$B\to \pi\pi$ decays and effects of the next-to-leading order contributions

TL;DR

This paper systematically studies B to pi pi decays using perturbative QCD with all known NLO contributions, finding improved agreement with experimental data for some decay modes and analyzing the impact of NLO effects.

Contribution

It provides a comprehensive NLO analysis of B to pi pi decays within pQCD, enhancing theoretical predictions and understanding of decay mechanisms.

Findings

NLO predictions agree with data for B0→π+π− and B+→π+π0 decay rates

NLO contributions significantly enhance the LO result for B0→π0π0 but do not fully explain the data

The central values of NLO CP asymmetries match experimental measurements

Abstract

In this paper we perform a systematic study for the three $B \to (\pi^+\pi^-,\pi^+\pi^0,\pi^0\pi^0)$ decays in the perturbative QCD (pQCD) factorization approach with the inclusion of all currently known next-to-leading order (NLO) contributions from various sources. We found that (a) for the CP-averaged decay rates $Br(B^0\to \pi^+\pi^-)$ and $Br(B^+\to \pi^+\pi^0)$, the NLO pQCD predictions agree with the data within one standard dviation; (b) for $Br(B^0\to \pi^0\pi^0)$, however, although the NLO contributions can provide a $\sim 100\%$ enhancement to the leading order (LO) result, it is still not large enough to interpret the data; (c) for the CP-violating asymmetries of $B^0\to \pi^+\pi^-$ decay, the central values of the NLO PQCD predictions agree with the data; and (d) we also examined the relative strength of the LO and NLO contributions from different sources.