Chiral symmetry restoration and the linear form of baryonic Regge trajectories

Abstract

It has recently been suggested that the observed structure of parity doublets, seen in the spectrum of highly excited baryons, may be due to the effective restoration of chiral symmetry for these states. This chiral symmetry restoration high in the spectrum is consistent with the concept of quark-hadron duality. Moreover, if QCD dynamics implies the linear Regge trajectories for highly excited baryons, then the MacDowell symmetry requires the parity doubling to appear, which shows that linear Regge trajectories and chiral symmetry restoration are well compatible. On the contrary, in the low-energy part of baryon spectrum the parity doublets are absent because of spontaneous chiral symmetry breaking. Then the MacDowell symmetry implies that there should be no linear parallel Regge trajectories. Experimental data shows that this is indeed the case.