Speaker
Kazuya Mameda
(The University of Tokyo)
Description
We study the quark mass dependence of the QCD $\theta$-vacua in the framework
using the Veneziano－Di-Vecchia Lagrangian, which reproduces
topological properties of QCD on the two boundaries related to the
quark mass, i.e. the chiral limit and the quenched limit. Then we find
that for any quark mass, there are the continuous structures of the
vacua, including the first order phase transitions at $\theta = \pi$. We also
investigate general mechanisms of the QCD $\theta$-vacua dependent on the quark
mass; how the vacuum is determined in QCD and what role then the quark
mass plays for the determination. To do this we reveal the quark mass
dependence of the chiral condensate. Additionaly we discuss what is the differece of the phase transition at $\theta =\pi$ in the chiral and quenched limit from the point of view of the $\theta$-vacuum struture dependent on the quark mass.
Primary author
Kazuya Mameda
(The University of Tokyo)
