ω Meson from Lattice QCD.

Many excited states in the hadron spectrum have large branching ratios to three-hadron final states. Understanding such particles from first principles QCD requires input from lattice QCD with one-, two-, and three-meson interpolators as well as a reliable three-body formalism relating finite-volume spectra at unphysical pion mass values to the scattering amplitudes at the physical point. In this work, we provide the first-ever calculation of the resonance parameters of the ω meson from lattice QCD, including an update of the formalism through matching to effective field theories. The main result of this pioneering study, the pole position of the ω meson at sqrt[s_{ω}]=(778.0(11.2)-i3.0(5))  MeV, agrees reasonably well with experiment. In addition we provide an estimate of the ω-ρ mass difference as 29(15) MeV.