2025/08/04 by Skrzypek, Barbara, Klein, Spencer
#FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #High Energy Physics - Experiment (hep-ex)
paper · doi:10.48550/arxiv.2508.02795
Recent measurements of astrophysical neutrinos have expanded our understanding of their nature and origin. However, very little is still known about the astrophysical ν:ν ratio. The only prior measurement is the recent, single Glashow event seen by IceCube. Understanding the astrophysical ν:ν ratio has a bearing on multiple questions, including the astrophysical spectral shape and neutrino production mechanisms. This analysis uses a new approach to measuring the astrophysical muon ν:ν ratio at various energies. It uses inelasticity, the fraction of the initial neutrino energy carried away by the hadronic shower. Inelasticity probes the ν:ν ratio due to the fact that at energies below roughly 100 TeV, valence quarks dominate in deep inelastic scattering interactions, leading to different neutrino and antineutrino inelasticities and cross-sections. We use 10.3 years of IceCube data consisting of starting tracks at energies between 1 TeV and 1 PeV with a self-veto selection that enhances astrophysical event purity in the down-going direction. Based on this sample and analysis method, we present the first measurement of the astrophysical ν:ν ratio at sub-PeV energies.