Chiral condensates in massless QCD and the U(1)A boson mass

Abstract

The U(1)A boson mass is calculated through the phenomenological characteristics of the vacuum related to spontaneous breaking of chiral symmetry in QCD. The mass is determined by the mixed quark-gluon condensate q G q that emerges in an appropriate correlation function due to triangle anomaly. For three flavor QCD in chiral limit we find the numerical value for the U(1)A boson mass to be M0=310 50~ MeV.