Studies of Missing Energy Decays at Belle II

Yinghui Guan

doi:10.1142/s2010194518600728

Abstract

The Belle II experiment at the SuperKEKB collider is a major upgrade of the KEK “B factory” facility in Tsukuba, Japan. The machine is designed for an instantaneous luminosity of [Formula: see text], and the experiment is expected to accumulate a data sample of about 50 ab[Formula: see text]. With this amount of data, decays sensitive to physics beyond the Standard Model can be studied with unprecedented precision. One promising set of modes are physics processes with missing energy such as [Formula: see text], [Formula: see text], and [Formula: see text] decays. The [Formula: see text] decay provides one of the cleanest experimental probes of the flavour-changing neutral current process [Formula: see text], which is sensitive to physics beyond the Standard Model. However, the missing energies of the neutrinos in the final state makes the measurement challenging and requires full reconstruction of the spectator [Formula: see text] meson in [Formula: see text] events. This report discusses the expected sensitivities of Belle II for these rare decays.

Highlights

New Physics Searches with Missing Energy at Belle II The Belle II detector at the Super-KEKB accelerator will collect data from asymmetric e+e− collisions at centre-of-mass energies equivalent to those of Υ(nS) resonances, mainly the Υ(4S), which is perfectly suited for the studies of B decays
The background can be drastically reduced by discarding events with extra tracks or extra energy clusters in the rest of the event. This technique was already employed at Belle, known as Full Reconstruction (FR) and has achieved a great success
Intermediate particle candidates are reconstructed and a multivariate classifiers (MVC) is trained for each employed decay channel

Summary

Introduction

1. New Physics Searches with Missing Energy at Belle II The Belle II detector at the Super-KEKB accelerator will collect data from asymmetric e+e− collisions at centre-of-mass energies equivalent to those of Υ(nS) resonances, mainly the Υ(4S), which is perfectly suited for the studies of B decays. As a unique analysis technique at B factories, the B-tagging plays an important role in the measurement of these decays.

Results

Conclusion