Measurement of the CKM angle alpha/phi2 with B -> rho rho decays at Belle and BABAR

TL;DR

This paper reviews recent measurements of B -> rho rho decays from Belle and BABAR, focusing on CP violation and constraining the CKM angle alpha/phi2 with isospin analysis, resulting in a range consistent with the standard model.

Contribution

It provides updated experimental measurements of B -> rho rho decays and refines the determination of the CKM angle alpha/phi2 using isospin analysis.

Findings

Measured CP-violating coefficients A and S for B -> rho+ rho- decays.

Constrained the CKM angle alpha/phi2 to 71° < alpha < 113° at 68% confidence level.

Determined branching fractions and polarization fractions of B -> rho rho decays.

Abstract

We overview recent measurements in B -> rho rho decays which are based on data samples collected at the PEP-II and KEKB asymmetric-energy e+e- colliders with the BABAR and Belle detectors. Special emphasis is given to the determination of the CP-violating coefficients A and S from an analysis of B -> rho+ rho- decays. The values of A and S, branching fractions, and longitudinal polarization fractions of B -> rho rho decays are used to constrain the Cabibbo-Kobayashi-Maskawa phase alpha/phi2 using an isospin analysis; the solution consistent with the standard model is 71 deg. < alpha < 113 deg. at 68 C.L.