Leading isospin-breaking corrections to meson masses on the lattice

We present a study of the isospin-breaking (IB) corrections to pseudoscalar (PS) meson masses using the gauge configurations produced by the ETM Collaboration with Nf = 2+1+1 dynamical quarks at three lattice spacings varying from 0.089 to 0.062 fm. Our method is based on a combined expansion of the path integral in powers of the small parameters m d-m u/ΛQCD and αem, where m f is the renormalized quark mass and αem the renormalized fine structure constant. We obtain results for the pion, kaon and Dmeson mass splitting; for the Dashen's theorem violation parameters ∈ γ(MM, 2 GeV), ∈ π 0 ∈ K 0(MS, 2 GeV) for the light quark masses m d-m uMS̄,2GeV,m u/m dMS̄,2GeV; for the flavour symmetry breaking parameters R(MS, 2 GeV) and Q(MS, 2 GeV) and for the strong IB effects on the kaon decay constants. © The Authors, published by EDP Sciences, 2018.