Polarized antiquark flavor asymmetry in Drell–Yan pair production

Abstract

We investigate the role of the flavor asymmetry of the nucleon's polarized antiquark distributions in Drell-Yan lepton pair production in polarized nucleon-nucleon collisions at HERA (fixed-target) and RHIC energies. It is shown that the large polarized antiquark flavor asymmetry predicted by model calculations in the large-N c limit (chiral quark-soliton model) has a dramatic effect on the double spin asymmetries in high mass lepton pair production, as well as on the single spin asymmetries in lepton pair production through W ± -bosons at M 2 = M 2 W .

Sivers effect in the Drell-Yan process at BNL RHIC

“…Similar and other spin physics prospects at RHIC are discussed in [28][29][30][31][32][33][34]. Other earlier predictions for SSAs in DY were given in [35,36].…”

Short-range correlations of partons & 3D nucleon structure

“…Typically χQSM results are found to agree within (10-30) % accuracy with phenomenology. Among the most interesting predictions of the χQSM is that there is a large flavor asymmetry also in the helicity sea [24,25] which leads to specific predictions for the Drell-Yan process [27]. Recent global QCD fits [41] and especially preliminary data from RHIC on W ± production data [42] support the prediction.…”

“…The chiral quark soliton model [21], which was derived from the instanton model of the QCD vacuum [22], is an effective theory which successfully and consistently accounts for sea quark effects [23][24][25][26][27][28][29][30]. The model was recently applied to TMDs [31][32][33] and yields remarkable predictions for the 3D nucleon structure at a low scale.…”

Sivers effect in semiinclusive deeply inelastic scattering

“…For example, in longitudinal double spin asymmetries A LL ∝ a e 2 a g a 1 (x)D a 1 (z) it is presently [58] not possible to resolve a flavour asymmetry in the helicity sea as sizeable as predicted in the chiral quark-soliton model [59], namely larger [60] than the known flavour asymmetry in the unpolarized sea (gū 1 − gd 1 )(x) > |(fū 1 − fd 1 )(x)|. As in the case of the much better known distribution functions f a 1 (x) and g a 1 (x) (see [61] for the specific example of helicity sea flavour asymmetry from the chiral quark-soliton model), it is necessary to study the Drell-Yan process in order to learn more about Sivers antiquark distribution functions.…”