Speaker
Description
Latest measurements of branching ratios, related to hadronic decays of $B$ meson to charm and pseudo-scalar final states ($DP$), showed disagreements with theoretical predictions of QCD factorization. Meanwhile, SU(3) symmetry-breaking was found in recent studies to exceed the Standard Model threshold of 30% (in $B$ decays to two pseudo-scalars). In the light of these results, an analysis of SU(3)-flavour symmetry in $\bar B \to DP$ decays is essential to quantify the degree of the symmetry-breaking and to look for possible 'New Physics'.
To achieve that, we consider both decay channels of $\bar B \to DP$: where $B$ decays to $DP$ and $\bar DP$. We use decay observables: branching ratios, direct and indirect CP asymmetries. We then perform a global fit by computing $\chi^2$, using two approaches: topological diagrams and a group theory approach, using reduced matrix elements (RMEs). The best fit results have shown that a symmetry-breaking of 30% was not sufficient; rather, a breaking of 60% was more likely to explain the data. We then discuss the implications of such a result, in particular what it entails for the value of the CKM angle $\gamma$. We also make valuable predictions for the unmeasured decays based on our best-fit topological amplitudes.