Transverse momentum, rapidity, and centrality dependence of inclusive production in √ measured by the ATLAS experiment

Measurements of the per-event charged-particle yield as a function of the charged-particle transverse momentum and rapidity are performed using p + Pb collision data collected by the ATLAS experiment at the LHC at a centre-of-mass energy of √ s NN = 5 . 02 TeV. Charged particles are reconstructed over pseudorapidity | η | < 2 . 3 and transverse momentum between 0 . 1 GeV and 22 GeV in a dataset corresponding to an integrated luminosity of 1 μb − 1 . The results are presented in the form of charged- particle nuclear modification factors, where the p + Pb charged-particle multiplicities are compared between central and peripheral p + Pb collisions as well as to charged-particle cross sections measured in pp collisions. The p + Pb collision centrality is characterized by the total transverse energy measured in − 4 . 9 < η < − 3 . 1, which is in the direction of the outgoing lead beam. Three different estimations of the number of nucleons participating in the p + Pb collision are carried out using the Glauber model and two Glauber–Gribov colour-fluctuation extensions to the Glauber model. The values of the nuclear modification factors are found to vary significantly as a function of rapidity and transverse momentum. A broad peak is observed for all centralities and rapidities in the nuclear modification factors for charged- particle transverse momentum values around 3 GeV. The magnitude of the peak increases for more central collisions as well as rapidity ranges closer to the direction of the outgoing lead nucleus.

A. Trzupek | B. Wosiek | V. Tsulaia | C. Troncon | M. Trottier-McDonald | G. Tsipolitis | S. Tsiskaridze | S. Tsuno | D. Tsybychev | R. Turra | P. Tuts | M. Tyndel | I. Ueda | R. Ueno | G. Unal | A. Undrus | G. Unel | P. Urquijo | L. Vacavant | B. Vachon | S. Valkar | S. Vallecorsa | W. Vandelli | R. Vanguri | A. Vaniachine | P. Vankov | R. Vari | T. Varol | D. Varouchas | A. Vartapetian | F. Vazeille | S. Veneziano | M. Verducci | I. Vichou | T. Vickey | S. Viel | I. Vivarelli | S. Vlachos | M. Vlasak | P. Vokac | M. Volpi | I. Vukotic | S. Wahrmund | J. Wakabayashi | J. Walder | W. Walkowiak | C. Weiser | S. Wenig | K. Whalen | C. Wiglesworth | S. Willocq | J. Wotschack | S. Xella | B. Yabsley | S. Yacoob | S. Yamamoto | Y. Yasu | R. Yoshida | S. Youssef | R. Zaidan | D. Zanzi | C. Zeitnitz | M. Zeman | A. Zemla | O. Zenin | Z. Zinonos | D. Zerwas | D. Zhang | B. Zhou | A. Zoccoli | L. Zwalinski | M. Trovatelli | N. Tsirintanis | S. Turchikhin | M. Ughetto | F. Ungaro | A. Usanova | N. Valencic | L. Valéry | J. Nieuwkoop | G. Vardanyan | J. Veatch | O. Viazlo | R. Vigne | Z. Vykydal | Y. Yamazaki | E. Yatsenko | E. Yildirim | C. Young | A. Zaman | S. Zambito | K. Zengel | A. Zibell | C. Zimmermann | A. Turvey | C. Unverdorben | W. Wollenberg | M. Villa | K. Vorobev | C. Wanotayaroj | B. Weinert | R. Yakabe | I. Yeletskikh | I. Yusuff | K. Zhukov | P. Urrejola | F. Veloso | J. Yu | D. Turgeman | G. Ucchielli | C. Valderanis | E. Santurio | J. Vasquez | C. Vittori | F. Wilk | D. Yamaguchi | N. Zakharchuk | J. Zalieckas | C. Zhou | M. Zinser | M. Vogel | H. Yang | F. Zhang | Z. Yang | T. Schroeder | Y. Yang | J. Zhu | M. Vos | Y. Zhu | A. Yamamoto | J. Zhang | A. Valero | K. Yamauchi | Q. Zeng | Z. Yan | J. Wilson | J. Vermeulen | P. Wagner | K. Yoshihara | W. Yao | Y. Zhao | K. Yorita | D. Zieminska | M. Ziolkowski | G. Zobernig | V. Tsiskaridze | F. Ukegawa | G. Usai | S. Valentinetti | W. Verkerke | L. Vigani | E. Vilucchi | R. Vuillermet | H. Wolters | J. Zeng | X. Zhuang | L. Živković | Y. Unno | B. Zabinski | S. Zimmermann | L. Xu | M. V. Perez | E. Varnes | A. Ventura | V. Vorobel | K. Wong | M. Trzebiński | A. Warburton | L. Truong | J. Ye | W. Wagner | R. Walker | A. Zhemchugov | G. Volpi | J. Zhong | Y. Yamaguchi | X. Zhao | P. Gemmeren

[1]  J. Katzy,et al.  QCD Monte-Carlo model tunes for the LHC , 2013 .

[2]  Cms Collaboration.  Multiplicity and transverse-momentum dependence of two- and four-particle correlations in pPb and PbPb collisions , 2013, 1305.0609.

[3]  Wojciech Broniowski,et al.  Collective dynamics in high-energy proton-nucleus collisions , 2013, 1304.3044.

[4]  Raju Venugopalan,et al.  Comparison of the color glass condensate to dihadron correlations in proton-proton and proton-nucleus collisions , 2013, 1302.7018.

