Abstract
In this work, we complete our CT18qed study with the neutron’s photon parton distribution function (PDF), which is essential for the nucleus scattering phenomenology. Two methods, CT18lux and CT18qed, based on the LUXqed formalism and the DGLAP evolution, respectively, to determine the neutron’s photon PDF have been presented. Various low-Q2 non-perturbative variations have been carefully examined, which are treated as additional uncertainties on top of those induced by quark and gluon PDFs. The impacts of the momentum sum rule as well as isospin symmetry violation have been explored and turned out to be negligible. A detailed comparison with other neutron’s photon PDF sets has been performed, which shows a great improvement in the precision and a reasonable uncertainty estimation. Finally, two phenomenological implications are demonstrated with photon-initiated processes: neutrino-nucleus W-boson production, which is important for the near-future TeV–PeV neutrino observations, and the axion-like particle production at a high-energy muon beam-dump experiment.
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Acknowledgments
We thank Thomas Cridge for the help with the clarification of MSHT20qed results, and our CTEQ-TEA colleagues for useful discussions. The work of KX was supported by the U.S. Department of Energy under grant No. DE-SC0007914, the U.S. National Science Foundation under Grants No. PHY-2112829, No. PHY-2013791, and No. PHY-2310497, and also in part by the PITT PACC. The work of BZ was supported by the Simons Foundation. The work of TJH was supported by Argonne National Laboratory, operated by UChicago Argonne, LLC, for the U.S. Department of Energy under Contract No. DE-AC02-06CH11357. The work of KX was performed partly at the Aspen Center for Physics, which is supported by the U.S. National Science Foundation under Grant No. PHY-1607611 and No. PHY-2210452. This work used resources of high-performance computing clusters from SMU M2/M3, MSU HPCC, as well as Pitt CRC.
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The CTEQ-TEA collaboration., Xie, K., Zhou, B. et al. The photon content of the neutron. J. High Energ. Phys. 2024, 22 (2024). https://doi.org/10.1007/JHEP04(2024)022
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DOI: https://doi.org/10.1007/JHEP04(2024)022