Search for double charmonium decays of theP-wave spin-triplet bottomonium states

Abstract

Using a sample of 158 million Υ(2S) events collected with the Belle detector, we search for the first time for double charmonium decays of the P -wave spin-triplet bottomonium states (Υ(2S) → γχ bJ , χ bJ → J/ψJ/ψ, J/ψψ ′ , ψ ′ ψ ′ for J = 0, 1, and 2). No significant χ bJ signal is observed in the double charmonium mass spectra, and we obtain the following upper limits, B(χ bJ → J/ψJ/ψ) < 7.1×10 −5 , 2.7 × 10 −5 , 4.5 × 10 −5 , B(χ bJ → J/ψψ ′ ) < 1.2 × 10 −4 , 1.7 × 10 −5 , 4.9 × 10 −5 , B(χ bJ → ψ ′ ψ ′ ) < 3.1×10 −5 , 6.2×10 −5 , 1.6×10 −5 for J = 0, 1, and 2, respectively, at the 90% confidence level. These limits are significantly lower than the central values (with uncertainties of 50% to 70%) predicted using the light cone formalism but are consistent with calculations using the NRQCD factorization approach.

Exclusive decay ofΥintoJ/ψ+χc0,1,2

“…As a matter of fact, this method has already been used by the BELLE collaboration to impose the upper bound for the exclusive bottomonium decays b0;1;2 ! J=c J=c ; J=c c 0 [54].…”

Evidence of $Υ(1S) \to J/ψ+χ_{c1}$ and search for double-charmonium production in $Υ(1S)$ and $Υ(2S)$ decays

“…Several theoretical calculations have focused on these processes in perturbative QCD, e.g., η b → J/ψJ/ψ [22][23][24][25] and χ b0,1,2 → J/ψJ/ψ [26][27][28][29]. Experimentally, however, such studies are extremely sparse, apart from the recent searches for several channels of χ bJ into double charmonia for the first time by the Belle Collaboration [30]. The measurements are consistent with NRQCD predictions, though no significant signals are observed; it is reasonable to extend the search for double-charmonium production to the C-odd Υ decays.…”