Paramagnetic effect of light quark loops on Chiral Symmetry Breaking

TL;DR

This paper discusses how light quark loops influence chiral symmetry breaking, suggesting a paramagnetic suppression of order parameters and exploring implications for the quark condensates and phase transition behavior.

Contribution

It introduces the concept that light quark loops cause a paramagnetic suppression of chiral order parameters and examines the implications for the phase transition and quark condensate measurements.

Findings

Light quark loops suppress <qq> as N_f increases

Potential strong dependence of <qq> on N_f observed

Discussion of phenomenological determination of condensates and quark mass ratios

Abstract

We argue that light quark loops produce a paramagnetic suppression of infrared-sensitive order parameters such as <qq>, as the number N_f of light fermions increases. The possibly strong dependence of <qq> on N_f is related to the observed Zweig rule violation in the scalar channel. Presuming the existence of a chiral phase transition for not too large N_f, we discuss the phenomenological possibilities of separately determining the two-flavour and three-flavour condensates and the quark mass ratio r=2m_s/(m_u+m_d). The issue is closely related to the interpretation of new forthcoming precise pi-pi data at low energy.