A search for squarks of Rp-violating SUSY at HERA

A search for squarks ofR-parity violating supersymmetry is performed inep collisions at HERA using H1 1994e + data. Direct single production of squarks of each generation bye +-quark fusion via a Yukawa coupling λ′ is considered. All possibleR-parity violating decays and gauge decays of the squarks are taken into account. No significant deviation from the Standard Model predictions is found in the various multi-lepton and multi-jet final states studied and exclusion limits are derived. At 95% confidence level, the existence of first generation squarks is excluded for masses up to 240 GeV for coupling values λ′≳√4πα em. The limits obtained are shown to be only weakly dependent on the free parameters of the Minimal Supersymmetric Standard Model. Stop squarks are excluded for masses up to 138 GeV for coupling λ′×cosθ t toe +d pairs ≳0.1×√4πα em, whereθ t is the mass mixing angle. Light stop squarks are furthermore searched for through pair production inγ-gluon fusion processes. No signal is observed and exclusion limits are derived. Masses in the range 9 to 24.4 GeV are excluded at 95% confidence level for λ′×cosθ t>10−4.