Propagation of GeV neutrinos through Earth

TL;DR

This study investigates how Earth's matter affects GeV neutrino oscillations, revealing resonance behaviors and flux ratios that can be tested by upcoming detectors like PINGU to understand neutrino properties and sources.

Contribution

It provides a detailed analysis of Earth matter effects on GeV neutrino oscillations, including resonance conditions and flux predictions for different source scenarios.

Findings

Resonant peaks at specific densities for neutrino oscillations.

Second resonance peak at 6.18 GeV does not occur in realistic Earth profiles.

Flux ratios differ between standard and muon damped source scenarios.

Abstract

We have studied the Earth matter effect on the oscillation of upward going GeV neutrinos by taking into account the three active neutrino flavors. For neutrino energy in the range 3 to 12 GeV we observed three distinct resonant peaks for the oscillation process $\nu_e\leftrightarrow \nu_{\mu,\tau}$ in three \textit{distinct} densities. However, according to the most realistic density profile of the Earth, the second peak at neutrino energy 6.18 GeV corresponding to the density $6.6\,g/cm^3$ does not exist. So the resonance at this energy can not be of MSW-type. For the calculation of observed flux of these GeV neutrinos on Earth, we considered two different flux ratios at the source, the standard scenario with the flux ratio $1:2:0$ and the muon damped scenario with $0:1:0$. It is observed that at the detector while the standard scenario gives the observed flux ratio $1:1:1$, the muon damped scenario has a different ratio. For muon damped case with $E_{\nu} < 20$ GeV, we always get observed neutrino fluxes as $\Phi_{\nu_e} < \Phi_{\nu_\mu}\simeq \Phi_{\nu_\tau}$ and for $E_{\nu} > 20$ GeV, we get the average $\Phi_{\nu_e}\sim 0$ and $\Phi_{\nu_\mu}\simeq \Phi_{\nu_\tau}\simeq 0.45$. The upcoming PINGU will be able to shed more light on the nature of the resonance in these GeV neutrinos and hopefully will also be able to discriminate among different processes of neutrino production at the source in GeV energy range.