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ISSN - 03702693, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2007, vol. 654, p. 65-73

Study of τ- → KS π- ντ decay at Belle

Epifanov D., Adachi I., Aihara H., Arinstein K., Aulchenko V., Aushev T., Bakich A. M., Balagura V., Barberio E., Bedny I., Belous K., Bitenc U., Bizjak I., Bondar A., Bozek A., Bračko M., Browder T. E., Chao Y., Chen A., Chen K. F., Chen W. T., Cheon B. G., Chiang C. C., Chistov R., Cho I. S., Choi Y., Choi Y. K., Dalseno J., Dash M., Drutskoy A., Eidelman S., Gokhroo G., Golob B., Ha H., Haba J., Hayasaka K., Hayashii H., Hazumi M., Heffernan D., Hokuue T., Hoshi Y., Hou W. S., Hsiung Y. B., Hyun H. J., Iijima T., Ikado K., Inami K., Ishikawa A., Itoh R., Iwasaki M., Iwasaki Y., Kah D. H., Kaji H., Kang J. H., Kawai H., Kawasaki T., Kichimi H., Kim H. O., Kim S. K., Kim Y. J., Križan P., Krokovny P., Kumar R., Kuo C. C., Kuzmin A., Kwon Y. J., Lee J. S., Lee M. J., Lee S. E., Lesiak T., Li J., Limosani A., Lin S. W., Liu Y., Liventsev D., Mandl F., Marlow D., Matsumoto T., Matyja A., McOnie S., Medvedeva T., Miyata H., Miyazaki Y., Mizuk R., Moloney G. R., Mori T., Nakano E., Nakao M., Nakazawa H., Natkaniec Z., Nishida S., Nitoh O., Ogawa S., Ohshima T., Onuki Y., Ostrowicz W.

We present a study of the decay τ- → KS π- ντ using a 351  fb-1 data sample collected with the Belle detector. The analysis is based on 53, 110 lepton-tagged signal events. The measured branching fraction B (τ- → KS π- ντ) = (0.404 ± 0.002 (stat .) ± 0.013 (syst .)) % is consistent with the world average value and has better accuracy. An analysis of the KS π- invariant mass spectrum reveals contributions from the K* (892)- as well as other states. For the first time the K* (892)- mass and width have been measured in τ decay: M (K* (892)-) = (895.47 ± 0.20 (stat .) ± 0.44 (syst .) ± 0.59 (mod .))   MeV / c2, Γ (K* (892)-) = (46.2 ± 0.6 (stat .) ± 1.0 (syst .) ± 0.7 (mod .))   MeV. The K* (892)- mass is significantly different from the current world average value. © 2007 Elsevier B.V. All rights reserved.