Corrections to Bino Annihilation II: One-Loop Contribution to B~B~→Z∗\widetilde B \widetilde B \to Z^*

We calculate the one-loop contribution to the bino annihilation rate due to the process $\widetilde B \widetilde B \to Z^*$, which vanishes at tree level.Comment: 8 pages in LaTex plus 5 postscript figures (included), UCSBTH--94--02, UMN--TH--1233/9

Detecting an Invisibly Decaying Higgs Boson at a Hadron Supercollider

We demonstrate that an invisibly decaying Higgs boson with Standard Model coupling strength to top--anti-top can be detected at the LHC for masses up to about 250 GeV.Comment: 7 pages, requires phyzzx.tex and tables.tex, revised to convert results from SSC to LHC and include additional top quark mass cases, full postscript file including embedded figure available via anonymous ftp at ucdhep.ucdavis.edu as [anonymous.gunion]hinvisible_revised.ps, preprint UCD-93-2

Phases in the MSSM, Electric Dipole Moments and Cosmological Dark Matter

We consider the effect of CP violating phases in the MSSM on the relic density of the lightest supersymmetric particle (LSP). In particular, we find that the upper limits on the LSP mass are relaxed when phases in the MSSM are allowed to take non-zero values when the LSP is predominantly a gaugino (bino). Previous limits of \mb \la 250 GeV for $\Omega h^2 < 0.25$ can be relaxed to \mb \la 650 GeV. We also consider the additional constraints imposed by the neutron and electron electric dipole moments induced by these phases. Though there is some restriction on the phases, the bino mass may still be as large as $\sim$ 350 GeV and certain phases can be arbitrarily large.Comment: 10 pages in LaTeX, with 4 Postscript figures (included

Corrections to Bino Annihilation I: Sfermion Mixing

We consider corrections to bino annihilation due to sfermion mixing.Comment: 11 pages in LaTex plus 4 postscript figures (included), CfPA--93--th--21, UMN--TH--1205/9

Gauge Singlet Scalars as Cold Dark Matter

In light of recent interest in minimal extensions of the Standard Model and gauge singlet scalar cold dark matter, we provide an arXiv preprint of the paper, published as Phys.Rev. D50 (1994) 3637, which presented the first detailed analysis of gauge singlet scalar cold dark matter.Comment: 37 pages, 11 figures, LaTe

Electric Dipole Moment Constraints on Phases in the Constrained MSSM

We consider constraints on \cp-violating phases in the Constrained Minimal Supersymmetric Standard Model. We find that by combining cosmological limits on gaugino masses with experimental bounds on the neutron and electron electric dipole moments, we can constrain the phase of the Higgs mixing mass $\mu$ to be $|\theta_\mu| < \pi/10$, independent of choices of the other mass parameters in the model. The other \cp-violating phase $\theta_A$ is essentially unconstrained.Comment: 10 pages in LaTeX + 3 postscript figures, uses epsf.st

Light Stops in the MSSM: Implications for Photino Dark Matter and Top Quark Decay

We consider the viability of the minimal supersymmetric standard model with a light ($m_{\tilde t_1} <$ 45 GeV) stop. In order for its relic abundance to be cosmologically significant, the photino as dark matter must be quite close in mass to the stop, $(m_{\tilde t_1} - m_{\tilde \gamma}) \simeq 3 - 7$ GeV. However, as we show, the photino despite its low mass is virtually undetectable by either direct or indirect means. We also discuss the implications of these masses on the top quark branching ratios.Comment: 11pages, LaTex, UMN-TH-1309/9

CP Violation and Dark Matter

A brief review is given of the effects of CP violation on the direct detection of neutralinos in dark matter detectors. We first summarize the current developments using the cancellation mechanism which allows for the existence of large CP violating phases consistent with experimental limits on the electron and on the neutron electric dipole moments in a broad class of SUSY, string and D brane models. We then discuss their effects on the scattering of neutralinos from quarks and on the event rates. It is found that while CP effects on the event rates can be enormous such effects are reduced significantly with the imposition of the EDM constraints. However, even with the inclusion of the EDM constraints the effects are still very significant and should be included in a precision prediction of event rates in any SUSY, string or D brane model.Comment: Based on an invited talk at the conference "Sources and Detection of Dark Matter in the Universe", at Marina del Rey, CA, Feb. 23-25, 2000; 12 pages, Latex including 2 figure

Predictions of Neutralino Dark Matter Event Rates in Minimal Supergravity Unification

A detailed analysis of dark matter event rates in minimal supergravity models (MSGM) is given. It is shown analytically that the lightest neutralino the ${{\tilde {Z}_{1}}}$ is the LSP over almost all of the parameter space, and hence the natural candidate for cold dark matter (CDM). The radiative breaking of $SU(2)\times U(1)$ constraints are shown to be crucial in determining the expected event rates. Approximate analytic formulae are obtained to determine the gaugino-higgsino content of the ${{\tilde{Z}_{1}}}$ particle.From this one can deduce the behavior of the event rates as one varies the SUSY soft breaking parameters and tan $\beta$. The constraint on the event rates due to the recently measured $b\rightarrow s+\gamma$ decay is calculated. It is seen that this data eliminates most of the parameter space where $\mu$ (the Higgs mixing parameter) and $A_t$ (the t-quark cubic soft breaking parameter) have the same sign. Since the t-quark is close to its Landau pole, $A_t$ is restricted to be mostly positive, and so most of the $\mu>0$ part of the parameter space is eliminated...Comment: Revised version for easier TeXing, with some typos corrected. 25 pages + 12 figs.The figs can be faxed on request