Measurements Of Branching Ratio For χ_cJâ†'BB(B∈∧,∑⁰,∑⁺) On Besâ…¢

Charmonium is the Pairs of cc quark bound state formed by strong interaction.The first mem-ber of charmonium family,J/(?) particle,was discovered in1974.Subsequently,so many charmo-nium states were discovered,such as (?)(2S),(?)(3S),(?)(4S),etc,where,(?)(2S)state is the heaviest charmonium state under the DD mass threshold,and it can radiatively decay to positive charge-conjugation parity charmonium state,such as ηc(1s), ηc(2s),XcJ(J=0,1,2).As one important member of charmonium states,XcJ(J=0,1,2)meson,it is essential and important to study the Violation of Helicity Selection Rule(HSR)and the Color Octet Mechanism (COM).According to the earlier theories of QCD,HSR prohibits XcO meson from decaying into the pairs of baryon-antibaryon(pp,AA,∑0∑0.,∑+∑-,Ξ0Ξ0,Ξ-Ξ+),but the observation of XcJ,decaying into baryon anti-baryon pairs indicates that those branching ratios did not vanish.However,the statistic of previous measurements are very low so that the precision of measured branching ratios for XcJ,decays in the previous measurements by other collaborations is not high and even so far many decay channels haven't been observed.Therefore,using the106×106(?)(2s)events collected by BESIII detector at BEPCII,which is about4times of the CLEO-c data sample,the XcJ(J0,1,2)meson decaying into BB(B=A,∑0,∑+)in this article have been studied in detail to further understand and test HSR and COM.And the corresponding branching ratios are measured to be Br(Xc0â†'AA)=(33.3土2.0土2.6)×105, Br(Xc1â†'AA)=(12.2土1.1土1.1)×105, Br(Xc2â†'AA)=(20.8土1.6土2.2)×10-5, Br(Xc0â†'∑0∑0)=(47.8土3.4土3.8)×105, Br(Xc1â†'∑0∑0)=(3.8土1.0土0.5)×10-5, Br(Xc2â†'∑0∑0)=(4.0土1.1土0.4)×105, Br(Xc0â†'∑-∑+)=(45.4土4.2土2.5)×10-5, Br(Xc1â†'∑-∑+)=(5.4土1.5土0.4)×10-5, Br(Xc3â†'∑∑1)=(4.9土1.9土0.6)×105.The BESIII's measurements further improve the Precision of the those decays by comparing with the previous works,and meanwhile we firstly provide the evidence for Xcl,2decays into∑0∑0,∑-∑-with the significance of4.3σ,4.6σ,4.4σand3.0σ.For the decays with more than3σ, we also present their upper limits at90%confidence level by using Bayesian method to be Br(Xc1â†'Σ0Σ0)<6.1×10-5, Br(Xc2â†'Σ0Σ0)<6.4×105, Br(Xc1â†'Σ-Σ+)<8.5×10-5, Br(Xc1â†'Σ-Σ+)<8.6×10-5.