Symmetry Considerations for detection of Time-reversal Breaking Phases in Cuprates by X-ray Diffraction and Absorption

Time-reversal and inversion breaking in the pseudogap region of the cuprate compounds have been proposed and detected by means of ARPES in the compound Bi-2212. Given the implication of the effect in the physics of the cuprate superconductors, it is important to check the conclusions through quite independent experimental techniques. We show how time-reversal and inversion breaking may be revealed in the Cuprates through resonant x-ray scattering and through non-reciprocal or magnetochiral dichroism.