118609463
Implications of an astrophysical interpretation of PAMELA and Fermi-LAT data for future searches of a positron signal from dark matter annihilations
The recent data from PAMELA and Fermi-LAT can be interpreted as evidence of new astrophysical sources of high energy positrons. In that case, such astrophysical positrons constitute an additional background against the positrons from dark matter annihilation. In this paper, we study the effect of that background on the prospects for the detection of a positron dark matter signal in future experiments. In particular, we determine the new regions in the (mass, $⟨\ensuremath{\sigma}v⟩$) plane that are detectable by the AMS-02 experiment for several dark matter scenarios and different propagation models. We find that, due to the increased background, these regions feature annihilation rates that are up to a factor of 3 larger than those obtained for the conventional background. That is, an astrophysical interpretation of the present data by PAMELA and Fermi-LAT implies that the detection of positrons from dark matter annihilation is slightly more challenging than previously believed.
7390821
Spectral running and non-Gaussianity from slow-roll inflation in generalized two-field models
Theories beyond the standard model such as string theory motivate low energy effective field theories with several scalar fields which are not only coupled through a potential but also through their kinetic terms. For such theories we derive the general formulae for the running of the spectral indices for the adiabatic, isocurvature and correlation spectra in the case of two-field inflation. We also compute the expected non-Gaussianity in such models for specific forms of the potentials. We find that the coupling has little impact on the level of non-Gaussianity during inflation.
42769057
Conditions for large non-Gaussianity in two-field slow-roll inflation
We study the level of primordial non-Gaussianity in slow-roll two-field inflation. Using an analytic formula for the non-linear parameter fNL in the case of a sum or product separable potential, we find that it is possible to generate significant non-Gaussianity even during slow-roll inflation with Gaussian perturbations at Hubble exit. In this paper we give the general conditions for obtaining large non-Gaussianity and calculate the level of fine-tuning required to obtain this. We present explicit models in which the non-Gaussianity at the end of inflation can exceed the current observational bound of .
119366917
Double suppression of FCNCs in supersymmetric models
A mechanism for double suppression of flavor-changing neutral currents (FCNCs) and CP violating phases in supersymmetric models is suggested. At M{sub SUSY} they are suppressed due to a nonabelian discrete flavor symmetry, and the infrared attractive force of gauge interactions in extra dimensions are used to suppress them at the compactification scale. We present a concrete model, which is a simple extension of S{sub 3} invariant minimal supersymmetric standard model, where only SU(2){sub L} and SU(3){sub C} gauge multiplets are assumed to propagate in the bulk. We find that a disorder of 2 orders of magnitude in soft supersymmetry breaking parameters above the compactification scale may be allowed to satisfy experimental constraints on FCNC processes and CP violating phenomena.
118604242
Quasar polarization with two axionlike particles
Abstract Recently, it was shown, that the absence of circular polarization of visible light from quasars, severely constrains the interpretation of axion like particles (ALPs) as a solution for the generation of the linear polarization. Furthermore, the new observation of the linear polarization in the radio wavelength from quasars, similar to the earlier observation performed in the optical band, makes the ALPs scenario inconsistent with at least one of the two observations. In this study we extend this scenario, to two axion like particles, one scalar and another pseudoscalar. We find, that the effects from scalar and pseudoscalar cancel out each other, thereby suppressing the circular polarization, while preserving consistent linear polarization, as observed in both visible and radio waves bands.
14862395
Softness of brane-localized supersymmetry breaking on orbifolds
Abstract We consider the brane-localized supersymmetry breaking in 5D compactified on S 1 / Z 2 . In case of a bulk gaugino with arbitrary brane masses for its even and odd modes, we find the mass spectrum and the wave functions of gaugino. We show that the gaugino masses at the distant brane are soft in the usual sense in the effective field theory with zero modes of bulk gauge fields and they are also extremely soft in view of the one-loop finite mass of a brane scalar in the KK regularization.
120248095
Axial Properties of Baryon Ground and Resonant States
We report results from a study of axial charges of baryon ground and resonant states with relativistic constituent quark models. In particular, we consider the axial charges of the octet and decuplet baryons N, Σ, Ξ, Δ, Σ*, and Ξ*. The theoretical predictions are compared to experiment, in the case of the N, and to results from other approaches, especially from lattice quantum chromodynamics and chiral perturbation theory. Some remarks are also made regarding the role of axial charges for spontaneous breaking of chiral symmetry.
53991379
Higgs mixing and diphoton rate enhancement in NMSSM models
A bstractWe study the implications of the LHC Higgs signals on the Higgs mixing in the next-to-minimal supersymmetric standard model (NMSSM). The Higgs couplings can depart from their values in the standard model (SM) due to mixing effects. However the Higgs signal rate in the WW and ZZ channels can remain close to the SM values, as observed at the LHC, even if the SM-like Higgs boson with a mass near 125 GeV has a large singlet component. This allows to get a sizable enhancement in the Higgs to diphoton rate through the charged-higgsino loop contribution, as well as a sizable reduction of the Higgs to $ b\overline{b} $ and ττ rates through the mixing effects, with little deviation in the WW and ZZ signal rates from the SM prediction. We find that an enhancement of diphoton signals by a factor of 1.5 or more, and also a reduction of $ b\overline{b} $ and ττ signals by a factor of 0.5, can be obtained in the region of parameter space consistent with the constraints on the higgsino mass parameter and the singlet coupling to the Higgs doublets, which determine the Higgs mixing.
119438711
Unification in intersecting brane models
We propose a unification scenario for supersymmetric intersecting brane models. The quarks and leptons are embedded into adjoint representations of $SO(32)$, which are obtained by type I string and broken by compactification on orbifolds. Its single unified gauge coupling can give rise to different gauge couplings below the unification scale, due to effects of magnetic fluxes. The crucial mechanism is brane recombination preserving supersymmetry.
15756286
Non-Abelian discrete flavor symmetries from magnetized/intersecting brane models
Abstract We study non-Abelian discrete flavor symmetries, which appear in magnetized brane models. For example, D 4 , Δ ( 27 ) and Δ ( 54 ) flavor symmetries can appear with matter fields in several representations. We also study the orbifold background, where non-Abelian flavor symmetries are broken in a certain way.
118237829
UV Completion of Axion
A multiple number of global U(1)s, arising from accidental symmetries up to a certain order of the potential, enjoy lowering the axion decay constant from UV‐scale and evading supersymmetric Fayet–Illiopoulos term constraints.