B-quark mediated neutrinoless μ^--e^- conversion in presence of R-parity violation

We found that in supersymmetric models with R-parity non-conservation the b-quarks may appreciably contribute to exotic neutrinoless muon-electron conversion in nuclei via the triangle diagram with two external gluons. This allowed us to extract previously overlooked constraints on the third generation trilinear R-parity violating parameters significantly more stringent than those existing in the literature.