We report the first observation of the Ξ c(2930) 0 charmed-strange baryon with a significance greater than 5σ. The Ξ c(2930) 0 is found in its decay to K-Λc+ in B-→K-Λc+Λ¯c- decays. The measured mass and width are [2928.9±3.0(stat.)-12.0+0.9(syst.)] MeV/c2 and [19.5±8.4(stat.)-7.9+5.9(syst.)] MeV, respectively, and the product branching fraction is B(B-→Ξc(2930)0Λ¯c-)B(Ξc(2930)0→K-Λc+)=[1.73±0.45(stat.)±0.21(syst.)]×10-4. We also measure B(B-→K-Λc+Λ¯c-)=[4.80±0.43(stat.)±0.60(syst.)]×10-4 with improved precision, and search for the charmonium-like state Y(4660) and its spin partner, Yη, in the Λc+Λ¯c- invariant mass spectrum. No clear signals of the Y(4660) nor its spin partner are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. These measurements are obtained from a sample of (772 ± 11) × 10 6BB¯ pairs collected at the Υ (4 S) resonance by the Belle detector at the KEKB asymmetric energy electron–positron collider.
Bibliographical noteFunding Information:
We thank the KEKB group for the excellent operation of the accelerator; the KEK cryogenics group for the efficient operation of the solenoid; and the KEK computer group, the National Institute of Informatics, and the PNNL/EMSL computing group for valuable computing and SINET5 network support. We acknowledge support from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan, the Japan Society for the Promotion of Science (JSPS), and the Tau-Lepton Physics Research Center of Nagoya University; the Australian Research Council; Austrian Science Fund under Grant No. P 26794-N20; the National Natural Science Foundation of China under Contracts No. 10575109, No. 10775142, No. 10875115, No. 11175187, No. 11475187, No. 11521505, No. 11575017 and No. 11761141009; the Chinese Academy of Science Center for Excellence in Particle Physics; Key Research Program of Frontier Sciences, Chinese Academy of Science, Grant No. QYZDJ-SSW-SLH011; the Ministry of Education, Youth and Sports of the Czech Republic under Contract No. LTT17020; the Carl Zeiss Foundation, the Deutsche Forschungsgemeinschaft, the Excellence Cluster Universe, and the VolkswagenStiftung; the Department of Science and Technology of India; the Istituto Nazionale di Fisica Nucleare of Italy; National Research Foundation (NRF) of Korea Grants No. 2014R1A2A2A01005286, No. 2015R1A2A2A01003280, No. 2015H1A2A1033649, No. 2016R1D1A1B01010135, No. 2016K1A3A7A09005603, No. 2016R1D1A1B02012900; Radiation Science Research Institute, Foreign Large-size Research Facility Application Supporting project and the Global Science Experimental Data Hub Center of the Korea Institute of Science and Technology Information; the Polish Ministry of Science and Higher Education and the National Science Center; the Ministry of Education and Science of the Russian Federation and the Russian Foundation for Basic Research; the Slovenian Research Agency; Ikerbasque, Basque Foundation for Science and MINECO (Juan de la Cierva), Spain; the Swiss National Science Foundation; the Ministry of Education and the Ministry of Science and Technology of Taiwan; and the U.S. Department of Energy and the National Science Foundation.
All Science Journal Classification (ASJC) codes
- Engineering (miscellaneous)
- Physics and Astronomy (miscellaneous)