Alignment function as a new kind of transverse momentum dependent functions

TL;DR

This paper introduces a new class of transverse momentum dependent functions related to the collective alignment of quark spins, which can be observed in Drell-Yan and SIDIS processes, expanding the understanding of parton transverse motion.

Contribution

It proposes the existence of new $k_ot$-dependent functions sensitive to quark spin alignment, distinct from known functions like Boer-Mulders.

Findings

New $k_ot$-dependent functions identified

Functions are sensitive to collective quark spin alignment

Potentially observable in Drell-Yan and SIDIS processes

Abstract

We argue the existence of new $k_\perp$-dependent functions which can be manifested in the Drell-Yan (SIDIS)-like processes. The presented new functions resemble the well-known Boer-Mulders function associated with the quark spin asymmetry, but in contrast they are sensitive to the transverse motion of partons inside the hadron due to the collective alignment of quark spin vectors.