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

Observation of two resonancelike structures: Observation of two resonancelike structures in the Ic1 mass distribution in exclusive BA0K-I+Ic1

Mizuk R., Chistov R., Adachi I., Aihara H., Arinstein K., Aulchenko V., Aushev T., Bakich A. M., Balagura V., Barberio E., Bay A., Bhardwaj V., Bitenc U., Bondar A., Bozek A., Bračko M., Brodzicka J., Browder T. E., Chang M. C., Chang P., Chen A., Chen K. F., Cheon B. G., Chiang C. C., Cho I. S., Choi S. K., Choi Y., Dalseno J., Danilov M., Drutskoy A., Eidelman S., Epifanov D., Goldenzweig P., Golob B., Ha H., Haba J., Hayasaka K., Hayashii H., Hazumi M., Hoshi Y., Hou W. S., Hsiung Y. B., Hyun H. J., Iijima T., Inami K., Ishikawa A., Ishino H., Itoh R., Iwasaki M., Iwasaki Y., Kah D. H., Kaji H., Kang J. H., Kawasaki T., Kichimi H., Kim H. J., Kim H. O., Kim Y. I., Kim Y. J., Kinoshita K., Korpar S., KriŽan P., Krokovny P., Kumar R., Kuzmin A., Kwon Y. J., Kyeong S. H., Lange J. S., Lee J. S., Lee M. J., Lin S. W., Liu C., Liu Y., Liventsev D., Mandl F., McOnie S., Miyabayashi K., Miyata H., Miyazaki Y., Nakano E., Nakao M., Nakazawa H., Nishida S., Nitoh O., Ogawa S., Ohshima T., Okuno S., Olsen S. L., Ozaki H., Pakhlov P., Pakhlova G., Palka H., Park C. W., Park H.

© 2008 The American Physical Society. We report the first observation of two resonancelike structures in the π+χc1 invariant mass distribution near 4.1GeV/c2 in exclusive B¯0→K-π+χc1 decays. From a Dalitz plot analysis in which the π+χc1 mass structures are represented by Breit-Wigner resonance amplitudes, we determine masses and widths of: M1=(4051±14-41+20)MeV/c2, Γ1=(82-17-22+21+47)MeV, M2=(4248-29-35+44+180)MeV/c2, and Γ2=(177-39-61+54+316)MeV; and product branching fractions of B(B¯0→K-Z1,2+)×B(Z1,2+→π+χc1)=(3.0-0.8-1.6+1.5+3.7)×10-5 and (4.0-0.9-0.5+2.3+19.7)×10-5, respectively. Here the first uncertainty is statistical, the second is systematic. The significance of each of the π+χc1 structures exceeds 5σ, including the systematic uncertainty from various fit models. This analysis is based on 657×106 BB¯ events collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.