First Extraction of Transversity from a Global Analysis of Electron-Proton and Proton-Proton Data

TL;DR

This work presents the first extraction of the transversity distribution in the framework of collinear factorization based on the global analysis of pion-pair production in deep-inelastic scattering and in proton-proton collisions with a transversely polarized proton.

Abstract

We present the first extraction of the transversity distribution in the framework of collinear factorization based on the global analysis of pion-pair production in deep-inelastic scattering off transversely polarized targets and in proton-proton collisions with one transversely polarized proton. The extraction relies on the knowledge of di-hadron fragmentation functions, which are taken from the analysis of electron-positron annihilation data. For the first time, the chiral-odd transversity is extracted from a global analysis similar to what is usually done for the chiral-even spin-averaged and helicity distributions. The knowledge of transversity is important for, among other things, detecting possible signals of new physics in high-precision low-energy experiments.

Figures (1)

• Figure 1: The transversity $x\, h_1$ as a function of $x$ at $Q^2 = 2.4$ GeV$^2$. Dark (blue) lines represent the Soffer bounds. Dark bands with solid borders for the global fit of this work including all options $D_1^g (Q_0^2) = 0$, $D_1^u (Q_0^2) / 4$ and $D_1^u (Q_0^2)$. (Top) For valence up quark: comparison with our previous fit in Ref. Radici:2015mwa (lighter band with dashed borders). (Bottom) For valence down quark: comparison with this global fit with only $D_1^g (Q_0^2) = 0$ (hatched area with lighter borders).