Astrophysical Tau Neutrino Identification with IceCube Waveforms

Abstract

The standard neutrino oscillation paradigm predicts almost equal fractions of astrophysical neutrino flavors at Earth regardless of their production ratio at the sources. Therefore, identification of astrophysical tau neutrinos could not only reconfirm the astrophysical neutrino flux measured by IceCube, but also is essential in precisely determining the astrophysical neutrino flavor ratio at Earth, which is an important probe for physics beyond the Standard Model over astronomical baselines. A tau neutrino undergoing a charged current (CC) interaction in IceCube could produce a double deposition of energy, with the first one from the CC hadronic shower and the second from the subsequent tau lepton decay shower. Above an energy of ~100 TeV, such consecutive energy depositions might be resolvable in the sensor waveforms and hence can be a signature of an individual tau neutrino interaction in IceCube. We will present the results of a search for astrophysical tau neutrinos in IceCube waveforms with improved double pulse waveform identification techniques and using 8 years of data.