Measurement of CP-violating asymmetries in B^0 -> (rho pi)^0 decays using a time-dependent Dalitz plot analysis

TL;DR

This study measures CP-violating asymmetries in B^0 -> pi^+ pi^- pi^0 decays using a time-dependent Dalitz plot analysis with a large dataset, providing insights into CP violation parameters and the CKM angle alpha.

Contribution

It presents the first comprehensive time-dependent Dalitz plot analysis of B^0 -> rho pi decays, extracting CP asymmetry parameters with high statistical significance.

Findings

Measured CP asymmetry parameters with statistical and systematic uncertainties.

Performed a likelihood scan indicating potential direct CP violation.

Provided constraints on the CKM angle alpha using combined measurements.

Abstract

We present results for a time-dependent Dalitz plot measurement of CP-violating asymmetries in the mode B^0 -> pi^+ pi^- pi^0. The dataset is derived from the complete sample of 471 x 10^6 BBbar meson pairs collected with the BABAR detector at the PEP-II asymmetric-energy e^+e^- collider at the SLAC National Accelerator Laboratory operating on the Upsilon(4S) resonance. We extract parameters describing the time-dependent B^0 -> rho pi decay probabilities and CP asymmetries, including C = 0.016\pm0.059\pm0.036, DeltaC = 0.234\pm0.061\pm0.048, S = 0.053\pm0.081\pm0.034, and DeltaS = 0.054\pm0.082\pm0.039, where the uncertainties are statistical and systematic, respectively. We perform a two-dimensional likelihood scan of the direct CP-violation asymmetry parameters for B^0 -> rho^\pm pi^\mp decays, finding the change in chi^2 between the minimum and the origin (corresponding to no direct CP violation) to be Delta(chi^2)=6.42. We present information on the CP-violating parameter alpha in a likelihood scan that incorporates B^\pm -> rho pi measurements.