学术报告（9月21日下午14:00-15:00

主持人：尤郑昀 教授

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报告人简介：

易凯 博士，2004年在美国Johns Hopkins University 获得粒子物理博士学位，之后在美国斯坦福直线加速器国家实验室从事博士后研究，2012年起在University of Iowa 任Research Scientist，2014年受聘为Adjunct Assistant Professor。

先后参与了美国费米国家实验室Tevatron上的CDF实验，美国斯坦福直线加速器国家实验室SLAC上的Babar实验，目前从事欧洲核子中心(CERN)大强子对撞机上CMS实验的新强子研究。

From J/ψ Phi to 4-lepton Mass Spectrum

Dr. Kai Yi

The discovery of numerous new Charmonium-like structures since 2003 have revitalized interest in exotic meson spectroscopy. These structures do not fit easily into the conventional Charmonium model, and proposals like four-quark states, hybrids, and rescattering effects have been suggested as explanations. Since 2009, several new structures were reported in the J/psi+phi mass spectrum with the following characteristics: they are the first ones reported decaying into two heavy mesons which contain both a cc¯ pair and a ss¯ pair; and their masses are well beyond the open charm pair threshold. Conventional cc¯ states with a mass beyond the J/psi+phi threshold are not expected to decay into this channel and the width is expected to be large, thus they are good candidates for exotic mesons. The development on the structures in the J/psi+phi mass spectrum from CDF, LHCb, CMS, D0 and Babar etc will be reviewed, and further prospect at LHC will be outlined.