Rediscovery of $B^0\to J\mskip 1mu / \psi\mskip 2mu K^0_{\scriptscriptstyle L}$ at Belle II

TL;DR

This paper reports the preliminary reconstruction results of the decay $B^0 o J/\psi K^0_L$ at Belle II, measuring candidate counts with different $J/\psi$ decay modes using 62.8 fb$^{-1}$ of data.

Contribution

It demonstrates the first reconstruction of this decay mode at Belle II with specific candidate counts and statistical uncertainties.

Findings

267±21 candidates with $J/\psi\to\mu^+\mu^-$

226±20 candidates with $J/\psi\to e^+e^-$

Preliminary results with statistical errors only

Abstract

We present preliminary results on the reconstruction of the $B^0\to J\mskip 1mu / \psi\mskip 2mu K^0_{\scriptscriptstyle L}$ decay, where $J\mskip 1mu / \psi\mskip 2mu\to\mu^+\mu^-$ or $e^+e^-$. Using a dataset corresponding to a luminosity of $62.8\pm0.6\mbox{fb}^{-1}$ collected by the Belle II experiment at the SuperKEKB asymmetric energy $e^+e^-$ collider, we measure a total of $267\pm21$ candidates with $J\mskip 1mu / \psi\mskip 2mu\to\mu^+\mu^-$ and $226\pm20$ with with $J\mskip 1mu / \psi\mskip 2mu\to e^+e^-$. The quoted errors are statistical only.