Two-Photon Decay of the Neutral Pion in Lattice QCD

Xu Feng, Sinya Aoki, Hidenori Fukaya, Shoji Hashimoto, Takashi Kaneko, Jun-ichi Noaki, Eigo Shintani
2012 Physical Review Letters  
We perform non-perturbative calculation of the \pi^0 to {\gamma}{\gamma} transition form factor and the associated decay width using lattice QCD. The amplitude for two-photon final state, which is not an eigenstate of QCD, is extracted through an Euclidean time integral of the relevant three-point function. We utilize the all-to-all quark propagator technique to carry out this integral as well as to include the disconnected quark diagram contributions. The overlap fermion formulation is
more » ... mulation is employed on the lattice to ensure exact chiral symmetry on the lattice. After examining various sources of systematic effects except for possible discretization effect, we obtain \Gamma=7.83(31)(49) eV for the pion decay width, where the first error is statistical and the second is our estimate of the systematic error.
doi:10.1103/physrevlett.109.182001 pmid:23215272 fatcat:be37ipy47valhnjezgimbmskjm