Abstract
We perform a comprehensive new Monte Carlo analysis of high-energy lepton-lepton, lepton-hadron and hadron-hadron scattering data to simultaneously determine parton distribution functions (PDFs) in the proton and parton to hadron fragmentation functions (FFs). The analysis includes all available semi-inclusive deep-inelastic scattering and single-inclusive $e^+ e^-$ annihilation data for pions, kaons and unidentified charged hadrons, which allows the flavor dependence of the fragmentation functions to be constrained. Employing a new multi-step fitting strategy and more flexible parametrizations for both PDFs and FFs, we assess the impact of different data sets on sea quark densities, and confirm the previously observed suppression of the strange quark distribution. The new fit, which we refer to as "JAM20-SIDIS", will allow for improved studies of universality of parton correlation functions, including transverse momentum dependent (TMD) distributions, across a wide variety of process, and the matching of collinear to TMD factorization descriptions.
Highlights
The standard parton correlation functions of QCD, such as collinear parton distribution functions (PDFs) and fragmentation functions (FFs), are being utilized in an increasingly diverse range of phenomenological applications. Beyond their traditional role in predicting new high energy phenomena, they enter frequently into the study of more complex and extended objects like transverse momentum dependent (TMD) PDFs and FFs and generalized parton distributions (GPDs), where they are needed to understand the transition between different factorization regions
We extend the previous work by performing the first simultaneous and overconstrained fit of unpolarized PDFs and FFs that utilizes both charged hadron production in semi-inclusive deep-inelastic scattering (SIDIS) and single-inclusive eþe− annihilation (SIA)
The data sets used in the present analysis include the primary electromagnetic processes that traditionally have been used in global QCD analyses, namely, inclusive DIS, Drell-Yan lepton-pair production, SIA, and SIDIS
Summary
The standard parton correlation functions of QCD, such as collinear parton distribution functions (PDFs) and fragmentation functions (FFs), are being utilized in an increasingly diverse range of phenomenological applications Beyond their traditional role in predicting new high energy phenomena, they enter frequently into the study of more complex and extended objects like transverse momentum dependent (TMD) PDFs and FFs and generalized parton distributions (GPDs), where they are needed to understand the transition between different factorization regions. We extend the previous work by performing the first simultaneous and overconstrained fit of unpolarized PDFs and FFs that utilizes both charged hadron production in semi-inclusive deep-inelastic scattering (SIDIS) and single-inclusive eþe− annihilation (SIA) This is partly motivated by a number of recent observations associated with the study of TMD PDFs. For example, significant tension has recently been found between fits performed with standard sets of PDFs and FFs and fixed order perturbative QCD calculations in processes including SIDIS [4,5], Drell-Yan (DY) [6], and SIA into wide-angle hadron pairs [7]. Some formulas for SIDIS cross sections and structure functions are collected in the Appendix
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