Loop-induced determinations of Vub and Vcb

Abstract

We use loop induced processes like meson oscillations and rare $b$ hadron decays to determine the absolute values of the Cabibbo-Kobayashi-Maskawa matrix elements $|{V}_{ub}|$ and $|{V}_{cb}|$ and compare our results to the standard determinations based on inclusive and exclusive semileptonic tree-level decays of $B$ mesons. For many years there have been tensions between the inclusive and exclusive determinations. Assuming the absence of new physics, we find that meson oscillation data shows a slight preference for the inclusive value of $|{V}_{cb}|$ and the exclusive value for $|{V}_{ub}|$. Rare $b$ decay data prefers values for $|{V}_{cb}|$ far below the inclusive and exclusive determinations, offering a new perspective on some of the persistent rare $b$ decay anomalies.