Experimental HEP Seminar

Search for gaugino production in R-parity violating supersymmetry at HERA

Chi-Nhan Nguyen

Hamburg Universität

I will present a search for gaugino production in R-parity violating supersymmetry with the ZEUS detector at HERA. The data set has been recorded in the years 1996-2000 at a centre of mass energy of 300 GeV and 318 GeV and corresponds to an integrated luminosity of 121 pb^-1. Theoretically, neutralinos and charginos are produced via t-channel exchange of a left-handed scalar electron or a scalar neutrino. It is assumed that one Yukawa coupling λ'_1j1, with j=1,2, is dominant at a time, while the contributions from the other Yukawa couplings are negligible. No deviation from the Standard Model was observed and exclusion limits on parameters of the Minimal Supersymmetric Standard Model were obtained. Excluded areas in the (μ,M₂)-plane were derived, which partially extend the corresponding results from LEP. In addition, limits on the masses of left-handed selectrons and the lightest neutralino were derived assuming that ~χ⁰₁ is the lightest supersymmetric particle (LSP) and has a dominant photino component. Selectron masses up to 150 GeV and LSP masses up to 89 GeV were excluded at 95% C.L.