Search for Scalar Leptons and Scalar Quarks at LEP.pdfVIP

EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH CERN-EP/2003-059 July 31, 2003 Search for Scalar Leptons and Scalar Quarks at LEP 3 0 0 2 t c O The L3 collaboration 5 1 v 7 0 0 0 1 3 Abstract 0 / x Scalar partners of quarks and leptons, predicted in supersymmetric models, are e - searched for in e+e− collisions at centre-of-mass energies between 192 GeV and 209 p e GeV at LEP. No evidence for any such particle is found in a data sample of 450 h pb−1. Upper limits on their production cross sections are set and lower limits on : v their masses are derived in the framework of the Minimal Supersymmetric Standard i X Model. r a Submitted to Phys. Lett. B 1 Introduction The Minimal Supersymmetric extension of the Standard Model (MSSM) [1, 2] postulates a ˜ scalar partner, fL,R , for each weak eigenstate of Standard Model (SM) fermions fL,R . Generally, ˜ ˜ the left, fL , and right, fR , eigenstates mix to form mass eigenstates. This mixing is an unitary ˜ ˜ transformation of the fR and fL states, parameterised by a mixing angle, θLR . Since the off- diagonal elements of the sfermion mass matrix are proportional to the SM partner mass, the mixing is expected to be relevant only for scalar fermions of the third family: the scalar top, ˜ ˜ t , the scalar bottom, b , and the scalar tau, τ˜ . The lightest scalar quarks are denoted L,R L,R