Improved Measurement of the Cabibbo-Kobayashi-Maskawa Angle $α$ Using $B^{0} (\bar{B}) \to ρ^{+} ρ^{-}$ Decays

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21 July 2005

journal article
research article
Published by American Physical Society (APS) in Physical Review Letters

Vol. 95 (4) , 041805
https://doi.org/10.1103/physrevlett.95.041805

Abstract

We present results from an analysis of

B^{0} ({\bar{B}}^{0}) \to ρ^{+} ρ^{-}

using

232 \times 10^{6}

Υ (4 S) \to B \bar{B}

decays collected with the BABAR detector at the PEP-II asymmetric-energy

B

factory at SLAC. We measure the longitudinal polarization fraction

f_{L} = 0.978 \pm 0.014 (stat) \binom{+ 0.021}{- 0.029} (syst)

and the

C P

-violating parameters

S_{L} = - 0.33 \pm 0.24 (stat) \binom{+ 0.08}{- 0.14} (syst)

and

C_{L} = - 0.03 \pm 0.18 (stat) \pm 0.09 (syst)

. Using an isospin analysis of

B \to ρ ρ

decays, we determine the unitarity triangle parameter

α

. The solution compatible with the standard model is

α = (100 \pm 13) °

.

Keywords

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This publication has 19 references indexed in Scilit:

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