Rizwan Khalid

Yukawa Unification and Neutralino Dark Matter in SU(4)(c) x SU(2)(L) x SU(2)(R)

We consider a left-right symmetric SU(4){sub c}xSU(2){sub L}xSU(2){sub R} (4-2-2) model with gravity mediated supersymmetry breaking. We find that with 4-2-2 compatible nonuniversal gaugino masses, t-b-{tau} Yukawa coupling unification is consistent with neutralino dark matter abundance and with constraints from collider experiments (except (g-2){sub {mu}}). The gluino mass lies close to that of the lightest neutralino, so that the gluino coannihilation channel plays an important role in determining the neutralino relic abundance. By relaxing the Yukawa unification constraint we find stau and stop masses as low as 200-220 GeV. We highlight some benchmark points for these cases with 40{<=}tan{beta}{<=}58.

Higgs and sparticle spectroscopy with Gauge-Yukawa unification

We explore the Higgs and sparticle spectroscopy of supersymmetric SU(4)c × SU(2)L × SU(2)R models in which the three MSSM gauge couplings and third family (t-b-τ) Yukawa couplings are all unified at MGUT. This class of models can be obtained via compactification of a higher dimensional theory. Allowing for opposite sign gaugino masses and varying mt within 1σ of its current central value yields a variety of gauge-Yukawa unification as well as WMAP compatible neutralino dark matter solutions. They include mixed bino-Higgsino dark matter, stau and gluino coannihilation scenarios, and the A-resonance solution.

Constrained minimal supersymmetric standard model spectroscopy in light of PAMELA and ATIC observations

Dark matter neutralinos in the constrained minimal supersy mmetric model (CMSSM) may account for the recent cosmic ray electron and positron observations repor t d by the PAMELA and ATIC experiments either through self annihilation or via decay. However, to achieve this, both scenarios require new physics beyond the ‘standard’ CMSSM, and a unified explanation of the two exp eriments suggests a neutralino mass of order 700 GeV 2 TeV. A relatively light neutralino with mass aroun d 100 GeV (300 GeV) can accomodate the PAMELA but not the ATIC observations based on a model of annih ilat ng (decaying) neutralinos. We study the implications of these scenarios for Higgs and sparticle spe ctroscopy in the CMSSM and highlight some benchmark points. An estimate of neutrino flux expected from the an nihilating and decaying neutralino scenarios is provided.

t − b − τ Yukawa unification for μ < 0 with a sub-TeV sparticle spectrum

We show compatibility with all known experimental constraints of t − b − τ Yukawa coupling unification in supersymmetric SU(4)c × SU(2)L × SU(2)R which has non-universal gaugino masses and the MSSM parameter μ < 0. In particular, the relic neutralino abundance satisfies the WMAP bounds and Δ(g − 2)μ is in good agreement with the observations. We identify benchmark points for the sparticle spectra which can be tested at the LHC, including those associated with gluino and stau coannihilation channels, mixed bino-Higgsino state and the A-funnel region. We also briefly discuss prospects for testing Yukawa unification with the ongoing and planned direct detection experiments.

3.5 keV X-ray line and R-parity conserving supersymmetry

A bstractWe present some R-parity conserving supersymmetric models which can accommodate the 3.5 keV X-ray line reported in recent spectral studies of the Perseus galaxy cluster and the Andromeda galaxy. Within the Minimal Supersymmetric Standard Model (MSSM) framework, the dark matter (DM) gravitino (or the axino) with mass of around 7 keV decays into a massless neutralino (bino) and a photon with lifetime ∼ 1028 sec. The massless bino contributes to the effective number of neutrino species Neff and future data will test this prediction. In the context of NMSSM, we first consider scenarios where the bino is massless and the singlino mass is around 7 keV. We also consider quasi-degenerate bino-singlino scenarios where the mass scale of DM particles are O(GeV) or larger. In such a scenario we require the mass gap to generate the 3.5 keV line. We comment on the possibility of a 7 keV singlino decaying via R parity violating couplings while all other neutralinos are heavy.

Coannihilation scenarios and particle spectroscopy in SU(4)c X SU(2)L X SU(2)R

We identify a variety of coannihilation scenarios in a supersymmetric SU(4){sub c}xSU(2){sub L}xSU(2){sub R} model with discrete left-right symmetry. Nonuniversal gaugino masses, compatible with the gauge symmetry, play an essential role in realizing gluino and bino-wino coannihilation regions that are consistent with the WMAP dark matter constraints. We also explore regions of the parameter space in which the little hierarchy problem is partially resolved. We present several phenomenologically interesting benchmark points and the associated sparticle and Higgs mass spectra.

Soft probes of SU(5) unification

We explore the sparticle and Higgs spectroscopy of an SU(5) inspired extension of the constrained minimal supersymmetric standard model. The universal soft parameter

Direct and indirect detection and LHC signals of bino-Higgsino dark matter

{m}_{0}

Top quark and Higgs boson masses in supersymmetric models

is replaced by

CDMS II Inspired Neutralino Dark Matter in Flipped SU(5)

{m}_{\overline{5}}