Implications of the Partial Width Z->bb for Supersymmetry Searches and Model-Building

Abstract

Assuming that the actual values of the top quark mass at FNAL and of the ratio of partial widths Z->bb/Z->hadrons at LEP are within their current one-sigma reported ranges, we present a No-Lose Theorem for superpartner searches at LEP II and an upgraded Tevatron. We impose only two theoretical assumptions: the Lagrangian is that of the Minimal Supersymmetric Standard Model with arbitrary soft-breaking terms, and all couplings remain perturbative up to scales of order 10^16 GeV; there are no assumptions about the soft SUSY breaking parameters, proton decay, cosmology, etc. In particular, if the LEP and FNAL values hold up and supersymmetry is responsible for the discrepancy with the SM prediction of the partial width of Z->bb, then we must have charginos and/or top squarks observable at the upgraded machines. Furthermore, little deviation from the SM is predicted within "super-unified" SUSY. Finally, it appears to be extremely difficult to find any unified MSSM model, regardless of the form of soft SUSY breaking, that can explain the partial width for large tan(beta); in particular, no model with top-bottom-tau Yukawa coupling unification appears to be consistent with the experiments.

15 pages, University of Michigan preprint UM-TH-94-23. LaTeX file with 4 uuencoded figures sent separately. Compressed PS file (114Kb) available by anonymous FTP from 141.211.96.66 in /pub/preprints/UM-TH-94-23.ps.Z

References in corpus (2)

• Study of Constrained Minimal Supersymmetry
• Supersymmetric QCD corrections to quark pair production in e+ e- annihilation

Cited by in corpus (71)

• Precision Corrections in the Minimal Supersymmetric Standard Model
• Opening the Window for Electroweak Baryogenesis
• Muon anomalous magnetic dipole moment in supersymmetric theories
• Leptophobic U(1)'s and the R_b - R_c Crisis
• Searching for supersymmetry in rare B decays
• Search for supersymmetry with a light gravitino at the Fermilab Tevatron and CERN LEP colliders
• The strong coupling, unification, and recent data
• Leading QCD Corrections to Scalar Quark Contributions to Electroweak Precision Observables
• Renormalization of the Minimal Supersymmetric Standard Model
• Low-energy supersymmetry with D-term contributions to scalar masses
• Supersymmetry versus precision experiments revisited
• Higgs and Supersymmetric Particle Signals at the Infrared Fixed Point of the Top Quark Mass
• Bounds on Supersymmetry from Electroweak Precision Analysis
• Theory, Phenomenology, and Prospects for Detection of Supersymmetric Dark Matter
• A Global Fit of LEP/SLC Data with Light Superpartners
• Mass Degeneracy of the Higgsinos
• Bottom-up approach and supersymmetry breaking
• Sphalerons in the MSSM
• Possible Signals of Constrained Minimal Supersymmetry at a High Luminosity Fermilab Tevatron Collider
• Implications of the reported deviations from the standard model for Z->bb and alpha_s
• Supersymmetric QCD Corrections to the Charged Higgs Boson Decay of the Top Quark
• Low energy supersymmetry with a neutralino LSP and the CDF eeγγ+ missing E_T event
• The Light Higgsino-Gaugino Window
• Global Fits of the SM and MSSM to Electroweak Precision Data
• THE QUANTUM CORRELATION R_b-R_c IN THE MSSM: MORE HINTS OF SUPERSYMMETRY?
• $R_b$ and $R_c$ in the Two Higgs Doublet Model with Flavor Changing Neutral Currents
• Matching the Low and High Energy Determinations of ${\alpha }_s(M_z)$ in the MSSM
• Determination of Fundamental Supersymmetry Parameters from Chargino Production at Lepii
• Precision tests of the MSSM
• CONFRONTING LEFT-RIGHT SYMMETRIC MODELS WITH ELECTROWEAK PRECISION DATA AT THE Z PEAK
• Leptophobic $Z^{\prime }$ in stringy flipped SU(5)
• Reconciling Supersymmetric Grand Unification with ${\alpha }_s(m_Z)\approx 0.11$
• $R_b$ in supersymmetric models
• Enhanced Supersymmetric Corrections to Top-Quark Production at the Tevatron
• Low ${\alpha }_{strong}(M_Z)$, Intermediate Scale SUSY SO(10) GUT and Its Implications
• $SU(2)\otimes SU(2)$ Gauge Extensions of the MSSM Revisited
• Four-Generation Low Energy Supersymmetry with a Light Top Quark
• Higgs Bosons Strongly Coupled to the Top Quark
• Supersymmetry: From the Fermi Scale to the Planck Scale
• Electroweak radiative corrections in Z boson decays
• Supersymmetry and R_b in the light of LEP 1.5
• Electroweak versus high scale finetuning in the 19-parameter SUGRA model
• Effective lagrangian description of top production and decay
• A Consistent model of Electroweak data including $Z\to b\overline{b}$ and $Z\to c\overline{c}$
• The $Z\to b\bar{b}$ Excess and Top Decay
• SUSY Contributions to R_b and Top Quark Decay
• Solutions to the R_b, R_c and alpha_s puzzles by Vector Fermions
• The Effective Weak Mixing Angle in the MSSM
• Searching for a Light Stop at the Tevatron
• Quark Mass Corrections to the Z Boson Decay Rates
• The effect of new physics on R_b = Γ(Z->b bbar) / Γ(Z->hadrons)
• Supersymmetry, Supergravity and R_b revisited in the light of LEP 2
• SUSY effects in $R_b$: revisited under current experimental constraints
• Decoupling or nondecoupling: is that the $R_b$ question?
• $R_b$ -- $R_c$ Crisis and New Physics
• An R-Parity Breaking SUSY Solution to the R_b and ALEPH Anomalies
• $Z\to b\bar{b}$ in $U(1{)}_R$ Symmetric Supersymmetry
• Chargino Production at LEP2 in a Supergravity Model
• Upper Bound on R_b in Two Higgs Doublet Model from Lepton Universality
• ${\alpha }_s(M_Z^2)$ and $R_b$ discrepancy with nonuniversal interactions
• Leptophobic U(1)'s and R_b, R_c at LEP
• Probing Supergravity Models with Indirect Experimental Signatures
• Supersymmetry and the spontaneous breaking of a U(1) gauge factor
• chi^2 Analysis of Supersymmetric Models
• Light Higgsino Detection at LEP1.5
• Supersymmetry and Electroweak Leptonic Observables
• R_b in Supergravity Grand Unification with Non-universal Soft SUSY Breaking
• Virtual Supersymmetric Corrections in e^+e^- Annihilation
• SUSY/SUGRA/String Phenomenology
• Electroweak interactions: a theoretical overview
• SUSY Contributions to $R_b$ and Top Decay