$R_b$ and $R_c$ in the Two Higgs Doublet Model with Flavor Changing Neutral Currents

Abstract

A study of $R_b$ and $R_c$ is presented in the context of a Two Higgs Doublet Model (2HDM) with flavor changing scalar currents (FCSC). Implications of the model for the $\rho$-parameter and for $b\to s\gamma$ are also considered. The experimental data on $R_b$ places stringent constraints on the model parameters. The configuration of the model needed to account for $R_b$ is found to be irreconcilable with constraints from $b\to s\gamma$ and $\rho$. In particular, if $R^{\rm exp}_b>R^{\sss{\rm SM}}_b$ persists then this version of 2HDM will be ruled out or require significant modifications. Noting that aspects of the experimental analysis for $R_b$ and $R_c$ may be of some concern, we also disregard $R_b^{\exp }$ and $R_c^{\exp }$ and give predictions for these using constraints from $b\to s\gamma$ and $\rho$ parameter only. We emphasize the theoretical and experimental advantages of the observable $R_{b+c}\equiv Γ(Z\to b\bar b\mbox{ or } c\bar c)/Γ(Z\to\mbox{hadrons})$. We also stress the role of $R_\ell\equiv Γ(Z\to\mbox{hadrons})/Γ(Z\to \ell^+\ell^-)$ in testing the Standard Model (SM) despite its dependence on QCD corrections. Noting that in models with FCNC the amplitude for $Z\to c\bar{c}$ receives a contribution which grows with $m_t^2$, the importance and uniqueness of precision $Z\to c\bar{c}$ measurements for constraining flavor changing $t\bar{c}$ currents is underscored.

35 pages, 5 Postscript figures, 10 Postscript files used in the tex file, uses epsf.sty

References in corpus (12)

• Observation of Top Quark Production in Pbar-P Collisions
• Observation of the Top Quark
• Probing flavor changing top-charm-scalar interactions in $e^{+}{e}^{-}$ collisions
• Top-Quark Decay Via Flavor-Changing Neutral Currents at Hadron Colliders
• Precision determination of ${\alpha }_s$ and $m_b$ from QCD sum rules for $b\overline{b}$.
• Flavor Changing Neutral Scalar Currents at ${\mu }^{+}{\mu }^{-}$ Colliders
• The heavy top quark in the two Higgs doublet model
• Hadrophilic Z':a bridge from LEP1, SLC and CDF to LEP2 anomalies
• Implications of the reported deviations from the standard model for Z->bb and alpha_s
• Rb, Rc and Jet Distributions at the Tevatron in a Model with an extra vector boson
• The $Z\to b\bar{b}$ Excess and Top Decay
• $R_b$ -- $R_c$ Crisis and New Physics

Cited by in corpus (28)

• New Method for Detecting Charged (Pseudo-)Scalars at Colliders
• QCD Corrections to Scalar Production via Heavy Quark Fusion at Hadron Colliders
• New Physics in CP Asymmetries and Rare B Decays
• Z and Z' decays with and without FCNC in 331 models
• Probing Topcolor-Assisted Technicolor from Top-Charm Associated Production at LHC
• The branching ratio $R_b$ in the littlest Higgs model
• Lepton Flavor Violation in the Two Higgs Doublet Model type III
• Search for single top-quark production via flavour changing neutral currents at 8 TeV with the ATLAS detector
• Two Higgs doublets with 4th generation fermions - models for TeV-scale compositeness
• Probing New Physics from Top-charm Associated Productions at Linear Colliders
• Probing Topcolor-Assisted Technicolor from Like-sign Top Pair Production at LHC
• Bounds for Lepton Flavor Violation and the Pseudoscalar Higgs in the General Two Higgs Doublet Model using $g-2$ muon factor
• B^0-\bar{B}^0 mixing and B \to X_s γdecay in the third type 2HDM: effects of NLO QCD contributions
• The $B->X_{s}gammagamma$ decay in the standard model and the general two-Higgs-doublet model
• Charmless hadronic decays $B\to PP,PV,VV$ and new physics effects in the general two-Higgs doublet models
• Mass-matrix ansatz and constraints on $B_s^0-{\bar{B}}_s^0$ mixing in 331 models
• Texture of Yukawa coupling matrices in general two-Higgs-doublet model
• The Landau Pole and $Z^{\prime }$ decays in the 331 bilepton model
• The Study of the contribution of the LHT model to $Zb\bar{b}$ coupling
• Effective lagrangian description of top production and decay
• Search for t->ch at e+e- Linear Colliders
• Rare top decay $t\to c\gamma$ with flavor changing neutral scalar interactions in two Higgs doublet model
• SM Higgs boson and $t\to cZ$ decays in the 2HDM type III with CP violation
• Top quark electric and chromo electric dipole moments in the general two Higgs Doublet model
• Charm multiplicity and the branching ratios of inclusive charmless b quark decays in the general two-Higgs-doublet models
• Gluon penguin enhancements to inclusive charmless decays of b quark in the 2HDM with flavor changing couplings
• Bounds on charged higgs boson in the 2HDM type III from Tevatron
• Implications for new physics from ${\bar{B}}^0\to {\pi }^0{\pi }^0$ and ${\bar{B}}^0\to {\bar{K}}^0{K}^0$