Katharina Dort ; Stephanie Käs ; Jens Sören Lange

09 March 2021
DPG Spring Meeting 2021

Abstract: The Belle II experiment at the high luminosity SuperKEKB e+e- collider has started operation in 2018. The present setup features a 1-layer DEPFET pixel detector with 4 M pixels and trigger rates up to 5 kHz, installed in close proximity to the interaction region. It offers the unique opportunity of detecting highly ionising particles such as antideuterons, pions with small transverse momentum < 100 MeV or exotic particle species like magnetic monopoles with a very short track length. Multivariate techniques are attractive tools to cope with the identification of these particles against the high beam background rates. In this contribution, we evaluate the performance of unsupervised autoencoders, in order to discriminate signal from beam background. In particular, we investigate the possibility of performing the training directly on background data, an unbiased approach to (a) avoid theoretical assumptions about the nature of signal and (b) avoid supervised training with Monte-Carlo data.