Lepton Energy Asymmetry and Precision SUSY study at Hadron Colliders

We study the distribution of lepton pairs from the second lightest neutralino decay \tilde{\chi}^0_2-->\tilde{l}l followed by \tilde{l}\to \tilde{\chi}^0_1 l. The distribution of the ratio of lepton transverse momenta A_T shows peak structure if m_{ll}< m^{max}_{ll}/2 is required. The peak position A_T^{peak} is described by a simple function of the ino and slepton masses in the m_{ll}\sim 0 limit. When a moderate m_{ll} cut is applied, A_T^{peak} depends on the \tilde{\chi}^0_2 velocity distribution, but the dependence would be corrected by studying the lepton P_T distribution. A_T^{peak} and the edge of m_{ll} distributions are used to determine the mass parameters involved in the decay for parameters of interest to LHC experiments. For some cases the ino and slepton masses may be determined within 10% by the lepton distribution only independent of model assumptions. Correct combinations of A_{T}^{peak} and m_{ll}^{edge} would be identified even if different \tilde{\chi}^0_2 decay chains are co-existing. The analysis could be extended to the Tevatron energy scale or other cascade decays.Comment: 31 pages, 15 figure

Scrutinizing LSP Dark Matter at the LHC

We show that LHC experiments might well be able to determine all the parameters required for a prediction of the present density of thermal LSP relics from the Big Bang era. If the LSP is an almost pure bino we usually only need to determine its mass and the mass of the SU(2) singlet sleptons. This information can be obtained by reconstructing the cascade $\tilde{q}_L \to \tilde{\chi}_2^0 q \to \tilde{\ell}_R \ell q \to \tilde{\chi}_1^0 \ell^+ \ell^- q$. The only requirement is that $m_{\tilde{\ell}_R} < m_{\tilde{\chi}_2^0}$, which is true for most of the cosmologically interesting parameter space. If the LSP has a significant higgsino component, its predicted thermal relic density is smaller than for an equal--mass bino. We show that in this case squark decays also produce significant numbers of $\tilde{\chi}_4^0$ and $\tilde{\chi}_2^\pm$. Reconstructing the corresponding decay cascades then allows to determine the higgsino component of the LSP

アタラシイハドロンスキームニヨルバリオンキョウメイジョウタイノホウカイ

京都大学0048新制・論文博士理学博士乙第3266号論理博第564号新制||理||244(附属図書館)5163UT51-52-L83(主査)教授 田中 正, 教授 町田 茂, 教授 三宅 弘三学位規則第5条第2項該当Kyoto UniversityDA

Genealogy of Modern Physics : From Einstein to Yukawa and Tomonaga

この論文は国立情報学研究所の電子図書館事業により電子化されました

基研：大学共同利用研究所の誕生

第Ⅰ部　研究会「大学共同利用研究所・研究機関の成立」 第１章登谷　美穂子［京都大学理学研究科