Tsutomu T. Yanagida

Natural chaotic inflation in supergravity

We propose a chaotic inflation model in supergravity. In the model the Kahler potential has a Nambu-Goldstone-type shift symmetry of the inflaton chiral multiplet which ensures the flatness of the inflaton potential beyond the Planck scale. We show that chaotic inflation naturally takes place by introducing a small breaking term of the shift symmetry in the superpotential. This may open a new branch of model building for inflationary cosmology in the framework of supergravity.

Gravitino dark matter in R-parity breaking vacua

We show that in the case of small R-parity and lepton number breaking couplings, primordial nucleosynthesis, thermal leptogenesis and gravitino dark matter are naturally consistent for gravitino masses m3/25 GeV. We present a model where R-parity breaking is tied to B-L breaking, which predicts the needed small couplings. The metastable next-to-lightest superparticle has a decay length that is typically larger than a few centimeters, with characteristic signatures at the LHC. The photon flux produced by relic gravitino decays may be part of the apparent excess in the extragalactic diffuse gamma-ray flux obtained from the EGRET data for a gravitino mass m3/2 ~ 10 GeV. In this case, a clear signal can be expected from GLAST in the near future.

LEPTOGENESIS IN INFLATON DECAY

Abstract We study a leptogenesis via decays of heavy Majorana neutrinos produced non-thermally in inflaton decays. We find that this scenario is fully consistent with existing supersymmetric inflation models such as for topological or for hybrid inflation and the Froggatt-Nielsen mechanism generating hierarchies in quark and lepton mass matrices. The reheating temperature T R of inflation may be taken as low as T R ≃10 8 GeV to avoid the cosmological gravitino problem.

Leptogenesis in inflationary universe

We investigate leptogenesis via decays of heavy Majorana neutrinos which are produced nonthermally in inflaton decays. We make a comprehensive study on leptogenesis assuming various supersymmetric (SUSY) models for hybrid, new, and topological inflations. For an estimation of the lepton asymmetry we adopt the Froggatt-Nielsen mechanism for mass matrices of quarks and leptons. We find that all of these models are successful in producing enough lepton asymmetry to explain the baryon number in the present universe. Here we impose low reheating temperatures such as

Leptogenesis from (tilde)N-dominated early universe

{T}_{R}\ensuremath{\lesssim}{10}^{8}\mathrm{GeV}

LSND, SN1987A, and CPT violation

in order to suppress the abundance of gravitinos so they do not conflict with big-bang nucleosynthesis. Furthermore, we find that leptogenesis works very well even with

Atmospheric neutrino oscillation and a phenomenological lepton mass matrix

{T}_{R}\ensuremath{\simeq}{10}^{6}\mathrm{GeV}

Chaotic inflation and baryogenesis in supergravity.

in the SUSY hybrid or new inflation model. It is known that such a reheating temperature is low enough to suppress the abundance of gravitinos of mass

Large lepton mixing in a coset-space family unification on E7/SU(5)×U(1)3

{m}_{3/2}\ensuremath{\simeq}100\mathrm{GeV}

Neutrinos at IceCube from Heavy Decaying Dark Matter

\char21{}1 TeV. Thus, leptogenesis is fully consistent with big-bang nucleosynthesis in a wide region of the gravitino mass.