Observation of the Decay X(3872)→π0χc1(1P)

Abstract

Using a total of 9.0 fb −1 of e + e − collision data with center-of-mass energies between 4.15 and 4.30 GeV collected by the BESIII detector, we search for the processes e + e − → γX(3872) with X(3872) → π 0 χcJ for J = 0, 1, 2. We report the first observation of X(3872) → π 0 χc1, a new decay mode of the X(3872), with a statistical significance of more than 5σ. Normalizing to the previously established process e + e − → γX(3872) with X(3872) → π + π − J/ψ, we find B(X(3872) → π 0 χc1)/B(X(3872) → π + π − J/ψ) = 0.88 +0.33 −0.27 ±0.10, where the first error is statistical and the second is systematic. We set 90% confidence level upper limits on the corresponding ratios for the decays to π 0 χc0 and π 0 χc2 of 19 and 1.1, respectively.

Decays of X(3872) to χcJπ0 and Zhou1, Yu2, Xiao3 2019Phys. Rev. D

“…The decay rate of Xð3872Þ to χ c1 π 0 is 1 order of magnitude smaller than Xð3872Þ to J=ψπ þ π − in this calculation. Our result is smaller than the central value measured by BESIII [8], but we noticed that the result of BESIII has sizable uncertainties, and more data are needed to increase the statistics and reduce the error bar. In Belle's experiment, no significant evidence of the Xð3872Þ signal was observed in B þ → χ c1 π 0 K þ [9], though its upper limit of BðXð3872Þ→χ c1 π 0 Þ BðXð3872Þ→J=ψπ þ π − Þ does not contradict with BESIII's result.…”

“…[5][6][7]. Recently, the BESIII Collaboration searched for the Xð3872Þ signals in e þ e − → γχ cJ π 0 (J ¼ 0, 1, 2) and reported an observation of Xð3872Þ → χ c1 π 0 with a ratio of branching fractions [8] BðXð3872Þ → χ c1 π 0 Þ BðXð3872Þ → J=ψπ þ π − Þ ¼ 0.88 þ0.33 −0.27 AE 0.10: ð1Þ…”

Search for X(3872) and X(3915) decay into Bhardwaj1, Jia2, Adachi3 et al. 2019Phys. Rev. DSelf Cite

“…The Xð3872Þ has also been seen in other decay modes: D 0DÃ0 , J=ψγ, ψð2SÞγ, and J=ψπ þ π − π 0 [3][4][5][6][7]. Very recently, a new decay mode, χ c1 π 0 , was reported by BESIII [8] in e þ e − → χ c1 π 0 γ. According to their measurement, R X χ c1 =ψ ≡ BðXð3872Þ → χ c1 π 0 Þ=BðXð3872Þ → J=ψπ þ π − Þ ¼ 0.88 þ0.33 −0.27 AE 0.10, where the first uncertainty is statistical and the second is systematic.…”