Inflation With A Realistic SO(10) Model

We implement inflation within a realistic supersymmetric SO(10) model in which the doublet-triplet splitting is realized through the Dimopoulos-Wilczek mechanism, the MSSM $\mu$ problem is resolved, and higgsino mediated dimension five nucleon decay is heavily suppressed. The cosmologically unwanted topological defects are inflated away, and from $\delta T/ T$, the $B-L$ breaking scale is estimated to be of order $10^{16}-10^{17}$ GeV. Including supergravity corrections, the scalar spectral index $n_s = 0.99\pm 0.01$, with |dn_s/ d{\rm ln}k| \lapproxeq 10^{-3}.Comment: 4 pages. Talk presented by B. Kyae at PASCOS'05, Gyeongju, Korea (May 30 - June 4, 2005), at PPP'05, YITP, Kyoto, Japan (June 20-24, 2005), and at COSMO'05, Bonn, Germany (Aug. 28 - Sept. 1, 2005

Primordial gravitational wave of BICEP2 from dynamical double hybrid inflation

BICEP2 has observed a primordial gravitational wave corresponding to the tensor-to-scalar ratio of 0.16. It seems to require a super-Planckian inflationary model. In this paper, we propose a double hybrid inflation model, where the inflaton potential dynamically changes with the evolution of the inflaton fields. During the first phase of inflation over 7 e-folds, the power spectrum can be almost constant by a large linear term in the hybrid potential, which is responsible also for the large tensor-to-scalar ratio. In the second phase of 50 e-folds, the dominant potential becomes dynamically changed to the logarithmic form as in the ordinary supersymmetric hybrid inflation, which is performed by the second inflaton field. In this model, the sub-Planckian field values (~0.9 M_P) can still yield the correct cosmic observations with the sufficient e-folds.Comment: 12 pages, 1 figure, version to appear in Phys. Lett.