Search

Your search keyword '"HARD PROCESSES"' showing total 20 results
Start Over Descriptor "HARD PROCESSES"
20 results on '"HARD PROCESSES"'

2. Modeling the Impact Parameter Dependence of the nPDFs With EKS98 and EPS09 Global Fits.

Author

Helenius, I., Eskola, K.J., Honkanen, H., and Salgado, C.A.

Subjects
*NUCLEAR models, *PARAMETER estimation, *RELATIVISTIC Heavy Ion Collider, *ERROR analysis in mathematics, *LARGE Hadron Collider, *DEUTERONS, *NEUTRAL pion
Abstract

Abstract: So far the nuclear PDFs (nPDFs) in the global DGLAP fits have been taken to be spatially independent. In this work [I. Helenius, K. J. Eskola, H. Honkanen, C. A. Salgado, JHEP 1207 (2012) 073], using the A-dependence of the globally fitted sets EPS09 and EKS98, we have determined the spatial dependence of the nPDFs in terms of powers of the nuclear thickness functions. New spatially dependent nPDF sets EPS09s (NLO, LO, error sets) and EKS98s (LO) are released. As an application, we consider the nuclear modification factor at midrapidity for neutral pion production in deuteron-gold collisions at RHIC in NLO. Comparison with the PHENIX data in different centrality classes is also shown. In addition, predictions for the corresponding nuclear modification factor in proton–lead collisions at the LHC are discussed. [Copyright &y& Elsevier]

Published
2013
Full Text
View/download PDF

3. ON PERTURBATIVE QCD OF HARD AND SOFT PROCESSES.

Author

EFREMOV, A. V. and RADYUSHKIN, A. V.

Subjects
*QUANTUM chromodynamics, *PARTICLES (Nuclear physics), *NUCLEAR physics, *SCATTERING (Physics), *BOOTSTRAP theory (Nuclear physics)
Abstract

We discuss some problems concerning the application of perturbative QCD to high energy processes. In particular for hard processes, we analyze higher order and higher twist corrections. It is argued that these effects are of great importance for understanding the behaviour of pion electromagnetic form factor at moderately large momentum transfers. For soft processes, we show that summing the contributions of the lowest twist operators leads to a Regge-like amplitude. [ABSTRACT FROM AUTHOR]

Published
2009
Full Text
View/download PDF

4. Non-universality of transverse momentum dependent parton distribution functions

Author

Bomhof, C.J. and Mulders, P.J.

Subjects
*PARTICLES (Nuclear physics), *SYMMETRY (Physics), *DISTRIBUTION (Probability theory), *COLLISIONS (Nuclear physics)
Abstract

Abstract: In the field theoretical description of hadronic scattering processes, single transverse-spin asymmetries arise due to gluon initial and final state interactions. These interactions lead to process dependent Wilson lines in the operator definitions of transverse momentum dependent parton distribution functions. In particular for hadron–hadron scattering processes with hadronic final states this has important ramifications for possible factorization formulas in terms of (non)universal TMD parton distribution functions. In this paper we will systematically separate the universality-breaking parts of the TMD parton correlators from the universal T-even and T-odd parts. This might play an important role in future factorization studies for these processes. We also show that such factorization theorems will (amongst others) involve the gluonic pole cross sections, which have previously been shown to describe the hard partonic scattering in weighted spin asymmetries. [Copyright &y& Elsevier]

Published
2008
Full Text
View/download PDF

5. Studium tvrdých procesů na LHC

Author

Zívr, Vojtěch, Spousta, Martin, and Faltová, Jana

Subjects
tvrdé procesy, LHC, gluons, kvarky, quarks, gluony, hard processes, jety, jets, High Energy Physics::Lattice, Nuclear Theory, High Energy Physics::Phenomenology, High Energy Physics::Experiment, Nuclear Experiment
Abstract

There were studied PbPb collisions at a per-nucelon center-of-mass en- ergy of 2760 GeV. Such collisions produce quark-gluon plasma and jets. Specifically, the properties of events dominated by gluon and quark jets were studied. The properties were multiplicity, pseudorapidity and trans- verse momentum. The study found greater multiplicity in events dominated by gluon jets, compared to quark jets. Furthermore, it was found that more electrically charged particles are formed than their electrically neutral part- ners. Examination of pseudorapidity revealed that particles in jets have lower pseudorapidity compared to background. In contrast, no statistically significant differences were observed in the distribution of transverse mo- mentum depending on the type of hadron. 1

Published
2019

6. On exclusive hard processes with light-mesons

Author

Passek-Kumerički, Kornelija

Subjects
mesons, hard processes, exclusive processes, High Energy Physics::Lattice, Nuclear Theory, High Energy Physics::Phenomenology, High Energy Physics::Experiment
Abstract

The description of the exclusive hard processes with mesons within the perturbative QCD framework are renewed. The application of such approach is demonstrated on both pseudoscalar and scalar meson transition form factors. The relevant recent Belle experimental result are commented and new theoretical results presented.

