Guaranteed Detection of a Minimal Supersymmetric Model Higgs Boson at Hadron Supercolliders

We demonstrate that expected efficiencies and purities for $b$-tagging at SSC/LHC detectors should allow detection of at least one of the Higgs bosons of the Minimal Supersymmetric Model in t\anti t~Higgs production, with Higgs\rta b\anti b decay, over a substantial range of supersymmetric parameter space. In particular, with the addition of this mode to those previously considered, there is no region of supersymmetric parameter space for which {\it none} of the Higgs bosons of the model can be seen at the SSC/LHC.Comment: 9 pages, uses phyzzx.tex and tables.tex macros, full postscript file, including embedded figures, available via anonymous ftp at ucdhep.ucdavis.edu as [anonymous.gunion]hbb_susy.ps, preprint UCD-93-2

Using Back-Scattered Laser Beams to Detect CP Violation in the Neutral Higgs Sector

We demonstrate that the ability to polarize the photons produced by back-scattering laser beams at a TeV scale linear \epem collider could make it possible to determine whether or not a neutral Higgs boson produced in photon-photon collisions is a CP eigenstate. The relative utility of different types of polarization is discussed. Asymmetries that are only non-zero if the Higgs boson is a CP mixture are defined, and their magnitudes illustrated for a two-doublet Higgs model with CP-violating neutral sector.Comment: 15 pages, UCD-92-18, 4 figures, postscript figure files available by request, uses phyzzx.te

Determining the CP-eigenvalues of the Neutral Higgs Bosons of the Minimal Supersymmetric Model in \gam\gam Collisions

We determine the optimal laser and \ep/\em energies and polarizations for {\it directly} determining the CP eigenvalue of each of the neutral Higgs bosons of the Minimal Supersymmetric Model via measurement of transverse polarization cross section asymmetry in back-scattered laser photon collisions. Approximate statistical significances are computed for the measurement of the CP eigenvalue as a function of Higgs mass and other parameters of the model.Comment: 14 pages, requires phyzzx.tex and tables.tex, full postscript file including embedded figures available via anonymous ftp at ucdhep.ucdavis.edu as [anonymous.gunion]a3susy.ps, revised to correct Eq. (3), various wordings improvements also made, including a better version of final paragraph of conclusion, preprint UCD-94-2

Probing Exotic Higgs Sectors in ℓ−ℓ−\ell^-\ell^- Collisions

I review extended Higgs sectors and constraints thereon arising from $\rho=1$, gauge-coupling unification and b\to s\gam. The couplings and decays of the Higgs boson eigenstates are outlined for triplet representations. Direct experimental probes of exotic Higgs bosons are reviewed with a focus on the important role that would be played by an $e^-e^-$ or $\mu^-\mu^-$ collider.Comment: 21 pages, full postscript file is available via anonymous ftp at ftp://ucdhep.ucdavis.edu/gunion/emem97.ps; one reference adde

Variation of the cross section for e+e- --> W+H- in the Minimal Supersymmetric Standard Model

We study the loop-induced process e+e- --> W+H- in the Minimal Supersymmetric Standard Model (MSSM). This process allows the charged Higgs boson to be produced in e+e- collisions when its mass is larger than half the center-of-mass energy, so that e+e- --> H+H- is kinematically forbidden. By scanning over the MSSM parameters subject to experimental constraints we examine the range of values possible for this cross section. We find that, in regions of parameter space where this cross section is large enough to be of interest, the contributions from supersymmetric particles typically increase the cross section by 50-100% compared to the non-supersymmetric two Higgs doublet model result. Choosing a few typical MSSM parameter sets, we show the regions in the m_{H^{\pm}}-tan(beta) plane in which at least 10 W^{\pm}H^{\mp} events would be produced at the e+e- collider for m_{H^{\pm}} >= sqrt(s)/2. We also show that including radiative corrections to the MSSM Higgs sector has only a small effect on the cross section.Comment: 5 pages, 4 figures, v2: minor changes; v3: extensive changes to text and figures, version to appear in PR

