Mihoko M. Nojiri

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High-precision analyses of supersymmetry parameters aim at reconstructing the fundamental supersymmetric theory and its breaking mechanism. A well defined theoretical framework is needed when higher-order corrections are included. We propose such a scheme, Supersymmetry Parameter Analysis SPA, based on a consistent set of conventions and input parameters. A(More)
We propose an inclusive analysis of a stransverse mass (mT2) using a hemisphere method for supersymmetry studies at the LHC . The hemisphere method is an algorithm to group collinear and high pT particles and jets, assuming that there are two of such groups in a event. The mT2 is defined as a function of the unknown LSP mass, two hemisphere momenta, and(More)
Detection of gamma rays from dark matter annihilation in the galactic center is one of the feasible techniques to search for dark matter. We evaluate the gamma ray flux in the case that the dark matter has an electroweak SU(2)L charge. Such dark matter is realized in the minimal supersymmetric standard model (MSSM) when the lightest SUSY particle is the(More)
The ATLAS and CMS experiments at the Large Hadron Collider (LHC) may discover the squarks (q̃) and gluino (g̃) of the minimal supersymmetric standard model (MSSM) in the early stage of the experiments if their masses are lighter than 1.5 TeV. In this paper we propose the sub-system mT2 variable (m sub T2 ), which is sensitive to the gluino mass when mq̃ >(More)
We study the distribution of lepton pairs from the second lightest neutralino decay χ̃2 → l̃l followed by l̃ → χ̃ 0 1l. The distribution of the ratio of lepton transverse momenta AT shows peak structure if mll < ∼ m max ll /2 is required. The peak position A peak T is described by a simple function of the ino and slepton masses in the mll ∼ 0 limit. When a(More)
We study the production and decay of a scalar (t̃1t̃ ∗ 1) bound state σt̃1 at hadron supercolliders, where t̃1 is the lighter stop eigenstate. If t̃1 has no tree–level 2–body decays, the dominant decay modes of σt̃1 are gg or, if mh < mt̃1 ≪ mt̃2 , a pair of light scalar Higgs bosons h. Nevertheless the branching ratio into two photons is often large enough(More)
1550-7998=20 We propose a new mass reconstruction technique for SUSY processes at the LHC. The idea is to completely solve the kinematics of the SUSY cascade decay by using the assumption that the selected events satisfy the same mass shell conditions of the sparticles involved in the cascade decay. Using this technique, we study the measurement of the mass(More)
In this Letter we study pair annihilation processes of dark matter (DM) in the Universe, in the case that the DM is an electroweak gauge nonsinglet. In the current Universe, in which the DM is highly nonrelativistic, the nonperturbative effect may enhance the DM annihilation cross sections, especially for that to two photons, by several orders of magnitude.(More)