Volume Effects for Pion Two-Point Functions in Constant Electric and Magnetic Fields

摘要

We compute finite volume effects relevant for lattice QCD simulations usingbackground fields. Focusing on constant electric and magnetic fields on aperiodic lattice, we determine volume corrections to pion two-point functionsusing chiral perturbation theory. Among such corrections are the finite volumeshifts to the electric and magnetic polarizabilities, which are numericallyshown to be non-negligible. We additionally find that all terms in thesingle-particle effective action can be renormalized by infrared effects. Thisincludes Born couplings to the pion current and total charge-squared, which canbe renormalized due to the nature of gauge invariance on a torus.