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We consider a simplified version of supersymmetric smooth hybrid inflation which contains a single ultraviolet cutoff mP = 2.4 × 1018 GeV, instead of the two cutoffs mP and M* ∼ few × 1017 GeV that are normally employed. With global supersymmetry the scalar spectral index ns ≃ 0.97, which is in very good agreement with the WMAP observations. With a nonminimal Kahler potential, the supergravity version of the model is compatible with the current central values of ns and also yields potentially observable gravity waves (tensor to scalar ratio r ≲ 0.02). [ABSTRACT FROM AUTHOR]

We present a successful inflation model based on λφ4 potential in which a standard model (SM) singlet inflaton φ, with mass of around a TeV or less, also plays the role of a weakly interacting scalar dark matter particle (WIMP). The WIMP relic abundance generated after inflation is in accord with the current observations. The spectral index ns lies within the Wilkinson Microwave Anisotropy Probe (WMAP) satellite 1-σ bounds, while the Planck satellite may observe the tensor-to-scalar ratio, a canonical measure of gravity waves, which we estimate lies between 0.003 and 0.007. An unbroken Z2 parity ensures that the scalar WIMP is absolutely stable. [ABSTRACT FROM AUTHOR]

It is shown that a tensor-to-scalar ratio close to r = 0.03, which can be observed by Planck, is realized in supersymmetric hybrid inflation models with TeV-scale soft supersymmetry breaking terms. This extends our previous analysis, which also found r ≲ 0.03 but employed intermediate scale soft terms. Other cosmological observables such as the scalar spectral index are in good agreement with the WMAP data. [ABSTRACT FROM AUTHOR]

We investigate the impact of Coleman-Weinberg inflation on the stochastic gravity wave background spectrum emitted by intermediate-scale cosmic strings. The string network is partially inflated and reenters the horizon at later times after the end of inflation, such that the short string loops are not produced. This leads to a significant modification of the gravity wave spectrum that we explore in detail. We find that Coleman-Weinberg inflation can help to satisfy the Parkes Pulsar Timing Array (PPTA) bound for dimensionless string tension values in the range Gμ1.1×10-10. We also identify the modified gravity wave spectra which, in the case of inflation, are compatible with the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) data. We then discuss the formation of monopoles and strings at the same breaking scale and the compatibility of the Monopole, Astrophysics and Cosmic Ray Observatory (MACRO) bound with the PPTA bound, and also with the NANOGrav data. Finally, an example of a realistic nonsupersymmetric E6 model incorporating successful Coleman-Weinberg inflation is presented in which monopoles and strings both survive inflation and are present at an observable level. [ABSTRACT FROM AUTHOR]

We investigate supersymmetric hybrid inflation in a realistic model based on the gauge symmetry SU(4)c×SU(2)L×SU(2)R. The minimal supersymmetric standard model (MSSM) μ term arises, following Dvali, Lazarides, and Shafi, from the coupling of the MSSM electroweak doublets to a gauge singlet superfield, which plays an essential role in inflation. The primordial monopoles are inflated away by arranging that the SU(4)c×SU(2)L×SU(2)R symmetry is broken along the inflationary trajectory. The interplay between the (above) μ coupling, the gravitino mass, and the reheating following inflation is discussed in detail. We explore regions of the parameter space that yield gravitino dark matter and observable gravity waves with the tensor-to-scalar ratio r∼10-4-10-3. [ABSTRACT FROM AUTHOR]