Exotic muon-electron conversion in nuclei and R-parity violating supersymmetry

TL;DR

This paper investigates muon-electron conversion in nuclei within R-parity violating supersymmetry, providing new limits on model parameters based on experimental data and nuclear structure considerations.

Contribution

It offers a comprehensive analysis of R-parity violating effects on muon-electron conversion, including nucleon structure and experimental constraints, which is a novel approach.

Findings

Strange quark sea contribution is comparable to valence quarks.

New stringent limits on R-parity violating parameters from experimental data.

Nuclear structure effects are crucial in the conversion process.

Abstract

The flavor violating $\mu^--e^-$ conversion in nuclei is studied within the minimal supersymmetric standard model. We focus on the R-parity violating contributions at tree level including the trilinear and the bilinear terms in the superpotential as well as in the soft supersymmetry breaking sector. The nucleon and nuclear structure have consistently been taken into account in the expression of the $\mu^--e^-$ conversion branching ratio constructed in this framework. We have found that the contribution of the strange quark sea of the nucleon is comparable with that of the valence quarks. From the available experimental data on $\mu^--e^-$ conversion in $^{48}$Ti and $^{208}$Pb and the expected sensitivity of the MECO experiment for $^{27}$Al we have extracted new stringent limits on the R-parity violating parameters.