Inflation in Supersymmetric SU(5)

We analyze the adjoint field inflation in supersymmetric (SUSY) SU(5) model. In minimal SUSY SU(5) hybrid inflation monopoles are produced at the end of inflation. We therefore explore the non-minimal model of inflation based on SUSY SU(5), like shifted hybrid, which provides a natural solution for the monopole problem. We find that the supergravity corrections with non-minimal Kahler potential are crucial to realize the central value of the scalar spectral index n_s ~ 0.96 consistent with the seven year WMAP data. The tensor to scalar ratio r is quite small, taking on values r < 10^{-5}. Due to R-symmetry massless SU(3) octet and SU(2) triplet Higgs bosons are present and could spoil for gauge coupling unification. To keep gauge coupling unification intact, light vector-like particles are added which are expected to be observed at LHC.Comment: 16 page

Supersymmetric contributions to B -> D K and the determination of angle \gamma

We analyze supersymmetric contributions to B^- -> D^0 K^- and B^- ->\bar{D}^0 K^- processes. We investigate the possibility that supersymmetric CP violating phases can affect our determination for the angle \gamma in the unitary triangle of Cabibbo-Kobayashi-Maskaw mixing matrix. We calculate the gluino and chargino contributions to b--> u(\bar{c}s) and b-->c(\bar{u}s) transitions in a model independent way by using the mass insertion approximation method. We also revise the D^0 - \bar{D}^0 mixing constraints on the mass insertions between the first and second generations of the up sector. We emphasize that in case of negligible D^0 -\bar{D}^0 mixing, one should consider simultaneous contributions from more than one mass insertion in order to be able to obtain the CP asymmetries of these processes within their 1\sigma experimental range. However, with a large D^0-\bar{D}^0 mixing, one finds a significant deviation between the two asymmetries and it becomes natural to have them of order the central values of their experimental measurements.Comment: 20 page

Quintessential Kination and Thermal Production of SUSY e-WIMPs

The impact of a kination-dominated phase generated by a quintessential exponential model on the thermal abundance of Supersymmetric (SUSY) extremely Weekly Interacting Massive Particles (e-WIMPs) is investigated. For values of the quintessential energy-density parameter on the eve of nucleosynthesis close to its upper bound, we find that: (i) the gravitino constraint is totally evaded for unstable gravitinos; (ii) the thermal abundance of stable gravitinos is not sufficient to account for the cold dark matter of the universe; (iii) the thermal abundance of axinos can satisfy the cold dark matter constraint for values of the initial (``reheating'') temperature well above those required in the standard cosmology.Comment: To appear in the proceedings of 4th International Workshop On The Dark Side Of The Universe (DSU 2008) 1-5 Jun 2008, Cairo, Egyp

On supersymmetric contributions to the CP asymmetry of the B -> phi K_S

We analyse the CP asymmetry of the B -> phi K_S process in general supersymmetric models. In the framework of the mass insertion approximation, we derive model independent limits for the mixing CP asymmetry. We show that chromomagnetic type of operator may play an important role in accounting for the deviation of the mixing CP asymmetry between B -> phi K_S and B -> J/psi K_S processes observed by Belle and BaBar experiments. A possible correlation between the direct and mixing CP asymmetry is also discussed. Finally, we apply our result in minimal supergravity model and supersymmetric models with non-universal soft terms.Comment: 19 pages, 3 figure

Sterile neutrino dark matter in B−LB-L extension of the standard model and galactic 511 keV line

Sterile right-handed neutrinos can be naturally embedded in a low scale gauged $U(1)_{B-L}$ extension of the standard model. We show that, within a low reheating scenario, such a neutrino is an interesting candidate for dark matter. We emphasize that if the neutrino mass is of order of MeV, then it accounts for the measured dark matter relic density and also accommodates the observed flux of 511 keV photons from the galactic bulge.Comment: 10 pages, 1 figure, references added, final version appeared in JCA

Constraining supersymmetric models from B_d - B-bar_d mixing and the B_d --> J/psi K_S asymmetry

We analyze the chargino contributions to B_d - B-bar_d mixing and CP asymmetry of the B_d --> J/psi K_S decay, in the framework of the mass insertion approximation. We derive model independent bounds on the relevant mass insertions. Moreover, we study these contributions in supersymmetric models with minimal flavor violation, Hermitian flavor structure, and small CP violating phases and universal strength Yukawa couplings. We show that in supersymmetric models with large flavor mixing, the observed values of sin(2 beta) may be entirely due to the chargino-up-squark loops.Comment: 22 pages, 1 figure, minor corrections, version to appear in Phys. Rev.

Solving the SUSY CP problem with flavor breaking F-terms

Supersymmetric flavor models for the radiative generation of fermion masses offer an alternative way to solve the SUSY-CP problem. We assume that the supersymmetric theory is flavor and CP conserving. CP violating phases are associated to the vacuum expectation values of flavor violating susy-breaking fields. As a consequence, phases appear at tree level only in the soft supersymmetry breaking matrices. Using a U(2) flavor model as an example we show that it is possible to generate radiatively the first and second generation of quark masses and mixings as well as the CKM CP phase. The one-loop supersymmetric contributions to EDMs are automatically zero since all the relevant parameters in the lagrangian are flavor conserving and as a consequence real. The size of the flavor and CP mixing in the susy breaking sector is mostly determined by the fermion mass ratios and CKM elements. We calculate the contributions to epsilon, epsilon^{prime} and to the CP asymmetries in the B decays to psi Ks, phi Ks, eta^{\prime} Ks and Xs gamma. We analyze a case study with maximal predictivity in the fermion sector. For this worst case scenario the measurements of Delta mK, Delta mB and epsilon constrain the model requiring extremely heavy squark spectra.Comment: 21 pages, RevTex

Fermion Masses and Mixing in Four and More Dimensions

We give an overview of recent progress in the study of fermion mass and flavor mixing phenomena. Mass matrix ansatze are considered within the SM and SUSY GUTs where some predictive frameworks based on SU(5) and SO(10) are reviewed. We describe a variety of schemes to construct quark mass matrices in extra dimensions focusing on four major classes: models with the SM residing on 3-brane, models with universal extra dimensions, models with split fermions and models with warped extra dimensions. We outline how realistic patterns of quark mass matrices could be derived from orbifold models in heterotic superstring theory. Finally, we address the fermion mass problem in intersecting D-branes scenarios, and present models with D6-branes able to give a good quantitatively description of quark masses and mixing. The role of flavor/CP violation problem as a probe of new physics is emphasized.Comment: a review based on seminars presented by S.K. in different places, 34 pages, late