Probing Earth's core using atmospheric neutrino oscillations in the presence of NSI at INO-ICAL

Abstract

Neutrinos can serve as a complementary and independent tool to gravitational and seismic studies in exploring the interior of Earth, thanks to their unique properties: extremely low interaction cross sections and flavor oscillations. With the precise measurements of neutrino oscillation parameters and observation of the non-zero value of mixing angle $θ_{13}$, it has become feasible to detect the forward scattering of GeV-energy atmospheric neutrinos passing through Earth with ambient electrons in the form of matter effects on neutrino oscillation probabilities. These matter effects depend on both the neutrino energy and electron density distribution along their path, making them ideally suited for exploring the inner structure of Earth. Furthermore, in the presence of non-standard interactions (NSI) of neutrinos with matter, oscillation patterns undergo additional modifications. In this study, we quantify the capability of an atmospheric neutrino experiment, such as a magnetized iron calorimeter detector, to validate the Earth's core and measure the position of the core-mantle boundary in the presence of NSI. We perform this study considering a three-layered density profile of Earth. Our analysis demonstrates that neutrino non-standard interactions impact these Earth tomography measurements in comparison to standard interactions.

Figures (14)

• Figure 1: Layer densities as functions of radial distances for the three-layered and two-layered density profiles of Earth. The solid-black curve represents the density profile with a core, whereas the dashed-blue curve corresponds to a density profile without a core. The inset plot illustrates the expected sensitivity to validate the core inside Earth in the presence of NC-NSI parameters. See section \ref{['sec:results_vc']} for details. Our sensitivities indicate that the significance for validating the core is substantially affected by the presence of NSI.
• Figure 2: Layer densities as functions of radial distances for the three-layered density profiles of Earth with modified-CMB locations. The solid-black curves represent the standard three-layered density profile. The dashed-black lines indicate the standard CMB location. The dark-green (light-blue) bands in all three panels show the $1\sigma$ bounds on the CMB location with SI (NSI). The dark-colored bands in the left, middle, and right panels correspond to the NC-NSI parameters $\varepsilon_{e\mu}$, $\varepsilon_{e\tau}$, and $\varepsilon_{\mu\tau}$ with the true values of $0.1$, respectively. See section \ref{['sec:results_cmb']} for details. These plots demonstrate that the limits on the location of the core-mantle boundary are significantly modified by the presence of NSI.
• Figure 3: The three-flavor $\nu_\mu \rightarrow \nu_\mu$ survival probability oscillogram for the standard three-layered density profile of Earth with standard CMB radius, $R_\text{CMB} = 3480$ km (as shown by the vertical dashed-white lines). The left (right) panel corresponds to neutrino (antineutrino). The green bands represent the first oscillation valley. We consider the benchmark values of neutrino oscillation parameters as given in table \ref{['tab:osc-param-value']}, assuming the neutrino mass ordering to be NO.
• Figure 4: The top (bottom) panels show differences between the three-flavor neutrino oscillation probabilities for ${\nu_\mu} \rightarrow {\nu_\mu}$ ($\bar{\nu}_{\mu} \rightarrow \bar{\nu}_{\mu}$) channel considering Earth density models with and without a core. The left, middle, and right columns correspond to the probability differences with NC-NSI parameter $\varepsilon_{\mu\tau}=-\,0.1, \,0.0,$ and 0.1, respectively. The top and bottom middle columns with $\varepsilon_{\mu\tau} = 0.0$ represent the SI scenario. The dashed-gray vertical lines in each panel represent the standard CMB position with radius of $R_\text{CMB} = 3480$ km. We consider the benchmark values of neutrinos oscillation parameters as given in table \ref{['tab:osc-param-value']} assuming NO.
• Figure 5: Difference in the three-flavour neutrino oscillation probabilities for ${\nu_\mu} \rightarrow {\nu_\mu}$ channel between the Earth density profiles with and without core in the presence of NC-NSI parameters $\varepsilon_{e\mu}$ (top panel) and $\varepsilon_{e\tau}$ (bottom panel). The left, middle, and right columns correspond to the probability differences for value of $\varepsilon_{e\mu}$ (or $\varepsilon_{e\tau}) =$$-\,0.1$, $0.0$, and $0.1$, respectively. The middle column presents the SI scenario. The dashed-grey vertical lines in each panel represent the standard CMB position with radius of $R_\text{CMB} = 3480$ km. We consider the benchmark oscillation parameters as given in table \ref{['tab:osc-param-value']}, assuming NO.