Probing scalar non-standard interaction of supernova neutrinos in next-generation neutrino experiments

Abstract

A new neutrino-matter interaction can potentially affect neutrino propagation through matter. In this work, we explore the impact of a flavor-conserving scalar-mediated non-standard neutrino interaction in the supernova neutrino flux. We observe that the presence of a scalar interaction involving muon and tau neutrinos (parameterized as $η_{μμ}$ and $η_{ττ}$, respectively) can invert the neutrino mass eigenstate in which three neutrino flavor states are produced inside the supernova core, resulting in a significant modification of the electron neutrino flux from the supernova reaching the Earth. In the context of the DUNE experiment, we estimate the number of supernova neutrino events in the presence of scalar non-standard neutrino interaction $η_{μμ}$ or $η_{ττ}$ and contrast with the case without scalar-mediated non-standard interactions. Our results indicate that such scalar interactions introduce a new degeneracy in the measurement of neutrino mass ordering from supernova neutrinos. We show how the $\barν_e$ event distribution in Hyper-Kamiokande experiment may help resolve the degeneracy between a model with new scalar interactions for normal ordered neutrino masses and the standard model with inverted mass ordering for a galactic supernova.

Figures (5)

• Figure 1: For normal mass ordering, the effective mixing elements $|U_{e1}^{\rm eff}|$, $|U_{e2}^{\rm eff}|$, and $|U_{e3}^{\rm eff}|$ as a functions of matter density in the presence of scalar mediated NSI parameters, $\eta_{ee}$ (left column), $\eta_{\mu\mu}$ (middle column), and $\eta_{\tau\tau}$ (right column). The top and bottom rows correspond to the strength of the SNSI parameters $\eta_{\alpha\alpha} = 0.1$ and $\eta_{\alpha\alpha} = 0.01$, respectively. We consider neutrino energy $E = 10$ MeV in the plot. The value of oscillation parameters used to compute the mixing matrix elements are taken from NuFit-6 Esteban:2024eli.
• Figure 2: Same as fig. \ref{['fig:mass-mix-nu-nmo']}, but with inverted mass ordering of neutrino masses.
• Figure 3: Left: For neutrinos, the resonance density $\rho_{\rm res}$ (eq. (\ref{['eq:rho_res']})) as a function of the SNSI strength $\eta_{\mu\mu}$ estimated analytically with two flavor approximation. The shaded region shows the possible matter densities inside the supernova ($\rho<10^{14}$ g/cc). The orange vertical line corresponds to the minimum value of $\eta_{\mu\mu}$, which keeps the new resonance inside the supernova. The magenta vertical line depicts the $\eta_{\mu\mu}$ for which resonance occurs at $\rho \simeq 10^{11}$ g/cc, the density at the core boundary. The red and blue dots show the resonance densities that correspond to the $\eta_{\mu\mu} = 0.01$ and $\eta_{\mu\mu} = 0.1$, respectively. Right: Effective mixing $|U^{\rm eff}_{e2}|$ as function of the $\eta_{\mu\mu}$ for four benchmark value of the matter density inside the supernova: $\rho = 4.2\times 10^8$ g/cc ($\rho_{res}$ for $\eta_{\mu\mu} = 0.1$), $\rho = 4.2\times 10^{10}$ g/cc ($\rho_{res}$ for $\eta_{\mu\mu} = 0.01$), $\rho = 4.2\times 10^{11}$ g/cc ($\rho_{res}$ for $\eta_{\mu\mu} = 0.006$), and $\rho = 10^{14}$ g/cc ($\rho_{res}$ for $\eta_{\mu\mu} = 2\times 10^{-4}$ g/cc). $|U^{\rm eff}_{e2}|$ is computed numerically with full three-flavor formalism. We consider neutrino energy $E= 10$ MeV in both the panels.
• Figure 4: The expected supernova neutrino events ($\nu_e$) distribution at DUNE as a function time after the core bounce. The left (right) panels shows the distributions for NMO (IMO). In the top (bottom) panels, we use 10 kpc (20 kpc) as distance of the supernova from the Earth. For the $\nu_e$ flux, we consider a supernova explosion with $25_\odot$ progenitor mass at a distance 10 kpc from the Earth. The blue line correspond to the case with standard CC interaction (SI) of neutrinos with background matter in supernova, whereas red line shows the same in the presence of additional SNSI interaction with $\eta_{\mu\mu} = 0.1$ or $\eta_{\tau\tau} = 0.1$. The error bar shows the event rates considering flux and statistical uncertainties. The values of the other oscillation parameters are taken from ref. Esteban:2024eli.
• Figure 5: The expected supernova neutrino events ($\bar{\nu}_e$) distribution at Hyper-K with two identical detectors as a function time after the core bounce. The left (right) panels shows the distributions for NMO (IMO). In the top (bottom) panels, we use $R=10$ kpc (20 kpc) as the distance of the supernova from the Earth. For the $\bar{\nu}_e$ flux, we consider a supernova explosion with $25_\odot$ progenitor mass. The blue line corresponds to the case with standard CC interaction (SI) of neutrinos with background matter in supernova, whereas the overlapping red dashed line shows the same in the presence of additional SNSI interaction with $\eta_{\mu\mu} = 0.1$ or $\eta_{\tau\tau} = 0.1$. The error bar shows the event rates considering flux and statistical uncertainties. The values of the other oscillation parameters are taken from ref. Esteban:2024eli.