Time-reversal odd distribution functions in chiral models with vector mesons

TL;DR

The paper investigates whether time-reversal-odd distribution functions, known to arise in QCD due to gauge links, can also be nonzero in chiral models. By employing a hidden local symmetry where vector mesons act as gauge fields, a gauge-invariant link operator is defined within an effective theory, enabling T-odd distributions to emerge via vector-meson exchange with the vector mass serving as an infrared regulator. In the large-Nc limit, the model yields a clean up/down Sivers function relation, Δ0^T f_u = -Δ0^T f_d, providing a distinctive phenomenological signature compared to non-chiral approaches. This framework offers a route to compute T-odd PDFs in chiral theories and to use experimental data to distinguish between chiral and non-chiral models of hadron structure.

Abstract

The so-called time-reversal odd distribution functions are known to be non-vanishing in QCD due to the presence of the link operator in the definition of these quantities. I show that T-odd distributions can be non-vanishing also in chiral models, if vector mesons are introduced as dynamical gauge bosons of a hidden local symmetry. Moreover, since the flavor dependence of these distributions is different in chiral models respect to non chiral ones, the phenomenological analysis of experimental data will be able to distinguish between these two classes of models.