Nucleon tensor charge from Collins azimuthal asymmetry measurements

TL;DR

This paper provides a comprehensive analysis of the nucleon tensor charge by combining Collins asymmetry measurements from different experiments, incorporating transverse momentum evolution, and extracting quark contributions with quantified uncertainties.

Contribution

It introduces the first global fit of Collins functions and transversity distributions that includes transverse momentum evolution at next-to-leading order.

Findings

Nucleon tensor charge for up quarks: δu=+0.30^{+0.12}_{-0.08}

Nucleon tensor charge for down quarks: δd=-0.20_{-0.11}^{+0.28}

Analysis covers momentum fraction 0.0065 ≤ x_B ≤ 0.35 at Q^2=10 GeV^2

Abstract

We investigate the nucleon tensor charge from current experiments by a combined analysis of the Collins asymmetries in two hadron production in $e^+e^-$ annihilations and semi-inclusive hadron production in deep inelastic scattering processes. The transverse momentum dependent evolution is taken into account, for the first time, in the global fit of the Collins fragmentation functions and the quark transversity distributions at the approximate next-to-leading logarithmic order. We obtain the nucleon tensor charge contribution from up and down quarks as $\delta u=+0.30^{+0.12}_{-0.08}$ and $\delta d=-0.20_{-0.11}^{+0.28}$ at 90\% confidence level for momentum fraction $0.0065 \le x_B \le 0.35$ and $Q^2=$ 10 GeV$^2$.