Time reversal symmetry breaking in cuprates induced by the spiral spin order

We propose a new interpretation of the spontaneous time reversal symmetry breaking (TRSB) observed recently in a pseudogap state of cuprate (Kaminsky et al.). It is shown that the TRSB dichroism in ARPES signal may be connected with the local spiral spin structures in system. It may be caused by a spin-orbit interaction and by spin polarization of electrons at various sections of Fermi surface in spiral state. Angular dependence of dichroism signal is studied in schematic KKR approximation. Tests are proposed to check an existence of the local spiral spin structure and to distiguish it from the TRSB state with micro-currents constructed by Varma.