Spontaneous breaking of discrete symmetries in QCD on a small volume

TL;DR

This paper demonstrates that in small-volume QCD, discrete symmetries like C, P, and T are spontaneously broken, leading to observable persistent baryonic currents, confirmed through analytical and lattice methods.

Contribution

It reveals spontaneous breaking of discrete symmetries in small-volume QCD and identifies persistent baryonic currents as a physical signature, supported by both perturbative and non-perturbative analyses.

Findings

Spontaneous breaking of C, P, T symmetries in small-volume QCD.

Existence of persistent baryonic currents as a signature.

Analytical and lattice confirmation of the currents.

Abstract

In a compact space with non-trivial cycles, for sufficiently small values of the compact dimensions, charge conjugation (C), spatial reflection (P) and time reversal (T) are spontaneously broken in QCD. The order parameter for the symmetry breaking is the trace of the Wilson line wrapping around the compact dimension, which acquires an imaginary part in the broken phase. We show that a physical signature for the symmetry breaking is a persistent baryonic current wrapping in the compact directions. The existence of such a current is derived analytically at first order in perturbation theory and confirmed in the non-perturbative regime by lattice simulations.