Published
2018

7. Aspects of hard QCD processes in proton-nucleus collisions

Author

François Arleo, Laboratoire Leprince-Ringuet ( LLR ), Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -École polytechnique ( X ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
Nuclear and High Energy Physics, Particle physics, Proton, Field (physics), Nuclear Theory, FOS: Physical sciences, radiation: induced, Parton, Radiation induced, 01 natural sciences, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), nucleus: shadowing, [ PHYS.HEXP ] Physics [physics]/High Energy Physics - Experiment [hep-ex], parton: multiple scattering, quantum chromodynamics: factorization, 0103 physical sciences, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], medicine, 010306 general physics, Nuclear Experiment, p nucleus: scattering, Physics, Quantum chromodynamics, 010308 nuclear & particles physics, Scattering, factorization: collinear, Hard processes, High Energy Physics::Phenomenology, nuclear matter: effect, QCD, Gluon, High Energy Physics - Phenomenology, proton–nucleus collisions, medicine.anatomical_structure, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], gluon: radiation, [ PHYS.HPHE ] Physics [physics]/High Energy Physics - Phenomenology [hep-ph], High Energy Physics::Experiment, Nucleus
Abstract

Hard processes in high-energy proton-nucleus collisions are a powerful tool in order to investigate several importants aspects of QCD in a nuclear medium, such as nuclear shadowing, parton multiple scattering or medium-induced gluon radiation. I review in these proceedings recent progress in that field., Comment: 6 pages, 4 pages, contribution to Hard Probes 2016 proceedings

Published
2016
Full Text
View/download PDF

8. Operator analysis of $p_T$-widths of TMDs

Author

Daniël Boer, M. G. A. Buffing, Piet J. Mulders, High-Energy Frontier, (Astro)-Particles Physics, and Theoretical Physics

Subjects
Quark, Particle physics, Nuclear and High Energy Physics, DRELL-YAN, FOS: Physical sciences, Parton, 01 natural sciences, High Energy Physics - Phenomenology (hep-ph), LEPTOPRODUCTION, 0103 physical sciences, DISTRIBUTIONS, SDG 7 - Affordable and Clean Energy, 010306 general physics, Nuclear Experiment, Physics, TRANSVERSE-SPIN ASYMMETRIES, 010308 nuclear & particles physics, Operator (physics), PARTON DISTRIBUTION-FUNCTIONS, High Energy Physics::Phenomenology, Observable, Lattice QCD, Deep inelastic scattering, QCD Phenomenology, SINGLE-SPIN, QCD, Gluon, High Energy Physics - Phenomenology, Distribution function, HARD PROCESSES, High Energy Physics::Experiment, STATE INTERACTIONS, TWIST-4
Abstract

Transverse momentum dependent (TMD) parton distribution functions (PDFs), TMDs for short, are defined as the Fourier transform of matrix elements of nonlocal combinations of quark and gluon fields. The nonlocality is bridged by gauge links, which for TMDs have characteristic paths (future or past pointing), giving rise to a process dependence that breaks universality. It is possible, however, to construct sets of universal TMDs of which in a given process particular combinations are needed with calculable, process-dependent, coefficients. This occurs for both T-odd and T-even TMDs, including also the {\it unpolarized} quark and gluon TMDs. This extends the by now well-known example of T-odd TMDs that appear with opposite sign in single-spin azimuthal asymmetries in semi-inclusive deep inelastic scattering or in the Drell-Yan process. In this paper we analyze the cases where TMDs enter multiplied by products of two transverse momenta, which includes besides the $p_T$-broadening observable, also instances with rank two structures. To experimentally demonstrate the process dependence of the latter cases requires measurements of second harmonic azimuthal asymmetries, while the $p_T$-broadening will require measurements of processes beyond semi-inclusive deep inelastic scattering or the Drell-Yan process. Furthermore, we propose specific quantities that will allow for theoretical studies of the process dependence of TMDs using lattice QCD calculations., Comment: 10 pages, no figures; expanded discussions, matches version accepted by JHEP

Published
2015
Full Text
View/download PDF

9. KOs and lambda production associated to high-p T charged hadrons in Pb-Pb collisions at √sNN = 2.76 TeV with ALICE : comparison between the hard and 'soft' processes related to the production of hadrons

Author

Sanchez Castro, Xitzel and STAR, ABES

Subjects
Heavy-ion collisions, Milieu thermalisé, Rapport baryon sur méson, Nuclear Theory, High Energy Physics::Phenomenology, Hard processes, Quark-gluon plasma, Bulk, Plasma de quarks et de gluons, ALICE, Baryon-to-meson ratio, Collisions d'ions lourds, Thermalised medium, Processus durs, Parton fragmentation, High Energy Physics::Experiment, [PHYS.PHYS] Physics [physics]/Physics [physics], Fragmentation de partons, Nuclear Experiment
Abstract

In ultrarelativistic heavy-ion collisions, the QCD matter is under extreme conditions of energy density, forming a quark-gluon plasma (QGP), in which quarks and gluons are deconfined. At RHIC and LHC energies, a large baryon-to-meson ratio, like Λ/K0S, was observed within the transverse momentum range 2 < pT < 6 GeV/c for central heavy-ion collisions. The goal of this dissertation is to verify if the baryon-to-meson enhancement is only due to collective effects of the bulk of matter, and if there is also a contribution related to in-medium modifications of parton fragmentation.With two-hadron angular correlations, the K0S and Λ produced in association to an energetic hadron (hard processes) are separated from those originated from the thermalised medium (soft processes). The differential Λ/K0S ratios related to the soft or hard production processes are extracted. The results are obtained for the Pb-Pb collisions at √sNN = 2.76 TeV recorded in 2011 with the ALICE experiment., Dans les collisions d'ions lourds ultra-relativistes (A-A), la matière se trouve dans des conditions extrêmes de densité d'énergie; elle forme un plasma de quarks et de gluons déconfinés. Aux énergies du RHIC et du LHC, le rapport baryon sur méson, tel Λ/K0S, prend des valeurs élevées sur une plage d'impulsions transverses intermédiaires pour les collisions centrales A-A. L'objectif de ce travail est de vérifier si la production accrue de baryons est seulement due à des effets collectifs au cœur du système formé ou s'il existe aussi un impact lié à une fragmentation des partons modifiée par le milieu. À l'aide de corrélations angulaires à deux hadrons, les K0S et Λ produits en association avec un hadron de haut pT (processus durs) sont séparés de ceux issus du milieu thermalisé (processus softs). Les rapports Λ/K0S à relier aux mécanismes durs et softs sont établis; les résultats sont obtenus pour les collisions Pb-Pb à √sNN = 2.76 TeV enregistrées en 2011 avec l'expérience ALICE.

