BOUNDS ON SUPERSYMMETRY FROM ELECTROWEAK PRECISION ANALYSIS

The Standard Model global fit to precision data is excellent. The Mini mal Supersymmetric Standard Model can also fit the data well, though n ot as well as the Standard Model. At best, supersymmetric contribution s either decouple or only slightly decrease the total chi(2), at the e xpense of decreasing the number of degrees of freedom. In general, reg ions of parameter space with large supersymmetric corrections from lig ht superpartners are associated with poor fits to the data. We contras t results of a simple (oblique) approximation with full one-loop resul ts, and show that for the most important observables the non-oblique c orrections can be larger than the oblique corrections, and must be tak en into account. We elucidate the regions of parameter space in both g ravity- and gauge-mediated models which are excluded. Significant regi ons of parameter space are excluded, especially with positive supersym metric mass parameter mu. We give a complete listing of the bounds on all the superpartner and Higgs boson masses. For either sign of mu, an d for all supersymmetric models considered, we set a lower limit on th e mass of the lightest CP-even Higgs scaler, m(h) greater than or equa l to 78 GeV. Also, the first and second generation squark masses are c onstrained to be above 280 (325) GeV in the supergravity (gauge-mediat ed) model. (C) 1998 Elsevier Science B.V.