Search

We study the implications of light third generation sparticles on the production cross section and decay widths of a light CP-even Higgs boson. For simplicity, we consider scenarios in which only one of the sfermions from the third generation is light. For each case, we attempt to explain the apparently large enhancement in the Higgs production and decay in the diphoton channel with small deviations in the ZZ channel. In the minimal supersymmetric standard model (MSSM) framework we find that only a light stau can explain these observations while keeping the lightest CP-even Higgs boson mass in the interval 123 GeV ≲ mh ≲ 127 GeV. For the light stop scenario, the observations related to the diphoton and ZZ channel can be accommodated but, in order to satisfy the Higgs mass bound, one needs to go beyond the MSSM. In particular, we invoke vectorlike particles with masses around a TeV. These new particles preserve gauge coupling unification and provide additional contributions to the Higgs mass. With these new contributions a 126 GeV Higgs mass is easily achieved. We also find that with only a light sbottom quark, the above mentioned excess is hard to accommodate. [ABSTRACT FROM AUTHOR]

We examine the low scale particle spectroscopy of an SO(10) [or equivalently SU(5)] inspired supersymmetric model with nonuniversal gaugino masses. The model assumes minimal supergravity and contains the same number of fundamental parameters as the constrained minimal supersymmetric standard model. Realistic solutions compatible with dark matter and other applicable experimental constraints are shown to exist for both positive and negative signs of the minimal supersymmetric standard model parameter μ. We present several benchmark points which will be tested at the LHC and by the ongoing direct and indirect dark matter detection experiments. [ABSTRACT FROM AUTHOR]

We propose a pseudo-Goldstone boson dark matter (pGDM) particle in SO(10) grand unified theory (GUT). Due to its Goldstone nature, this pGDM evades the direct DM detection experiments which, otherwise, severely constrain the parameter space of DM models. In SO(10), the pGDM is embedded as a linear combination of the Standard Model (SM) singlet scalars in 16H and ̅126H representations. We consider two scenarios for the intermediate route of SO(10) symmetry breaking (SB) to the SM: SU(5)×U(1)X and Pati-Salam the SU(4)c×SU(2)L×SU(2)R(4-2-2) gauge groups. The vacuum expectation value of ̅126H, which triggers the breaking of U(1)X and 4-2-2 symmetry in the two scenarios, respectively, determines the pGDM lifetime whose astrophysical lower bound provides one of the most stringent constraints. For the 4-2-2 route to SO(10), the successful SM gauge coupling unification requires the 4-2-2 breaking scale to be O(1011) GeV, and most of the parameter space is excluded. For the SU(5)×U(1)X route, on the other hand, the U(1)X breaking scale can be significantly higher, and a wide range of the parameter space is allowed. Furthermore, the proton lifetime in the SU(5) case is predicted to be 4.53×1034 years, which lies well within the sensitivity reach of the Hyper-Kamiokande experiment. We also examine the constraints on the model parameter space from the Large Hadron Collider and the indirect DM search by Fermi-LAT and MAGIC experiments. [ABSTRACT FROM AUTHOR]

Gauging the global B-L (Baryon number minus Lepton number) symmetry in the standard model (SM) is well motivated since anomaly cancellations require the introduction of three right-handed neutrinos which play an essential role in naturally generating tiny SM neutrino masses through the seesaw mechanism. In the context of the B-L extended SM, we propose a pseudo-Goldstone boson dark matter (DM) scenario in which the imaginary component of a complex B-L Higgs field serves as the DM in the universe. The DM relic density is determined by the SM Higgs boson mediated process, but its elastic scattering with nucleons through the exchange of Higgs bosons is highly suppressed due to its pseudo-Goldstone boson nature. The model is therefore free from the constraints arising from direct DM detection experiments. We identify regions of the model parameter space for reproducing the observed DM density compatible with the constraints from the Large Hadron Collider and the indirect DM searches by Fermi Large Area Telescope and Major Atmospheric Gamma Imaging Cherenkov. [ABSTRACT FROM AUTHOR]

The standard model (SM) supplemented by type II seesaw and a SM gauge-singlet scalar dark matter (DM) is a very simple framework to incorporate the observed neutrino oscillations and provide a plausible DM candidate. In this framework, the scalar DM naturally has a leptophilic nature with a pair annihilating mainly into the SM SU(2)L triplet Higgs scalar of type II Seesaw which, in turn, decay into leptons. In this work, we consider indirect signatures of this leptophilic DM and examine the spectrum of the cosmic ray electron/positron flux from DM pair annihilations in the Galactic halo. Given an astrophysical background spectrum of the cosmic ray electron/positron flux, we find that the contributions from DM annihilations can nicely fit the observed data from the AMS-02, DAMPE and Fermi-LAT collaborations, with a multi-TeV range of DM mass and a boost factor for the DM annihilation cross section of O(1000). The boost factor has a tension with the Fermi-LAT data for gamma-ray from dwarf spheroidal galaxies and the limit from CMB anisotropies, which can be ameliorated with enhanced local DM density by a factor of about two. [ABSTRACT FROM AUTHOR]