Structure-dependent electromagnetic finite-volume effects through order 1/L³

We consider electromagnetic finite-volume effects through order 1/L³ in different formulations of QED, where L is the periodicity of the spatial volume.An inherent problem at this order is the appearance of structure-dependent quantities related to form factors and the analytical structure of the correlation functions.The non-local constraint of the widely used QED_L regularization gives rise to structure-dependent effects that are difficult to evaluate analytically and can act as a precision bottleneck in lattice calculations.For this reason, we consider general volume expansions relevant for the mass spectrum as well as leptonic decay rates in QED_C, QED_L and QED^IR_L , the latter being a class of non-local formulations generalising QED_L.One choice within this class is QED_r, first introduced at this conference, and we show that the effects of non-locality for the 1/L³ term in the expansion can be removed.We observe that there are still 1/L³ contributions unrelated to the (non-)locality of the studied QED formulations, but rather to collinear singularities in the physical amplitudes.