Published
2015

10. Spatially dependent parton distribution functions and hard processes in nuclear collisions

Author

Helenius, Ilkka

Subjects
hadron production, parton distribution functions, Heavy ion phenomenology, thermal photons, Nuclear PDFs, Hard processes, termiset fotonit, nuclear collisions, fragmentation functions, Direct photons, QCD phenomenology, partonijakaumat, fragmentaatiofunktiot, ydintörmäykset, Forward rapidities, teoreettinen fysiikka, Proton+nucleus collisions, hadronituotto
Published
2014

12. Electron–deuteron DIS with spectator tagging at EIC: Development of theoretical framework

Author

Vadim Guzey, Wim Cosyn, Misak Sargsian, Christian Weiss, Mark Strikman, Marquet, Cyrille, Pire, Bernard, and Sabatie, Franck

Subjects
Particle physics, Nuclear Theory, QC1-999, FOS: Physical sciences, 01 natural sciences, law.invention, Nuclear Theory (nucl-th), Momentum, High Energy Physics - Phenomenology (hep-ph), Recoil, law, 0103 physical sciences, Neutron, Nuclear Experiment, 010306 general physics, Collider, Spin-½, Physics, NUCLEI, 010308 nuclear & particles physics, Nuclear structure, High Energy Physics - Phenomenology, HARD PROCESSES, Physics and Astronomy, Deuterium, Nucleon
Abstract

An Electron-Ion Collider (EIC) would enable next-generation measurements of deep-inelastic scattering (DIS) on the deuteron with detection of a forward-moving nucleon (p, n) and measurement of its recoil momentum ("spectator tagging"). Such experiments offer full control of the nuclear configuration during the high-energy process and can be used for precision studies of the neutron's partonic structure and its spin dependence, nuclear modifications of partonic structure, and nuclear shadowing at small x. We review the theoretical description of spectator tagging at EIC energies (light-front nuclear structure, on-shell extrapolation in the recoil nucleon momentum, final-state interactions, diffractive effects at small x) and report about on-going developments., 7 pages, 3 figures. Proceedings of 6th International Conference on Physics Opportunities at an Electron-Ion Collider (POETIC6), Palaiseau, France, 7-11 September 2015

Published
2016

13. Bessel-weighted asymmetries in semi-inclusive deep inelastic scattering

Author

Alexei Prokudin, Leonard Gamberg, Bernhard Musch, and Daniël Boer

Subjects
Nuclear and High Energy Physics, Particle physics, DRELL-YAN, Hadron, TO-BACK JETS, FOS: Physical sciences, Parton, PHASE-FACTORS, symbols.namesake, High Energy Physics - Phenomenology (hep-ph), Nuclear Experiment, Mathematical physics, Physics, QUANTUM CHROMODYNAMICS, PARTON DISTRIBUTION-FUNCTIONS, Deep Inelastic Scattering, Observable, Lattice QCD, Deep inelastic scattering, QCD, SINGLE-SPIN, AZIMUTHAL ASYMMETRIES, High Energy Physics - Phenomenology, Distribution function, HARD PROCESSES, Parton Model, symbols, High Energy Physics::Experiment, Nucleon, SPIN ASYMMETRIES, Bessel function, TRANSVERSE-MOMENTUM DISTRIBUTIONS
Abstract

The concept of weighted asymmetries is revisited for semi-inclusive deep inelastic scattering. We consider the cross section in Fourier space, conjugate to the outgoing hadron's transverse momentum, where convolutions of transverse momentum dependent parton distribution functions and fragmentation functions become simple products. Individual asymmetric terms in the cross section can be projected out by means of a generalized set of weights involving Bessel functions. Advantages of employing these Bessel weights are that they suppress (divergent) contributions from high transverse momentum and that soft factors cancel in (Bessel-) weighted asymmetries. Also, the resulting compact expressions immediately connect to previous work on evolution equations for transverse momentum dependent parton distribution and fragmentation functions and to quantities accessible in lattice QCD. Bessel weighted asymmetries are thus model independent observables that augment the description and our understanding of correlations of spin and momentum in nucleon structure., Comment: Matches published version, JHEP style, 36 pages and 2 figures, minor corrections

Published
2011

14. Dijet imbalance in hadronic collisions

Author

Daniël Boer, Piet J. Mulders, Cristian Pisano, Theoretical Physics, and High-Energy Frontier

Subjects
Quark, Nuclear and High Energy Physics, Particle physics, DRELL-YAN, Hadron, FOS: Physical sciences, Parton, Nuclear physics, High Energy Physics - Phenomenology (hep-ph), NEGATIVE PIONS, Nuclear Experiment, Quantum chromodynamics, Physics, ANGULAR-DISTRIBUTIONS, Linear polarization, P COLLISIONS, High Energy Physics::Phenomenology, Observable, SQUARE-ROOT-S, Polarization (waves), E(+)E(-) ANNIHILATION, QCD, EVENT SHAPES, Gluon, High Energy Physics - Phenomenology, HARD PROCESSES, High Energy Physics::Experiment, LARGE TRANSVERSE-MOMENTUM
Abstract

