Precision three-Dimensional Atmospheric Neutrino Flux Calculation Based on Honda Flux Model

Abstract

We present a comprehensive three-dimensional atmospheric neutrino flux calculation based on the well-recognized simulation framework develeped by Honda and his collaborators, incorporating for the first time the muon propagation inside the Earth and its subsequent decay or nuclear capture. Other updates of essential input models include: the AMS02-based primary cosmic ray model, IGRF2020 geomagnetic field, and muon-recalibrated hadronic interaction model. The calculation covers seven detector sites across diverse geomagnetic environments, spanning 10~MeV to $10^4$~GeV. Significant site-dependent differences appear at $E_\nu < 10$~GeV, with $\nu_\mu$ flux at IceCube approximately twice that at JUNO below 1~GeV. Compared to HKKMS15, deviations of 2\%--10\% are attributed to the updated input models. Below 100~MeV, we present precise flux results, revealing that muon propagation contributes a globally significant component to the low-energy neutrino flux at all sites, with an approximately site-independent absolute increment. The hadronic uncertainty is re-estimated across the energy range using the updated hadronic interaction model, with significant reduction of the systematic error compared to previous calculations. These results provide essential inputs for neutrino oscillation and rare-event search experiments including JUNO, Super-Kamiokande/Hyper-Kamiokande, DUNE, KM3NeT/ORCA, and IceCube, as well as direct dark matter detection experiments facing the neutrino fog.