Observation of a near-threshold enhancement in the Λ Λ ¯ mass spectrum from e+e- →φ Λ Λ ¯ at s from 3.51 to 4.60 GeV OBSERVATION of A NEAR-THRESHOLD ENHANCEMENT in ... M. ABLIKIM et al.

Date Issued
01-09-2021
Author(s)
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.
Baldini Ferroli, R.
Balossino, I.
Ban, Y.
Begzsuren, K.
Berger, N.
Bertani, M.
Bettoni, D.
Bianchi, F.
Bloms, J.
Bortone, A.
Boyko, I.
Briere, R. A.
Cai, H.
Cai, X.
Calcaterra, A.
Cao, G. F.
Cao, N.
Cetin, S. A.
Chang, J. F.
Chang, W. L.
Chelkov, G.
Chen, D. Y.
Chen, G.
Chen, H. S.
Chen, M. L.
Chen, S. J.
Chen, X. R.
Chen, Y. B.
Chen, Z. J.
Cheng, W. S.
Cibinetto, G.
Cossio, F.
Cui, X. F.
Dai, H. L.
Dai, X. C.
Dbeyssi, A.
De Boer, R. E.
Dedovich, D.
Deng, Z. Y.
Denig, A.
Denysenko, I.
Destefanis, M.
De Mori, F.
Ding, Y.
Dong, C.
Dong, J.
Dong, L. Y.
Dong, M. Y.
Dong, X.
Du, S. X.
Fan, Y. L.
Fang, J.
Fang, S. S.
Fang, Y.
Farinelli, R.
Fava, L.
Feldbauer, F.
Felici, G.
Feng, C. Q.
Feng, J. H.
Fritsch, M.
Fu, C. D.
Gao, Y.
Gao, Y.
Gao, Y.
Gao, Y. G.
Garzia, I.
Ge, P. T.
Geng, C.
Gersabeck, E. M.
Gilman, A.
Goetzen, K.
Gong, L.
Gong, W. X.
Gradl, W.
Greco, M.
Gu, L. M.
Gu, M. H.
Gu, S.
Gu, Y. T.
Guan, C. Y.
Guo, A. Q.
Guo, L. B.
Guo, R. P.
Guo, Y. P.
Guskov, A.
Han, T. T.
Han, W. Y.
DOI
Abstract
The process e+e-→φΛΛ¯ is studied using data samples collected with the BESIII detector at the BEPCII Collider at center of mass energies s ranging from 3.51 GeV to 4.60 GeV. An enhancement is observed near the threshold of ΛΛ¯. The lineshape of this enhancement is studied in different approaches, including fit with a Breit-Wigner function or a reversed exponential function. The Breit-Wigner function has a mass of (2262±4±28) MeV/c2 and a width of (72±5±43) MeV, where the quoted uncertainties are statistical and systematic, respectively. The rising rate of the reversed exponential function is measured as 33±11±6 MeV/c2. For the ΛΛ¯ system, the JPC quantum numbers of 0-+ and 0++ are rejected, while other JPC hypotheses are possible, according to the helicity-angle study. The energy-dependent cross section of the e+e-→φΛΛ¯ process is measured for the first time in this energy region, and contributions from excited ψ states and vector charmoniumlike Y-states are investigated.
Volume
104