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

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.

arXiv comment23 pages, 4 figures. v2: references added; updated numerics with latest B mixing lattice results; conclusions unchanged

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Cited by in corpus (7)

• 50 Years of Quantum Chromodynamics
• Standard Model Predictions for Rare K and B Decays without New Physics Infection
• The Exclusive Vision of Rare $K$ and $B$ Decays and of the Quark Mixing in the Standard Model
• Measurement of Differential Distributions of $B\to D^{\ast }\ell {\bar{\nu }}_{\ell }$ and Implications on $|V_{cb}|$
• Updated Constraints from Electric Dipole Moments in the MSSM with R-Parity Violation
• Re-evaluation of the isoscalar mixing angle within selected mesonic nonets
• On the Superiority of the $|V_{cb}|-\gamma$ Plots over the Unitarity Triangle Plots in the 2020s