Seasonal Variations of the Atmospheric Muon Neutrino Spectrum measured with IceCube

TL;DR

This paper analyzes seasonal variations in the atmospheric muon neutrino spectrum over 11.3 years using IceCube data, revealing energy-dependent amplitude changes consistent with theoretical models.

Contribution

It introduces a novel spectral unfolding method to measure energy-dependent seasonal variations in the neutrino spectrum from IceCube data.

Findings

Seasonal variation amplitude decreases with energy, reaching -4.6% in winter and +3.9% in summer at 10 TeV.

Unfolded flux exceeds model predictions by up to 30%.

Measured variations align with theoretical predictions using MCEq and NRLMSISE-00.

Abstract

This study presents an energy-dependent analysis of seasonal variations in the atmospheric muon neutrino spectrum, using 11.3 years of data from the IceCube Neutrino Observatory. By leveraging a novel spectral unfolding method, we explore the energy range from 125 GeV to 10 TeV for zenith angles between 90{\deg} to 110{\deg}, corresponding to the Antarctic atmosphere. Our findings reveal that the seasonal variation amplitude decreases with energy reaching ($-4.6 \pm 1.1$)\% during Austral winter and increases ($+3.9 \pm 1.2$)\% during Austral summer relative to the annual average at 10TeV. While the unfolded flux exceeds the model predictions by up to 30\%, the differential measurement of seasonal variations remains unaffected. The measured seasonal variations of the muon neutrino spectrum are consistent with theoretical predictions using the MCEq code and the NRLMSISE-00 atmospheric model.