# Isospin breaking in 2+1 flavor QCD+QED

## TL;DR

This paper investigates isospin breaking effects in 2+1 flavor QCD+QED by combining lattice simulations to determine meson mass splittings, low energy constants, and quark masses, including systematic uncertainties.

## Contribution

It introduces a method to extract QED low energy constants and quark masses in 2+1 flavor QCD+QED using lattice simulations with domain wall fermions and quenched QED configurations.

## Key findings

- Determined QED low energy constants up to next-to-leading order.
- Extracted non-degenerate u, d, s quark masses.
- Discussed systematic uncertainties from chiral extrapolations.

## Abstract

The mass splittings in the pseudoscalar mesons are studied by combining 2+1 flavor domain wall fermion gauge configurations, generated by the RBC/UKQCD collaborations, and quenched, non-compact, lattice QED configurations. We extract the QED low energy constants in SU(3) partially quenched chiral perturbation theory, up to next-to-leading order, and determine the non-degenerate u, d and s quark masses. Systematic uncertainties due to chiral extrapolations are discussed. The chiral symmetry breaking of domain wall fermions on the lattice and its effect in partially quenched chiral perturbation theory, including QED effects, is also investigated.