The imbalance of dijets produced in hadronic collisions has been used to extract the average transverse momentum of partons inside the hadrons. In this paper we discuss new contributions to the dijet imbalance that could complicate or even hamper this extraction. They are due to polarization of initial state partons inside unpolarized hadrons that can arise in the presence of nonzero parton transverse momentum. Transversely polarized quarks and linearly polarized gluons produce specific azimuthal dependences of the two jets that in principle are not suppressed. Their effects cannot be isolated just by looking at the angular deviation from the back-to-back situation, rather they enter jet broadening observables. In this way they directly affect the extraction of the average transverse momentum of unpolarized partons that is thought to be extracted. We discuss appropriately weighted cross sections to isolate the additional contributions., Comment: 15 pages, 2 figures; revised version, published in Phys. Rev. D

Published
2009

15. Measurement of semi-inclusive pi+ electroproduction off the proton

Author

L. C. Smith, E. Munevar, M. H. Wood, Y. Ilieva, M. E. McCracken, P. Nadel-Turonski, E. Wolin, R. J. Feuerbach, B. S. Ishkhanov, G. E. Dodge, Tsutomu Mibe, P. V. Degtyarenko, J. P. Ball, Y. Prok, D. S. Carman, M. R. Niroula, Alexander Ilyichev, O. P. Dzyubak, I. I. Strakovsky, Paolo Rossi, K. S. Egiyan, P. L. Cole, Z. W. Zhao, J. Lachniet, A. Tkabladze, W. Kim, I. Niculescu, R. A. Niyazov, D. G. Crabb, R. S. Hakobyan, L. El Fassi, Elton Smith, A. Deur, G. Niculescu, R. De Masi, B. L. Berman, J. Kuhn, B. McKinnon, W. K. Brooks, G. P. Gilfoyle, K. Livingston, R. Fatemi, N. Markov, A. V. Vlassov, J. P. Cummings, M. Anghinolfi, G. Ricco, B. Zhao, D. J. Tedeschi, S. Niccolai, R. Dickson, Ji Li, Y. G. Sharabian, S. Strauch, D. P. Watts, H. Egiyan, L. M. Qin, C. Paterson, L. Zana, D. Branford, J. M. Laget, M. Khandaker, G. Riccardi, N. Hassall, M. Bellis, Cynthia Marie Hadjidakis, R. De Vita, A. I. Ostrovidov, K. A. Griffioen, N. Guler, F. W. Hersman, J. Hardie, C. Butuceanu, M. J. Amaryan, M. Kossov, Shifeng Chen, E. N. Golovach, Volker D. Burkert, A. S. Biselli, Michael Dugger, J. Langheinrich, H. O. Funsten, H. G. Juengst, Luca Trentadue, M. MacCormick, I. Hleiqawi, M. D. Mestayer, C. Djalali, H. Denizli, P. Eugenio, S. Dytman, A. V. Skabelin, S. L. Careccia, I. Popa, P. Coltharp, R. A. Schumacher, P. Mattione, M. Osipenko, S. Barrow, M. Taiuti, A.V. Stavinsky, S. Anefalos Pereira, P. D. Rubin, R. W. Gothe, Laird Kramer, E. L. Isupov, D. Lawrence, D. Sokhan, M. M. Ito, H. Hakobyan, A. Cazes, J. R. Calarco, C. I O Gordon, K. L. Giovanetti, S. Mehrabyan, Alexei V. Klimenko, J. T. Goetz, R. Miskimen, C. Hanretty, G. V. O'Rielly, E. Polli, Michael L. Williams, Larry Weinstein, M. Mirazita, Kalvir S. Dhuga, J. D. Kellie, P. Collins, Friedrich Klein, F. Sabatié, Nikolay Shvedunov, J. J. Melone, V. Sapunenko, Sylvain Bouchigny, S. Bültmann, L. Todor, Barry Ritchie, Dinko Pocanic, Victor Mokeev, Brian Raue, G. Asryan, E. De Sanctis, M. Battaglieri, I. Bedlinskiy, V. A. Drozdov, S. Stepanyan, S. E. Kuhn, N. A. Baltzell, D. Protopopescu, S. Pozdniakov, M. Garçon, M. F. Vineyard, J. Pierce, Avraham Klein, Z. Krahn, N. Dashyan, S. Boiarinov, U. Thoma, D. I. Sober, R. Bradford, N. Kalantarians, Latifa Elouadrhiri, V. Gyurjyan, G. S. Mutchler, D. G. Ireland, V. Crede, N. Baillie, B. B. Niczyporuk, R. C. Minehart, Kei Moriya, S. McAleer, N. Pivnyuk, B. E. Stokes, J. Napolitano, G. S. Adams, J. Zhang, B. M. Preedom, F. X. Girod, L. Blaszczyk, H. Bagdasaryan, J. P. Santoro, C. Tur, C. A. Meyer, L. Guo, M. Ungaro, G. Gavalian, J. Donnelly, S. Tkachenko, D. Heddle, J. Salamanca, N. Benmouna, G. V. Fedotov, M. Ripani, J. W C McNabb, D. Jenkins, R. Nasseripour, S. A. Morrow, K. Joo, Maryam Moteabbed, Bernhard Mecking, K. V. Dharmawardane, A. Yegneswaran, Atilla Gonenc, P. Ambrozewicz, J. W. Price, M. Holtrop, D. P. Weygand, P. Corvisiero, H. S. Jo, Gerald Feldman, Federico A. Ceccopieri, C. Salgado, G. Rosner, M. Guillo, K. Mikhailov, M. Guidal, H. Y. Lu, C. E. Hyde-Wright, P. Stoler, Sergey Kuleshov, M. Bektasoglu, M. Nozar, K. Hicks, S. S. Stepanyan, S. A. Philips, J. Mueller, K. Hafidi, V. S. Serov, K. Park, V. P. Kubarovsky, O. Pogorelko, L. C. Dennis, B. E. Bonner, H. Avakian, W. J. Briscoe, E. Pasyuk, D. Doughty, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, CLAS, and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Particle physics, Nuclear and High Energy Physics, Proton, DEEP-INELASTIC-SCATTERING, TARGET FRAGMENTATION REGION, TRANSVERSE-MOMENTUM, PARTON DISTRIBUTIONS, AZIMUTHAL ASYMMETRY, PION ELECTROPRODUCTION, CHARGED HADRONS, HARD PROCESSES, LEADING ORDER, CROSS-SECTION, TARGET FRAGMENTATION REGION, Hadron, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Spectral line, Nuclear physics, Pion, Factorization, 0103 physical sciences, 010306 general physics, Nuclear Experiment, PION ELECTROPRODUCTION, Physics, DEEP-INELASTIC-SCATTERING, 010308 nuclear & particles physics, LEADING ORDER, TRANSVERSE-MOMENTUM, Azimuth, Diquark, CHARGED HADRONS, HARD PROCESSES, PARTON DISTRIBUTIONS, Cathode ray, AZIMUTHAL ASYMMETRY, High Energy Physics::Experiment, CROSS-SECTION
Abstract

