B- -> pi- pi0/rho- rho0 to NNLO in QCD factorization

TL;DR

This paper compares NNLO QCD factorization calculations with experimental data on B meson decays to test the theory's validity and explores implications for the strong interaction dynamics in these processes.

Contribution

It provides the first NNLO QCD factorization analysis of B -> pi pi/rho rho decays and supports the factorization hypothesis with detailed decay mode analysis.

Findings

Support for the factorization assumption in B decays.

Indication of enhanced colour-suppressed amplitudes.

Potential to determine lambda_B from B -> rho l nu measurements.

Abstract

The approximate tree decays B- -> pi- pi0/rho- rho0 may serve as benchmark channels for testing the various theoretical descriptions of the strong interaction dynamics in hadronic B meson decays. The ratios of hadronic and differential semileptonic B -> pi l nu/rho l nu decay rates at maximum recoil provide particularly clean probes of the QCD dynamics. We confront the recent NNLO calculation in the QCD factorization framework with experimental data and find support for the factorization assumption. A detailed analysis of all tree-dominated B -> pi pi/pi rho/rho rho decay modes seems to favour somewhat enhanced colour-suppressed amplitudes, which may be accommodated in QCD factorization by a small value of the first inverse moment of the B meson light-cone distribution amplitude, lambda_B ~ 250 MeV. Precise measurements of the B -> rho l nu spectrum could help to clarify this point.