title: Small-x Asymptotics of the Quark Helicity Distribution.
abstract: We construct a numerical solution of the small-x evolution equations derived in our recent work [J. High Energy Phys. 01 (2016) 072.JHEPFG1029-847910.1007/JHEP01(2016)072] for the (anti)quark transverse momentum dependent helicity TMDs and parton distribution functions (PDFs) as well as the g_{1} structure function. We focus on the case of large N_{c}, where one finds a closed set of equations. Employing the extracted intercept, we are able to predict directly from theory the behavior of the quark helicity PDFs at small x, which should have important phenomenological consequences. We also give an estimate of how much of the proton's spin carried by the quarks may be at small x and what impact this has on the spin puzzle.
authors.affiliation: Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Yuri V
authors.initials: YV
authors.lastname: Kovchegov
authors.affiliation: Division of Science, Penn State University-Berks, Reading, Pennsylvania 19610, USA.|RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Pitonyak
authors.affiliation: Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.|Physics Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Sievert