# Determination of ${\vert V_{ub} \vert}$ at Belle II

## TL;DR

This paper discusses the potential for measuring the CKM matrix element |V_{ub}| through exclusive B meson decays at Belle II, emphasizing the importance of precise determination for understanding the Standard Model.

## Contribution

It provides prospects and estimates for measuring |V_{ub}| at Belle II using the full dataset, focusing on exclusive B to pi lepton neutrino decays.

## Key findings

- Estimates for |V_{ub}| measurement precision at Belle II.
- Analysis of the decay channel B → π ℓ ν for |V_{ub}| extraction.
- Projected improvements in CKM matrix parameter constraints.

## Abstract

Semileptonic ${B}$ meson decays involving low-mass charged leptons ${e}$ or ${\mu}$ are expected to be free of non-Standard Model contributions and therefore play a critical role in determinations of ${\vert V_{ub} \vert}$ and ${\vert V_{cb} \vert}$. Of all the CKM matrix parameters, ${\vert V_{ub} \vert}$ is the least precisely measured and in most need of additional studies in order to better constrain the apex of the Unitarity Triangle. We focus on exclusive reconstruction of charmless semileptonic ${B}$ meson decay ${B \to \pi \ell \nu}$, and present prospects and estimates for measuring ${\vert V_{ub} \vert}$ at Belle II with the full planned dataset of ${50~\mathrm{ab}^{-1}}$ of integrated luminosity.