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ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2007, vol. 76, p. -

Study of B0→ρ+ρ- decays and constraints on the CKM angle α

Aubert B., Bona M., Boutigny D., Karyotakis Y., Lees J. P., Poireau V., Prudent X., Tisserand V., Zghiche A., Tico J. Garra, Grauges E., Lopez L., Palano A., Eigen G., Ofte I., Stugu B., Sun L., Abrams G. S., Battaglia M., Brown D. N., Button-Shafer J., Cahn R. N., Groysman Y., Jacobsen R. G., Kadyk J. A., Kerth L. T., Kolomensky Yu G., Kukartsev G., Pegna D. Lopes, Lynch G., Mir L. M., Orimoto T. J., Pripstein M., Roe N. A., Ronan M. T., Tackmann K., Wenzel W. A., Del Amo Sanchez P., Hawkes C. M., Watson A. T., Held T., Koch H., Lewandowski B., Pelizaeus M., Schroeder T., Steinke M., Cottingham W. N., Walker D., Asgeirsson D. J., Cuhadar-Donszelmann T., Fulsom B. G., Hearty C., Knecht N. S., Mattison T. S., McKenna J. A., Khan A., Saleem M., Teodorescu L., Blinov V. E., Bukin A. D., Druzhinin V. P., Golubev V. B., Onuchin A. P., Serednyakov S. I., Skovpen Yu I., Solodov E. P., Todyshev K. Yu, Bondioli M., Curry S., Eschrich I., Kirkby D., Lankford A. J., Lund P., Mandelkern M., Martin E. C., Stoker D. P., Abachi S., Buchanan C., Foulkes S. D., Gary J. W., Liu F., Long O., Shen B. C., Zhang L., Paar H. P., Rahatlou S., Sharma V., Berryhill J. W., Campagnari C., Cunha A., Dahmes B., Hong T. M., Kovalskyi D., Richman J. D., Beck T. W., Eisner A. M., Flacco C. J., Heusch C. A., Kroseberg J., Lockman W. S.

We present results from an analysis of B0→ρ+ρ- decays using (383.6±4.2)×106 BB̄ pairs collected by the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. The measurements of the B0→ρ+ρ- branching fraction, longitudinal polarization fraction fL, and the CP-violating parameters Slong and Clong are as follows: B(B0→ρ+ρ-)=(25.5±2.1(stat)-3.9+3.6(syst))×10-6, fL=0.992±0.024(stat)-0.013+0.026(syst), Slong=-0.17±0.20(stat)-0. 06+0.05(syst), Clong=0.01±0.15(stat)±0.06(syst). We determine the unitarity triangle angle α, using an isospin analysis of B→ρρ decays. One of the two solutions, α=[73.1,117.0]° at 68% confidence level, is compatible with standard model-based fits of existing data. Constraints on the unitarity triangle are also evaluated using an SU(3) symmetry-based approach. © 2007 The American Physical Society.