Speaker
Description
In this talk, we provide compact analytic expressions for the one- and two-loop pion-pion partial-wave ChPT amplitudes for $J=0,\,1,\, 2$. We use these results to analyze lattice-QCD data of the ππ → ππ P wave obtained at unphysical-high pion masses using the inverse-amplitude method at next-to-leading order and next-to-next-to-leading order. We then extrapolate to the physical pion mass and determine the properties of the ρ meson from its pole in the complex plane. By comparing both orders, we estimate the systematic error associated with the truncation. Finally, we study the pion-mass dependence of the two-pion channel in the hadronic-vacuum-polarization contribution to the anomalous magnetic moment of the muon. These results constrain the dominant isospin-1 part of the isospin-symmetric light-quark contribution and should thus allow one to better control the chiral extrapolation of HVP required for lattice-QCD calculations performed at larger-than-physical pion masses.
