Muon g-2, Dark Matter Detection and Accelerator Physics

We examine the recently observed deviation of the muon g - 2 from the Standard Model prediction within the framework of gravity mediated SUGRA models with R parity invariance. Universal soft breaking (mSUGRA) models, and models with non-universal Higgs and third generation squark/slepton masses at M_G are considered. All relic density constraints from stau-neutralino co-annihilation and large \tan\beta NLO corrections for b \to s\gamma decay are included, and we consider two possibilities for the light Higgs: m_h > 114 GeV and m_h > 120 GeV. The combined m_h, b \to s\gamma and a_{\mu} bounds give rise to lower bounds on \tan\beta and m_{1/2}, while the lower bound on a_{\mu} gives rise to an upper bounds on m_{1/2}. These bounds are sensitive to A_0, e.g. for m_h > 114 GeV, the 95% C.L. is \tan\beta > 7(5) for A_0 = 0(-4m_{1/2}), and for m_h > 120 GeV, \tan\beta > 15(10). The positive sign of the a_{\mu} deviation implies \mu > 0, eliminating the extreme cancellations in the dark matter neutralino-proton detection cross section so that almost all the SUSY parameter space should be accessible to future planned detectors. Most of the allowed parts of parameter space occur in the co-annihilation region where m_0 is strongly correlated with m_{1/2}. The lower bound on a_{\mu} then greatly reduces the allowed parameter space. Thus using 90% C. L. bounds on a_{\mu} we find for A_0 = 0 that \tan\beta \geq 10 and for \tan\beta \leq 40 that m_{1/2} = (290 - 550) GeV and m_0 = (70 - 300) GeV. Then the tri-lepton signal and other SUSY signals would be beyond the Tevatron Run II (except for the light Higgs), only the \tilde{\tau}_1 and h and (and for part of the parameter space) the \tilde{e}_1 will be accessible to a 500 GeV NLC, while the LHC would be able to see the full SUSY mass spectrum.Comment: 10 pages, latex, 6 figure

Yukawa Textures, Neutrino Masses and Horava-Witten M-Theory

We consider the Horava-Witten based model with 5-branes situated near the distant orbifold plane and with vanishing instanton numbers on the physical plane. This model has a toric fibered Calabi-Yau with del Pezzo base dP_7 which allows three generations with Standard Model gauge group at the GUT scale. Previous analysis showed that the quark hierarchy at the electroweak scale could be achieved qualitatively without undue fine tuning due to the effects of the 5-branes on the Kahler potential. We extend here this analysis to include the leptons. A new mechanism is introduced to obtain neutrino masses by assuming massless right handed neutrinos exist in the particle spectrum, which allows a cubic holomorphic term to exist in the Kahler metric, l_L*H_2*nu_R, scaled by the 11D Planck mass. After transferring this term to the superpotential, this term gives rise to neutrino masses of the correct size at the electroweak scale. With natural choices of the Yukawa and Kahler matrix entries, it is possible to fit all mass, CKM and MNS experimental data. The model predicts mu -> e + gamma decay at a rate that should be detectable for much of the SUSY parameter space in the next round of experiments.Comment: 24 pages, 4 figures. Minor changes, references added. Some discussion on neutrino mass generating mechanism added; no other change. Accepted for publication in Nucl. Phys.

Update on the Direct Detection of Dark Matter in MSSM Models with Non-Universal Higgs Masses

We discuss the possibilities for the direct detection of neutralino dark matter via elastic scattering in variants of the minimal supersymmetric extension of the Standard Model (MSSM) with non-universal supersymmetry-breaking contributions to the Higgs masses, which may be either equal (NUHM1) or independent (NUHM2). We compare the ranges found in the NUHM1 and NUHM2 with that found in the MSSM with universal supersymmetry-breaking contributions to all scalar masses, the CMSSM. We find that both the NUHM1 and NUHM2 offer the possibility of larger spin-independent dark matter scattering cross sections than in the CMSSM for larger neutralino masses, since they allow the density of heavier neutralinos with large Higgsino components to fall within the allowed range by astrophysics. The NUHM1 and NUHM2 also offer more possibilities than the CMSSM for small cross sections for lower neutralino masses, since they may be suppressed by scalar and pseudoscalar Higgs masses that are larger than in the CMSSM.Comment: 35 pages, 14 figures, submitted to New Journal of Physics focus issue "Dark Matter and Particle Physics

B^0 -> phi K_S in SUGRA models with CP violations

We examine the B -> phi K decays within the framework of SUGRA models making use of the improved QCD factorization method of Beneke et al. which allows calculations of non-factorizable contributions. All other experimental constraints (B -> X_S gamma, neutron and electron electric dipole moments, dark matter constraints, etc.) are imposed. We calculate the CP violating parameters S_{phi K_S}, C_{phi K_S} and A_{phi K^{-+}} as well as the branching ratios (BR) of B^0 and B^{+-}, Br[B -> phi K]. We find for the Standard Model(SM) and mSUGRA it is not possible to account for the observed 2.7 sigma deviation between S_{phi K_S} and S_{J/Psi K_S}. In general the BRs are also in 3 sigma disagreement with experiment, except in the parameter region where the weak annihilation terms dominate the decay (and hence where the theory is least reliable). Thus if future data confirm the current numbers, this would represent the first significant breakdown of both the SM and mSUGRA. We show then that adding a SUGRA non-universal A soft breaking left-right term mixing the second and third generations in either the down or up quark sector, all data can be accommodated for a wide range of parameters. The full 6x6 quark mass matrices are used and the SUSY contributions calculated without approximation.Comment: 22 pages, 3 figures. Added references. Minor changes, to be published in Phys. Rev.

Inflationary perturbations in anisotropic backgrounds and their imprint on the CMB

We extend the standard theory of cosmological perturbations to homogeneous but anisotropic universes. We present an exhaustive computation for the case of a Bianchi I model, with a residual isotropy between two spatial dimensions, which is undergoing complete isotropization at the onset of inflation; we also show how the computation can be further extended to more general backgrounds. In presence of a single inflaton field, there are three physical perturbations (precisely as in the isotropic case), which are obtained (i) by removing gauge and nondynamical degrees of freedom, and (ii) by finding the combinations of the remaining modes in terms of which the quadratic action of the perturbations is canonical. The three perturbations, which later in the isotropic regime become a scalar mode and two tensor polarizations (gravitational wave), are coupled to each other already at the linearized level during the anisotropic phase. This generates nonvanishing correlations between different modes of the CMB anisotropies, which can be particularly relevant at large scales (and, potentially, be related to the large scale anomalies in the WMAP data). As an example, we compute the spectrum of the perturbations in this Bianchi I geometry, assuming that the inflaton is in a slow roll regime also in the anisotropic phase. For this simple set-up, fixing the initial conditions for the perturbations appears more difficult than in the standard case, and additional assumptions seem to be needed to provide predictions for the CMB anisotropies.Comment: 31 pages, 3 figure

Dark Matter Candidates: A Ten-Point Test

An extraordinarily rich zoo of non-baryonic Dark Matter candidates has been proposed over the last three decades. Here we present a 10-point test that a new particle has to pass, in order to be considered a viable DM candidate: I.) Does it match the appropriate relic density? II.) Is it {\it cold}? III.) Is it neutral? IV.) Is it consistent with BBN? V.) Does it leave stellar evolution unchanged? VI.) Is it compatible with constraints on self-interactions? VII.) Is it consistent with {\it direct} DM searches? VIII.) Is it compatible with gamma-ray constraints? IX.) Is it compatible with other astrophysical bounds? X.) Can it be probed experimentally?Comment: 29 pages, 12 figure