On $SU(2)_{CS}$-like groups and invariance of the fermionic action in QCD

TL;DR

This paper explores new $U(1)$ symmetry groups in fermionic actions, investigates their invariance under gauge interactions in QCD, and constructs $SU(2)_{CS}$-like groups inspired by lattice results, analyzing their implications for hadron correlators.

Contribution

It introduces new $U(1)$ symmetry groups, constructs $SU(2)_{CS}$-like groups in Euclidean space, and discusses their potential invariance in fermionic actions within QCD.

Findings

Identification of new $U(1)$ symmetry groups from parity and time-reversal.

Construction of $SU(2)_{CS}$-like groups based on these $U(1)$ groups.

Discussion on the potential invariance of fermionic actions and implications for hadron correlators.

Abstract

In this work, we introduce some new $U(1)$ symmetry groups of the free fermionic action in euclidean space-time, which are a consequence of parity and time-reversal symmetries. Afterwards, we discuss how the introduction of a gauge interaction affects the invariance of the action, with special reference to QCD. Moreover, inspired by recent QCD lattice results of \textit{Glozman et al.}, in which an interesting and unexpected symmetry group has been observed, namely $SU(2)_{CS}$ (that contains $U(1)_A$ as subgroup), we build other $SU(2)_{CS}$-like groups in euclidean space-time using the previous introduced $U(1)$ groups. Finally we argue about the possible invariance of the fermionic action with respect these new $SU(2)_{CS}$-like groups and its consequence on the hadron temporal correlators.