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ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2008, vol. 78, p. -

Study of hadronic transitions between Υ states and observation of Υ(4S)→ηΥ(1S) decay

Aubert B., Bona M., Karyotakis Y., Lees J. P., Poireau V., Prencipe E., Prudent X., Tisserand V., Tico J. Garra, Grauges E., Lopez L., Palano A., Pappagallo M., Eigen G., Stugu B., Sun L., Abrams G. S., Battaglia M., Brown D. N., Cahn R. N., Jacobsen R. G., Kerth L. T., Kolomensky Yu G., Kukartsev G., Lynch G., Osipenkov I. L., Ronan M. T., Tackmann K., Tanabe T., Hawkes C. M., Soni N., Watson A. T., Koch H., Schroeder T., Walker D., Asgeirsson D. J., Fulsom B. G., Hearty C., Mattison T. S., McKenna J. A., Barrett M., Khan A., Teodorescu L., Blinov V. E., Bukin A. D., Buzykaev A. R., Druzhinin V. P., Golubev V. B., Onuchin A. P., Serednyakov S. I., Skovpen Yu I., Solodov E. P., Todyshev K. Yu, Bondioli M., Curry S., Eschrich I., Kirkby D., Lankford A. J., Lund P., Mandelkern M., Martin E. C., Stoker D. P., Abachi S., Buchanan C., Gary J. W., Liu F., Long O., Shen B. C., Vitug G. M., Yasin Z., Zhang L., Sharma V., Campagnari C., Hong T. M., Kovalskyi D., Mazur M. A., Richman J. D., Beck T. W., Eisner A. M., Flacco C. J., Heusch C. A., Kroseberg J., Lockman W. S., Schalk T., Schumm B. A., Seiden A., Wang L., Wilson M. G., Winstrom L. O., Cheng C. H., Doll D. A., Echenard B., Fang F., Hitlin D. G., Narsky I., Piatenko T., Porter F. C.

We present a study of hadronic transitions between Υ(mS) (m=4, 3, 2) and Υ(nS) (n=2, 1) resonances based on 347.5fb-1 of data taken with the BABAR detector at the PEP-II storage rings. We report the first observation of Υ(4S)→ηΥ(1S) decay with a branching fraction B(Υ(4S)→ηΥ(1S))=(1.96±0.06stat±0.09syst) ×10-4 and measure the ratio of partial widths Γ(Υ(4S) →ηΥ(1S))/Γ(Υ(4S)→π+π-Υ(1S))=2. 41±0.40stat±0.12syst. We set 90% CL upper limits on the ratios Γ(Υ(2S)→ηΥ(1S))/Γ(Υ(2S)→π+π- Υ(1S))<5.2×10-3 and Γ(Υ(3S)→ηΥ(1S))/ Γ(Υ(3S)→π+π-Υ(1S))<1.9×10-2. We also present new measurements of the ratios Γ(Υ(4S)→π+π-Υ(2S))/ Γ(Υ(4S)→π+π-Υ(1S))=1.16±0.16stat±0. 14syst and Γ(Υ(3S)→π+π-Υ(2S))/Γ(Υ(3S) →π+π-Υ(1S))=0.577±0.026stat±0.060syst. © 2008 The American Physical Society.