  Recently, it was suggested that there was some sort of breakdown of quantum
field theory in the presence of boundaries, manifesting itself as a torque
anomaly. In particular, Fulling et al. used the finite energy-momentum-stress
tensor in the presence of a perfectly conducting wedge, calculated many years
ago by Deutsch and Candelas, to compute the torque on one of the wedge
boundaries, where the latter was cutoff by integrating the torque density down
to minimum lower radius greater than zero. They observed that that torque is
not equal to the negative derivative of the energy obtained by integrating the
energy density down to the same minimum radius. This motivated a calculation of
the torque and energy in an annular sector obtained by the intersection of the
wedge with two coaxial cylinders. In a previous paper we showed that for the
analogous scalar case, which also exhibited a torque anomaly in the absence of
the cylindrical boundaries, the point-split regulated torque and energy indeed
exhibit an anomaly, unless the point-splitting is along the axis direction. In
any case, because of curvature divergences, no unambiguous finite part can be
extracted. However, that ambiguity is linear in the wedge angle; if the
condition is imposed that the linear term be removed, the resulting torque and
energy is finite, and exhibits no anomaly. In this paper, we demonstrate the
same phenomenon takes place for the electromagnetic field, so there is no
torque anomaly present here either. This is a nontrivial generalization, since
the anomaly found by Fulling et al. is linear for the Dirichlet scalar case,
but nonlinear for the conducting electromagnetic case.

High Energy Physics - Theory;Quantum Physics