Abstract
This paper focuses on hadron mass effects in calculations of semi-inclusive kaon production in lepton-Deuteron deeply inelastic scattering at HERMES and COMPASS kinematics. In the collinear factorization framework, the corresponding cross section is shown to factorize, at leading order and leading twist, into products of parton distributions and fragmentation functions evaluated in terms of kaon- and nucleon-mass-dependent scaling variables, and to respect gauge invariance. It is found that hadron mass corrections for integrated kaon multiplicities sizeably reduce the apparent large discrepancy between measurements of $K^+ + K^-$ multiplicities performed by the two collaborations, and fully reconcile their $K^+/K^-$ ratios.
Highlights
During the last decade, significant advances have been made in the understanding of the partonic structure of the nucleon [1,2]
While most of the discussion has centered on kinematic and binning issues, here we argue that hadron mass corrections” (HMCs) may play an essential role due to the relatively low average values of Q2 dominating the HERMES and COMPASS measurements
The HMCs are non-negligible and of the same order of the HERMES to COMPASS evolution effects. (The FF systematics has not been evaluated because the HKNS fit cannot extract reliable charge separated fragmentation functions.)
Summary
Significant advances have been made in the understanding of the partonic structure of the nucleon [1,2]. The strange quark PDF has been extracted phenomenologically in global QCD fits by several groups [3,4,5,6], largely relying on data on dimuon production in neutrino-nucleus scattering [7,8], as well as from data on weak boson production in proton-proton collisions by the ATLAS and CMS experiments at the LHC [9,10,11,12] It has been extracted experimentally from semi-inclusive deeply inelastic scattering (SIDIS) data in kaon production by the HERMES collaboration [13,14], and, with decreased sensitivity, from pion production data [15]. VI we summarize our findings and discuss prospects for future theoretical and phenomenological work, and in Appendix we discuss in some detail our treatment of baryon number conservation
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