E. Shintani, S. Aoki, S. Hashimoto, T. Onogi, N. Yamada. Two-photon decay of pi^0 from two-flavor lattice Qcd

Natural Sciences / Physics / Particle physics

Submitted on: Sep 20, 2012, 17:35:42

Description: We study the correction to the radiative $pi^0$ decay width due to finite light quark mass. Using lattice QCD with the overlap fermion formulation, we calculate the three-point function of the form $$ in the (Euclidean) momentum space, which corresponds to the $pi^0rightarrow gamma^*gamma^*$ amplitude. To fit the lattice data, we use two different modifications of vector meson dominance (VMD) ansatz. One is a combined form of VMD with the next-to-leading order (NLO) chiral perturbation theory (ChPT), and the other is a resummed form of pion-loop diagrams. We extract one of the low energy constants in NLO ChPT, and estimate $pi^0rightarrow gammagamma$ decay width including finite mass correction. *** Journal reference: PoS(Lattice 2010)159 ***