Measurement of the branching fractions of the $B^+ \to \eta \ell^+ \nu_{\ell} $ and $B^+ \to \eta^{\prime} \ell^+ \nu_{\ell} $ decays with signal-side only reconstruction in the full $q^2$ range

TL;DR

This paper measures the branching fractions of specific B meson decays involving eta and eta prime mesons with leptons, using full q^2 range data to reduce model dependence, providing precise experimental results.

Contribution

First measurement of B+ to eta and eta prime semileptonic decays over the entire q^2 range with reduced model dependence.

Findings

Branching fraction for B+ to eta l+ nu: (2.83 ± 0.55 (stat) ± 0.34 (syst)) × 10^-5

Branching fraction for B+ to eta' l+ nu: (2.79 ± 1.29 (stat) ± 0.30 (syst)) × 10^-5

Measurement performed with 711 fb^-1 data sample at Belle detector.

Abstract

The branching fractions of the decays $B^{+} \to \eta \ell^{+} \nu_{\ell}$ and $B^{+} \to \eta^{\prime} \ell^{+} \nu_{\ell}$ are measured, where $\ell$ is either an electron or a muon, using a data sample of $711\,{\rm fb}^{-1}$ containing $772 \times 10^6 B\bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. To reduce the dependence of the result on the form factor model, the measurement is performed over the entire $q^2$ range. The resulting branching fractions are ${\cal B}(B^{+} \rightarrow \eta \ell^{+} \nu_{\ell}) = (2.83 \pm 0.55_{\rm (stat.)} \pm 0.34_{\rm (syst.)}) \times 10^{-5}$ and ${\cal B}(B^{+} \rightarrow \eta' \ell^{+} \nu_{\ell}) = (2.79 \pm 1.29_{\rm (stat.)} \pm 0.30_{\rm (syst.)}) \times 10^{-5}$.