CharmlessBc→PP,PVDecays in the QCD Factorization Approach

Na Wang

doi:10.1155/2016/6314675

Abstract

The charmlessBc→PP,PVdecays (wherePandVdenote the light pseudoscalar and vector mesons, resp.) can occur only via the weak annihilation diagrams within the Standard Model. In this paper, we study these kinds of decays in the framework of QCD factorization, by adopting two different schemes: scheme I is similar to the method usually adopted in the QCD factorization approach, while scheme II is based on the infrared behavior of gluon propagator and running coupling. For comparison, in our calculation, we adopt three kinds of wave functions forBcmeson. The branching ratios based on the two schemes are given. It is found that (a) the predicted branching ratios in scheme I are, however, quite small and almost impossible to be measured at the LHCb experiment and (b) in scheme II, by assigning a dynamical gluon mass to the gluon propagator, we can avoid enhancements of the contribution from soft endpoint region. The strength of annihilation contributions predicted in scheme II is enhanced compared to that obtained in scheme I.

Highlights

The Bc meson is the lowest-lying bound state of two heavy quarks with different flavors (b and c)
We will focus on the two-body charmless hadronic Bc decays, which can proceed only via the weak annihilation diagrams in the Standard Model (SM): the initial b and c quarks annihilate into u and d/s quarks, which form two light mesons by hadronizing with qq (q = u, d, s) pair emitted from a gluon
We find that the first equality holds exactly in both scheme I and scheme II, because the exact isospin symmetry is assumed in our calculation

Summary

Introduction

The Bc meson is the lowest-lying bound state of two heavy quarks with different flavors (b and c). We will focus on the two-body charmless hadronic Bc decays, which can proceed only via the weak annihilation diagrams in the Standard Model (SM): the initial b and c quarks annihilate into u and d/s quarks, which form two light mesons by hadronizing with qq (q = u, d, s) pair emitted from a gluon Detailed studies of these decays will be certainly helpful for further improving our understanding of the weak annihilation contributions, the size of which is currently an important issue in B physics. The charmless Bc decays into two light mesons, coming only from a single tree operator, provide an ideal testing ground for annihilation in heavy meson decays and deserve detailed studies using different theoretical approaches [25,26,27,28]. The explicit expressions for the decay amplitudes and the relevant input parameters are collected in Appendices A and B, respectively

Theoretical Framework and Calculation

Numerical Results and Discussions

Summary

Decay Amplitudes in the QCDF Approach

Input Parameters