@article{78b811e9075144529b6898b5858e9436,
title = "Observation of a cross-section enhancement near mass threshold in e + e - → Λ Λ",
abstract = "The process e+e-→ΛΛ is studied using data samples at s=2.2324, 2.400, 2.800 and 3.080 GeV collected with the BESIII detector operating at the BEPCII collider. The Born cross section is measured at s=2.2324 GeV, which is 1.0 MeV above the ΛΛ mass threshold, to be 305±45-36+66 pb, where the first uncertainty is statistical and the second systematic. The cross section near threshold is larger than that expected from theory, which predicts the cross section to vanish at threshold. The Born cross sections at s=2.400, 2.800 and 3.080 GeV are measured and found to be consistent with previous experimental results, but with improved precision. Finally, the corresponding effective electromagnetic form factors of Λ are deduced.",
keywords = "TIME-LIKE REGION, ELECTROMAGNETIC FORM-FACTORS, NEAR-THRESHOLD, P(P)OVER-BAR, BESIII, PROTON",
author = "{BESIII Collaboration} and M. Ablikim and Achasov, {M. N.} and S. Ahmed and Ai, {X. C.} and O. AlbayraK and M. Albrecht and Ambrose, {D. J.} and A. Amoroso and An, {F. F.} and Q. An and Bai, {J. Z.} and O. Bakina and {Baldini Ferroli}, R. and Y. Ban and Bennett, {D. W.} and Bennett, {J. V.} and N. Berger and M. Bertani and D. Bettoni and Bian, {J. M.} and F. Bianchi and E. Boger and I. Boyko and Briere, {R. A.} and H. Cai and X. Cai and O. Cakir and A. Calcaterra and Cao, {G. F.} and Cetin, {S. A.} and J. Chai and Chang, {J. F.} and G. Chelkov and G. Chen and Chen, {H. S.} and Chen, {J. C.} and Chen, {M. L.} and S. Chen and Chen, {S. J.} and X. Chen and Chen, {X. R.} and Chen, {Y. B.} and Chu, {X. K.} and G. Cibinetto and Dai, {H. L.} and Dai, {J. P.} and A. Dbeyssi and D. Dedovich and Muchnoi, {N. Yu} and Nikolaev, {I. B.}",
note = "Funding Information: The BESIII Collaboration thanks the staff of BEPCII, the IHEP computing center and the supercomputing center of USTC for their strong support. This work is supported in part by National Key Basic Research Program of China under Contract No. 2015CB856700; National Natural Science Foundation of China (NSFC) under Contracts No. 11235011, No. 11322544, No. 11335008, No. 11425524, No. 11635010; the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program; the CAS Center for Excellence in Particle Physics (CCEPP); the Collaborative Innovation Center for Particles and Interactions (CICPI); Joint Large-Scale Scientific Facility Funds of the NSFC and CAS under Contracts No. U1232201, No. U1332201, No. U1532257, No. U1532258; CAS under Contracts No. KJCX2-YW-N29, No. KJCX2-YW-N45; 100 Talents Program of CAS; National 1000 Talents Program of China; INPAC and Shanghai Key Laboratory for Particle Physics and Cosmology; German Research Foundation DFG under Contracts No. Collaborative Research Center CRC 1044, No. FOR 2359; Istituto Nazionale di Fisica Nucleare, Italy; Koninklijke Nederlandse Akademie van Wetenschappen (KNAW) under Contract No. 530-4CDP03; Ministry of Development of Turkey under Contract No. DPT2006K-120470; National Natural Science Foundation of China (NSFC) under Contract No. 11505010; The Swedish Resarch Council; U.S. Department of Energy under Contracts No. DE-FG02-05ER41374, No. DE-SC-0010504, No. DE-SC-0010118, No. DE-SC-0012069; U.S. National Science Foundation; University of Groningen (RuG) and the Helmholtzzentrum fuer Schwerionenforschung GmbH (GSI), Darmstadt; WCU Program of National Research Foundation of Korea under Contract No. R32-2008-000-10155-0.",
year = "2018",
month = feb,
day = "1",
doi = "10.1103/PhysRevD.97.032013",
language = "English",
volume = "97",
journal = "Physical Review D",
issn = "2470-0010",
publisher = "AMER PHYSICAL SOC",
number = "3",
}