Observation of the $Y(4140)$ structure in the $J/\psi\,\phi$ Mass Spectrum in $B^\pm\to J/\psi\,\phi K$ cays

Abstract

The observation of the $Y(4140)$ structure in $B^\pm\rightarrow J/\psi\,\phi K^\pm$ decays produced in $\bar{p} p $ collisions at $\sqrt{s}=1.96~\TeV$ is reported with a statistical significance greater than 5 standard deviations. A fit to the $J/\psi\,\phi$ mass spectrum is performed assuming the presence of a Breit-Wigner resonance. The fit yields a signal of $19^{+6}_{-5}$ resonance events, and resonance mass and width of $4143.4^{+2.9}_{-3.0}(\mathrm{stat})\pm0.6(\mathrm{syst})~\MeVcc$ and $15.3^{+10.4}_{-6.1}(\mathrm{stat})\pm2.5(\mathrm{syst})~\MeVcc$ respectively. The parameters of this resonance-like structure are consistent with values reported from an earlier CDF analysis.