# A Study of $B^0 \to \rho^+\rho^-$ Decays and Constraints on the CKM Angle $\alpha$

Abstract : We present results from an analysis of B0 to rho+rho- decays using 383.6 million BB-bar pairs collected by the BaBar detector at the PEP-II asymmetric-energy $B$ Factory at SLAC. The measurements of the B0 to rho+rho- branching fraction, longitudinal polarization fraction f_L, and the CP-violating parameters S_{long} and C_{long} are: B(B0-> rho+rho-) = (25.5 +/- 2.1 (stat) +3.6/-3.9 (syst))*10^-6 f_L = 0.992 +/- 0.024 (stat) +0.026/-0.013 (syst) S_{long} = -0.17 +/- 0.20 (stat) +0.05/-0.06 (syst) C_{long} = 0.01 +/- 0.15 (stat) +/- 0.06 (syst) We determine the unitarity triangle angle alpha, using an isospin analysis of B to rhorho decays. One of the two solutions, alpha = [73.1, 117.0] degrees at 68% CL 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.
Document type :
Journal articles

http://hal.in2p3.fr/in2p3-00149846
Contributor : Claudine Bombar <>
Submitted on : Monday, May 28, 2007 - 5:37:56 PM
Last modification on : Wednesday, September 16, 2020 - 4:21:36 PM

### Citation

B. Aubert, M. Bona, D. Boutigny, Y. Karyotakis, J.P. Lees, et al.. A Study of $B^0 \to \rho^+\rho^-$ Decays and Constraints on the CKM Angle $\alpha$. Physical Review D, American Physical Society, 2007, 76, pp.052007. ⟨10.1103/PhysRevD.76.052007⟩. ⟨in2p3-00149846⟩

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