ar X iv : h ep - p h / 96 11 39 5 v 1 2 2 N ov 1 99 6 Global Fits of the MSSM and SM to Electroweak Precision Data
نویسنده
چکیده
The Minimal supersymmetric extension of the Standard Model (MSSM) with light stops, charginos or pseu-doscalar Higgs bosons has been suggested as an explanation of the too high value of the branching ratio of the Z 0 boson into b quarks (R b anomaly). A program including all radiative corrections to the MSSM at the same level as the radiative corrections to the SM has been developed and used to perform global fits to all electroweak data from LEP, SLC and the Tevatron. Recent updates onelectroweak data, presented at this conference, reduce the R b anomaly from a 3.2σ to a 1.8σ effect. In addition, the b → sγ decay is 30% below the SM prediction. In the MSSM light stops and light charginos increase R b and decrease the b → sγ rate, so both observations can be brought into agreement with the MSSM for the same region of parameter space. However, the resulting χ 2 value for the MSSM fits is only marginally lower. In addition, the splitting in the stop sector has to be unnaturally high, so it remains to be seen if these effects are real or due to a fluctuation.
منابع مشابه
ar X iv : h ep - p h / 96 11 45 1 v 1 2 7 N ov 1 99 6 ELECTROWEAK INTERACTIONS
The status of the SM is measured by a comparison of precision data with precision calculations. The data are summarized by Alain Blondel 1 and the precision calculations have been reviewed in the parallel session . Not only complete one-loop calculations of the electroweak observables are available (already for several years) but also a steady progress is being made in including the dominant hi...
متن کاملar X iv : h ep - p h / 95 05 30 4 v 1 1 5 M ay 1 99 5 PRECISION TESTS OF THE MSSM . ∗ †
We present the results of a first global fit to the electroweak observables in the MSSM. The best fit selects either very low or very large values of tanβ and, correspondingly, chargino (higgsino–like) and stop or the CP−odd Higgs boson are within the reach of LEP 2. Moreover, the best fit gives αs(MZ) = 0.118 +0.005 −0.010, which is lower than the one obtained from the SM fits. The overall fit...
متن کاملar X iv : h ep - p h / 02 11 06 5 v 1 5 N ov 2 00 2 Recent Developments in Precision Electroweak Physics ∗
Developments in precision electroweak physics in the two years since the symposium are briefly summarized.
متن کاملar X iv : h ep - p h / 96 11 39 4 v 1 2 2 N ov 1 99 6 The Constrained MSSM
Within the Constrained Minimal Supersymmetric Model (CMSSM) it is possible to predict the low energy gauge couplings and masses of the 3 generation particles from a few supergravity inspired parameters at the GUT scale. Moreover, the CMSSM predicts electroweak symmetry breaking due to large radiative corrections from the Yukawa couplings, thus relating the Z 0 boson mass to the top quark mass v...
متن کامل