Dihadron Fragmentation Functions and Transversity

TL;DR

This paper updates the extraction of the transversity parton distribution using pion-pair production data from deep-inelastic scattering and $e^+ e^-$ annihilation, providing a more precise and realistic uncertainty estimate.

Contribution

It introduces a refined analysis combining HERMES, COMPASS, and Belle data with improved uncertainty estimation for the transversity distribution.

Findings

Valence up transversity appears smaller with narrower errors

Enhanced uncertainty estimates improve the reliability of transversity extraction

Updated analysis offers the most realistic current transversity measurements

Abstract

We present preliminary results for an updated extraction of the transversity parton distribution based on the analysis of pion-pair production in deep-inelastic scattering off transversely polarized targets in collinear factorization. Data for proton and deuteron targets by HERMES and COMPASS allow for a flavor separation of the valence components of transversity, while di-hadron fragmentation functions are taken from the semi-inclusive production of two pion pairs in back-to-back jets in $e^+ e^-$ annihilation. The latter data from Belle have been reanalyzed using the replica method and a more realistic estimate of the uncertainties on the chiral-odd interference fragmentation function has been obtained. After encoding this piece of information into the deep-inelastic scattering cross section, the transversity has been re-extracted by using the most recent and more precise COMPASS data for proton target. This picture represents the current most realistic estimate of the uncertainties on our knowledge of transversity. The preliminary results indicate that the valence up component seems smaller and with a narrower error band than in previous extraction.