THE SUPERSYMMETRIC CP PROBLEM IN ORBIFOLD COMPACTIFICATIONS

The possibility of spontaneous breaking of CP symmetry by the expectat ion values of orbifold moduli is investigated with particular referenc e to CP-violating phases in soft supersymmetry-breaking terms. The eff ect of different mechanisms for stabilizing the dilation and the form of the non-perturbative superpotential on the existence and size of th ese phases is studied. Models with modular symmetries which are subgro ups of PSL(2, Z), as well as the single overall modulus T case with th e full PSL(2, Z) modular symmetry, are discussed. Non-perturbative sup erpotentials involving the absolute modular invariant j(T), such as ma y arise from F-theory compactifications, are considered. (C) 1998 Else vier Science B.V.