Impact of LHC vector boson production in heavy ion collisions on strange PDFs
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Regular Article - Theoretical Physics
Impact of LHC vector boson production in heavy ion collisions on strange PDFs A. Kusina1,a , T. Ježo2,b , D. B. Clark3 , P. Duwentäster4 , E. Godat3 , T. J. Hobbs3,5 , J. Kent3 , M. Klasen4 , K. Kovaˇrík4,c , F. Lyonnet3 , K. F. Muzakka4 , F. I. Olness3,d , I. Schienbein6,e , J. Y. Yu6 1
Institute of Nuclear Physics Polish Academy of Sciences, 31342 Kraków, Poland Institute for Theoretical Physics, KIT, Karlsruhe, Germany 3 Southern Methodist University, Dallas, TX 75275, USA 4 Institut für Theoretische Physik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Straße 9, 48149 Münster, Germany 5 Jefferson Lab, EIC Center, Newport News, VA 23606, USA 6 Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble-Alpes, CNRS/IN2P3, 53 avenue des Martyrs, 38026 Grenoble, France
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Received: 27 July 2020 / Accepted: 2 October 2020 © The Author(s) 2020
Abstract The extraction of the strange quark parton distribution function (PDF) poses a long-standing puzzle. Measurements from neutrino-nucleus deep inelastic scattering (DIS) experiments suggest the strange quark is suppressed compared to the light sea quarks, while recent studies of W ±/Z boson production at the LHC imply a larger strange component at small x values. As the parton flavor determination in the proton depends on nuclear corrections, e.g. from heavy-target DIS, LHC heavy ion measurements can provide a distinct perspective to help clarify this situation. In this investigation we extend the nCTEQ15 nPDFs to study the impact of the LHC proton-lead W ±/Z production data on both the flavor differentiation and nuclear corrections. This complementary data set provides new insights on both the LHC W ±/Z proton analyses and the neutrino-nucleus DIS data. We identify these new nPDFs as nCTEQ15WZ. Our calculations are performed using a new implementation of the nCTEQ code (nCTEQ++) based on C++ which enables us to easily interface to external programs such as HOPPET, APPLgrid and MCFM. Our results indicate that, as suggested by the proton data, the small x nuclear strange sea appears larger than previously expected, even when the normalization of the W ± /Z data is accommodated in the fit. Extending the nCTEQ15 analysis to include LHC W ±/Z data represents an important step as we advance toward the next generation of nPDFs. a e-mail:
[email protected]
b e-mail:
[email protected]
c e-mail:
[email protected]
d e-mail:
[email protected] (corresponding author)
e e-mail:
[email protected]
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Contents 1 Introduction . . . . . . . 2 Fits to experimental data . 3 Results and discussion . . 4 Comparisons . . . . . . . 5 Conclusion . . . . . . . . A Fitting data normalizations References . . . . . . . . . .
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1 Introduction Parton dist
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