Effect of sea quarks on the single-spin asymmetries ALW± in polarized pp collisions at RHIC

Abstract

We calculate the single-spin asymmetries A W ± L of W ± bosons produced in polarized pp collisions with the valence part of the up and down quark helicity distributions modeled by the light-cone quark-spectator-diquark model while the sea part helicity distributions of the up and down quarks treated as parametrization. Comparing our results with those from experimental data at RHIC, we find that the helicity distributions of sea quarks play an important role in the determination of the shapes of AThe experimental data of the polarized structure functions and the sum of helicities are also important to constrain the sizes of quark helicity distributions both for the sea part and the valence part of the nucleon.

Quark-antiquark asymmetry of helicity distributions in the nucleon sea

“…The bad performances of the thin-solid (green) curves accord with the results in Ref. [21], which show that it is difficult to give a simultaneous description of both the experimental data from DIS processes and that from W ± productions with a quarkantiquark symmetry of helicity distributions. However, after taking into account the the quark-antiquark asymmetry of helicity distribution of nucleon sea q q pairs, the thick-solid (red) curves are consistent with the experimental data.…”

“…Nevertheless, the sea quark spin contribution to the proton is believed to be nontrivial, as reflected in the recent observations [21,22] of single spin asymmetries of W ± production in polarized proton-proton collisions [23,24]. It is shown [21] that a reasonable description of W ± single spin asymmetry data [23] can be achieved by adopting sizable helicity distributions of the light-flavor up (u) and down (d) antiquarks. More explicitly, the antiquark helicity is positive for the ū quark (∆ū > 0) and negative for the d quark (∆ d < 0).…”

Nucleon strangeness polarization from $$\varLambda /\bar{\varLambda }$$ hyperon production in polarized proton–proton collision at RHIC

“…There have been significant progress on spin distributions of light flavor valence quarks both experimentally and theoretically. Recently, some efforts have been made on the polarization of the light flavor sea quarks [3,4] and the quark-antiquark asymmetry of helicity distributions in nucleon sea [5]. Studies of the momentum distribution asymmetry between strange and antistrange [6][7][8][9][10] are of significance for the study of nonperturbative quantum chromodynamics (QCD) with fruitful progress [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29].…”

Nucleon strangeness polarization from $Λ/\barΛ$ hyperon production in polarized proton-proton collision at RHIC

“…There have been significant progress on spin distributions of light flavor valence quarks both experimentally and theoretically. Recently, some efforts have been made on the polarization of the light flavor sea quarks [3,4] and the quark-antiquark asymmetry of helicity distributions in nucleon sea [5]. Studies of the momentum distribution asymmetry between strange and antistrange [6][7][8][9][10] are of significance for the study of nonperturbative quantum chromodynamics (QCD) with fruitful progress [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29].…”