Search for bosonic stop decays in R-parity violating supersymmetry in e^+ p collisions at HERA

TL;DR

This paper searches for scalar top quarks decaying via R-parity violating processes in electron-proton collisions at HERA, setting limits on their mass and couplings with no evidence of their existence found.

Contribution

It presents the first search for bosonic stop decays in R-parity violating supersymmetry at HERA, establishing new mass and coupling limits.

Findings

No evidence for stop production was observed.

Stop quarks with masses up to 275 GeV are excluded at 95% confidence level.

Limits on the Yukawa coupling lambda' were set based on the data.

Abstract

A search for scalar top quarks in R-parity violating supersymmetry is performed in e^+ p collisions at HERA using the H1 detector. The data, taken at sqrt{s}=319 GeV and 301 GeV, correspond to an integrated luminosity of 106 pb^-1. The resonant production of scalar top quarks \tilde{t} in positron quark fusion via an R-parity violating Yukawa coupling lambda' is considered with the subsequent bosonic stop decay \tilde{t} -> \tilde{b} W. The R-parity violating decay of the sbottom quark tilde{b} -> d \bar{nu_e} and leptonic and hadronic W decays are considered. No evidence for stop production is found in the search for bosonic stop decays nor in a search for the direct R-parity violating decay \tilde{t} -> eq. Mass dependent limits on lambda' are obtained in the framework of the Minimal Supersymmetric Standard Model. Stop quarks with masses up to 275 GeV can be excluded at the 95% confidence level for a Yukawa coupling of electromagnetic strength.