CP symmetry and lattice chiral gauge theories

Abstract

The CP symmetry is a fundamental discrete symmetry in chiral gauge theory. Therefore this symmetry is expected to be kept also on the lattice. However, it has been pointed out by Hasenfratz that the chiral fermion action in Luscher's formulation of lattice chiral gauge theory is not invariant under CP transformation. In this thesis, we first review the method of constructing chiral gauge theory on the lattice. Then we generalize the analysis of Hasenfratz and show that CP symmetry is not manifestly implemented for the local and doubler-free Ginsparg-Wilson operator under rather general assumptions for chiral projection operators. We next calculate the fermion generating functional and precisely identify where the effects of this CP breaking appear in this formulation. The basics of lattice gauge theory are briefly summarized in Appendix.A.