Vector meson mass in the chiral symmetry restored vacuum

TL;DR

This paper investigates the mass of vector mesons in a vacuum where chiral symmetry is restored, revealing that chiral symmetry breaking contributes only marginally to the meson mass.

Contribution

It introduces a method to separate chiral symmetric and breaking parts of four-quark operators in meson sum rules, providing new insights into meson mass origins.

Findings

Chiral symmetric part of vector meson mass is between 550-600 MeV.

Chiral symmetry breaking accounts for a small fraction of the meson mass.

Chiral symmetry breaking explains the mass difference between chiral partners.

Abstract

We calculate the mass of the vector meson in the chiral symmetry restored vacuum. This is accomplished by separating the four quark operators appearing in the vector and axial vector meson sum rules into chiral symmetric and symmetry breaking parts depending on the contribution of the fermion zero modes. We then identify each part from the fit to the vector and axial vector meson masses. By taking the chiral symmetry breaking part to be zero while keeping the symmetric operator to the vacuum value, we find that the chiral symmetric part of the vector and axial vector meson mass to be between 550 and 600 MeV. This demonstrates that chiral symmetry breaking, while responsible for the mass difference between chiral partner, accounts only for a small fraction of the symmetric part of the mass.