Radiative charmless B_{(s)}\to V \gamma and B_{(s)}\to A \gamma decays in pQCD approach

TL;DR

This paper uses perturbative QCD to predict branching ratios and CP asymmetries for radiative charmless B_{(s)} decays to vector and axial-vector mesons, aligning with current data and providing new form factor estimates.

Contribution

It offers the first comprehensive pQCD-based predictions for B_{(s)} o V(A)\gamma decays, including form factors and CP asymmetries, with updated inputs and detailed diagram calculations.

Findings

Predicted branching ratios agree with experimental data.

Calculated CP asymmetries and asymmetry variables.

Provided new form factor estimates for B o A transitions.

Abstract

We study the radiative charmless $B_{(s)}\to V(A)\gamma $ decays in perturbative QCD (pQCD) approach to the leading order in $\alpha_s$ (here $V$ and $A$ denotes vector mesons and two kinds of axial-vector mesons: $^3P_1$ and $^1P_1$ states, respectively.). Our predictions of branching ratios are consistent with the current available experimental data. We update all $B_{(s)}\to V$ form factors and give the predictions for $B\to A$ form factors using the recent hadronic inputs. In addition to the dominant factorizable spectator diagrams, which is form factor like, we also calculate the so-called ``power suppressed'' annihilation type diagrams, the gluonic penguin, charming penguin, and two photon diagrams. These diagrams give the main contributions to direct CP asymmetries, mixing-induced CP asymmetry variables, the isospin asymmetry and U-spin asymmetry variables. Unlike the branching ratios, these ratios or observables possess higher theoretical precision in our pQCD calculation, since they do not depend on the input hadronic parameters too much. Most of the results still need experimental tests in the on-going and forthcoming experiments.