Вы находитесь на старом сайте НГУ. Перейти на новый сайт

ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2012, vol. 86, p. -

Measurement of branching fraction and first evidence of CP violation in B0→a1±(1260)π- Decays

Dalseno J., Adachi I., Aihara H., Asner D. M., Aulchenko V., Aushev T., Bakich A. M., Bay A., Belous K., Bhuyan B., Bozek A., Bračko M., Brovchenko O., Browder T. E., Chekelian V., Chen A., Chen P., Cheon B. G., Chilikin K., Chistov R., Cho I. S., Cho K., Choi Y., Doleal Z., Drásal Z., Eidelman S., Fast J. E., Gaur V., Gabyshev N., Garmash A., Goh Y. M., Hayashii H., Horii Y., Hoshi Y., Hou W. S., Hsiung Y. B., Hyun H. J., Iijima T., Inami K., Ishikawa A., Itoh R., Iwabuchi M., Iwasaki Y., Iwashita T., Julius T., Kang J. H., Kiesling C., Kim H. O., Kim J. B., Kim Y. J., Kinoshita K., Ko B. R., Koblitz S., Kody P., Korpar S., Krian P., Krokovny P., Kronenbitter B., Kuhr T., Kumita T., Kwon Y. J., Lee S. H., Li J., Libby J., Liu C., Liu Z. Q., Louvot R., MacNaughton J., Matvienko D., McOnie S., Miyabayashi K., Miyata H., Miyazaki Y., Mohanty G. B., Mohapatra D., Moll A., Muramatsu N., Nakao M., Natkaniec Z., Nedelkovska E., Ng C., Nishida S., Nishimura K., Nitoh O., Ogawa S., Ohshima T., Okuno S., Pakhlov P., Pakhlova G., Park C. W., Park H. K., Pedlar T. K., Pestotnik R., Petrič M.

We present a measurement of the branching fraction and time-dependent CP violation parameters in B0→a1±(1260)π - decays. The results are obtained from the final data sample containing 772×106 BB̄ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e +e - collider. We obtain the product branching fraction B(B0→a1±(1260)π -) ×B(a1±(1260)→π ±π -π ±)=(11.1±1.0(stat)±1.4(syst))×10 -6 and an upper limit on the product branching fraction for a possible decay with the same final state B(B0→a2±(1320)π -)×B(a2±(1320)→π ±π -π ±)<2.2×10 -6at90%CL. In a time-dependent measurement to extract CP asymmetries, we obtain the CP violation parameters A CP=-0.06±0.05(stat)±0.07(syst), C CP=-0.01±0.11(stat)±0.09(syst), S CP=-0. 51±0.14(stat)±0.08(syst), representing time- and flavor-integrated direct, flavor-dependent direct and mixing-induced CP violation, respectively. Simultaneously, we also extract the CP-conserving parameters ΔC=+0.54±0.11(stat)±0.07(syst), ΔS=-0.09±0. 14(stat)±0.06(syst), which, respectively, describe a rate difference and strong phase difference between the decay channels where the a1± does not contain the spectator quark and those where it does. We find first evidence of mixing-induced CP violation in B0→a1±(1260)π - decays with 3.1σ significance. The rate where the a1± does not contain the spectator quark from the B meson is found to dominate the rate where it does at the 4.1σ level. However, there is no evidence for either time- and flavor-integrated direct CP violation or flavor-dependent direct CP violation. © 2012 American Physical Society.