Extraction of isoscalar ππ phase shifts from lattice QCD

Here, we conduct a two-flavor (N _f = 2) lattice QCD calculation of the elastic phase shifts for pion-pion scattering in the scalar, isoscalar channel (the σ-meson). The calculation is performed for two quark masses corresponding to pion masses of 315 and 227 MeV. The σ-meson parameters are extracted using various parametrizations of the scattering amplitude. The results obtained from a chiral unitary parametrization are extrapolated to the physical point and read M _σ = (440 ⁺¹⁰ _–16(50) – i240(20)(25)) MeV, where the uncertainties in the parentheses denote the stochastic and systematic ones. The behavior of the σ-meson parameters with increasing pion mass is discussed as well.