David Atwood

R{sub b} and R{sub c} in the two Higgs Doublet Model with flavor changing neutral currents

A study of {ital R}{sub {ital b}} and {ital R}{sub {ital c}} is presented in the context of a two-Higgs-doublet model with flavor-changing scalar currents (FCSC{close_quote}s). Implications of the model for the {rho} parameter and for {ital b}{r_arrow}{ital s}{gamma} are also considered. The experimental data on {ital R}{sub {ital b}} places stringent constraints on the model parameters that are difficult to reconcile with the constraints from {ital b}{r_arrow}{ital s}{gamma} and {rho}. If we treat the couplings of the model as purely phenomenological, then the model can still survive albeit in a rather narrow region of the parameter space. Noting that aspects of the experimental analysis for {ital R}{sub {ital b}} and {ital R}{sub {ital c}} may be of some concern, we also disregard {ital R}{sub {ital b}}{sup expt} and {ital R}{sub {ital c}}{sup expt} and give predictions for these using constraints from {ital b}{r_arrow}{ital s}{gamma} and the {rho} parameter only. We emphasize the theoretical and experimental advantages of the observable {ital R}{sub {ital b}+{ital c}}{equivalent_to}{Gamma}({ital Z}{r_arrow}{ital b{bar b}}or{ital c{bar c}})/{Gamma}({ital Z}{r_arrow}hadrons). We also stress the role of {ital R}{sub {ital l}}{equivalent_to}{Gamma}({ital Z}{r_arrow}hadrons)/{Gamma}({ital Z}{r_arrow}{ital l}{sup +}{ital l}{sup {minus}}) in testing the standard model despite its dependence on QCD corrections. Noting thatmorexa0» in models with FCNC{close_quote}s the amplitude for {ital Z}{r_arrow}{ital c{bar c}} receives a contribution which grows with {ital m}{sup 2}{sub {ital t}} the importance and uniqueness of precision {ital Z}{r_arrow}{ital c{bar c}} measurements for constraining flavor-changing {ital t{bar c}} currents is underscored. {copyright} {ital 1996 The American Physical Society.}«xa0less

Large tree-level {ital CP} violation in {ital e}{sup +}{ital e}{sup {minus}}{r_arrow}{ital t{bar t}H}{sup 0} in the two-Higgs-doublet model

We find a large CP violation effect within the two-Higgs-doublet model for the reaction

CP Violation In Single Top Production And Decay Via p p-bar -> t b-bar +X -> W^+ b b-bar +X Within The MSSM: A Possible Application For Measuring \arg(A_t) At Hadron Colliders

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CP violation in single top quark production and decay via p{bar p}{r_arrow}t{bar b}+X{r_arrow}W{sup +}b{bar b}+X within the MSSM: A possible application for measuring arg(A{sub t}) at hadron colliders

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{ital R}{sub {ital b}} and {ital R}{sub {ital c}} in the two-Higgs-doublet model with flavor-changing neutral currents

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CP nonconservation in pp-bar-->tb-barX at the Fermilab Tevatron.

{mathit{H}}^{0}

Dipole moment effects in e+e--->Z-->bb-barg with polarized and unpolarized beams.

at future linear colliders. The CP asymmetry arises already at the tree level as a result of interference between diagrams with

A striking signature of heavy Majorana neutrinos in charged Higgs pair production at the ILC

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'Seesawing' away the hierarchy problem

emission from t (and tifmmodebarelsetextasciimacronfi{}) and its emission from a