[5]  M. Alvioli,et al.  Color fluctuation effects in proton-nucleus collisions , 2013, 1301.0728.

[6]  Matthias Rudolph Richter,et al.  Long-range angular correlations on the near and away side in p-Pb collisions at root S-NN=5.02 TeV , 2012, 1212.2001.

[7]  C. Collaboration,et al.  Observation of long-range near-side angular correlations in proton-lead collisions at the LHC , 2012 .

[8]  A. Rezaeian.  CGC predictions for p+A collisions at the LHC and signature of QCD saturation , 2012, 1210.2385.

[9]  I. Vitev,et al.  Nuclear modification of high transverse momentum particle production in p + A collisions at RHIC and LHC , 2012, 1209.6030.

[10]  J. Albacete,et al.  CGC predictions for p + Pb collisions at the LHC , 2012, 1209.2001.

[11]  I. Helenius,et al.  Impact-parameter dependent nuclear parton distribution functions: EPS09s and EKS98s and their applications in nuclear hard processes , 2012, 1205.5359.

[12]  Marco Stratmann,et al.  Global analysis of nuclear parton distributions , 2011, 1112.6324.

[13]  P. Tribedy,et al.  QCD saturation at the LHC: Comparisons of models to p + p and A + A data and predictions for p + Pb collisions , 2011, 1112.2445.

[14]  M. Gyulassy,et al.  Predictions for p + Pb at 4.4A TeV to test initial-state nuclear shadowing at energies available at the CERN Large Hadron Collider , 2011, 1111.3646.

[15]  J. Jalilian-Marian,et al.  Hadron production in pA collisions at the LHC from the Color Glass Condensate , 2011, 1110.2810.

[16]  J. T. Childers,et al.  Performance of the ATLAS Trigger System in 2010 , 2011, 1110.1530.

[17]  M. L. Ferrer,et al.  Charged-particle multiplicities in pp interactionsmeasured with the ATLAS detector at the LHC , 2010, 1012.5104.

[18]  A. Bocci,et al.  Measurement of inclusive jet and dijet cross sections in proton-proton collisions at 7 TeV centre-of-mass energy with the ATLAS detector , 2010, 1009.5908.

[19]  D. Volyanskyy,et al.  Observation of long-range, near-side angular correlations in proton-proton collisions at the LHC , 2010, 1009.4122.

[20]  J. T. Childers,et al.  The ATLAS Simulation Infrastructure , 2010, 1005.4568.

[21]  J. Albacete,et al.  Single Inclusive Hadron Production at RHIC and the LHC from the Color Glass Condensate , 2010, 1001.1378.

[22]  K. Eskola,et al.  EPS09: A New Generation of NLO and LO Nuclear Parton Distribution Functions , 2009, 0902.4154.

[23]  M. P. Casado,et al.  The ATLAS Experiment at the CERN Large Hadron Collider , 2008 .

[24]  M. Gigg,et al.  Herwig++ physics and manual , 2008, 0803.0883.

[25]  T. Cornelissen,et al.  Single Track Performance of the Inner Detector New Track Reconstruction (NEWT) , 2008 .

[26]  Peter Steinberg,et al.  Glauber Modeling in High Energy Nuclear Collisions , 2007, nucl-ex/0701025.

[27]  S. Kumano,et al.  Determination of nuclear parton distribution functions and their uncertainties at next-to-leading order , 2005, 0709.3038.

[28]  V. Guzey,et al.  Proton-nucleus scattering and cross section fluctuations at RHIC and LHC , 2005, hep-ph/0505088.

[29]  I. Vitev,et al.  Coherent QCD multiple scattering in proton–nucleus collisions , 2004, hep-ph/0405068.

[30]  D. Kharzeev,et al.  Cronin effect and high p(T) suppression in pA collisions , 2003, hep-ph/0307037.

[31]  C. Henderson,et al.  Centrality dependence of charged-hadron transverse-momentum spectra in d+Au collisions at sqrt[s(NN)]=200 GeV. , 2003, Physical review letters.

[32]  I. Vitev.  Initial State Parton Broadening and Energy Loss Probed in d+Au at RHIC , 2003, nucl-th/0302002.

[33]  B. Kopeliovich,et al.  Cronin effect in hadron production off nuclei. , 2002, Physical review letters.

[34]  B. Kopeliovich,et al.  Nonperturbative effects in gluon radiation and photoproduction of quark pairs , 1999, hep-ph/9908245.

[35]  K. Eskola,et al.  Scale evolution of nuclear parton distributions , 1998, hep-ph/9802350.

[36]  R. Venugopalan,et al.  Computing quark and gluon distribution functions for very large nuclei. , 1993, Physical review. D, Particles and fields.

[37]  M. Shochet,et al.  Production of hadrons with large transverse momentum at 200, 300, and 400 GeV , 1975 .

[38]  N. Armesto,et al.  Predictions for p+Pb Collisions at √ s NN = 5 TeV , 2013 .

[39]  Improved Luminosity Determination in Pp Collisions at √ S = 7 Tev Using the Atlas Detector at the Lhc , 2013 .

[40]  W. Bhimji,et al.  A study of the material in the ATLAS inner detector using secondary hadronic interactions , 2012 .

[41]  A. Dell'Acqua,et al.  Geant4—a simulation toolkit , 2003 .

[42]  F. Fleuret,et al.  Absence of Suppression in Particle Production at Large Transverse Momentum in sNN p 200 GeV d Au Collisions , 2003 .