Direct detection of neutralino dark matter and b->s+gamma decays

We analyze the direct detection rate of minimal supersymmetric neutralino dark matter in germanium, sapphire and sodium iodide detectors, imposing cosmological and accelerator bounds including those from \bsg\ decay. In contrast with several other recent analyses we find models with light charged higgsinos and large stop mixing in which the counting rate in solid state detectors exceeds 10 events/kg/day.Comment: Talk presented by P. Gondolo at TAUP95, Toledo, Sept. 1995. 3 pages, 2 Postscript figures, uses epsf.sty and espcrc2.st

Limits on direct detection of neutralino dark matter from b -> s gamma decays

We analyze the rate of detection of minimal supersymmetric neutralino dark matter in germanium, sapphire and sodium iodide detectors, imposing cosmological and recent accelerator bounds including those from \bsg\ decay. We find, in contrast with several other recent analyses, that although the \bsg\ constraint reduces the number of viable models, models still remain where the counting rate in solid state detectors exceeds 10 kg$^{-1}$ day$^{-1}$.Comment: uuencoded, gzipped postscript (17 pages), figures available at http://vanosf.physto.se/lbe/bg_figs.u

Model-Independent Comparison of Direct vs. Indirect Detection of Supersymmetric Dark Matter

We compare the rate for elastic scattering of neutralinos from various nuclei with the flux of upward muons induced by energetic neutrinos from neutralino annihilation in the Sun and Earth. We consider both scalar and axial-vector interactions of neutralinos with nuclei. We find that the event rate in a kg of germanium is roughly equivalent to that in a $10^5$- to $10^7$-m$^2$ muon detector for a neutralino with primarily scalar coupling to nuclei. For an axially coupled neutralino, the event rate in a 50-gram hydrogen detector is roughly the same as that in a 10- to 500-m$^2$ muon detector. Expected experimental backgrounds favor forthcoming elastic-scattering detectors for scalar couplings while the neutrino detectors have the advantage for axial-vector couplings.Comment: 10 pages, self-unpacking uuencoded PostScript fil

Cold Dark Matter in SUSY Theories. The Role of Nuclear Form Factors and the Folding with the LSP Velocity

The momentum transfer dependence of the total cross section for elastic scattering of cold dark matter candidates, i.e. lightest supersymmetric particle (LSP), with nuclei is examined. The presented calculations of the event rates refer to a number of representative nuclear targets throughout the periodic table and have been obtained in a relatively wide phenomenologically allowed SUSY parameter space. For the coherent cross sections it is shown that, since the momentum transfer can be quite big for large mass of the LSP and heavy nuclei even though the energy transfer is small ($\le 100 KeV$), the total cross section can in such instances be reduced by a factor of about five. For the spin induced cross section of odd-A nuclear targets, as is the case of $^{207}Pb$ studied in this work, we found that the reduction is less pronounced, since the high multipoles tend to enhance the cross section as the momentum transfer increases (for LSP $mass < 200 GeV$) and partially cancell the momentum retardation. The effect of the Earth's revolution around the sun on these event rates is also studied by folding with a Maxwellian LSP-velocity distribution which is consistent with its density in the halos. We thus found that the convoluted event rates do not appreciably change compared to those obtained with an average velocity. The event rates increase with A and, in the SUSY parameter space considered, they can reach values up to 140 $y^{-1}Kg^{-1}$ for Pb. The modulation effect, however, was found to be small (less than $\pm 5$).Comment: 23 LATEX pages, 4 Tables, 3 PostScript Figures included. Phys. Rev. D, to be publishe

Nuclear Shell Model Calculations of Neutralino-Nucleus Cross Sections for Silicon 29 and Germanium 73

