nCTEQ15WZ results:

Grids:

• nCTEQ15WZ bound proton grids:  
• Full PDF uncertainty sets: here (131 Mb)
• Mathematica ManeParse Testing Code for nCTEQ15WZ: here (4.3 Mb)

• nCTEQ15WZ_FullNuc full nucleus grids   (Z f_p + N f_n)/A
  
• Full PDF uncertainty sets: here (131 Mb)

• doQcdCase Bash Script: Some older grids had a typo in the .info file: "OrderQcd" should be "OrderQCD" The zip files have been updated, but this bash script will fix older files.

If you use any of the grids provided here, please cite

• nCTEQ15WZ: "Impact of LHC vector boson production in heavy ion collisions on strange PDFs"
  A. Kusina, T. Jezo, D.B. Clark, P. Duwentaster, E. Godat, T.J. Hobbs, J. Kent, M. Klasen, K. Kovarik, F. Lyonnet, K.F. Muzakka, F.I. Olness, I. Schienbein, J.Y. Yu
  https://arxiv.org/abs/2007.09100
  https://doi.org/10.1140/epjc/s10052-020-08532-4

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.

nCTEQ PDFs

PDF Comparison

for comments or requests contact K.Kovarik karol.kovarik@uni-muenster.de
                                 F.Olness  olness@smu.edu