Observation of a near-threshold omega-J/psi mass enhancement in exclusive B-->K omega J/psi decays

TL;DR

The observation of a near-threshold enhancement in the omegaJ/psi invariant mass distribution for exclusive B-->KomegaJ/PSi decays is reported and is estimated to be greater than 8sigma.

Abstract

We report the observation of a near-threshold enhancement in the omega-J/psi invariant mass distribution for exclusive B-->K omega J/psi decays. The results are obtained from a 253 fb-1 data sample that contains 275 million BB-bar meson pairs that were collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+e- collider. The statistical significance of the omega-J/psi mass enhancement is estimated to be greater than 8 sigma.

Figures (4)

• Figure 1: (a)$M_{\rm bc}$ distributions for $B\rightarrow K\omega J/\psi$ candidates in the $\Delta E$ and $\omega\rightarrow\pi^{+}\pi^{-}\pi^0$ signal regions. (b)$\Delta E$ distribution for events in the $M_{\rm bc}$ and $\omega$ signal regions. (c)$M(\pi^{+}\pi^{-}\pi^0)$ distribution for events in the $M_{\rm bc}$ and $\Delta E$ signal regions. The curves are the results of fits described in the text; the arrows indicate the signal region for each quantity.
• Figure 2: Dalitz-plot distribution for $B\rightarrow K\omega J/\psi$ candidate events. The dotted line indicates the boundary of the $M(K\omega)>1.6$ GeV selection requirement.
• Figure 3: $M_{\rm bc}$ distributions for $B^-\rightarrow K^-\omega J/\psi$ candidates in the $\Delta E$ signal region for 40 MeV-wide $\omega J/\psi$ invariant mass intervals. The curves are the results of fits described in the text.
• Figure 4: $B\rightarrow K\omega J/\psi$ signal yields $vs$$M(\omega J/\psi).$ The curve in (a) indicates the result of a fit that includes only a phase-space-like threshold function. The curve in (b) shows the result of a fit that includes an $S$-wave Breit-Wigner resonance term.