KAI-FENG CHENRONG-SHYANG LU2022-04-252022-04-252022319007https://www.scopus.com/inward/record.uri?eid=2-s2.0-85123710396&doi=10.1103%2fPhysRevLett.128.032001&partnerID=40&md5=c6ec0d43d202a45b6ce9d7f79079215bhttps://scholars.lib.ntu.edu.tw/handle/123456789/606496The first evidence for X(3872) production in relativistic heavy ion collisions is reported. The X(3872) production is studied in lead-lead (Pb-Pb) collisions at a center-of-mass energy of sNN=5.02 TeV per nucleon pair, using the decay chain X(3872)→J/ψπ+π-→μ+μ-π+π-. The data were recorded with the CMS detector in 2018 and correspond to an integrated luminosity of 1.7 nb-1. The measurement is performed in the rapidity and transverse momentum ranges |y|<1.6 and 15<pT<50 GeV/c. The significance of the inclusive X(3872) signal is 4.2 standard deviations. The prompt X(3872) to ψ2S yield ratio is found to be ρPb-Pb=1.08±0.49(stat)±0.52(syst), to be compared with typical values of 0.1 for pp collisions. This result provides a unique experimental input to theoretical models of the X(3872) production mechanism, and of the nature of this exotic state. ? 2022 CERN.Colliding beam accelerators; Heavy ions; Lead alloys; Tellurium compounds; A-center; Center-of-mass energies; Centre-of-mass energies; CMS detectors; Decay chains; Integrated luminosity; Momentum range; Pb-Pb collisions; Relativistic heavy ion collision; Transverse momenta; Binary alloysjournal article10.1103/PhysRevLett.128.032001351198782-s2.0-85123710396