Electromagnetic contribution to $\Sigma$-$\Lambda$ mixing using lattice QCD+QED

Abstract

Mixing in the $\Sigma^0$-$\Lambda^0$ system is a direct consequence of broken isospin symmetry and is a measure of both isospin-symmetry breaking as well as general SU(3)-flavour symmetry breaking. In this work we present a new scheme for calculating the extent of $\Sigma^0$-$\Lambda^0$ mixing using simulations in lattice QCD+QED and perform several extrapolations that compare well with various past determinations. Our scheme allows us to easily contrast the QCD-only mixing case with the full QCD+QED mixing.