A closer look at the extraction of $|V_{ub}|$ from $B\to\pi l\nu$

TL;DR

This paper re-analyzes all available data and theoretical inputs on $B\to\pi l\nu$ decays to refine the extraction of the CKM matrix element $|V_{ub}|$, incorporating new form-factor inputs and addressing outliers.

Contribution

It provides a comprehensive re-evaluation of $|V_{ub}|$ from $B\to\pi l\nu$ decays, including new form-factor data and outlier analysis, resulting in higher $|V_{ub}|$ values consistent with inclusive decay measurements.

Findings

Extracted $|V_{ub}|$ values are higher than previous HFLAV results.

Best $|V_{ub}|$ values are approximately $3.88\times 10^{-3}$, consistent with inclusive decay results.

Outlier removal impacts the fit and the resulting $|V_{ub}|$ estimates.

Abstract

To extract the Cabibbo-Kobayashi-Maskawa (CKM) matrix element $|V_{ub}|$, we have re-analyzed all the available inputs (data and theory) on the $B\to\pi l\nu$ decays including the newly available inputs on the form-factors from light cone sum rule (LCSR) approach. We have reproduced and compared the results with the procedure taken up by the Heavy Flavor Averaging Group (HFLAV), while commenting on the effect of outliers on the fits. After removing the outliers and creating a comparable group of data-sets, we mention a few scenarios in the extraction of $|V_{ub}|$. In all those scenarios, the extracted values of $|V_{ub}|$ are higher than that obtained by HFLAV. Our best results for $|V_{ub}|^{exc.}$ are $(3.88 \pm 0.13)\times 10^{-3}$ and $(3.87 \pm 0.13)\times 10^{-3}$ in frequentist and Bayesian approaches, respectively, which are consistent with that extracted from inclusive decays $|V_{ub}|^{inc}$ within $1~\sigma$ confidence interval.