Chiral and U(1)_A restorations high in the hadron spectrum and the semiclassical approximation

Abstract

In quantum systems with large $n$ (radial quantum number) or large angular momentum the semiclassical (WKB) approximation is valid. A physical content of the semiclassical approximation is that the quantum fluctuations effects are suppressed and vanish asymptotically. The chiral as well as $U(1)_A$ breakings in QCD is a result of quantum fluctuations. Hence these breakings must be absent (suppressed) high in the spectrum and the spectrum of high-lying hadrons must exhibit symmetries of the classical QCD Lagrangian.