Coleman-Weinberg Potential In Good Agreement With WMAP

We briefly summarize and update a class of inflationary models from the early eighties based on a quartic (Coleman-Weinberg) potential for a gauge singlet scalar (inflaton) field. For vacuum energy scales comparable to the grand unification scale, the scalar spectral index n_s=0.94-0.97, in very good agreement with the WMAP three year results. The tensor to scalar ratio r<~0.14, while alpha=dn/dlnk is =~-10^-3. An SO(10) version naturally explains the observed baryon asymmetry via non-thermal leptogenesis.Comment: v1: 6 pages, 1 table. v2: minor corrections. v3: 8 pages, added some details, comments, references and 3 figures. v4: minor corrections, published versio

Reheat temperature in supersymmetric hybrid inflation models

The allowed range of parameters for supersymmetric hybrid inflation and its extensions are investigated. The lower bound on the reheat temperature T_r in these models with hierarchical right handed neutrinos is found to be 3*10^7 GeV. (T_r as low as 100 GeV is possible for quasi degenerate right handed neutrinos.) We also present revised estimates for the scalar spectral index and the symmetry breaking scale associated with inflation.Comment: 15 pages, 8 figures, revtex4. v2: minor changes, matches published versio

Non-Canonical MSSM, Unification, And New Particles At The LHC

We consider non-canonical embeddings of the MSSM in high-dimensional orbifold GUTs based on the gauge symmetry SU(N), N=5,6,7,8. The hypercharge normalization factor k_Y can either have unique non-canonical values, such as 23/21 in a six-dimensional SU(7) model, or may lie in a (continuous) interval. Gauge coupling unification and gauge-Yukawa unification can be realized in these models by introducing new particles with masses in the TeV range which may be found at the LHC. In one such example there exist color singlet fractionally charged states.Comment: 1+25 pages, 5 figures. v2: Introduction revised, sections reordered, figure 4 correcte

TeV scale leptogenesis with heavy neutrinos

Following a baryogenesis scenario proposed by Lazarides, Panagiotakopoulos and Shafi, we show how the observed baryon asymmetry can be explained via resonant leptogenesis in a class of supersymmetric models with an intermediate mass scale M_I<~10^9 GeV. It involves the out of equilibrium decay of heavy (<~M_I) right handed neutrinos at a temperature close to the TeV supersymmetry breaking scale. Such models can also resolve the MSSM mu problem.Comment: 1+9 pages, no figure, comments added, minor revisions, to appear in PR