CP Violating Phases and the Dark Matter Problem

New CP violating phases in the MSSM can affect both the abundance and detection of neutralino dark matter. We discuss the effect of including cosmological constraints in the limits on new sources of CP violation in the MSSM and the effects of new CP violating parameters on dark matter densities and detection.Comment: 9 pages in LaTeX2e, including 8 encapsulated postscript figures; uses ws-p8-50x6-00.cls (included); to appear in the proceedings of COSMO99: 3rd International Conference on Particle Physics and the Early Universe, Trieste, Ital

The Angular Dependence of the Three-Point Correlation Function of the Cosmic Microwave Background Radiation as Predicted by Inflationary Cosmologies

Inflationary models predict a definite, model independent, angular dependence for the three-point correlation function of $\Delta T/T$ at large angles (greater than $\sim 1^\circ$) which we calculate. The overall amplitude is model dependent and generically unobservably small, but may be large in some specific models. We compare our results with other models of nongaussian fluctuations.Comment: 7 pages, 3 figures (described but not included, available on request), in Plain Tex, UCSBTH-92-3

More on Electric Dipole Moment Constraints on Phases in the Constrained MSSM

We reconsider constraints on \cp-violating phases in the Constrained Minimal Supersymmetric Standard Model. We include the recent calculations of Ibrahim and Nath on the chromoelectric and purely gluonic contributions to the quark electric dipole moment and combine cosmological limits on gaugino masses with experimental bounds on the neutron (and electron) electric dipole moments. The constraint on the phase of the Higgs mixing mass $\mu$, |\thm|, is dependent on the value of the trilinear mass parameter, $A$, in the model and on $\tan \beta$. For values of |A| < 300 \gev at the GUT scale, we find |\thm|/\pi \la 0.05, while for |A| < 1500 \gev, |\thm|/\pi \la 0.3. Thus, we find that in principle, large CP violating phases are compatible with the bounds on the electric dipole moments of the neutron and electron, as well as remaining compatible with the cosmological upper bound on the relic density of neutralinos. The other \cp-violating phase \tha is essentially unconstrained.Comment: 11 pages in LaTeX + 4 postscript figures, uses epsf.sty. Added two references, clarified figures. Accepted to Physics Letter

Supersymmetric Dark Matter in the Light of LEP and the Tevatron Collider

We analyze the accelerator constraints on the parameter space of the Minimal Supersymmetric extension of the Standard Model, comparing those now available from LEP II and anticipating the likely sensitivity of Tevatron Run II. The most important limits are those from searches for charginos, neutralinos and Higgs bosons at LEP, and searches for stop squarks, charginos and neutralinos at the Tevatron Collider. We also incorporate the constraints derived from b --> s + gamma decay, and discuss the relevance of charge- and colour-breaking minima in the effective potential. We combine and compare the different constraints on the Higgs-mixing parameter mu, the gaugino-mass parameter m_{1/2} and the scalar-mass parameter m0, incorporating radiative corrections to the physical particle masses. We focus on the resulting limitations on supersymmetric dark matter, assumed to be the lightest neutralino, incorporating coannihilation effects in the calculation of the relic abundance. We find that m_chi > 51 GeV and tan(beta) > 2.2 if all soft supersymmetry-breaking scalar masses are universal, including those of the Higgs bosons, and that these limits weaken to m_chi > 46 GeV and tan(beta) > 1.9 if non-universal scalar masses are allowed. Light neutralino dark matter cannot be primarily Higgsino in composition.Comment: 39 pages in LaTeX, including 44 encapsulated postscript figure

Charginos and Neutralinos in the Light of Radiative Corrections: Sealing the Fate of Higgsino Dark Matter

We analyze the LEP constraints from searches for charginos $\chi^{\pm}$ and neutralinos $\chi_i$, taking into account radiative corrections to the relations between their masses and the underlying Higgs-mixing and gaugino-mass parameters $\mu, m_{1/2}$ and the trilinear mass parameter $A_t$. Whilst radiative corrections do not alter the excluded domain in $m_{\chi^{\pm}}$ as a function of $m_{\chi^{\pm}} - m_{\chi}$, its mapping into the $\mu, m_{1/2}$ plane is altered. We update our previous lower limits on the mass of gaugino dark matter and on tan$\beta$, the ratio of Higgs vacuum expectation values, in the light of the latest LEP data and these radiative corrections. We also discuss the viability of Higgsino dark matter, incorporating co-annihilation effects into the calculation of the Higgsino relic abundance. We find that Higgsino dark matter is viable for only a very limited range of $\mu$ and $m_{1/2}$, which will be explored completely by upcoming LEP runs.Comment: Version to appear in Phys. Rev. D., 21 pages in LateX, including 10 encapsulated postscript figures; uses epsf.sty.; Figures modified (one deleted), conclusions unchange

Calculations of Neutralino-Stau Coannihilation Channels and the Cosmologically Relevant Region of MSSM Parameter Space

Assuming that the lightest supersymmetric particle (LSP) is the lightest neutralino, we present a detailed exploration of neutralino-stau coannihilation channels, including analytical expressions and numerical results. We also include neutralino coannihilations with the selectron and smuon. We evaluate the implications of coannihilations for the cosmological relic density of the LSP, which is assumed to be stable, in the constrained minimal supersymmetric extension of the Standard Model (CMSSM), in which the soft supersymmetry-breaking parameters are universal at the supergravity GUT scale. We evaluate the changes due to coannihilations in the region of the MSSM parameter space that is consistent with the cosmological upper limit on the relic LSP density. In particular, we find that the upper limit on the mass of the neutralino is increased from about 200 GeV to about 600 GeV in the CMSSM, and estimate a qualitatively similar increase for gauginos in the general MSSM.Comment: 38 pages in LaTeX, including 25 encapsulated postscript figures. Added small clarification in the text, corrected some typos in the appendix. Figures and conclusions unchange

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

Neutralino-Stau Coannihilation and the Cosmological Upper Limit on the Mass of the Lightest Supersymmetric Particle

We consider the effects of neutralino-stau coannihilations on the cosmological relic density of the lightest supersymmetric particle (LSP) $\chi$ in the minimal supersymmetric extension of the Standard Model (MSSM), particularly in the constrained MSSM in which universal supergravity inputs at the GUT scale are assumed. For much of the parameter space in these models, $\chi$ is approximately a U(1) gaugino ${\tilde B}$, and constraints on the cosmological relic density $\Omega_{\tilde B} h^2$ yield an upper bound on the bino mass. We show that in regions of parameter space for which the cosmological bound is nearly saturated, coannihilations of the $\tilde B$ with the stau, the next lightest sparticle, are important and may reduce significantly the bino relic density. Including also bino coannihilations with the selectrons and smuons, we find that the upper limit on $m_{\chi}$ is increased from about 200 GeV to about 600 GeV in the constrained MSSM, with a similar new upper limit expected in the MSSM.Comment: 10 pages in LaTeX, including 2 encapsulated postscript figures; uses epsf.sty; typo correcte