Probing the MSSM Higgs Sector at an e-e- Collider

The theoretical structure of the Higgs sector of the Minimal Supersymmetric Standard Model (MSSM) is briefly described. An outline of Higgs phenomenology at future lepton colliders is presented, and some opportunities for probing the physics of the MSSM Higgs sector at an e-e- collider are considered.Comment: 14 pages, needs e-e-ijmpa.sty and psfig.sty, to appear in the Proceedings of e-e- 97, International Journal of Modern Physics A, Special Proceedings Issue, June 199

Studying possible CP-violating Higgs couplings through top-quark pair productions at muon colliders

We study possible anomalous CP-violating Higgs couplings to mu mu-bar and t t-bar fully model-independent way through top-quark pair productions at muon colliders. Assuming additional non-standard neutral Higgs bosons, whose couplings with top-quark and muon are expressed in the most general covariant form, we carry out analyses of effects which they are expected to produce via CP-violating asymmetries and also the optimal-observable (OO) procedure under longitudinal and transverse muon polarizations. We find the measurement of the asymmetry for longitudinal beam polarization could be useful to catch some signal of CP violation, and an OO analysis might also be useful if we could reduce the number of unknown parameters with a help of other experiments and if the size of the parameters is at least O(1) ~ O(10).Comment: Final version (to appear in JHEP

SUSY-QCD decoupling properties in H+ -> t \bar b decay

The SUSY-QCD radiative corrections to the \Gamma (H+ -> t \bar b) partial decay width are analyzed within the Minimal Supersymmetric Standard Model at the one-loop level, {\mathcal O}(\alpha_s), and in the decoupling limit. We present the analytical expressions of these corrections in the large SUSY masses limit and study the decoupling behaviour of these corrections in various limiting cases. We find that if the SUSY mass parameters are large and of the same order, the one loop SUSY-QCD corrections {\it do not decouple}. The non-decoupling contribution is enhanced by \tan \beta and therefore large corrections are expected in the large \tan \beta limit. In contrast, we also find that the SUSY-QCD corrections decouple if the masses of either the squarks or the gluinos are separately taken large.Comment: LaTeX, 33 pages, 7 figure included. Uses cite.st

Using Decay Angle Correlations to Detect CP Violation in the Neutral Higgs Sector

We demonstrate that decay angle correlations in \taum\taup and t\anti t decay modes could allow a determination of whether or not a neutral Higgs boson is a CP eigenstate. Sensitivity of the correlations is illustrated in the case of the \epem\rta Z \hn and \mupmum\rta \hn production processes for a two-doublet Higgs model with CP-violating neutral sector. A very useful technique for minimizing `depolarization-factor' suppressions of the correlations in the t\anti t mode is introduced.Comment: 13 pages, phyzzx.tex macro, full postscript file including embedded figure available at ftp://ucdhep.ucdavis.edu/gunion/cpasym.p

Associated production of H^{\pm} and W^{\mp} in high-energy e+e- collisions in the Minimal Supersymmetric Standard Model

We study the associated production of the charged Higgs boson and W^{\pm} gauge boson in high energy e+e- collisions in the Minimal Supersymmetric Standard Model (MSSM). This associated production, which first arises at the one loop level, offers the possibility of producing the charged Higgs boson at the e+e- collider with mass more than half the center-of-mass energy, when the charged Higgs pair production is kinematically forbidden. We present analytic and numerical results for the cross section for e+e- --> W+ H- in the full MSSM, taking into account the previously uncalculated contributions from supersymmetric (SUSY) particles. We find that the contributions of the SUSY particles enhance the cross section over most of SUSY parameter space, especially when the SUSY particles are light, ~200 GeV. With favorable SUSY parameters, at small tan beta, this process can yield more than ten W^{\pm}H^{\mp} events for m_{H^{\pm}} <~ 350 GeV in 500 fb-1 at a 500 GeV e+e- collider, or m_{H^{\pm}} <~ 600 GeV in 1000 fb-1 at a 1000 GeV collider. 80% left-handed polarization of the e- beam improves these reaches to m_{H^{\pm}} <~ 375 GeV and m_{H^{\pm}} <~ 670 GeV, respectively.Comment: v2: 21 pages, 9 figures, comments on Higgs search bounds and new references added, and minor changes; v3: 23 pages, 11 figures, review of literature moved from introduction to new Sec.5 and 2 plots added, references added, typos corrected; v4: bug fixed in nu nubar H0 cross section (Fig.11), version to appear in PR