Semi-inclusive {pi}{sup +} electroproduction on protons has been measured with the CLAS detector at Jefferson Lab. The measurement was performed on a liquid-hydrogen target using a 5.75 GeV electron beam. The complete five-fold differential cross sections were measured over a wide kinematic range including the complete range of azimuthal angles between hadronic and leptonic planes, {phi}, enabling us to separate the {phi}-dependent terms. Our measurements of the {phi}-independent term of the cross section at low Bjorken x were found to be in fairly good agreement with pQCD calculations. Indeed, the conventional current fragmentation calculation can account for almost all of the observed cross section, even at small {pi}{sup +} momentum. The measured center-of-momentum spectra are in qualitative agreement with high-energy data, which suggests a surprising numerical similarity between the spectator diquark fragmentation in the present reaction and the antiquark fragmentation measured in e{sup +}e{sup -} collisions. We have observed that the two {phi}-dependent terms of the cross section are small. Within our precision the cos2{phi} term is compatible with zero, except for the low-z region, and the measured cos{phi} term is much smaller in magnitude than the sum of the Cahn and Berger effects.

Published
2009

16. Non-universality of transverse momentum dependent parton distribution functions

Author

C. J. Bomhof, Piet J. Mulders, and Theoretical Physics

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Scattering, Hard processes, Hadron, High Energy Physics::Phenomenology, FOS: Physical sciences, Parton, Universality, Universality (dynamical systems), Gluon, High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), Distribution function, Factorization, Partonic intrinsic transverse momentum, High Energy Physics::Experiment, Gauge theory, Nuclear Experiment, Gauge invariance, Distribution functions
Abstract

In the field theoretical description of hadronic scattering processes, single transverse-spin asymmetries arise due to gluon initial and final state interactions. These interactions lead to process dependent Wilson lines in the operator definitions of transverse momentum dependent parton distribution functions. In particular for hadron-hadron scattering processes with hadronic final states this has important ramifications for possible factorization formulas in terms of (non)universal TMD parton distribution functions. In this paper we will systematically separate the universality-breaking parts of the TMD parton correlators from the universal T-even and T-odd parts. This might play an important role in future factorization studies for these processes. We also show that such factorization theorems will (amongst others) involve the gluonic pole cross sections, which have previously been shown to describe the hard partonic scattering in weighted spin asymmetries., v2: some textual changes in the paper and corrections in references, to appear in Nucl. Phys. B

