Data Driven calibration of Atmospheric Neutrino Fluxes using deep underground data in DAEMONFLUX

Maheen Tariq^1*, Anatoli Fedynitch¹, Juan Pablo Yanez²

¹Physics, Academia Sinica, Taipei, Taiwan
²Physics, University of Alberta, Edmonton, Alberta, Canada

* Presenter:Maheen Tariq, email:mtariq2@gate.sinica.edu.tw

Atmospheric neutrinos between GeV and PeV energies are copiously observed by Water and Ice Cerenkov Detectors, such as IceCube and KM3NeT. Beyond studying standard neutrino properties the wide energy range opens interesting paths to studying physics beyond the standard model. From the astrophysical perspective, the flux of atmospheric neutrinos is the most significant background, demanding very accurate theoretical characterization of errors.

Although the features of the atmospheric neutrino flux are understood, there is the limitation of increased uncertainty in the flux at high energies. This uncertainty can be attributed to multiple factors. One source is the lack of knowledge about the flux and mass composition of primary cosmic rays. The second dominant uncertainty stems from the characterization of hadronic interactions within the relevant phase space. Light meson production in the very foward phase space is described via non-pertubative QCD and hence cannot be explained through first principles. Phenomenological models (event generators) have been used, but must be compared to data from fixed target experiments which do not cover the relevant phase space and beam energy.

In our previous work, two adjustable data-driven models, for cosmic ray nucleon flux (GSF) and for the parametrization of secondary particle production (DDM), were combined. The precision of this new flux model, called daemonflux, was improved by calibrating the free parameters of these data-driven models by fitting to the muon flux and charge ratio data at the surface. Compared to previous calculations, daemonflux reduced the uncertainties by an order of magnitude compared to previous estimates in the 10's to 100's GeV range.

The purpose of the present work is to introduce underground muon data in the calibration of atmospheric neutrino fluxes. Underground muons relate to hadron interaction energies and phase space which can not be probed in laboratory experiments, resulting in unique constraints on neutrino fluxes at much higher energies in the multi-TeV to 100's TeV range. We demonstrate how the addition of underground data to the model shows a promising reduction of errors on fitting parameters in the 10 TeV range.

Keywords: neutrino, muon, flux, calibration, daemonflux