Valence Quarks Polarization from COMPASS

TL;DR

This paper presents the first evaluation of the polarized valence quark distribution from COMPASS data, using difference asymmetries to directly access valence quark polarization in a broad kinematic range.

Contribution

It provides a novel analysis of polarized valence quark distributions using difference asymmetries from COMPASS data collected between 2002 and 2004.

Findings

First evaluation of polarized valence quark distribution from COMPASS data.

Use of difference asymmetry to directly access valence quark polarization.

Data covers a wide range of Q^2 and x values.

Abstract

A first evaluation of the polarized valence quark distribution $\Delta u_v(x)+\Delta d_v(x)$ from the COMPASS experiment (CERN/SPS) is presented. The data were collected by COMPASS in the years 2002--2004 using a 160 GeV polarized muon beam scattered off a large polarized $^6$LiD target and cover the range $1< Q^2 < 100$ GeV$^2$ and $0.006<x<0.7$. The analysis is based on the difference asymmetry, $A^{h^+ - h^-}$, for hadrons of opposite charges, which gives a direct access to the polarization of valence quarks.