Particle production and dissipative cosmic field

Large amplitude oscillation of cosmic field that may occur right after inflation and in the decay process of weakly interacting fields gives rise to violent particle production via the parametric resonance. In the large amplitude limit the problem of back reaction against the field oscillation is solved and the energy spectrum of created particles is determined in a semi-classical approximation. For large enough coupling or large enough amplitude the resulting energy spectrum is broadly distributed, implying larger production of high energy particles than what a simple estimate of the reheating temperature due to the Born formula would suggest

Production of massive stable particles in inflaton decay

We point out that inflaton decays can be a copious source of stable or long--lived particles $\chi$ with mass exceeding the reheat temperature $T_R$. Once higher order processes are included, this statement is true for any $\chi$ particle with renormalizable (gauge or Yukawa) interactions. This contribution to the $\chi$ density often exceeds the contribution from thermal $\chi$ production, leading to significantly stronger constraints on model parameters than those resulting from thermal $\chi$ production alone. For example, we all but exclude models containing stable charged particles with mass less than half the mass of the inflaton.Comment: 4 revtex pages, 1 figure (uses axodraw). Slightly modified for better clarification, few changes in references. Final verssion published in Phys. Rev. Let

A New Inflation Model with Anomaly-mediated Supersymmetry Breaking

If there are a large number of vacua, multi-inflation may be a more mediocre phenomenon rather than a single inflation. In the multi-inflation scenario, new inflation is most likely the last inflation, since its energy scale is naturally low. Furthermore, it may explain the observed spectral index of the cosmic microwave background radiations. We show, in this letter, that a new inflation model proposed in supergravity accounts for all the present observations assuming anomaly mediation of supersymmetry breaking. As a result, we find that the relic density of the winos is consistent with the observed dark matter density in a wide range of the wino mass, 100 GeV lsim m_{tilde{w}} lsim 2 TeV, albeit for a low reheating temperature T_{R} simeq 10^{6-7},GeV.Comment: 14 pages, 4 figures, the title is correcte

Particle Production and Gravitino Abundance after Inflation

Thermal history after inflation is studied in a chaotic inflation model with supersymmetric couplings of the inflaton to matter fields. Time evolution equation is solved in a formalism that incorporates both the back reaction of particle production and the cosmological expansion. The effect of the parametric resonance gives rise to a rapid initial phase of the inflaton decay followed by a slow stage of the Born term decay. Thermalization takes place immediately after the first explosive stage for a medium strength of the coupling among created particles. As an application we calculate time evolution of the gravitino abundance that is produced by ordinary particles directly created from the inflaton decay, which typically results in much more enhanced yield than what a naive estimate based on the Born term would suggest.Comment: 23 pages + 13 figure

Dark Matter and Baryon Asymmetry of the Universe in Large-Cutoff Supergravity

We propose a consistent scenario of the evolution of the universe based on the large cutoff supergravity (LCSUGRA) hypothesis of supersymmetry breaking, where the gravitino and sfermion become as heavy a $\sim O(1-10 {\rm TeV})$. With such a heavy gravitino, baryon asymmetry of the universe can be generated by the non-thermal leptogenesis via an inflaton decay without conflicting the serious gravitino problem. We also see that, in the LCSUGRA scenario, relic density of the lightest superparticle becomes consistent with the WMAP value of the dark matter density in the parameter region required for the successful non-thermal leptogenesis.Comment: 13 pages, 2 figure

Dynamical Tuning of the Initial Condition for New Inflation in Supergravity

We point out that for a class of `new inflation' models in supergravity the required initial value of the inflaton field is dynamically set if there is another inflation (`pre-inflation') before the `new inflation'. We study the dynamics of both inflatons by taking a hybrid inflation model for the `pre-inflation' as an example. We find out that our `new inflation' model provides reheating temperatures T_R \simeq 10 MeV - 10^4 GeV low enough to avoid the gravitino problem even in gauge-mediated supersymmetry-breaking models. We also construct a model where the scale for the `new inflation' is generated by nonperturbative dynamics of a supersymmetric gauge theory.Comment: 16 pages, late

The Polonyi Problem and Upper bound on Inflation Scale in Supergravity

We reconsider the Polonyi problem in gravity-mediation models for supersymmetry (SUSY) breaking. It has been argued that there is no problem in the dynamical SUSY breaking scenarios, since the Polonyi field acquires a sufficiently large mass of the order of the dynamical SUSY-breaking scale Lamada_{SUSY}. However, we find that a linear term of the Polonyi field in the Kahler potential brings us back to the Polonyi problem, unless the inflation scale is sufficiently low, H_{inf} < 10^{8} GeV, or the reheating temperature is extremely low, T_{R} < 100 GeV. Here, this Polonyi problem is more serious than the original one, since the Polonyi field mainly decays into a pair of gravitinos.Comment: 17 pages, 1 figure, minor corrections, published versio

A Higher-dimensional Origin of the Inverted Mass Hierarchy for Neutrino

We present successful lepton mass matrices with an inverted mass hierarchy for neutrinos, which follow from a geometrical structure of a (1+5) dimensional space-time where two extra dimensions are compactified on the T^2/Z_3 orbifold. A 5^* and a right-handed neutrino N in each family are localized on each of the equivalent three fixed points of the orbifold while three 10's and Higgs doublets H_u and H_d live in the bulk. An S_3 family symmetry is assumed on three 5^*'s and on three N's, since the three fixed points are equivalent to one another. The Higgs field \phi responsible for the B-L breaking is localized on one of the three fixed points, which generates the inverted hierarchy for the neutrino masses. The baryon asymmetry is well explained in the non-thermal leptogenesis via inflaton decay. We emphasize that the present model predicts the effective neutrino mass, _{ee}, responsible for neutrinoless double beta decays as _{ee}\simeq 50 meV. This will be accessible to future experiments.Comment: 15 page

Baryogenesis and Gravitino Dark Matter in Gauge-Mediated Supersymmetry-Breaking Models

We discuss two cosmological issues in a generic gauge-mediated supersymmetry (SUSY)-breaking model, namely the Universe's baryon asymmetry and the gravitino dark-matter density. We show that both problems can be simultaneously solved if there exist extra matter multiplets of a SUSY-invariant mass of the order of the ``$\mu$-term'', as suggested in several realistic SUSY grand-unified theories. We propose an attractive scenario in which the observed baryon asymmetry is produced in a way totally independent of the reheating temperature of inflation without causing any cosmological gravitino problem. Furthermore, in a relatively wide parameter space, we can also explain the present mass density of cold dark matter by the thermal relics of the gravitinos without an adjustment of the reheating temperature of inflation. We point out that there is an interesting relation between the baryon asymmetry and the dark-matter density.Comment: 20 pages, 2 figure

Low-scale supergravity inflation with R-symmetry

We study a supergravity model of inflation with R-symmetry and a single scalar field, the inflaton, slowly rolling away from the origin. The scales of inflation can be as low as the supersymmetry breaking scale of 10^10 GeV or even the electroweak scale of 10^3 GeV which could be relevant in the context of theories with submillimiter dimensions. Exact analytical solutions are presented and a comparison with related models is given.Comment: 11 pages, 3 figures; added discussion and references in section 2; corrected Eqs. 24 and 26; minor corrections in the table and figures; one fig. added in section 1. Accepted for publication in Physics Letters