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Abstract We propose a novel reformulation of supersymmetric (more precisely μ -) hybrid inflation based on a local U(1) or any suitable extension of the minimal supersymmetric standard model (MSSM) which also resolves the μ problem. We employ a suitable Kahler potential which effectively yields quartic inflation with non-minimal coupling to gravity. Imposing the gravitino Big Bang Nucleosynthesis (BBN) constraint on the reheat temperature (T r ≲ 10 6 GeV) and requiring a neutralino LSP, the tensor to scalar ratio (r) has a lower bound r ≳ 0.004. The U(1) symmetry breaking scale lies between 108 and 1012 GeV. We also discuss a scenario with gravitino dark matter whose mass is a few GeV. [ABSTRACT FROM AUTHOR]

We consider μ -term hybrid inflation which, in its minimal format with gravity mediated supersymmetry breaking, leads to split supersymmetry. The MSSM μ -term in this framework is larger than the gravitino mass m G , and successful inflation requires m G (and hence also | μ | ) ≳ 5 × 10 7 GeV, such that the gravitino decays before the LSP neutralino freezes out. Assuming universal scalar masses of the same order as m G , this leads to split supersymmetry. The LSP wino with mass ≃ 2 TeV is a plausible dark matter candidate, the gluino may be accessible at the LHC, and the MSSM parameter tan ⁡ β ≃ 1.7 in order to be compatible with the measured Higgs boson mass. The tensor-to-scalar ratio r , a canonical measure of gravity waves, can be as high as 0.001. [ABSTRACT FROM AUTHOR]

We present an inflationary model in which the Standard Model Higgs doublet field with non-minimal coupling to gravity drives inflation, and the effective Higgs potential is stabilized by new physics which includes a dark matter particle and right-handed neutrinos for the seesaw mechanism. All of the new particles are fermions, so that the Higgs doublet is the unique inflaton candidate. With central values for the masses of the top quark and the Higgs boson, the renormalization group improved Higgs potential is employed to yield the scalar spectral index n s ≃ 0.968 , the tensor-to-scalar ratio r ≃ 0.003 , and the running of the spectral index α = d n s / d ln ⁡ k ≃ − 5.2 × 10 − 4 for the number of e-folds N 0 = 60 ( n s ≃ 0.962 , r ≃ 0.004 , and α ≃ − 7.5 × 10 − 4 for N 0 = 50 ). The fairly low value of r ≃ 0.003 predicted in this class of models means that the ongoing space and land based experiments are not expected to observe gravity waves generated during inflation. [ABSTRACT FROM AUTHOR]

Abstract: It has been suggested that the dark energy density in the universe is associated with a metastable (false) vacuum, while the true vacuum has a vanishing cosmological constant. By including supergravity corrections we show how this is naturally realized in realistic supersymmetric hybrid inflation models. With a fundamental supersymmetry breaking scale , the LSP is not a suitable candidate for cold dark matter. We consider axion physics to overcome this and simultaneously provide a resolution of the MSSM μ problem. [Copyright &y& Elsevier]

We explore the gravitational wave spectrum generated by string-wall structures in an S O (10) (S p i n (10)) based scenario of pseudo-Goldstone boson dark matter (pGDM) particle. This dark matter candidate is a linear combination of the Standard Model (SM) singlets present in the 126 and 16 dimensional Higgs fields. The Higgs 126-plet vacuum expectation value (VEV) 〈 126 H 〉 leaves unbroken the Z 2 subgroup of Z 4 , the center of S O (10). Among other things, this yields topologically stable cosmic strings with a string tension μ ∼ 〈 126 H 〉 2. The subsequent (spontaneous) breaking of Z 2 at a significantly lower scale by the 16-plet VEV 〈 16 H 〉 leads to the appearance of domain walls bounded by the strings produced earlier. We display the gravitational wave spectrum for Gμ values varying between 10 − 15 and 10 − 9 (〈 126 H 〉 ∼ 10 11 - 1014 GeV), and 〈 16 H 〉 ∼ 0.1 - 102 TeV range (G denotes Newton's constant.) These predictions can be tested, as we show, by a variety of (proposed) experiments including LISA, ET, CE and others. [ABSTRACT FROM AUTHOR]

