Dark Sector Physics at the Belle II Experiment

TL;DR

The Belle II experiment is upgraded to explore dark sector particles in the GeV mass range, with early data showing promising potential for discoveries complementary to LHC and low-energy experiments.

Contribution

This paper reviews the dark sector search capabilities of Belle II with early data, highlighting its potential to discover new particles in the GeV range.

Findings

Early Belle II data enables dark sector searches.

Achieved peak luminosity of 5.5×10^{33} cm^{-2}s^{-1}.

First results show promising discovery potential.

Abstract

The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor. From February to July 2018, the machine has completed a commissioning run, achieved a peak luminosity of $5.5\times 10^{33}$ cm$^{-2}$s$^{-1}$, and Belle II has recorded a data sample of about 0.5 fb$^{-1}$. Main operation of SuperKEKB has started in March 2019. Already this early data set with specifically designed triggers offers the possibility to search for a large variety of dark sector particles in the GeV mass range complementary to the Large Hadron Collider (LHC) and dedicated low energy experiments; these searches will benefit from more data in the process of being accumulated. This talk will review the state of the dark sector searches at Belle II with a focus on the discovery potential of the early data, and show the first results.