Observation of Upsilon(2S)-->etaUpsilon(1S) and search for related transitions.

Journal article

We report the first observation of Upsilon(2S)-->etaUpsilon(1S), with a branching fraction B=(2.1(-0.6)+0.7(stat)+/-0.3(syst)) x 10(-4) and a statistical significance 5.3sigma. Data were acquired with the CLEO III detector at the CESR e+e(-) symmetric collider. This is the first process observed involving a b-quark spin flip. For related transitions, 90% confidence limits in units of 10(-4) are B(Upsilon(2S)-->pi0Upsilon(1S)) < 1.8, B(Upsilon(3S)-->etaUpsilon(1S)) < 1.8, B(Upsilon(3S)-->pi0Upsilon(1S)) < 0.7, and B(Upsilon(3S)-->pi0Upsilon(2S)) < 5.1.

Authors: He, Q; Insler, J; Muramatsu, H; Park, C; Thorndike, E

• Publication status: Published
• Journal: Physical Review Letters
• Volume: 101
• Issue: 19
• Pages: 192001
• Publication date: 2008-11-01
• DOI: 10.1103/physrevlett.101.192001
• EISSN: 1079-7114
• ISSN: 0031-9007
• Language: English
• Keywords: CLEO Collaboration