https://doi.org/10.1140/epjc/s10052-020-08532-4
Regular Article - Theoretical Physics
Impact of LHC vector boson production in heavy ion collisions on strange PDFs
1
Institute of Nuclear Physics Polish Academy of Sciences, 31342, Kraków, Poland
2
Institute for Theoretical Physics, KIT, Karlsruhe, Germany
3
Southern Methodist University, 75275, Dallas, TX, USA
4
Institut für Theoretische Physik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Straße 9, 48149, Münster, Germany
5
Jefferson Lab, EIC Center, 23606, Newport News, VA, USA
6
Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble-Alpes, CNRS/IN2P3, 53 avenue des Martyrs, 38026, Grenoble, France
Received:
27
July
2020
Accepted:
2
October
2020
Published online:
19
October
2020
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 
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 production data on both the flavor differentiation and nuclear corrections. This complementary data set provides new insights on both the LHC 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 
data is accommodated in the fit. Extending the nCTEQ15 analysis to include LHC data represents an important step as we advance toward the next generation of nPDFs.
© The Author(s) 2020
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