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Title: Understanding the large-distance behavior of transverse-momentum-dependent parton densities and the Collins-Soper evolution kernel

There is considerable controversy about the size and importance of non-perturbative contributions to the evolution of transverse momentum dependent (TMD) parton distribution functions. Standard fits to relatively high-energy Drell-Yan data give evolution that when taken to lower Q is too rapid to be consistent with recent data in semi-inclusive deeply inelastic scattering. Some authors provide very different forms for TMD evolution, even arguing that non-perturbative contributions at large transverse distance bT are not needed or are irrelevant. Here, we systematically analyze the issues, both perturbative and non-perturbative. We make a motivated proposal for the parameterization of the non-perturbative part of the TMD evolution kernel that could give consistency: with the variety of apparently conflicting data, with theoretical perturbative calculations where they are applicable, and with general theoretical non-perturbative constraints on correlation functions at large distances. We propose and use a scheme- and scale-independent function A(bT) that gives a tool to compare and diagnose different proposals for TMD evolution. We also advocate for phenomenological studies of A(bT) as a probe of TMD evolution. The results are important generally for applications of TMD factorization. In particular, they are important to making predictions for proposed polarized Drell- Yan experiments to measure the Siversmore » function.« less
 [1] ;  [2]
  1. Pennsylvania State Univ., University Park, PA (United States). Davey Lab.
  2. Stony Brook Univ., NY (United States). C.N. Yang Inst. for Theoreticl Physics; Southern Methodist Univ., Dallas, TX (United States); Old Dominion Univ., Norfolk, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
Publication Date:
Report Number(s):
JLAB-THY-15-2001; DOE/OR/23177-3268; arXiv:1412.3820
Journal ID: ISSN 1550-7998; PRVDAQ; ArticleNumber: 074020, NSF Grant PHY-0969739; NSF Grant PHY-1316617; DOE Grant DE-SC0008745; TRN: US1600841
Grant/Contract Number:
AC05-06OR23177; SC0008745
Accepted Manuscript
Journal Name:
Physical Review. D, Particles, Fields, Gravitation and Cosmology
Additional Journal Information:
Journal Volume: 91; Journal Issue: 7; Journal ID: ISSN 1550-7998
American Physical Society (APS)
Research Org:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1181493