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تسجيل مستخدم جديدA Search for Charged Excitation of Dark Matter with the KamLAND-Zen Detector
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There are many theories where a dark matter particle is part of a multiplet with an electrically charged state. If WIMP dark matter ($chi^{0}$) is accompanied by a charged excited state ($chi^{-}$) separated by a small mass difference, it can form a stable bound state with a nucleus. In supersymmetric models, the $chi^{0}$ and the $chi^{-}$ could be the neutralino and a charged slepton, such as the neutralino-stau degenerate model. The formation binding process is expected to result in an energy deposition of {it O}(1--10 MeV), making it suitable for detection in large liquid scintillator detectors. We describe new constraints on the bound state formation with a xenon nucleus using the KamLAND-Zen 400 Phase-II dataset. In order to enlarge the searchable parameter space, all xenon isotopes in the detector were used. For a benchmark parameter set of $m_{chi^{0}} = 100$ GeV and $Delta m = 10$ MeV, this study sets the most stringent upper limits on the recombination cross section $langlesigma vrangle$ and the decay-width of $chi^{-}$ of $2.0 times 10^{-31}$ ${rm cm^3/s}$ and $1.1 times 10^{-18}$ GeV, respectively (90% confidence level).
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