paper

Observation of a resonant structure near the $D_{s}^{+} D_{s}^{-}$ threshold in the $B^{+} \to D_{s}^{+} D_{s}^{-} K^{+}$ decay

arXiv:2210.15153 · doi:10.1103/PhysRevLett.131.071901

Abstract

An amplitude analysis of the $B^{+} \to D_{s}^{+} D_{s}^{-} K^{+}$ decay is carried out to study for the first time its intermediate resonant contributions, using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV. A near-threshold peaking structure, referred to as $X (3960)$ , is observed in the $D_{s}^{+} D_{s}^{-}$ invariant-mass spectrum with significance greater than 12 standard deviations. The mass, width and the quantum numbers of the structure are measured to be $3956 \pm 5 \pm 10$ MeV, $43 \pm 13 \pm 8$ MeV and $J^{P C} = 0^{++}$ , respectively, where the first uncertainties are statistical and the second systematic. The properties of the new structure are consistent with recent theoretical predictions for a state composed of $c c ˉ s s ˉ$ quarks. Evidence for an additional structure is found around 4140 MeV in the $D_{s}^{+} D_{s}^{-}$ invariant mass, which might be caused either by a new resonance with the $0^{++}$ assignment or by a $J / I ¨ I ¨ \leftrightarrow D_{s}^{+} D_{s}^{-}$ coupled-channel effect.

All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-018.html (LHCb public pages)

Observation of a resonant structure near the Ds+​Ds−​ threshold in the B+→Ds+​Ds−​K+ decay

Abstract

Observation of a resonant structure near the $D_{s}^{+} D_{s}^{-}$ threshold in the $B^{+} \to D_{s}^{+} D_{s}^{-} K^{+}$ decay