Amplitude Analysis of B0-->K+ pi- pi0 and Evidence of Direct CP Violation in B--> K* pi decays

TL;DR

This paper performs an amplitude analysis of B0 decays to K+ pi- pi0, revealing direct CP violation in B-->K* pi decays and providing insights into the CKM angle gamma and potential new physics effects.

Contribution

It introduces a combined amplitude analysis of multiple B decay channels to measure CP violation and constrain the CKM unitarity triangle, with evidence of direct CP violation at 3 sigma.

Findings

Measured phase of isospin amplitude Phi_3/2.

Observed direct CP violation in B0-->K*+ pi- at 3 sigma.

Constructed isospin amplitudes to test for new physics.

Abstract

We analyze the decay B0-->K+ pi- pi0 with a sample of 454 million B Bbar events collected by the BaBar detector at the PEP-II asymmetric-energy B factory at SLAC, and extract the complex amplitudes of seven interfering resonances over the Dalitz plot. These results are combined with amplitudes measured in B0-->K_S pi+ pi- decays to construct isospin amplitudes from B0-->K* pi and B0-->rho K decays. We measure the phase of the isospin amplitude Phi_3/2, useful in constraining the CKM unitarity triangle angle gamma and evaluate a CP rate asymmetry sum rule sensitive to the presence of new physics operators. We measure direct CP violation in B0-->K*+ pi- decays at the level of 3 sigma when measurements from both B0-->K+ pi- pi0 and B0-->K_S pi+ pi- decays are combined.