Loopy Determinations of $V_{ub}$ and $V_{cb}$
- Resource Type
- Working Paper
- Authors
- Altmannshofer, Wolfgang; Lewis, Nathan
- Source
- Subject
- High Energy Physics - Phenomenology
- Language
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.
Comment: 23 pages, 4 figures. v2: references added; updated numerics with latest B mixing lattice results; conclusions unchanged