Restoration of chiral symmetry in excited hadrons

TL;DR

This paper reviews how chiral symmetry, broken in low-lying hadrons, is restored in high-lying excited hadrons, revealing chiral multiplet structures and their relation to string models.

Contribution

It provides a comprehensive classification of meson and baryon chiral multiplets and discusses the connection between chiral symmetry restoration and string models of hadrons.

Findings

Chiral symmetry is restored in high-lying hadrons.

Chiral multiplet structures persist in excited hadron spectra.

A link between chiral symmetry restoration and string models is proposed.

Abstract

Physics of the low-lying and high-lying hadrons in the light flavor sector is reviewed. While the low-lying hadrons are strongly affected by the spontaneous breaking of chiral symmetry, in the high-lying hadrons the chiral symmetry is restored. A manifestation of the chiral symmetry restoration in excited hadrons is a persistence of the chiral multiplet structure in both baryon and meson spectra. Meson and baryon chiral multiplets are classified. A relation between the chiral symmetry restoration and the string picture of excited hadrons is discussed.