Search for R-Parity Violating Decays of Scalar Fermions at LEP

TL;DR

This paper reports a search for R-parity violating decays of scalar fermions at LEP, setting limits on production cross-sections and particle masses, with no significant deviations from the Standard Model observed.

Contribution

First comprehensive search for R-parity violating decays of scalar fermions at LEP, establishing new constraints on supersymmetric particle masses and production cross-sections.

Findings

No significant excess observed over Standard Model expectations.

Limits set on scalar fermion production cross-sections.

Constraints on supersymmetric particle masses within R-parity violating models.

Abstract

A search for pair-produced scalar fermions under the assumption that R-parity is not conserved has been performed using data collected with the OPAL detector at LEP. The data samples analysed correspond to an integrated luminosity of about 610 pb-1 collected at centre-of-mass energies of sqrt(s) 189-209 GeV. An important consequence of R-parity violation is that the lightest supersymmetric particle is expected to be unstable. Searches of R-parity violating decays of charged sleptons, sneutrinos and squarks have been performed under the assumptions that the lightest supersymmetric particle decays promptly and that only one of the R-parity violating couplings is dominant for each of the decay modes considered. Such processes would yield final states consisting of leptons, jets, or both with or without missing energy. No significant single-like excess of events has been observed with respect to the Standard Model expectations. Limits on the production cross- section of scalar fermions in R-parity violating scenarios are obtained. Constraints on the supersymmetric particle masses are also presented in an R-parity violating framework analogous to the Constrained Minimal Supersymmetric Standard Model.