No abstract

In their minimal form both supersymmetric and smooth hybrid inflation yield a scalar spectral index n s close to 0.98, to be contrasted with the result n s = 0.951 +0.015 −0.019 from WMAP3. To realize better agreement, following Ref.[1], we extend the parameter space of these models by employing a non-minimal Kähler potential. We also discuss non-thermal leptogenesis by inflaton decay and obtain new bounds in these models on the reheat temperature to explain the observed baryon asymmetry.

We investigate the impact of TeV-scale matter belonging to complete vectorlike multiplets of unified groups on the lightest Higgs boson in the MSSM. We find that consistent with perturbative unification and electroweak precision data the mass m h can be as large as 160 GeV. These extended MSSM models can also render the little hierarchy problem less severe, but only for lower values of m h ( 125) GeV. We present estimates for the sparticle mass spectrum in these models.

We discuss the important role played during inflation by one of the soft supersymmetry breaking terms in the inflationary potential of supersymmetric hybrid inflation models. With minimal Kähler potential, the inclusion of this term allows the prediction for the scalar spectral index to agree with the value n s = 0.963 +0.014 −0.015 found by WMAP5. In the absence of this soft term, and by taking into account only radiative and supergravity corrections, it is well known that n s ≥ 0.985. This same soft term has previously been shown to play a key role in resolving the MSSM µ problem. The tensor to scalar ratio r is quite small in these models, taking on values r ≤ 10 −5 in the WMAP5 2σ range of n s .

We employ Coleman-Weinberg and Higgs potentials to implement inflation in nonsupersymmetric grand unified theories (GUTs) such as SU(5) and SO(10). To realize a scalar spectral index close to 0.96, as indicated by the most recent WMAP 5-year anlaysis, the energy scale of observable inflation turns out to be of order 10 16 GeV. This implies a GUT symmetry breaking scale of similar magnitude, and proton lifetime of order 10 34 -10 38 years. In some SO(10) models with axion dark matter, the scalar leptoquark boson exchange leads to proton decay with a lifetime of order 10 34 -10 35 years.