The Inert Doublet Model relies on a discrete symmetry to prevent couplings of the new scalars to Standard Model fermions. This stabilizes the lightest inert state, which can then contribute to the observed dark matter density. In the presence of additional approximate symmetries, the resulting spectrum of exotic scalars can be compressed. Here, we study the phenomenological and cosmological implications of this scenario. We derive new limits on the compressed Inert Doublet Model from LEP, and outline the prospects for exclusion and discovery of this model at dark matter experiments, the LHC, and future colliders.

The reaction γp → K + has been investigated over the center-of-momentum energy, W , range from threshold up to 2.2 GeV in a tree-level effective Lagrangian model that incorporates most of the well-established baryon resonances with spins equal to or below 5 2 . Four less well-established nucleon resonances of higher mass are also included. The fitted parameters consist, for each resonance included, of the products of the coupling strengths at the electromagnetic and strong interaction vertices and, for the less-established nucleon resonances, of the total decay width. For the well-established nucleon resonances, the energy and momentum dependence of the widths are treated within a dynamical model that is normalized to give the empirical decay branching ratios on the resonance mass shells. For the less-established resonances, the total decay width is treated as a single parameter independent of the reaction kinematics. The model is used to fit recent data for the unpolarized differential cross section (CLAS), the induced hyperon polarization asymmetry, P (CLAS, GRAAL, SAPHIR), the beam spin asymmetry, (LEPS and GRAAL), and the double-polarization observables C x and C z (CLAS). The model results were also compared with LEPS data for the unpolarized differential cross section, but those data were not included in the fit. Two different fits were obtained: one that incorporates SU(3)-symmetry constraints on the Born contributions to the reaction amplitude and one in which these constraints are relaxed. Explicit numerical results are given only for the first fit because the two fits gave nearly identical results for the observables and the χ 2 per degree of freedom obtained with the second fit was only marginally better than that of the first fit (<1% better). Results are presented for the fitted observables at several different energies and center-of-momentum (CM) frame kaon angles.

We present a generalization of the next-to-minimal supersymmetric standard model, with an explicit μ term and a supersymmetric mass for the singlet superfield, as a route to alleviating the little hierarchy problem of the minimal supersymmetric standard model (MSSM). Though this model does not address the μ problem of the MSSM, we are able to generate masses for the lightest neutral Higgs boson up to 140 GeV with top squarks below the TeV scale, all couplings perturbative to the gauge unification scale, and with no need to fine-tune parameters in the scalar potential. This model more closely resembles the MSSM phenomenologically than the canonical next-to-minimal supersymmetric standard model.

Abstract:We study the production of scalar leptoquarks at IceCube, in particular, a particle transforming as a triplet under the weak interaction. The existence of electroweaktriplet scalars is highly motivated by models of grand unification and also within radiative seesaw models for neutrino mass generation. In our framework, we extend the Standard Model by a single colored electroweak-triplet scalar leptoquark and analyze its implications on the excess of ultra-high energy neutrino events observed by the IceCube collaboration. We consider only couplings between the leptoquark to first generation of quarks and first and second generations of leptons, and carry out a statistical analysis to determine the parameters that best describe the IceCube data as well as set 95% CL upper bounds. We analyze whether this study is still consistent with most up-to-date LHC data and various low energy observables.