Published
2008

17. Event shapes in deep inelastic scattering at HERA

Author

Chekanov, S, Derrick, M, Magill, S, Miglioranzi, S, Musgrave, B, Nicholass, D, Repond, J, Yoshida, R, Mattingly, MCK, Pavel, N, Molina, AGY, Antonelli, S, Antonioli, P, Bari, G, Basile, M, Bellagamba, L, Bindi, M, Boscherini, D, Bruni, A, Bruni, G, Cifarelli, L, Cindolo, F, Contin, A, Corradi, M, De Pasquale, S, Iacobucci, G, Margotti, A, Nania, R, Polini, A, Rinaldi, L, Sartorelli, G, Zichichi, A, Aghuzumtsyan, G, Bartsch, D, Brock, I, Goers, S, Hartmann, H, Hilger, E, Jakob, H-P, Juengst, M, Kind, OM, Paul, E, Rautenberg, J, Renner, R, Samson, U, Schoenberg, V, Wang, M, Wlasenko, M, Brook, NH, Heath, GP, Morris, JD, Namsoo, T, Capua, M, Fazio, S, Mastroberardino, A, Schioppa, M, Susinno, G, Tassi, E, Kim, JY, Ma, KJ, Ibrahim, ZA, Kamaluddin, B, Abdullah, WATW, Ning, Y, Ren, Z, Sciulli, F, Chwastowski, J, Eskreys, A, Figiel, J, Galas, A, Gil, M, Olkiewicz, K, Stopa, P, Zawiejski, L, Adamczyk, L, Bold, T, Grabowska-Bold, I, Kisielewska, D, Lukasik, J, Przybycien, M, Suszycki, L, Kotanski, A, Slominski, W, Adler, V, Behrens, U, Bloch, I, Bonato, A, Borras, K, Coppola, N, Fourletova, J, Geiser, A, Gladkov, D, Goettlicher, P, Gregor, I, Gutsche, O, Haas, T, Hain, W, Horn, C, Kahle, B, Koetz, U, Kowalski, H, Lim, H, Lobodzinska, E, Loehr, B, Mankel, R, Melzer-Pellmann, I-A, Montanari, A, Nguyen, CN, Notz, D, Nuncio-Quiroz, AE, Santamarta, R, Schneekloth, U, Stadie, H, Stoesslein, U, Szuba, D, Szuba, J, Theedt, T, Watt, G, Wolf, G, Wrona, K, Youngman, C, Zeuner, W, Schlenstedt, S, Barbagli, G, Gallo, E, Pelfer, PG, Bamberger, A, Dobur, D, Karstens, F, Vlasov, NN, Bussey, PJ, Doyle, AT, Dunne, W, Ferrando, J, Hanlon, S, Saxon, DH, Skillicorn, IO, Gialas, I, Gosau, T, Holm, U, Klanner, R, Lohrmann, E, Salehi, H, Schleper, P, Schoerner-Sadenius, T, Sztuk, J, Wichmann, K, Wick, K, Foudas, C, Fry, C, Long, KR, Tapper, AD, Kataoka, M, Matsumoto, T, Nagano, K, Tokushuku, K, Yamada, S, Yamazaki, Y, Barakbaev, AN, Boos, EG, Dossanov, A, Pokrovskiy, NS, Zhautykov, BO, Son, D, de Favereau, J, Piotrzkowski, K, Barreiro, F, Glasman, C, Jimenez, M, Labarga, L, del Peso, J, Ron, E, Terron, J, Zambrana, M, Corriveau, F, Liu, C, Walsh, R, Zhou, C, Tsurugai, T, Antonov, A, Dolgoshein, BA, Rubinsky, I, Sosnovtsev, V, Stifutkin, A, Suchkov, S, Dementiev, RK, Ermolov, R, Gladilin, LK, Katkov, II, Khein, LA, Korzhavina, IA, Kuzmin, VA, Levchenko, BB, Lukina, OY, Proskuryakov, AS, Shcheglova, LM, Zotkin, DS, Zotkin, SA, Abt, I, Buettner, C, Caldwell, A, Kollar, D, Liu, X, Schmidke, WB, Sutiak, J, Grigorescu, G, Keramidas, A, Koffeman, E, Kooijman, P, Pellegrino, A, Tiecke, H, Vazquez, M, Wiggers, L, Bruemmer, N, Bylsma, B, Durkin, LS, Lee, A, Ling, TY, Allfrey, PD, Bell, MA, Cooper-Sarkar, AM, Cottrell, A, Devenish, RCE, Foster, B, Gwenlan, C, Korcsak-Gorzo, K, Patel, S, Roberfroid, V, Robertson, A, Straub, PB, Uribe-Estrada, C, Walczak, R, Bellan, P, Bertolin, A, Brugnera, R, Carlin, R, Ciesielski, R, Dal Corso, F, Dusini, S, Garfagnini, A, Limentani, S, Longhin, A, Stanco, L, Turcato, M, Oh, BY, Raval, A, Whitmore, JJ, Iga, Y, D'Agostini, G, Marini, G, Nigro, A, Cole, JE, Hart, JC, Abramowicz, H, Gabareen, A, Ingbir, R, Kananov, S, Levy, A, Kuze, M, Hori, R, Kagawa, S, Shimizu, S, Tawara, T, Hamatsu, R, Kaji, H, Kitamura, S, Ota, O, Ri, YD, Ferrero, MI, Monaco, V, Sacchi, R, Solano, A, Arneodo, M, Ruspa, M, Fourletov, S, Martin, JF, Butterworth, JM, Hall-Wilton, R, Jones, TW, Loizides, JH, Sutton, MR, Targett-Adams, C, Wing, M, Brzozowska, B, Ciborowski, J, Grzelak, G, Kulinski, P, Luzniak, P, Malka, J, Nowak, RJ, Pawlak, JM, Tymieniecka, T, Ukleja, A, Ukleja, J, Zarnecki, AF, Adamus, M, Plucinski, P, Eisenberg, Y, Giller, I, Hochman, D, Karshon, U, Brownson, E, Danielson, T, Everett, A, Kcira, D, Reeder, DD, Rosin, M, Ryan, P, Savin, AA, Smith, WH, Wolfe, H, Bhadra, S, Catterall, CD, Cui, Y, Hartner, G, Menary, S, Noor, U, Soares, M, Standage, J, Whyte, J, Collaboration, ZEUS, UCL, S. CHEKANOV, M. DERRICK, S. MAGILL, S. MIGLIORANZI, B. MUSGRAVE, D. NICHOLASS, J. REPOND, R. YOSHIDA, M.C.K. MATTINGLY, N. PAVEL, A.G. YAGÜES MOLINA, S. ANTONELLI, P. ANTONIOLI, G. BARI, M. BASILE, L. BELLAGAMBA, M. BINDI, D. BOSCHERINI, A. BRUNI, G. BRUNI, L. CIFARELLI, F. CINDOLO, A. CONTIN, M. CORRADI, S. DE PASQUALE, G. IACOBUCCI, A. MARGOTTI, R. NANIA, A. POLINI, L. RINALDI, G. SARTORELLI, A. ZICHICHI, G. AGHUZUMTSYAN, D. BARTSCH, I. BROCK, S. GOERS, H. HARTMANN, E. HILGER, H.