Systematic errors in partially-quenched QCD plus QED lattice simulations
  At the precision reached in current lattice QCD calculations, electromagnetic effects are becoming numerically relevant. Here, electromagnetic effects are included by superimposing $\mathrm{U}(1)$ degrees of freedom on $N_f = 2+1$ QCD configurations from the Budapest-Marseille-Wuppertal Collaboration. We present preliminary results for the electromagnetic corrections to light pseudoscalars mesons masses and discuss some of the associated systematic errors. 
Antonin Portelli, Stephan D\"urr, Zolt\'an Fodor, Julien Frison,   Christian Hoelbling, Sandor D. Katz, Stefan Krieg, Thorst...
hep-lat