New constraints on R-parity violation from μ-e conversion in nuclei

Abstract

We derive new constraints on the products of explicitly R-parity violating couplings $λ$ and $λ'$ in MSSM from searches for μ-e conversion in nuclei. We concentrate on the loop induced photonic coherent conversion mode. For the combinations $|λλ|$ which in μ-e conversion can be probed only at loop level our constraints are in many cases more stringent than the previous ones due to the enhancement of the process by large $\ln(m^2_f/m^2_{\tilde f}).$ For the combinations of $|λ'λ'|$ the tree-level μ-e conversion constraints are usually more restrictive than the loop ones except for two cases which involve the third generation. With the expected improvements in the experimental sensitivity, the μ-e conversion will become the most stringent test for all the involved combinations of couplings.

15 pages, one figure included, needs elsart.sty