1994/11/01 by Jens Erler, Paul Langacker · 9 citations
Physics and Astronomy · #Black Holes and Theoretical Physics #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.1103/physrevd.52.441
published as Phys.Rev.D52:441-450,1995 · 23 pages REVTeX + 3 figures (not included); complete postscript file available via anonymous ftp ftp://dept.physics.upenn.edu/pub/Langacker/statussmprep.ps
arxiv created 1994/11/01 · openalex publication_date 1995/07/01 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We discuss the consequences of recent experimental results from CDF, SLC, CERN LEP, and elsewhere for the standard model and for new physics, A global fit to all indirect precision data yields mt=175\ifmmode±\else\textpm\fi11_\mathrm\ensuremath-19+17 GeV, sin2\ensuremathθ^MS\ifmmode\else\textasciimacron\fi=0.2317(3)(2), and \mathrm\ensuremathαs=0.127(5)(2), where the central values are for MH=300 GeV and the second uncertainties are for MH\ensuremath→1000 GeV (+) and 60 GeV (-). The mt value is in remarkable agreement with the value mt value is in remarkable agreement with the value mt=174\ifmmode±\else\textpm\fi16 GeV suggested by the CDF candidate events. There is a slight preference for a light Higgs boson with MH730 (880) GeV at 95% C.L. if the CDF mt value is (not) included. The sensitivity is, however, due almost entirely to the anomalously large observed values for the Z\ensuremath→bb\ifmmode\else\textasciimacron\fi width and left-right asymmetry. The value of \mathrm\ensuremathαs (from the line shape) is clean theoretically assuming the standard model, but is sensitive to the presence of new physics contributions to the Z\ensuremath→bb\ifmmode\else\textasciimacron\fi vertex. Allowing a vertex correction \mathrm\ensuremathδbbnew one obtains the significantly lower value \mathrm\ensuremathαs=0.111\ifmmode±\else\textpm\fi0.009, in better agreement with low energy determinations, and \mathrm\ensuremathδbbnew=0.023\ifmmode±\else\textpm\fi0.011.There is now enough data to perform more general fits to parameters describing new physics effects and to separate these from mt and MH. Allowing the parameter \mathrm\ensuremathρ0, which describes sources of SU(2) breaking beyond the standard model, to be free one finds \mathrm\ensuremathρ0=1.0012\ifmmode±\else\textpm\fi0.0017\ifmmode±\else\textpm\fi0.0017, remarkably close to unity. One can also separate the new physics contributions to the oblique parameters Snew, Tnew, and Unew, which all take values consistent with zero. The effects of supersymmetry on the determination of the standard model parameters are discussed.