## Abstract

We present a lattice calculation of the electromagnetic (EM) effects on the masses of light pseudoscalar mesons. The simulations employ 2+1 dynamical flavors of asqtad QCD quarks, and quenched photons. Lattice spacings vary from ≈0.12 fm to ≈0.045 fm. We compute the quantity ε, which parameterizes the corrections to Dashen’s theorem for the K^{+}–K^{0} EM mass splitting, as well as ε_{K}0, which parameterizes the EM contribution to the mass of the K^{0} itself. An extension of the nonperturbative EM renormalization scheme introduced by the BMW group is used in separating EM effects from isospin-violating quark mass effects. We correct for leading finite-volume effects in our realization of lattice electrodynamics in chiral perturbation theory, and remaining finite-volume errors are relatively small. While electroquenched effects are under control for ε, they are estimated only qualitatively for ε_{K}0, and constitute one of the largest sources of uncertainty for that quantity. We find ε = 0.78(1)_{stat}(^{+}_{−}_{11}^{8})_{syst} and ε_{K}0 = 0.035(3)_{stat}(20)_{syst}. We then use these results on 2+1+1 flavor pure QCD highly improved staggered quark (HISQ) ensembles and find m_{u}/m_{d} = 0.4529(48)_{stat}(^{+150}_{−}_{67})_{syst}.

Original language | English (US) |
---|---|

Journal | Unknown Journal |

State | Published - Jul 15 2018 |

## ASJC Scopus subject areas

- General