Origin of single transverse-spin asymmetries in high-energy collisions

Abstract

In this paper, we perform the first simultaneous QCD global analysis of data from semi-inclusive deep inelastic scattering, Drell-Yan, e þ e − annihilation into hadron pairs, and proton-proton collisions. Consequently, we are able to extract a universal set of nonperturbative functions that describes the observed asymmetries in these reactions. The outcome of our analysis indicates single transverse-spin asymmetries in high-energy collisions have a common origin. Furthermore, we achieve the first phenomenological agreement with lattice QCD on the up and down quark tensor charges.

Joint thrust and TMD resummation in electron-positron and electron-proton collisions

“…Various determinations of TMD PDFs and FFs from experimental data have been performed: global extractions of unpolarized TMD PDFs and FFs [13][14][15], extractions of TMD PDFs [16,17], and polarized TMD PDFs and FFs [18][19][20][21][22]. One process that is used for these extractions is hadron-pair production in e + e − annihilation, for which the factorization theorem of the cross section differential in the relative transverse momentum of the two hadrons has the following schematic form, σ ∼ HDDS.…”

QCD resummation on single hadron transverse momentum distribution with the thrust axis

“…Similar formulas describe the TMD factorization for the SIDIS process in electron-nucleon collisions, e − p → e − hX [16,[30][31][32], and for back-to-back hadron pair production in e + e − annihilation, e + e − → h 1 h 2 X [33][34][35]. The universality for the non-perturbative parametrization has been investigated in [5,6,17,[36][37][38][39][40]. Recently, the TMD factorization structure has been re-investigated using Soft-Collinear Effective Theory (SCET) [41][42][43][44] and the renormalization group (RG) techniques [45][46][47].…”

“…A lot of progress has been made in understanding 3D imagining of the nucleon via both unpolarized and polarized TMD PDFs, see some recent work in refs. [4][5][6][7][8][9][10][11][12][13][14][15]. On the other hand, in comparison with the fruitful results in TMD PDFs, the research on the TMD FFs of hadrons definitely needs more development.…”

The Sivers asymmetry in hadronic dijet production

“…Besides Sivers type correlations, whose collinear version is referred to as the Qiu-Sterman function [15,23] in the incoming nucleon, there could also be similar correlations in the hadronization process when the parton fragments into the hadrons [17,19,21,22,24]. See [25] for a recent development along this direction.…”

“…Active investigation has been performed both experimentally [41] and theoretically [43][44][45]. On the experimental side, the Sivers asymmetry for dijet production was found to be quite small, largely due to the cancellation between u-and d-quark Sivers functions, which have similar size but opposite sign [25,46,47]. On the theoretical side, dijet production in proton-proton collisions is also subject to TMD factorization breaking [48,49].…”