Muon number reconstruction with IceTop using a two-component lateral distribution function

Abstract: The IceCube Neutrino Observatory, situated at the geographic South Pole, comprises both a surface component, IceTop, and a deep in-ice component. This unique setup allows for simultaneous measurements of low-energy ($\sim \rm{GeV}$) and high-energy ($\gtrsim 400\,\rm{GeV}$) muons generated in cosmic-ray air showers. The correlation between these low- and high-energy muons can serve as a valuable tool not only for analyzing cosmic-ray composition but also for tests of hadronic interaction models. However, IceTop does not feature dedicated muon detectors, making it challenging to measure the low-energy muon component for individual air showers. \ \noindent For this reason, a two-component lateral distribution function is utilized for the simultaneous reconstruction of the primary energy and low-energy muon number on a single-event basis. This is achieved by combining analytical descriptions of the electromagnetic and muon lateral distributions. In this work, the underlying principles of this method will be discussed, as well as its capability for muon number reconstruction using the hadronic interaction models Sibyll 2.1, QGSJet-II.04, and EPOS-LHC.