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Observation of the Decay B0 => rho+ rho- and Measurement of the Branching Fraction and Polarization

The BABAR Collaboration·B. Aubert
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Abstract

We have observed the rare decay B0 => rho+ rho- in a sample of 89 million BB pairs recorded with the BABAR detector. The number of observed events is 88 +23-21 +-9, with a significance of 5.1 standard deviations with systematic uncertainties included. The branching fraction and the longitudinal polarization are measured to be BR(B0 => rho+ rho-) = (25 +7-6 +5-6)*10^{-6} and Gamma_L/Gamma = 0.98 +0.02-0.08 +-0.03, respectively.

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The BABAR Collaboration, B. Aubert. 2003-11-07. Observation of the Decay B0 => rho+ rho- and Measurement of the Branching Fraction and Polarization. https://doi.org/10.1103/physrevd.69.031102

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