We argue that light quark loops produce a paramagnetic suppression of infrared-sensitive order parameters such as < q-bar q >, as the number N-f of light fermions increases. The possibly strong dependence of < q-bar q > on N-f is related to the observed Zweig rule violation in the scalar channel. Presuming the existence of a chiral phase transition for not too large N-f, we discuss the phenomenological possibilities of separately determining the two-flavour and three-flavour condensates and the quark mass ratio r = 2m(s)=(m(u)+m(d)). The issue is closely related to the interpretation of new forthcoming precise pi pi data at low energy.
Paramagnetic effect of light quark loops on chiral symmetry breaking
GIRLANDA, Luca;
2000-01-01
Abstract
We argue that light quark loops produce a paramagnetic suppression of infrared-sensitive order parameters such as < q-bar q >, as the number N-f of light fermions increases. The possibly strong dependence of < q-bar q > on N-f is related to the observed Zweig rule violation in the scalar channel. Presuming the existence of a chiral phase transition for not too large N-f, we discuss the phenomenological possibilities of separately determining the two-flavour and three-flavour condensates and the quark mass ratio r = 2m(s)=(m(u)+m(d)). The issue is closely related to the interpretation of new forthcoming precise pi pi data at low energy.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