-P. JAKOB, M. JÜNGST, O.M. KIND, E. PAUL, J. RAUTENBERG, R. RENNER, U. SAMSON, V. SCHÖNBERG, M. WANG, M. WLASENKO, N.H. BROOK, G.P. HEATH, J.D. MORRIS, T. NAMSOO, M. CAPUA, S. FAZIO, A. MASTROBERARDINO, M. SCHIOPPA, G. SUSINNO, E. TASSI, J.Y. KIM, K.J. MA, Z.A. IBRAHIM, B. KAMALUDDIN, W.A.T. WAN ABDULLAH, Y. NING, Z. REN, F. SCIULLI, J. CHWASTOWSKI, A. ESKREYS, J. FIGIEL, A. GALAS, M. GIL, K. OLKIEWICZ, P. STOPA, L. ZAWIEJSKI, L. ADAMCZYK, T. BOLD, I. GRABOWSKA-BOLD, D. KISIELEWSKA, J. LUKASIK, M. PRZYBYCIEN, L. SUSZYCKI, A. KOTANSKI, W. SLOMINSKI, V. ADLER, U. BEHRENS, I. BLOCH, A. BONATO, K. BORRAS, N. COPPOLA, J. FOURLETOVA, A. GEISER, D. GLADKOV, P. GÖTTLICHER, I. GREGOR, O. GUTSCHE, T. HAAS, W. HAIN, C. HORN, B. KAHLE, U. KÖTZ, H. KOWALSKI, H. LIM, E. LOBODZINSKA, B. LÖHR, R. MANKEL, I.-A. MELZER-PELLMANN, A. MONTANARI, C.N. NGUYEN, D. NOTZ, A.E. NUNCIO-QUIROZ, R. SANTAMARTA, U. SCHNEEKLOTH, H. STADIE, U. STÖSSLEIN, D. SZUBA, J. SZUBA, T. THEEDT, G. WATT, G. WOLF, K. WRONA, C. YOUNGMAN, W. ZEUNER, S. SCHLENSTEDT, G. BARBAGLI, E. GALLO, P.G. PELFER, A. BAMBERGER, D. DOBUR, F. KARSTENS, N.N. VLASOV, P.J. BUSSEY, A.T. DOYLE, W. DUNNE, J. FERRANDO, S. HANLON, D.H. SAXON, I.O. SKILLICORN, I. GIALAS, T. GOSAU, U. HOLM, R. KLANNER, E. LOHRMANN, H. SALEHI, P. SCHLEPER, T. SCHÖRNER-SADENIUS, J. SZTUK, K. WICHMANN, K. WICK, C. FOUDAS, C. FRY, K.R. LONG, A.D. TAPPER, M. KATAOKA, T. MATSUMOTO, K. NAGANO, K. TOKUSHUKU, S. YAMADA, Y. YAMAZAKI, A.N. BARAKBAEV, E.G. BOOS, A. DOSSANOV, N.S. POKROVSKIY, B.O. ZHAUTYKOV, D. SON, J. DE FAVEREAU, K. PIOTRZKOWSKI, F. BARREIRO, C. GLASMAN, M. JIMENEZ, L. LABARGA, J. DEL PESO, E. RON, J. TERRÓN, M. ZAMBRANA, F. CORRIVEAU, C. LIU, R. WALSH, C. ZHOU, T. TSURUGAI, A. ANTONOV, B.A. DOLGOSHEIN, I. RUBINSKY, V. SOSNOVTSEV, A. STIFUTKIN, S. SUCHKOV, R.K. DEMENTIEV, P.F. ERMOLOV, L.K. GLADILIN, I.I. KATKOV, L.A. KHEIN, I.A. KORZHAVINA, V.A. KUZMIN, B.B. LEVCHENKO, O.YU. LUKINA, A.S. PROSKURYAKOV, L.M. SHCHEGLOVA, D.S. ZOTKIN, S.A. ZOTKIN, I. ABT, C. BÜTTNER, A. CALDWELL, D. KOLLAR, X. LIU, W.B. SCHMIDKE, J. SUTIAK, G. GRIGORESCU, A. KERAMIDAS, E. KOFFEMAN, P. KOOIJMAN, A. PELLEGRINO, H. TIECKE, M. VÁZQUEZ, L. WIGGERS, N. BRÜMMER, B. BYLSMA, L.S. DURKIN, A. LEE, T.Y. LING, P.D. ALLFREY, M.A. BELL, A.M. COOPER-SARKAR, A. COTTRELL, R.C.E. DEVENISH, B. FOSTER, C. GWENLAN, K. KORCSAK-GORZO, S. PATEL, V. ROBERFROID, A. ROBERTSON, P.B. STRAUB, C. URIBE-ESTRADA, R. WALCZAK, P. BELLAN, A. BERTOLIN, R. BRUGNERA, R. CARLIN, R. CIESIELSKI, F. DAL CORSO, S. DUSINI, A. GARFAGNINI, S. LIMENTANI, A. LONGHIN, L. STANCO, M. TURCATO, B.Y. OH, A. RAVAL, J.J. WHITMORE, Y. IGA, G. D'AGOSTINI, G. MARINI, A. NIGRO, J.E. COLE, J.C. HART, H. ABRAMOWICZ, A. GABAREEN, R. INGBIR, S. KANANOV, A. LEVY, M. KUZE, R. HORI, S. KAGAWA, S. SHIMIZU, T. TAWARA, R. HAMATSU, H. KAJI, S. KITAMURA, O. OTA, Y.D. RI, M.I. FERRERO, V. MONACO, R. SACCHI, A. SOLANO, M. ARNEODO, M. RUSPA, S. FOURLETOV, J.F. MARTIN, J.M. BUTTERWORTH, R. HALL-WILTON, T.W. JONES, J.H. LOIZIDES, M.R. SUTTON, C. TARGETT-ADAMS, M. WING, B. BRZOZOWSKA, J. CIBOROWSKI, G. GRZELAK, P. KULINSKI, P. LUZNIAK, J. MALKA, R.J. NOWAK, J.M. PAWLAK, T. TYMIENIECKA, A. UKLEJA, J. UKLEJA, A.F. ZARNECKI, M. ADAMUS, P. PLUCINSKI, Y. EISENBERG, I. GILLER, D. HOCHMAN, U. KARSHON, E. BROWNSON, T. DANIELSON, A. EVERETT, D. KÇIRA, D.D. REEDER, M. ROSIN, P. RYAN, A.A. SAVIN, W.H. SMITH, H. WOLFE, S. BHADRA, C.D. CATTERALL, Y. CUI, G. HARTNER, S. MENARY, U. NOOR, M. SOARES, J. STANDAGE, and J. WHYTE

