Light scalar susceptibilities and the pi(0)-eta mixing

Abstract

We have performed a thermal analysis of the light scalar susceptibilities in the context of SU(3)-Chiral Perturbation Theory to one loop taking into account the QCD source of isospin breaking (IB), i.e corrections coming from m(u) not equal m(d). We find that the value of the connected scalar susceptibility in the infrared regime and below the critical temperature is entirely dominated by the pi(0) - eta mixing, which leads to model-independent O(epsilon(0)) corrections, where epsilon similar to m(d) - m(u), in the combination chi(uu) - chi(ud) of flavour breaking susceptibilities.