New results on semileptonic $B$ decays from the Belle experiment

TL;DR

This paper reports recent measurements of semileptonic B decays from the Belle experiment, including inclusive and exclusive modes, with new differential and branching fraction results based on the full data set.

Contribution

It provides the first measurements of differential branching fractions for B to X_u l nu and new branching fractions for B+ to pi+ pi- l nu, eta l nu, and eta' l nu decays.

Findings

Partial branching fraction of B to X_u l nu measured.

First differential branching fractions of B to X_u l nu shown.

Branching fractions of B+ to pi+ pi- l nu, eta l nu, and eta' l nu measured.

Abstract

This proceeding summarizes the recent measurements of semileptonic $b\to u$ decays from the Belle experiment. These analyses use the full data set collected at the $\Upsilon(4S)$ resonance at KEKB accelerator complex with a center-of-mass energy of $\sqrt{s} = 10.58$ GeV, which contains an integrated luminosity of 711 fb$^{-1}$ and corresponds to 772 million $\Upsilon(4S) \to B\bar{B}$ events. In the sector of inclusive decay, the partial branching fraction of $B \to X_{u} \ell \nu$ decays and the CKM matrix element $|V_{ub}|$ are measured with hadronic tagging. The first measurement of differential branching fractions of $B \to X_{u} \ell \nu$ are shown as a function of different kinematic variables in this contribution as a preliminary result. For the exclusive mode, the branching fraction of $B^{+} \to \pi^{+}\pi^{-} \ell \nu$ including both resonant and non-resonant contributions is measured for the first time. The preliminary results on the branching fractions of $B^{+} \to \eta \ell \nu$ and $B^{+} \to \eta^{(\prime)} \ell \nu$ in the full $q^{2}$ range are also presented.