LONG-BASE-LINE NEUTRINO OSCILLATION EXPERIMENTS AND CP VIOLATION IN THE LEPTON SECTOR - ART. NO. 033001

We discuss possibilities to investigate the effects of CP (and T) viol ation in the lepton sector in neutrino oscillation experiments. We con sider the effects of CP violation in the framework of two schemes of m ixing of four massive neutrinos that can accommodate the results of al l neutrino oscillation experiments. Using the constraints on the mixin g parameters that follow from the results of short-baseline neutrino o scillation experiments, we derive rather strong upper bounds on the ef fects of CP violation in [GRAPHICS] transitions in long baseline neutr ino oscillation experiments. We show that the effects of CP violation in [GRAPHICS] transitions in long-baseline oscillation experiments can be as large as is allowed by the unitarity of the mixing matrix. The matter effects, which complicate the problem of searching for CP viola tion in long-baseline experiments, are discussed in detail. We conside r the T-odd asymmetries whose measurement could allow to reveal T and CP violation in the lepton sector independently from matter effects. [ S0556-2821(98)02313-3].