22 research outputs found
Supersymmetry preserving and breaking degenerate vacua, and radiative moduli stabilization
We propose a new type of moduli stabilization scenario where the
supersymmetric and supersymmetry-breaking minima are degenerate at the leading
level. The inclusion of the loop-corrections originating from the matter fields
resolves this degeneracy of vacua. Light axions are predicted in one of our
models.Comment: 18 pages, 14 figure
Constraints on small-field axion inflation
We study general class of small-field axion inflations which are the mixture
of polynomial and sinusoidal functions suggested by the natural and axion
monodromy inflations. The axion decay constants leading to the successful axion
inflations are severely constrained in order not to spoil the Big-Bang
nucleosynthesis and overproduce the isocurvature perturbation originating from
the QCD axion. We in turn find that the cosmologically favorable axion decay
constants are typically of order the grand unification scale or the string
scale which is consistent with the prediction of closed string axions.Comment: 17 pages, 6 figures; v2 published versio
Modular invariance and neutrino mixing
We study the phenomenological implications of the modular symmetry of lepton flavors facing recent experimental data of neutrino
oscillations. The mass matrices of neutrinos and charged leptons are
essentially given by fixing the expectation value of modulus , which is
the only source of modular invariance breaking. We introduce no flavons in
contrast with the conventional flavor models with symmetry. We classify
our neutrino models along with the type I seesaw model, the Weinberg operator
model and the Dirac neutrino model. In the normal hierarchy of neutrino masses,
the seesaw model is available by taking account of recent experimental data of
neutrino oscillations and the cosmological bound of sum of neutrino masses. The
predicted is restricted to be larger than and
\delta_{CP}=\pm (50^{\circ}\mbox{--}180^{\circ}). Since the correlation of
and is sharp, the prediction is testable in
the future. It is remarkable that the effective mass of the
neutrinoless double beta decay is around \,meV while the sum of neutrino
masses is predicted to be \,meV. On the other hand, for the inverted
hierarchy of neutrino masses, only the Dirac neutrino model is consistent with
the experimental data.Comment: 17 pages, 6 figures, 5 tables, major modification
Entropy production by domain wall decay in the NMSSM
We consider domain walls in the Z(3) symmetric next-to-minimal supersymmetric standard model. The spontaneous Z(3) discrete symmetry breaking produces domain walls, and the stable domain walls are problematic. Thus, we assume the Z(3) symmetry is slightly but explicitly broken and the domain walls decay. Such a decay causes a large late-time entropy production. We study its cosmological implications on unwanted relics such as the moduli, gravitino, lightest superparticle, and axion
Axion Dark Radiation and its Dilution
Axions in the Peccei-Quinn (PQ) mechanism provide a promising solution to the strong CP problem in the standard model of particle physics. Coherently generated PQ scalar fields could dominate the energy density in the early Universe and decay into relativistic axions, which would conflict with the current dark radiation constraints. We show that a thermal inflation driven by a gauged Higgs field dilutes such axions. We discuss an available baryogenesis mechanism for the gauge symmetry