ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2004, vol. 69, p. -
Observation of the decay B0 → ρ+ ρ- and measurement of the branching fraction and polarization
We have observed the rare decay B0 → ρ+ ρ- in a sample of 89 million BB̄ pairs recorded with the BABAR detector. The number of observed events is 88-21 +23±9 with a significance of 5.1 standard deviations with systematic uncertainties included. The branching fraction and the longitudinal polarization are measured to be β(B0 → ρ+ ρ-) = (25-6-6 +7+5× 10-6 and ΓLΓ = 0.98-0.08 +0.02±0. 03, respectively. © 2004 The American Physical Society.