|The guiding stars for physics beyond the standard model: Higgs boson and dark matter
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|Speaker : 朱守华 教授 北京大学
Date : 2007-11-27 12:00
Conference Hall 322, ITP/理论物理所322报告厅
Abstract : Physics beyond the standard model is likely hidden in the Higgs sector, which is the least known part of the standard model (SM). Moreover dark matter, which is required by cosmological observations, can be the decay products of the Higgs boson. Because the dark matter is the missing energy at modern detectors like CMS and ATLAS at LHC, the Higgs boson appears as invisible signal. Motivated by these conjectures, we will focus on our recent investigations on Higgs boson and dark matter, which can be divided into four specific topics. Firstly, we will focus on the possible scenario that SM-like Higgs boson evades current direct search at LEP and Tevatron due to the fault of the analysis method. This study is motivated by the Fermilab HyperCP experimental results in 2005. This scenario will alleviate, even eliminate, the tension between information from direct and indirect Higgs search. Secondly, we will discuss the scenario that the singlet scalar acts as the dark matter. If we assume that such kind of dark matter obtains mass solely via electroweak symmetry breaking, the relic density of dark matter and the SM Higgs boson are tightly correlated. The bound of SM Higgs boson is translated into the dark matter mass around 50-80 GeV. This dark matter mass region is consistent with that of W. de Boer, who inferred the dark matter mass from the ERGRET experiments. Thirdly, we propose to study the invisible Higgs boson decay via the Higgs boson pair production, which is commonly thought the useless channel. The final signature is supposed to be di-bottom jets plus missing energy. In the mirror model, this promising search strategy can provide the supplementary information besides other modes. If time permits, we will talk about the fourth topic, namely O(MeV) dark matter at BES in China. This study is originally motivated by the excess of 511 keV photon spectrum from INTEGRAL experiment. We argue that low energy experiments (like BES) maybe the best place to search the dark (invisible) physics beyond the SM. The main reason is due to the highly suppressed backgrounds from neutrino.