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ISSN - 00319007, EISSN - 10797114, Physical Review Letters, 2006, vol. 97, p. -

Study of decay mechanisms in B-→Λc+p̄π- decays and observation of low-mass structure in the Λc+p̄ system

Gabyshev N., Abe K., Abe K., Adachi I., Aihara H., Asano Y., Aulchenko V., Aushev T., Bakich A. M., Bitenc U., Bizjak I., Blyth S., Bondar A., Bozek A., Bračko M., Brodzicka J., Browder T. E., Chang P., Chao Y., Chen A., Chen W. T., Cheon B. G., Chistov R., Choi S. K., Choi Y., Chuvikov A., Cole S., Dalseno J., Danilov M., Dash M., Drutskoy A., Eidelman S., Enari Y., Fratina S., Gershon T., Gokhroo G., Golob B., Gorišek A., Hara T., Hayashii H., Hazumi M., Hokuue T., Hoshi Y., Hou S., Hou W. S., Hsiung Y. B., Iijima T., Imoto A., Inami K., Ishikawa A., Itoh R., Iwasaki M., Iwasaki Y., Kang J. H., Kang J. S., Kataoka S. U., Katayama N., Kawai H., Kawasaki T., Khan H. R., Kichimi H., Kim H. J., Kim H. O., Kim S. K., Kim S. M., Kinoshita K., Korpar S., Krokovny P., Kumar S., Kuo C. C., Kuzmin A., Kwon Y. J., Lange J. S., Leder G., Lesiak T., Lin S. W., Mandl F., Matsumoto T., Mikami Y., Mitaroff W., Miyake H., Miyata H., Mizuk R., Nagamine T., Nagasaka Y., Nakano E., Nakao M., Nakazawa H., Natkaniec Z., Nishida S., Nitoh O., Ogawa S., Ohshima T., Okabe T., Okuno S., Olsen S. L.

Using a sample of 152×106 BB̄ pairs accumulated with the Belle detector at the KEKB e+e- collider, we study the decay mechanism of three-body charmed decay B-→Λc+p̄π-. The intermediate two-body decay B-→Σc(2455)0p̄ is observed for the first time with a branching fraction of (3.7±0.7±0.4±1.0)×10-5 and a statistical significance of 8.4σ. We also observe a low-mass enhancement in the (Λc+p̄) system, which can be parametrized as a Breit-Wigner function with a mass of (3.35-0.02+0.01±0.02)GeV/c2 and a width of (0.07-0.03+0.04±0.04)GeV/c2. We measure its branching fraction to be (3.9-0.7+0.8±0.4±1.0)×10-5 with a statistical significance of 6.2σ. The errors are statistical, systematic, and that of the Λc+→pK-π+ decay branching fraction. © 2006 The American Physical Society.