The DArk Matter Particle Explorer (DAMPE) has reported a measurement of the flux of high energy cosmic ray electrons plus positrons (CREs) in the energy range between 25 GeV and 4.6 TeV . With unprecedented high energy resolution, the DAMPE data exhibit an excess of the CREs flux at an energy of around 1.4 TeV . In this letter, we discuss how the observed excess can be understood in a minimal framework where the Standard Model (SM) is supplemented by a stable SM singlet scalar as dark matter (DM) and type II seesaw for generating the neutrino mass matrix. In our framework, a pair of DM particles annihilates into a pair of the SM SU(2) triplet scalars (Δs) in type II seesaw, and the subsequent Δ decays create the primary source of the excessive CREs around 1.4 TeV . The lepton flavor structure of the primary source of CREs has a direct relation with the neutrino oscillation data. We find that the DM interpretation of the DAMPE excess determines the pattern of neutrino mass spectrum to be the inverted hierarchy type, taking into account the constraints from the Fermi-LAT observations of dwarf spheroidal galaxies. [ABSTRACT FROM AUTHOR]

Abstract: We show that b–τ Yukawa unification can be successfully implemented in the constrained minimal supersymmetric model and it yields the stop co-annihilation scenario. The lightest supersymmetric particle is a bino-like dark matter neutralino, which is accompanied by a 10–20% heavier stop of mass . We highlight some benchmark points which show a gluino with mass , while the first two family squarks and all sleptons have masses in the multi-TeV range. [Copyright &y& Elsevier]

Abstract: The ATLAS experiment has recently presented its search results for final states containing jets and/or b-jet(s) and missing transverse momentum, corresponding to an integrated luminosity of 165 pb−1. We employ this data to constrain a class of supersymmetric models with Yukawa unification, in which the gluino is the next to lightest supersymmetric particle (NLSP). The NLSP gluino is slightly (∼10–30%) heavier than the LSP dark matter neutralino, and it primarily decays into the latter and a quark–antiquark pair or gluon. We find that NLSP gluino masses below ∼300 GeV are excluded by the ATLAS data. For LSP neutralino mass ∼200–300 GeV and , where μ is the coefficient of the MSSM Higgs bilinear term, the LHC constraints in some cases on the spin-dependent (spin-independent) neutralino–nucleon cross section are significantly more stringent than the expected bounds from IceCube DeepCore (Xenon 1T/SuperCDMS). For , this also holds for the spin-dependent cross sections. [Copyright &y& Elsevier]

Abstract: We discuss how the cosmic ray signals reported by the PAMELA and ATIC/PPB-BETS experiments may be understood in a Standard Model (SM) framework supplemented by type II seesaw and a stable SM singlet scalar boson as dark matter. A particle physics explanation of the ‘boost’ factor can be provided by including an additional SM singlet scalar field. [Copyright &y& Elsevier]

Motivated by the recently proposed Trans-Planckian Censorship Conjecture (TCC), we propose a gauged B − L model of inflection-point inflation with axion dark matter. The Hubble scale during inflation (H inf) satisfies the TCC bound of H inf ≲ 1 GeV, the axion dark matter scenario is free from the axion domain wall and isocurvature problems. The seesaw mechanism is automatically incorporated in the model and the observed baryon asymmetry of the universe can be reproduced via resonant leptogenesis. [ABSTRACT FROM AUTHOR]

We consider a U(1) X gauge symmetry extension of the Standard Model (SM) with a Z ′ -portal Majorana fermion dark matter that allows for a relatively light gauge boson Z ′ with mass of 10 MeV− a few GeV and a much heavier dark matter through the freeze-in mechanism. In a second scenario the roles are reversed, and the dark matter mass, in the keV range or so, lies well below the Z ′ mass, say, ∼1 GeV. We outline the parameter space that can be explored for these two scenarios at the future Lifetime Frontier experiments including Belle-II, FASER, LDMX and SHiP. [ABSTRACT FROM AUTHOR]

A gauged U (1) X symmetry appended to the Standard Model (SM) is particularly well motivated since it can account for the light neutrino masses by the seesaw mechanism, explain the origin of baryon asymmetry of the universe via leptogenesis, and help implement successful cosmological inflation with the U (1) X breaking Higgs field as the inflaton. In this framework, we propose a light dark matter (DM) scenario in which the U (1) X gauge boson Z ′ behaves as a DM particle in the universe. We discuss how this scenario with Z ′ mass of a few keV and a U (1) X gauge coupling g X ≃ 10 − 16 can nicely fit the excess in the electronic recoil energy spectrum recently reported by the XENON1T collaboration. In order to reproduce the observed DM relic density in the presence of such a tiny gauge coupling, we propose an extension of the model to a two-component DM scenario. The Z ′ DM density can be comparable to the observed DM density by the freeze-in mechanism through the coupling of Z ′ boson to a partner Higgs-portal scalar DM with a large U (1) X charge. [ABSTRACT FROM AUTHOR]