Abstract
The 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 per nucleon pair, using the decay chain . The data were recorded with the CMS detector in 2018 and correspond to an integrated luminosity of . The measurement is performed in the rapidity and transverse momentum ranges and . The significance of the inclusive X(3872) signal is 4.2 standard deviations. The prompt X(3872) to yield ratio is found to be , to be compared with typical values of 0.1 for 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.
- Received 25 February 2021
- Revised 2 September 2021
- Accepted 22 December 2021
DOI:https://doi.org/10.1103/PhysRevLett.128.032001
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