Loopy Determinations of $V_{ub}$ and $V_{cb}$

TL;DR

This paper uses loop-induced processes such as meson oscillations and rare b decays to determine CKM matrix elements |V_{ub}| and |V_{cb}|, revealing preferences and tensions with standard methods and offering new insights into anomalies.

Contribution

It introduces a novel approach to determine CKM elements via loop processes, providing a fresh perspective on existing tensions and anomalies in flavor physics.

Findings

Meson oscillation data slightly favors inclusive |V_{cb}| and exclusive |V_{ub}| values.

Rare b decay data suggests much lower |V_{cb}| values, differing from standard determinations.

Offers new insights into persistent rare b decay anomalies.

Abstract

We use loop induced processes like meson oscillations and rare b hadron decays to determine the absolute values of the CKM 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.