Cosmological moduli problem and thermal inflation models

Abstract

In superstring theories, there exist various dilaton and modulus fields which masses are expected to be of the order of the gravitino mass m 3/2 . These fields lead to serious cosmological difficulties, so called "cosmological moduli problem", because a large number of moduli particles are produced as the coherent oscillations after the primordial inflation. We make a comprehensive study whether the thermal inflation can solve the cosmological moduli problem in the whole modulus mass region m φ ∼ 10 eV-10 4 GeV predicted by both hidden sector supersymmetry (SUSY) breaking and gauge-mediated SUSY breaking models. In particular, we take into account the primordial inflation model whose reheating temperature is so low that its reheating process finishes after the thermal inflation ends. We find that the above mass region m φ (≃ m 3/2 ) ∼ 10 eV-10 4 GeV survives from various cosmological constraints in the presence of the thermal inflation.

Adiabatic suppression of the axion abundance and isocurvature due to coupling to hidden monopoles

“…[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] for recent works.) 2 Thermal inflation is another possible solution to the cosmological moduli problem, where the moduli density is diluted by a mini-inflation around the TeV scale [23][24][25][26]. See refs.…”

“…(3.18) and (3.19). The equations of motion are now given bẏ 26) where (∂E/∂I) m,v (= m) is the frequency of the harmonic oscillator for the case of timeindependent parameters. These are rewritten aṡ…”

A Review of Gravitational Waves from Cosmic Domain Walls

“…After thermal inflation, the thermal effects become irrelevant and the flaton acquires non-zero VEVs, which break Z n symmetry and lead to the formation of domain walls. The domain walls can be annihilated if we introduce an additional term that explicitly breaks Z n symmetry [121,122] or if we assume that the Z n symmetry is anomalous for QCD [55,116]. It was shown that such domain walls can produce a significant amount of GWs if their lifetime is sufficiently long, and the peak frequency typically lies in the range of 10 −6 -10 −3 Hz [116].…”

Moduli-induced baryogenesis

“…In order to have a sizable branching fraction into gluino pair, and also to avoid the overproduction of axionic dark radiation, ξ must be highly suppressed below unity since the saxion coupling to the QCD gauge sector is one-loop suppressed for a given axion decay constant F a . 12 As the precise value of ξ depends on how the PQ scalars are stabilized, let us see the axion models in some detail. The axion models can be categorized according to whether the PQ symmetry is realized linearly or non-linearly.…”

“…As a consequence we have two possibilities for baryogenesis. One is to create a sufficiently large amount of baryon asymmetry before the moduli decay by, e.g., the Affleck-Dine mechanism [9,10], which has been extensively studied in a context of modular cosmology [11][12][13][14][15][16]. The other is to generate baryon asymmetry after the moduli decay.…”