Study of B0 →ρ0ρ0 decays, implications for the CKM angle φ2 and search for other B0 decay modes with a four-pion final state

P. Vanhoefer, J. Dalseno, C. Kiesling, I. Adachi, H. Aihara, D. M. Asner, V. Aulchenko, T. Aushev, A. M. Bakich, A. Bala, V. Bhardwaj, B. Bhuyan, G. Bonvicini, A. Bozek, M. Bračko, T. E. Browder, M. C. Chang, P. Chang, V. Chekelian, A. ChenP. Chen, B. G. Cheon, K. Chilikin, R. Chistov, K. Cho, V. Chobanova, Y. Choi, D. Cinabro, Z. DoleŽal, Z. Drásal, S. Eidelman, H. Farhat, J. E. Fast, T. Ferber, V. Gaur, N. Gabyshev, S. Ganguly, A. Garmash, R. Gillard, Y. M. Goh, B. Golob, T. Hara, K. Hayasaka, H. Hayashii, T. Higuchi, Y. Horii, Y. Hoshi, W. S. Hou, H. J. Hyun, T. Iijima, A. Ishikawa, R. Itoh, Y. Iwasaki, T. Iwashita, I. Jaegle, T. Julius, D. H. Kah, E. Kato, H. Kawai, T. Kawasaki, D. Y. Kim, H. O. Kim, J. B. Kim, J. H. Kim, M. J. Kim, Y. J. Kim, K. Kinoshita, J. Klucar, B. R. Ko, S. Korpar, P. KriŽan, P. Krokovny, B. Kronenbitter, T. Kuhr, T. Kumita, A. Kuzmin, Y. J. Kwon, J. S. Lange, S. H. Lee, J. Li, L. Li Gioi, J. Libby, C. Liu, Y. Liu, D. Liventsev, P. Lukin, K. Miyabayashi, H. Miyata, R. Mizuk, G. B. Mohanty, A. Moll, H. G. Moser, R. Mussa, E. Nakano, M. Nakao, Z. Natkaniec, E. Nedelkovska, N. K. Nisar, S. Nishida, O. Nitoh, S. Ogawa, P. Pakhlov, G. Pakhlova, C. W. Park, H. Park, H. K. Park, T. K. Pedlar, R. Pestotnik, M. Petrič, L. E. Piilonen, M. Ritter, M. Röhrken, A. Rostomyan, S. Ryu, H. Sahoo, T. Saito, Y. Sakai, S. Sandilya, L. Santelj, T. Sanuki, Y. Sato, V. Savinov, O. Schneider, G. Schnell, C. Schwanda, A. J. Schwartz, D. Semmler, K. Senyo, O. Seon, M. E. Sevior, M. Shapkin, C. P. Shen, T. A. Shibata, J. G. Shiu, B. Shwartz, A. Sibidanov, F. Simon, Y. S. Sohn, A. Sokolov, E. Solovieva, M. Starič, M. Steder, T. Sumiyoshi, U. Tamponi, G. Tatishvili, Y. Teramoto, K. Trabelsi, T. Tsuboyama, M. Uchida, S. Uehara, Y. Unno, S. Uno, S. E. Vahsen, C. Van Hulse, G. Varner, K. E. Varvell, A. Vinokurova, V. Vorobyev, M. N. Wagner, C. H. Wang, M. Z. Wang, P. Wang, X. L. Wang, Y. Watanabe, K. M. Williams, E. Won, Y. Yamashita, S. Yashchenko, Y. Yook, Z. P. Zhang, V. Zhilich, V. Zhulanov, A. Zupanc

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Abstract

We present a study of the branching fraction of the decay B0→ρ0ρ0 and the fraction of longitudinally polarized ρ0 mesons in this decay. The results are obtained from the final data sample containing 772×106 BB̄ pairs collected at the (4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We find 166±59 B0→ρ0ρ0 events (including systematic uncertainties), corresponding to a branching fraction of B(B0→ρ0ρ0)=(1.02±0.30(stat) ±0.15(syst))×10-6 with a significance of 3.4 standard deviations and a longitudinal polarization fraction fL=0.21-0.22+0.18(stat)±0. 15(syst). We use the longitudinal polarization fraction to determine the Cabibbo-Kobayashi-Maskawa matrix angle φ2=(84.9±13.5)° through an isospin analysis in the B→ρρ system. We furthermore find 125±41 B0→f0ρ0 events, corresponding to B(B0→f0ρ0) ×B(f0→π+π-)=(0.78±0.22(stat)±0.11(syst)) ×10-6, with a significance of 3.1 standard deviations. We find no other significant contribution with the same final state, and set upper limits at 90% confidence level on the (product) branching fractions, B(B0→π+π- π+π-)<11.2×10-6, B(B0→ρ0π+π-)<12.0×10-6, B(B0→f0π+π-)×B(f0→π+π-)<3.0×10-6 and B(B0→f0f0)×B(f0→π+π-)2<0.2×10-6.

Original languageEnglish
Article number072008
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume89
Issue number7
DOIs
Publication statusPublished - 2014 Apr 8

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)

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    Vanhoefer, P., Dalseno, J., Kiesling, C., Adachi, I., Aihara, H., Asner, D. M., Aulchenko, V., Aushev, T., Bakich, A. M., Bala, A., Bhardwaj, V., Bhuyan, B., Bonvicini, G., Bozek, A., Bračko, M., Browder, T. E., Chang, M. C., Chang, P., Chekelian, V., ... Zupanc, A. (2014). Study of B0 →ρ0ρ0 decays, implications for the CKM angle φ2 and search for other B0 decay modes with a four-pion final state. Physical Review D - Particles, Fields, Gravitation and Cosmology, 89(7), [072008]. https://doi.org/10.1103/PhysRevD.89.072008