Bounds on Vacuum-Orthogonal Lorentz and CPT Violation from Radiative Corrections

Certain forms of Lorentz violation in the photon sector are difficult to bound directly, since they are "vacuum orthogonal," meaning they do not change the solutions of the equations of motion in vacuum. However, these very same terms have a unique tendency to contribute large radiative corrections to effects in other sectors. Making use of this, we set bounds on four previously unconstrained $d=5$ photon operators at the $10^{-25}$-$10^{-31}$ GeV$^{-1}$ levels.