We present the results of detailed nuclear shell model calculations of the spin-dependent elastic cross section for neutralinos scattering from \si29 and \ge73. The calculations were performed in large model spaces which adequately describe the configuration mixing in these two nuclei. As tests of the computed nuclear wave functions, we have calculated several nuclear observables and compared them with the measured values and found good agreement. In the limit of zero momentum transfer, we find scattering matrix elements in agreement with previous estimates for \si29 but significantly different than previous work for \ge73. A modest quenching, in accord with shell model studies of other heavy nuclei, has been included to bring agreement between the measured and calculated values of the magnetic moment for \ge73. Even with this quenching, the calculated scattering rate is roughly a factor of 2 higher than the best previous estimates; without quenching, the rate is a factor of 4 higher. This implies a higher sensitivity for germanium dark matter detectors. We also investigate the role of finite momentum transfer upon the scattering response for both nuclei and find that this can significantly change the expected rates. We close with a brief discussion of the effects of some of the non-nuclear uncertainties upon the matrix elements.Comment: 31 pages, figures avaiable on request, UCRL-JC-11408

Effects of CP Violation on Event Rates in the Direct Detection of Dark Matter

A full analytic analysis of the effects of CP violating phases on the event rates in the direct detection of dark matter in the scattering of neutralinos from nuclear targets is given. The analysis includes CP violating phases in softly broken supersymmetry in the framework of the minimal supersymmetric standard model (MSSM) when generational mixings are ignored. A numerical analysis shows that large CP violating phases including the constraints from the experimental limits on the neutron and the electron electric dipole moment (EDM) can produce substantial effects on the event rates in dark matter detectors.Comment: 17 pages, LaTex, including 2 figures; revised version to appear in the Physical Review

About direct Dark Matter detection in Next-to-Minimal Supersymmetric Standard Model

Direct dark matter detection is considered in the Next-to-Minimal Supersymmetric Standard Model (NMSSM). The effective neutralino-quark Lagrangian is obtained and event rates are calculated for the Ge-73 isotope. Accelerator and cosmological constraints on the NMSSM parameter space are included. By means of scanning the parameter space at the Fermi scale we show that the lightest neutralino could be detected in dark matter experiments with sizable event rate.Comment: latex, 12 pages, 2 ps-figures; extra LEP constraint is included, extra figure is added, recorrected version, resubmitted to Phys.Rev.

Loop induced Higgs and Z boson couplings to Neutralinos and implications for collider and Dark Matter searches

We calculate the one-loop induced couplings of two gaugino-like neutralinos to the $Z$ and Higgs bosons in the Minimal Supersymmetric Standard Model. These couplings, which vanish at the tree level, can be generated through loops involving fermions and sfermions. We show that, while the neutralino contribution to the invisible $Z$ boson decay width remains small, the loop induced couplings to the lightest Higgs boson might be sufficiently large to yield a rate of invisible decays of this Higgs boson that should be detectable at future $e^+e^-$ colliders. We also study the implications of these couplings for direct searches of Dark Matter and show that they can modify appreciably the neutralino-nucleon elastic cross section for some parameter range.Comment: LaTeX with 6 (e)ps and 2 axodraw figures, 25 pages in total; axodraw.sty is included v.2: Added one figure and some discussions; version to appear in PR

Extending the DAMA annual-modulation region by inclusion of the uncertainties in the astrophysical velocities

The original annual-modulation region, singled out by the DAMA/NaI experiment for direct detection of WIMPs, is extended by taking into account the uncertainties in the galactic astrophysical velocities. Also the effect due to a possible bulk rotation for the dark matter halo is considered. We find that the range for the WIMP mass becomes 30 GeV < m_chi < 130 GeV at 1-sigma C.L. with a further extension in the upper bound, when a possible bulk rotation of the dark matter halo is taken into account. We show that the DAMA results, when interpreted in the framework of the Minimal Supersymmetric extension of the Standard Model, are consistent with a relic neutralino as a dominant component of cold dark matter (on the average in our universe and in our galactic halo). It is also discussed the discovery potential for the relevant supersymmetric configurations at accelerators of present generation.Comment: ReVTeX, 12 pages, 1 table, 7 figure