Observation of new resonances decaying to J/ψK+ and J/ψϕ

摘要：

The first observation of exotic states with a new quark content cc¯us¯ decaying to the J/ψK+ final state is reported with high significance from an amplitude analysis of the B+→J/ψϕK+ decay. The analysis is carried out using proton-proton collision data corresponding to a total integrated luminosity of 9 fb−1collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV. The most significant state, Zcs(4000)+, has a mass of 4003±6+4−14 MeV, a width of 131±15±26 MeV, and spin-parity JP=1+, where the quoted uncertainties are statistical and systematic, respectively. A new 1+ X(4685) state decaying to the J/ψϕ final state is also observed with high significance. In addition, the four previously reported J/ψϕ states are confirmed and two more exotic states, Zcs(4220)+ and X(4630), are observed with significance exceeding five standard deviations.

报告人简介：
张黎明，2006年于中国科学技术大学近代物理系取得博士学位。2014年加入清华大学工程物理系。近10年主要从事LHCb上的实验研究，在CP破坏的精确测量和奇特强子态的发现上取得显著成果。作为主要贡献者首次发现了五夸克态和含有奇异夸克的四夸克态，证实了夸克模型的预言，丰富了强子谱学研究内容；显著提升了CP破坏相角ϕs的测量精度，对标准模型的CP破坏产生机制进行了精确检验。曾任LHCb合作组“底强子到粲偶素衰变”物理工作组负责人、现任LHCb实验“报告人遴选委员会”成员。

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