Sivers function of sea quarks in the light-cone model

TL;DR

This paper models the Sivers function of sea quarks in the proton using a light-cone formalism and meson-baryon fluctuations, providing numerical predictions for the transverse momentum distributions of sea quarks.

Contribution

It introduces a light-cone model with meson-baryon fluctuations to calculate sea quark Sivers functions, incorporating final-state interactions at one-gluon exchange level.

Findings

Sea quark Sivers functions are negative.

First transverse moment magnitude is about 0.004.

Model fits unpolarized sea quark distributions.

Abstract

We calculate the Sivers function of $\bar{u}$ and $\bar{d}$ quarks using the overlap representation within the light-cone formalism. The light-cone wave functions of the proton is obtained in terms of the $|\bar{q} q B\rangle$ Fock states motivated by the meson-baryon fluctuation model. We consider the final-state interaction at the level of one gluon exchange. In a simplified scenario, the Sivers function of $\bar{u}$ and $\bar{d}$ can be expressed as the convolution of the Sivers function of the pion inside the proton and the unpolarized distribution of $\bar{q}$ inside the pion. The model parameters are fixed by fitting the unpolarized sea quark distributions to the known parameterizations. We present the numerical results for $f_1^{\perp \bar{u}/p}(x,\boldsymbol{k}_T^2)$ and $f_1^{\perp \bar{d}/p}(x,\boldsymbol{k}_T^2)$. The first transverse moment of the sea quark Sivers functions in our model are find to be negative and the magnitude is about 0.004 at most.