Subjects
Nuclear and High Energy Physics, Particle physics, MONTE-CARLO GENERATOR, HERA, FOS: Physical sciences, 01 natural sciences, CROSS-SECTIONS, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), High Energy Physics, ZEUS Collaboration, POWER CORRECTIONS, Consistency (statistics), LEPTON-NUCLEON SCATTERING, 0103 physical sciences, ddc:530, 010306 general physics, Boson, Quantum chromodynamics, Physics, Luminosity (scattering theory), ZEUS (particle detector), Neutral current, 010308 nuclear & particles physics, CENTRAL TRACKING DETECTOR, ZEUS BARREL CALORIMETER, PARTON DISTRIBUTIONS, HADRON-COLLISIONS, HARD PROCESSES, QCD, Deep inelastic scattering, High Energy Physics::Experiment
Abstract

Mean values and differential distributions of event-shape variables have been studied in neutral current deep inelastic scattering using an integrated {luminosity} of 82.2 pb$^{-1}$ collected with the ZEUS detector at HERA. The kinematic range was $80 < Q^2 < 20 480\gev^2$ and $0.0024 < x < 0.6$, where $Q^2$ is the virtuality of the exchanged boson and $x$ is the Bjorken variable. The data are compared with a model based on a combination of next-to-leading-order QCD calculations with next-to-leading-logarithm corrections and the Dokshitzer-Webber non-perturbative power corrections. The power-correction method provides a reasonable description of the data for all event-shape variables studied. Nevertheless, the lack of consistency of the determination of $��_s$ and of the non-perturbative parameter of the model, $\albar$, suggests the importance of higher-order processes that are not yet included in the model., 35 pages, 11 figures

Published
2007

18. 8.851 Strong Interactions, Spring 2003

Author

Stewart, Iain and Stewart, Iain

Abstract

The strong force which bind quarks together is described by a relativistic quantum field theory called quantum chromodynamics (QCD). Subject surveys: The QCD Langrangian, asymptotic freedom and deep inelastic scattering, jets, the QCD vacuum, instantons and the U(1) problem, lattice guage theory, and other phases of QCD. From the course home page: Course Description Strong Interactions is a course in the construction and application of effective field theories, which are a modern tool of choice in making predictions based on the Standard Model. Concepts such as matching, renormalization, the operator product expansion, power counting, and running with the renormalization group will be discussed. Topics will be taken from heavy quark decays and CP violation, factorization in hard processes (deep inelastic scattering and exclusive processes), non-relativistic bound states in field theory (QED and QCD), chiral perturbation theory, few-nucleon systems, and possibly other Standard Model subjects.

Published
2003

19. The resummation of soft gluon in hadronic collisions

Author

Luca Trentadue, Michelangelo L. Mangano, Paolo Nason, S. Catani, Catani, S, Mangano, M, Nason, P, and Trentadue, L

Subjects
Nuclear and High Energy Physics, Particle physics, HEAVY FLAVOR PRODUCTION, Flavour, Hadron, Drell-Yan, FOS: Physical sciences, Jet (particle physics), K-FACTOR, High Energy Physics - Phenomenology (hep-ph), POWER CORRECTIONS, DRELL-YAN PROCESS, threshold, Invariant mass, Resummation, Nuclear Experiment, PRINCIPAL-VALUE RESUMMATION, Particle Physics - Phenomenology, PRODUCTION, Physics, QUARK, High Energy Physics::Phenomenology, Top, QCD, LARGE PERTURBATIVE CORRECTIONS, Gluon, High Energy Physics - Phenomenology, HARD PROCESSES, Pair production, Jet, resummation, PARTON DISTRIBUTIONS, High mass, renormalon, High Energy Physics::Experiment, CROSS-SECTION
Abstract

We compute the effects of soft gluon resummation for the production of high mass systems in hadronic collisions. We carefully analyse the growth of the perturbative expansion coefficients of the resummation formula. We propose an expression consistent with the known leading and next-to-leading resummation results, in which the coefficients grow much less than factorially. We apply our formula to Drell--Yan pair production, heavy flavour production, and the production of high invariant mass jet pairs in hadronic collisions. We find that, with our formula, resummation effects become important only fairly close to the threshold region. In the case of heavy flavour production we find that resummation effects are small in the experimental configurations of practical interest., Comment: 45 pages, Latex, epsfig, 10 figures. Minor corrections to text, notation and references. The previously quoted HERAb NLO bottom production cross section was wrong, and it has been fixed. Accepted for Publication on Nucl. Phys. B

Published
1996

20. The resummation of soft gluons in hadronic collisions

Author

Catani, S, Mangano, M, Nason, P, Trentadue, L, Mangano, ML, Catani, S, Mangano, M, Nason, P, Trentadue, L, and Mangano, ML

Abstract

We compute the effects of soft-gluon resummation for the production of high mass systems in hadronic collisions. We carefully analyse the growth of the perturbative expansion coefficients of the resummation formula. We propose an expression consistent with the known leading and next-to-leading resummation results, in which the coefficients grow much less than factorially. We apply our formula to Drell-Yan pair production, heavy flavour production, and the production of high invariant mass jet pairs in hadronic collisions. We find that, with our formula, resummation effects become important only fairly close to the threshold region. In the case of heavy flavour production we find that resummation effects are small in the experimental configurations of practical interest.

Published
1996

Catalog

Books, media, physical & digital resources
See catalog results