Brief Report on the Extended Linear Sigma Model

TL;DR

This paper introduces an extended Linear Sigma Model that incorporates various mesons, glueballs, and baryons, successfully describing low-energy QCD phenomena, resonance structures, and phase transitions at finite temperature and density.

Contribution

The paper develops a comprehensive chiral effective model including multiple particle types, providing new insights into resonance structures and phase behavior in low-energy QCD.

Findings

f_0(1500) is a predominantly glueball state

f_0(1370) is likely the chiral partner of the pion

N(1650) is favored as the chiral partner of the nucleon (N(939))

Abstract

We present a chiral effective model which exhibits all the known symmetry features of the QCD Lagrangian. The extended Linear Sigma Model (eLSM) includes (pseudo-)scalar and (axial-) vector mesons, glueballs, and baryons. It has proven to be a useful tool to understand the nature of the low-energy resonances. It can be used to describe the masses and decay widths of the known low-energy mesons and to disentangle the complicated picture of resonances in the low-energy range. We can answer some of the open questions in the low-energy region, e.g. the resonance (f_0(1500)) is a predominantly glueball state and the resonance (f_0(1370)) is most likely the chiral partner of the pion. We could also find that the resonance (N(1650)) is favoured as the chiral partner of the nucleon (N(939)). In addition the temperature dependence of the chiral condensate and the glueball condensate can be used to study the phase diagram at nonzero temperatures and densities. At nonzero density we achieve nuclear matter saturation.