Measurement of CP-Violating Asymmetries in $B^0\to (\rho \pi {)}^0$ Using a Time-Dependent Dalitz Plot Analysis

Abstract

We report a measurement of CP-violating asymmetries in $B^0\to (\rho \pi {)}^0\to {\pi }^{+}{\pi }^{-}{\pi }^0$ decays using a time-dependent Dalitz plot analysis. The results are obtained from a data sample of 347 million ${\rm Y}(4S)\to B\bar{B}$ decays, collected by the BaBar detector at the PEP-II asymmetric-energy B Factory at SLAC. We measure 26 coefficients of the bilinear form factor terms occurring in the time-dependent decay rate of the \Bz meson and derive the physically relevant quantities from these coefficients. In particular we find a three standard deviation evidence of direct CP-violation in $B^0\to {\rho }^{\pm }{\pi }^{\mp }$ decays, with systematic uncertainties included. We also achieve a constraint of the angle $\alpha$ of the Unitarity Triangle. All results presented are preliminary.

32 pages, 13 postscript figures, submitted to ICHEP2006 Fixed typos in the statistical and systematic correlation matrices