' prescription used in renormalon calculus. It is first argued that, for on-shell external fields and at the strictly one-loop level, the required gluon self-energy-like function is precisely that obtained from S-matrix elements via the pinch technique. The generalization of the pinch technique to explicitly off-shell processes is then introduced. It is shown how, as a result of a fundamental cancellation among conventional perturbation theory diagrams, encoded in the QCD Ward identities, the pinch technique one-loop gluon self-energy iΠ μν ab (q) remains gauge-independent and universal regardless of the fact that the ''external'' fields in the given process are off-shell. This demonstration involves a simple technique enabling the isolation, in an arbitrary gauge, of iΠ μν ab (q) from subclasses of up to several hundred diagrams at once. Furthermore, it is shown how this one-loop cancellation mechanism iterates for the subclasses of n-loop diagrams containing implicitly the Dyson chains of n one-loop self-energies iΠ μν ab (q). The gauge cancellation required for the Dyson summation of iΠ μν ab (q) is thus demonstrated explicitly in a general class of ghost-free gauges for all orders n. (orig.)

  10. QCD, hadrons and nuclei

    International Nuclear Information System (INIS)

    Yazaki, K.

    1995-01-01

    The nuclear or color transparency in initial and final state interactions of protons, involved in high energy semi-exclusive processes such as (, e ' p) and (p, 2 p) reactions, is discussed first in the conventional Glauber approach and then in models taking account of the proton internal dynamics. The conventional approach includes nuclear many-body effects as well as multiple scattering effects and serves as a reference for finding the roles of the internal dynamics in the observed transparency. The models predict non-trivial effects on the transparency. (author)

  11. Lattice QCD. A critical status report

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, Karl

    2008-10-15

    The substantial progress that has been achieved in lattice QCD in the last years is pointed out. I compare the simulation cost and systematic effects of several lattice QCD formulations and discuss a number of topics such as lattice spacing scaling, applications of chiral perturbation theory, non-perturbative renormalization and finite volume effects. Additionally, the importance of demonstrating universality is emphasized. (orig.)

  12. Lattice QCD. A critical status report

    International Nuclear Information System (INIS)

    Jansen, Karl

    2008-10-01

    The substantial progress that has been achieved in lattice QCD in the last years is pointed out. I compare the simulation cost and systematic effects of several lattice QCD formulations and discuss a number of topics such as lattice spacing scaling, applications of chiral perturbation theory, non-perturbative renormalization and finite volume effects. Additionally, the importance of demonstrating universality is emphasized. (orig.)

  13. Fractal structures and intermittency in QCD

    International Nuclear Information System (INIS)

    Gustafson, Goesta.

    1990-04-01

    New results are presented for fractal structures and intermittency in QCD parton showers. A geometrical interpretation of the anomalous dimension in QCD is given. It is shown that model predications for factorial moments in the PEP-PETRA energy range are increased. if the properties of directly produced pions are more carefully taken into account

  14. HERA results on QCD and EW physics

    International Nuclear Information System (INIS)

    Zarnecki, A.F.

    1997-01-01

    Selected HERA results on QCD and EW interactions are presented. They include the measurement of the proton structure function and its analysis in terms of the QCD evolution, as well as results concerning deep inelastic scattering at very low and very high Q 2 . Selected HERA limits on new physics and parameters which extend the standard model are also presented. (author)

  15. Color-magnetic permeability of QCD vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Saito, T [Kyoto Prefectural Univ. of Medicine (Japan); Shigemoto, K

    1980-03-01

    In the very strong background gauge field the QCD true vacuum has been shown to have lower energy than the ''perturbative vacuum.'' The color-magnetic permeability of the QCD true vacuum is then calculated to be 1/2 within the quark-one-loop approximation.

  16. Recent developments in QCD for LHC physics

    International Nuclear Information System (INIS)

    Anastasiou, C.

    2006-01-01

    We will review recent theoretical developments in QCD, attempting to assess the phenomenological impact of new theoretical results and to identify potentially useful directions for the future. A part of the talk will be devoted to new imaginative ideas which are rapidly changing the traditional approach to QCD computations, and surprising theoretical discoveries from perturbative calculations on the structure of gauge theories. (author)

  17. Understanding of QCD through solvable models

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, G.

    1980-07-01

    Various aspects of strong interaction physics are discussed. It is shown that several nontrivial features arise from non-perturbative 'solutions' of QCD-like models in (1+1) dimensions. An attempt is made to bring these features in (3+1) dimensional semiclassical treatments of QCD.

  18. Academic Training Lectures - QCD for Postgraduates

    CERN Multimedia

    Maureen Prola-Tessaur

    2010-01-01

    by Giulia Zanderighi (University of Oxford) Monday 12 to Friday 16 April 2010 From 11:00 to 12:00 - Main Auditorium, Bldg. 500-1-001 Monday 12 - Modern QCD - Lecture 1 Starting from the QCD Lagrangian we will revisit some basic QCD concepts and derive fundamental properties like gauge invariance and isospin symmetry and will discuss the Feynman rules of the theory. We will then focus on the gauge group of QCD and derive the Casimirs CF and CA and some useful color identities. Tuesday 13 - Modern QCD - Lecture 2 We will start discussing the matter content of the theory and revisit the experimental measurements that led to the discovery of quarks. We will then consider a classic QCD observable, the R-ratio, and use it to illustrate the appearance of UV divergences and the need to renormalize the coupling constant of QCD. We will then discuss asymptotic freedom and confinement. Finally, we will examine a case where soft and collinear infrared divergences appear, will discuss the soft approximation in QCD ...

  19. Solving QCD via multi-Regge theory

    International Nuclear Information System (INIS)

    White, A. R.

    1998-01-01

    A high-energy, transverse momentum cut-off, solution of QCD is outlined. Regge pole and single gluon properties of the pomeron are directly related to the confinement and chiral symmetry breaking properties of the hadron spectrum. This solution, which corresponds to a supercritical phase of Reggeon Field Theory, may only be applicable to QCD with a very special quark content

  20. Solvable models and hidden symmetries in QCD

    International Nuclear Information System (INIS)

    Yepez-Martinez, Tochtli; Hess, P. O.; Szczepaniak, A.; Civitarese, O.; Lerma H., S.

    2010-01-01

    We show that QCD Hamiltonians at low energy exhibit an SU(2) structure, when only few orbital levels are considered. In case many orbital levels are taken into account we also find a semi-analytic solution for the energy levels of the dominant part of the QCD Hamiltonian. The findings are important to propose the structure of phenomenological models.