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Observation of a near-threshold enhancement in the e+e- -->Lambda+_(c)Lambda-_(c) cross section using initial-state radiation |
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| Authors: | Pakhlova G Adachi I Aihara H Arinstein K Aulchenko V Aushev T Bakich A M Balagura V Bedny I Bhardwaj V Bitenc U Bondar A Bozek A Bracko M Brodzicka J Browder T E Chang P Chen A Cheon B G Chiang C-C Chistov R Cho I-S Choi S-K Choi Y Dalseno J Danilov M Dash M Eidelman S Gabyshev N Ha H Haba J Hayasaka K Hazumi M Heffernan D Hoshi Y Hou W-S Hsiung Y B Hyun H J Iijima T Inami K Ishikawa A Ishino H Itoh R Iwasaki M Iwasaki Y Kah D H Kang J H Katayama N Kawai H Kawasaki T Kichimi H Kim H J Kim H O Kim S K Kim Y I Kim Y J Kinoshita K Krizan P Krokovny P Kumar R Kuzmin A Kwon Y-J Kyeong S-H |
| Institution: | Institute for Theoretical and Experimental Physics, Moscow. |
| Abstract: | We report a measurement of the exclusive e+ e- -->Lambda+_(c)Lambda-_(c) cross section as a function of center-of-mass energy near the Lambda+_(c)Lambda-_(c) threshold. A clear peak with a significance of 8.2sigma is observed in the Lambda+_(c)Lambda-_(c) invariant mass distribution just above threshold. With an assumption of a resonance origin for the observed peak, a mass and width of M=4634 (+8)_(-7)(stat)(+5)_(-8)(syst)] MeV/c(2) and Gamma_(tot)=92 (+40)_(-24)(stat)(+10)_(-21)(syst)] MeV are determined. The analysis is based on a study of events with initial-state-radiation photons in a data sample collected with the Belle detector at the Upsilon(4S) resonance and nearby continuum with an integrated luminosity of 695 fb(-1) at the KEKB asymmetric-energy e+ e- collider. |
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