Measurement of the cross section for e+e− → ΛΛ-bar and evidence of the decay ψ(3770) → ΛΛ-bar
Measurement of the cross section for e+e− → ΛΛ-bar and evidence of the decay ψ(3770) → ΛΛ-bar
复制标题
e e 的横截面测量和 ÎÎ-bar 的衰减证据 Ï(3770) – ÎÎ-bar
DOI：
10.1103/physrevd.104.l091104
复制
发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Briere R.
中科院分区：
文献类型：
--
作者：
Ablikim M.;Achasov M. N.;Adlarson P.;Ahmed S.;Albrecht M.;Aliberti R.;Amoroso A.;An M. R.;An Q.;Bai X. H.;Bai Y.;Bakina O.;Ferroli R. Baldini;Balossino I;Ban Y.;Begzsuren K.;Berger N.;Bertani M.;Bettoni D.;Bianchi F.;Bloms J.;Bortone A.;Boyko I;Briere R.
利用与北京正负电子对撞机上的−→ΛΛIII探测器收集的总积分光度20.0/fB相对应的数据，在3.51GeV和4.60GeV之间的33个质心能量下测量了过程e+e BAR的玻恩截面。描述截面的能量依赖关系需要ψ(3770)→ΛΛ-bar衰变的贡献，包括系统不确定度在内，该衰变的显著意义为4.64.9σ。在90%的可信度(C.L.)下，其分支分数的下限为2.4×10^-6，至少比根据观测到的电子宽度的标度预测的大一个数量级。这一结果表明，在用电磁结构可观测值来解释数据时，来自向量碳(类)态的影响是重要的。这些数据不允许对与其他矢量碳(类)态的相互作用作出明确的结论，我们为它们的电子宽度和分支分数的乘积设定了90%的C.L.上限。
The Born cross section of the process e+e− → ΛΛ-bar is measured at 33 center-of-mass energies between 3.51 and 4.60 GeV using data corresponding to the total integrated luminosity of 20.0/fb collected with the BESIII detector at the BEPCII collider. Describing the energy dependence of the cross section requires a contribution from the ψ(3770)→ΛΛ-bar decay, which is fitted with a significance of 4.6-4.9σ including the systematic uncertainty. The lower bound on its branching fraction is 2.4×10^-6 at the 90% confidence level (C.L.), at least an order of magnitude larger than expected from predictions using a scaling based on observed electronic widths. This result indicates the importance of effects from vector charmonium(like) states when interpreting data in terms of e.g., electromagnetic structure observables. The data do not allow for definite conclusions on the interplay with other vector charmonium(like) states, and we set 90% C.L. upper limits for the products of their electronic widths and the branching fractions.