Preliminary lattice QCD calculation of the σ meson decay width

A bstract We report an exploratory lattice QCD investigation of the σ meson decay width though the s -wave scattering phase shift for isospin I = 0 pion-pion ( ππ ) system. Rummukainen-Gottlieb formula is used to estimate the scattering phase for the two-pion system in the moving frame, which demonstrate the presence of a resonance around σ meson. Using the effective range formula we extract the effective σ → ππ coupling constant as g σππ = 2 . 69(44) GeV, which is consistent with the theoretical predictions. The estimated decay width is about 236 ± 49 MeV. These simulations are carried out on a 16 3 × 48 MILC gauge configuration with the N f = 2 + 1 flavor of the “Asqtad” improved staggered dynamical sea quarks at m π /m σ ≈ 0 . 414 and the lattice spacing a ≈ 0 . 15 fm.