Masato Yamanaka

Direct Detection of Vector Dark Matter

In this paper we complete formulae for the elastic cross section of general vector dark matter with nucleon in the direct detection at the leading order of the strong coupling constant, assuming that the dark matter is composed of vector particles. As an application of our formulae, the direct detection of the first Kaluza-Klein photon in the minimal universal extra dimension model is discussed. It is found that the cross section is larger than those in the previous works by up to a factor of ten.

Possible solution to theLi7problem by the long lived stau

Modification of standard big-bang nucleosynthesis is considered in the minimal supersymmetric standard model to resolve the excessive theoretical prediction of the abundance of primordial lithium 7. We focus on the stau as a next-lightest superparticle, which is long lived due to its small mass difference with the lightest superparticle. It provides a number of additional decay processes of {sup 7}Li and {sup 7}Be. A particularly important process is the internal conversion in the stau-nucleus bound state, which destroys the {sup 7}Li and {sup 7}Be effectively. We show that the modification can lead to a prediction consistent with the observed abundance of {sup 7}Li.

Big-bang nucleosynthesis with a long-lived charged massive particle including

We propose helium-4 spallation processes induced by long-lived stau in supersymmetric standard models, and investigate an impact of the processes on light elements abundances. We show that, as long as the phase space of helium-4 spallation processes is open, they are more important than stau-catalyzed fusion and hence constrain the stau property.

^4

The charged lepton flavor violating (CLFV) processes of µ e ! e e decay by four Fermi contact interactions in a muonic atom for various atoms are investigated. The wave functions of bound and scattering state leptons are properly treated by solving Dirac equations with Coulomb interaction of the finite nuclear charge distributions. This new effect contributes significantly in particular for heavier atoms, where the obtained decay rate is about one order of magnitude larger than the previous estimation for 208 Pb. We find that, as the atomic number Z increases, the µ e ! e e decay rates increase more rapidly than the result of the previous work of Z 3 , suggesting this decay as one of the promising processes to search for CLFV interaction.

He spallation processes

We studied allowed region on the intergenerational mixing parameters of sleptons from a viewpoint of big-bang nucleosynthesis in a slepton-neutralino coannihilation scenario. In this scenario,

Improved analyses for

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\mu^-e^-\rightarrow e^-e^-

Li and

in muonic atoms by contact interactions

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Allowed slepton intergenerational mixing in light of light element abundances

Li problems can be solved by considering exotic reactions caused by bound-state effects with a long-lived slepton. Light element abundances are calculated as functions of the relic density and lifetime of the slepton which considerably depend on the intergenerational mixing parameters. Compared with observational light element abundances, we obtain allowed regions on the intergenerational mixing. Ratio of selectron component to stau component,

Tests of a family gauge symmetry model at 103 TeV scale

c_e