Observation of a cross-section enhancement near mass threshold in e + e − → Λ Λ

The process e+e- → Λ Λ ¯ 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 Λ Λ ¯ mass threshold, to be 305±$45_{-36}^{+66}$ pb,...

Ausführliche Beschreibung

Gespeichert in:

Bibliographische Detailangaben
Veröffentlicht in:	Physical review. D 2018-02, Vol.97 (3), Article 032013
Hauptverfasser:	Ablikim, M., Achasov, M. N., Ahmed, S., Ai, X. C., Albayrak, O., Albrecht, M., Ambrose, D. J., Amoroso, A., An, F. F., An, Q., Bai, J. Z., Bakina, O., Baldini Ferroli, R., Ban, Y., Bennett, D. W., Bennett, J. V., Berger, N., Bertani, M., Bettoni, D., Bian, J. M., Bianchi, F., Boger, E., Boyko, I., Briere, R. A., Cai, H., Cai, X., Cakir, O., Calcaterra, A., Cao, G. F., Cetin, S. A., Chai, J., Chang, J. F., Chelkov, G., Chen, G., Chen, H. S., Chen, J. C., Chen, M. L., Chen, S., Chen, S. J., Chen, X., Chen, X. R., Chen, Y. B., Chu, X. K., Cibinetto, G., Dai, H. L., Dai, J. P., Dbeyssi, A., 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., Dou, Z. L., Du, S. X., Duan, P. F., Fan, J. Z., Fang, J., Fang, S. S., Fang, X., Fang, Y., Farinelli, R., Fava, L., Fegan, S., Feldbauer, F., Felici, G., Feng, C. Q., Fioravanti, E., Fritsch, M., Fu, C. D., Gao, Q., Gao, X. L., Gao, Y., Gao, Z., Garzia, I., Goetzen, K., Gong, L., Gong, W. X., Gradl, W., Greco, M., Gu, M. H., Gu, Y. T., Guan, Y. H., Guo, A. Q., Guo, L. B., Guo, R. P., Guo, Y., Guo, Y. P., Haddadi, Z., Hafner, A., Han, S., Hao, X. Q., Harris, F. A., He, K. L., Heinsius, F. H.
Format:	Artikel
Sprache:	eng
Schlagworte:	BESIII NUCLEAR PHYSICS AND RADIATION PHYSICS
Online-Zugang:	Volltext
Tags:	Tag hinzufügen Keine Tags, Fügen Sie den ersten Tag hinzu!

Beschreibung
Zusammenfassung:	The process e+e- → Λ Λ ¯ 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 Λ Λ ¯ mass threshold, to be 305±$45_{-36}^{+66}$ pb, where the first uncertainty is statistical and the second systematic. The substantial cross section near threshold is significantly 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.
ISSN:	2470-0010 2470-0029
DOI:	10.1103/PhysRevD.97.032013