Study of Spin–Spin Correlations between Quark and a Spin-1/2 Composite System

Satvir Kaur,Harleen Dahiya

doi:10.1155/2020/9429631

Abstract

We study the correlation between the fermion composite system and quark spins by using the light-cone quark–diquark model. We do the calculations for u-quark and d-quark in the fermion system by considering different polarization configurations of both. The contribution from scalar and axial-vector diquarks is taken into account. The overlap representation of light-front wavefunctions is used for the calculations. The spin–spin correlations for u and d quarks are presented in transverse impact-parameter plane and transverse momentum plane as well.

Highlights

To get precise information of hadrons in terms of its constituents, Wigner distributions of quark and gluon were introduced by Ji [1, 2]
Applying certain limits on Wigner distributions provide the probabilistic three-dimensional distributions namely generalized parton distributions (GPDs) [3,4,5,6] and transverse momentum-dependent distributions (TMDs) [7,8,9,10]. e reduction to GPDs is based on the integration of five-dimensional Wigner distributions over transverse momentum at zero skewness
We investigate the correlation between the quark spin and spin of fermion system by using the Wigner distributions evaluated in Ref. [27]. e quark Wigner distributions were calculated by considering different configuration combinations of quark spin direction and proton spin direction. e overlap representation of light-front wavefunctions is taken into account to evaluate the Wigner operators having different cases, depending upon the polarization of quark, i.e., either unpolarized, longitudinally-polarized or transversely-polarized. e Wigner operator is associated with the Wigner distributions by a Fourier transformation of total momentum transferred to the final state of the system

Summary

Introduction

To get precise information of hadrons in terms of its constituents, Wigner distributions of quark and gluon were introduced by Ji [1, 2]. Wigner distributions are supportive for evaluating the spin–spin correlations between a spin-1/2 composite system and a quark inside the fermion system. We investigate the correlation between the quark spin and spin of fermion system by using the Wigner distributions evaluated in Ref. E overlap representation of light-front wavefunctions is taken into account to evaluate the Wigner operators having different cases, depending upon the polarization of quark, i.e., either unpolarized, longitudinally-polarized or transversely-polarized.

Light-Front Quark–Diquark Model

Results

Conclusions