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ISSN - 00319007, EISSN - 10797114, Physical Review Letters, 2010, vol. 105, p. -

Observation of Bs0→Ds(*)+Ds(*)- using e⊃+e⊃- collisions and a determination of the Bs-B̄s width difference ΔΓs

Esen S., Schwartz A. J., Adachi I., Aihara H., Arinstein K., Aulchenko V., Aushev T., Aziz T., Bakich A. M., Balagura V., Barberio E., Bay A., Bischofberger M., Bondar A., Bozek A., Bračko M., Browder T. E., Chang M. C., Chang P., Chen A., Chen P., Cheon B. G., Chiang C. C., Choi Y., Dalseno J., Dash M., Doležl Z., Drásal Z., Drutskoy A., Eidelman S., Goldenzweig P., Golob B., Ha H., Haba J., Hara T., Hayasaka K., Higuchi T., Hoshi Y., Hou W. S., Hsiung Y. B., Hyun H. J., Iijima T., Inami K., Itoh R., Iwabuchi M., Joshi N. J., Julius T., Kang J. H., Kawasaki T., Kichimi H., Kim H. J., Kim H. O., Kim J. H., Kim Y. J., Kinoshita K., Ko B. R., Kodyš P., Korpar S., Križan P., Krokovny P., Kuhr T., Kumita T., Kwon Y. J., Kyeong S. H., Lange J. S., Lee S. H., Liu Y., Liventsev D., Louvot R., Matyja A., McOnie S., Miyata H., Mizuk R., Mohanty G. B., Nakano E., Nakao M., Nakazawa H., Natkaniec Z., Neubauer S., Nishida S., Nitoh O., Ohshima T., Okuno S., Olsen S. L., Pakhlov P., Park C. W., Park H., Park H. K., Petrič M.

We have made the first observation of Bs0→Ds(*)+Ds(*)- decays using 23.6fb⊃-1 of data recorded by the Belle experiment running on the Υ(5S) resonance. The branching fractions are measured to be B(Bs0→Ds+Ds-)=(1.03-0.32-0.25+0.39+0.26)%, B(Bs0→Ds*±Ds)= (2.75-0.71+0.83±0.69)%, and B(Bs0→Ds*+Ds*-)=(3.08-1.04- 0.86+1.22+0.85)%; the sum is B[Bs0→Ds(*)+Ds(*)-]=(6.85-1.30-1. 80+1.53+1.79)%. Assuming Bs0→Ds(*)+Ds(*)- saturates decays to CP-even final states, the branching fraction determines the ratio ΔΓs/cosφ, where ΔΓs is the difference in widths between the two Bs-B̄s mass eigenstates, and φ is a CP-violating weak phase. Taking CP violation to be negligibly small, we obtain ΔΓs/Γs=0. 147-0.030+0.036(stat)-0.041+0.042(syst), where Γs is the mean decay width. © 2010 The American Physical Society.