73 research outputs found

### Affleck-Dine leptogenesis with triplet Higgs

We study an extension of the supersymmetric standard model including a pair
of electroweak triplet Higgs $\Delta$ and ${\bar \Delta}$. The neutrinos
acquire Majorana masses mediated by these triplet Higgs fields rather than the
right-handed neutrinos. The successful leptogenesis for baryogenesis can be
realized after the inflation through the Affleck-Dine mechanism on a flat
manifold consisting of $\Delta$, ${\bar \Delta}$, ${\tilde e}^c$
(anti-slepton), even if the triplet Higgs mass $M_\Delta$ is much larger than
the gravitino mass $m_{3/2} \sim 10^3 {\rm GeV}$. Specifically, due to the
effects of the potential terms provided with the superpotential terms $M_\Delta
{\bar \Delta} \Delta$, $(\lambda_{L /} / 2M) {\bar \Delta} {\bar \Delta} e^c
e^c$, $(\lambda_\Delta / 2M) {\bar \Delta} \Delta {\bar \Delta} \Delta$
($\lambda_{L /} / \lambda_\Delta \sim 0.3 - 3$), the phases of $\Delta$, ${\bar
\Delta}$, ${\tilde e}^c$ are rotated at the time with the Hubble parameter $H
\sim M_\Delta$, producing generally the asymmetry with fraction $\epsilon_L
\sim 0.1$. If $M_\Delta$ is large enough, this early leptogenesis can be
completed before the thermal effects take place.Comment: 11 pages, 2 figure

### Leptogenesis with supersymmetric Higgs triplets in TeV region

The leptogenesis with supersymmetric Higgs triplets is studied in the light
of experimental verification in the TeV region. The lepton number asymmetry
appears just after the inflation via multiscalar coherent evolution of Higgs
triplets and antislepton on a flat manifold. If the Higgs triplet mass terms
dominate over the negative thermal-log term for the Hubble parameter H
comparable to the Higgs triplet mass M_\Delta, the asymmetry is fixed readily
to some significant value by the redshift and rotation of these scalar fields,
providing the sufficient lepton-to-entropy ratio n_L / s \sim 10^-10. This can
be the case even with M_\Delta \sim 1 TeV for the reheating temperature T_R
\sim 10^6 GeV and the mass parameter M / \lambda \sim 10^22 GeV of the
nonrenormalizable superpotential terms relevant for leptogenesis.Comment: 8 Pages, 2 figures. The discussion about the stability of the VEV's
of the Higgs triplets is adde

### Relic abundance of dark matter in the minimal universal extra dimension model

We investigate the relic abundance of dark matter in the minimal universal
extra dimension model including resonance processes by second Kaluza-Klein (KK)
particles in all coannihilation processes. After including second KK resonance
processes, the relic abundance of dark matter is reduced by about 30%. Thus,
the compactification scale 1/R of the extra dimension consistent with the WMAP
observation is increased by a few hundred GeV. As a result, the cosmologically
allowed compactification scale is 600 GeV < 1/R < 1400 GeV for Lambda R = 20.Comment: 24 pages, 7 figure

### The effect of electric current on chemical bonding of hydrogen adsorption on an aluminum nanowire

The effect of electric current on hydrogen adsorption on an aluminum nanowire surface is studied by using nonequilibrium Green's function method. We choose the models studied in the previous work of one of the authors as an aluminum nanowire model and a hydrogen‐adsorbed one. These nanowire models have conductive ability, because the aluminum part of these models is metallic. It is confirmed that electric current affects the strength of the adsorption of hydrogen atoms, and the change of the bonding of hydrogen to aluminum nanowire surface is larger for larger current. However, the change of the chemical bonding is negligibly small within the bias voltage ≤0.5 V

### Solving cosmological problem in universal extra dimension models by introducing Dirac neutrino

Universal extra dimension (UED) models with right-handed neutrinos are
studied. The introduction of the neutrinos makes us possible not only to
describe Dirac neutrino masses but also to solve the cosmological problem
called the KK graviton problem. This problem is essentially caused by the late
time decay of a KK photon into a KK graviton and a photon, and it distorts the
spectrum of the cosmic microwave background or the diffuse photon. We point out
that, once we introduce right-handed neutrinos to UED models, the KK photon
decays dominantly into neutrinos and does not emit a photon. We also discuss
sub-dominant modes with a photon in the decay quantitatively, and show that
their branching ratios are so small that the spectra are not distorted.Comment: Some discussions are added

### The neutrino masses and the change of allowed parameter region in universal extra dimension models

Relic abundance of dark matter is investigated in the framework of universal
extra dimension models with right-handed neutrinos. These models are free from
the serious Kaluza-Klein (KK) graviton problem that the original universal
extra dimension model possesses. The first KK particle of the right-handed
neutrino is a candidate for dark matter in this framework. When ordinary
neutrino masses are large enough such as the degenerate mass spectrum case, the
dark matter relic abundance can change significantly. The scale of the extra
dimension consistent with cosmological observations can be 500 GeV in the
minimal setup of universal extra dimension models with right-handed neutrinos.Comment: 3 pages, to appear in the conference proceedings of TAUP 200

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