R-parity Violating Contribution to Neutron EDM at One-loop Order

We present the full result for the down squark mass-squared matrix in the complete theory of supersymmetry without R-parity where all kind of R-parity violating terms are admitted without bias. An optimal parametrization, the single-VEV parametrization, is used. The major result is a new contribution to $LR$ squark mixing, involving both bilinear and trilinear R-parity violating couplings. Among other things, the latter leads to neutron electric dipole moment at one-loop level. Similiar mechanism leading to electron electric dipole moment at the same level. We present here a short report on major features of neutron electric dipole moment from supersymmetry without R-parity and give the interesting constraints obtained.