Observation ofΥ(2S)→ηΥ(1S)and Search for Related Transitions

Q He,Z Metreveli,H Muramatsu,D M Asner,G Bonvicini,S Stroiney,P Naik,P Rubin,R Gray,D Mohapatra,S Nisar,J Napolitano,B W Lang,A J Sadoff,B I Eisenstein,A Lincoln,B Xin,J Kandaswamy,R A Briere,R S Galik,T K Pedlar,B Moziak,E H Thorndike,G S Adams,S B Athar,D L Hartill,I Danko,J E Duboscq,S Mehrabyan,D Cinabro,S Blusk,E J White,L Fields,K K Seth,D Cronin-Hennessy,N Lowrey,M R Shepherd,V Savinov,K Randrianarivony,D Peterson,D G Cassel,K W Edwards,R Poling,T Wilksen,T Klein,D L Kreinick,K Y Gao,R Mountain,R E Mitchell,J Insler,S W Gray,B K Heltsley,R Ehrlich,J Libby,D Riley,C S Park,J Hietala,A Powell,G Tatishvili,D Hertz,H Mahlke-Krüger,M Dubrovin,I Karliner,G Wilkinson,M E Watkins,A W Scott,S Dobbs,X Shi,S Stone,A Tomaradze,J H Rademacker ,Jonathan L Rosner ,A Rýd ,I P J Shipsey,L M Zhang,Y Kubota,M Anderson,Dandan Hu ,W Sun ,P Zweber,P U E Onyisi,J C Wang,H Méndez ,J R Patterson,Jun Ge ,H Vogel,James Ledoux ,L Gibbons,J Alexander ,D Besson,M Selen,N Sultana,T Skwarnicki,K M Ecklund,D H Miller,J Reed,L M Garcia Martin ,S Khalil,J Yelton,J Wiss,R Patel,J Li,M Artuso,J Xavier ,J M Hunt,W A Love ,В Е Кузнецов ,F Yang,T Ferguson,J P Cummings

doi:10.1103/physrevlett.101.192001

Abstract

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.

Full Text