A search for selectrons and squarks at HERA

Abstract Data from electron-proton collisions at a center-of- massenergy of 300 GeV are used for a search for selectrons and squarks within the framework of the minimal supersymmetric model. The decays of selectrons and squarks into the lightest supersymmetric particlelead to final states with an electron and hadrons accompanied by large missing energyand transverse momentum. No signal is found and new bounds on the existence of these particles are derived. At 95% confidence level the excluded region extends to 65 GeV for selectron and squark masses, and to 40 GeV for the mass of the lightest supersymmetric particle.