相关论文: $R_b$ in supersymmetric models

We compute the supersymmetric contribution to $R_{b}\equiv \Gamma (Z\to b{\bar b})/\Gamma (Z\to {\rm hadrons})$ in a variety of supergravity models. We find $R^{\rm susy}_b\lsim0.0004$, which does not shift significantly the Standard Model…

We re-examine the possible magnitude of the supersymmetric contribution to $R_b\equiv\Gamma(Z^0\to\bar b b)/\Gamma(Z^0\to{\rm all})$ in the light of the constraints imposed by the absence of light charginos at LEP~1.5, implementing also…

An analysis of supersymmetric contributions to R_b in supergravity grand unification with non-universal boundary conditions on soft SUSY breaking in the scalar sector is given. Effects on R_b of Planck scale corrections on gaugino masses…

A previous study of supersymmetric models has indicated that they are unlikely to make a large contribution to R_b. We revisit this analysis, taking into account the improved lower limits on sparticle masses provided recently by LEP 2 and…

We address the computation of \Gamma_Z and of the intriguing quantity R_b in the MSSM including full treatment of the Higgs sector. For a pseudoscalar Higgs mass m_{A^0}>70\,GeV and CDF limits on m_t, the bounds on R_b at 1\sigma level…

We study a class of generalized models of gauge mediated supersymmetry breaking (GMSB). We find the parameters and the full particle spectrum of the minimal supersymmetric standard model (MSSM) for all GMSB models with messenger…

It is analyzed the branching ratio $B(b\rightarrow s\gamma)$ in the context of minimal $N=1$ supergravity with radiatively broken electroweak symmetry group. There is a strong dependence on supersymetric parameters, but constraints on the…

We perform the complete computation of the contributions to $b\to s+\gamma, b\to s e^{+}e^{-}, b\to s\sum \nu_{i} \bar{\nu}_{i}$ in supersymmetric model with bilinear R-parity violation. We compare our calculations with the evaluations in…

We evaluate the branching ratio BR($b\rightarrow s,\gamma$) in the minimal supersymmetric standard model (MSSM), determining the corresponding phenomenological restrictions on two attractive supergravity scenarios, namely minimal…

We compute the one-loop corrections to the $Z \to b\bar{b}$ vertex in the $U(1)_R$ symmetric minimal supersymmetric extension of the standard model. We find that the predicted value of $R_b$ is consistent with experiment if the mass of the…

Recent advances in the calculation of the $b\to s\gamma$ decay branching ratio are presented in the context of supersymmetric theories. Theoretical accuracy increased by inclusion of the next-to-leading order QCD corrections makes it…

The Minimal supersymmetric extension of the Standard Model (MSSM) with light stops, charginos or pseudoscalar Higgs bosons has been suggested as an explanation of the too high value of the branching ratio of the Z0 boson into b quarks (Rb…

We provide an analysis of the parameter space of several supersymmetry breaking scenarios such as the minimal supergravity (mSUGRA) model and the non universal Higgs mass (NUHM) framework, as well as the Anomaly Mediated Supersymmetry…

Supersymmetric (SUSY) theories are often thought to give large branching ratios for $b \rightarrow s \gamma$ from charged Higgs loops. We show that in many cases chargino loop contributions can cancel those of the Higgs, and SUSY can give…

We have performed a systematic analysis to compute the one-loop electroweak corrections to the Z->b b-bar vertex in terms of $\epsilon_b$ and $R_b$ in the context of the minimal $SU(5)$ and no-scale $SU(5)\times U(1)$ supergravity models.…

We propose a supersymmetric extension of the standard model which is a realistic alternative to the MSSM, and which has several advantages. No ``mu'' supersymmetric Higgs/Higgsino mass parameter is needed for sufficiently heavy charginos.…

We discuss supersymmetric contributions to the electroweak precision measurements in the Minimal Supersymmetric Standard Model for two cases: the quark-lepton universality violation $\delta_{q\ell}$ in charged currents and the ratio…

We study the correlation of quantum effects on the ratios R_b and R_c within the framework of the MSSM. While in the SM the quantity R_b is in discrepancy with experiment at the 2 \sigma level from below, and R_c differs from the…

We investigate how the predictions of the Minimal Supersymmetric Standard Model are modified by D-term contributions to soft scalar masses, which arise whenever the rank of the gauge group at very high energies is greater than four. We give…

We re-examine the possible magnitude of the supersymmetric contribution to $R_b$ with imposed all available phenomenological constraints and demanding good quality of the global fit to the precision electroweak data. For low $\tan\beta$ we…