Prospects for Exploring Non-Standard Neutrino Properties with Argon-Based CEvNS Experiments

TL;DR

The paper assesses how argon-based CEvNS experiments at stopped-pion sources can perform precision tests of the SM and probe non-standard neutrino properties. It combines SM cross sections with various argon form-factor models, realistic fluxes, and detector assumptions (CENNS-10/750, CCM, PIP2-BD) to project event rates and sensitivities, employing a chi-square framework that incorporates systematics. Key results show that PIP2-BD at F2D2, even with modest systematics, can achieve competitive low-$Q^2$ precision on the weak mixing angle $\sin^2\theta_W$ and tighten bounds on neutrino magnetic moments $\mu_\nu$ and charge radii $\langle r^2 \rangle_\nu$, as well as constrain neutrino NSIs with quarks. These findings establish argon CEvNS as a scalable, clean platform for precision electroweak measurements and broad BSM searches in the MeV regime, complementing other low-energy probes and informing global neutrino physics programs.

Abstract

Coherent elastic neutrino-nucleus scattering (CEvNS) provides a powerful framework for testing the Standard Model (SM) and searching for new physics at low energies. In this work, we examine the prospects for argon-based CEvNS experiments at stopped-pion sources to perform precision measurements of weak interactions and probe non-standard neutrino properties. Our study focused on the CENNS-10 and CENNS-750 detectors at the Spallation Neutron Source at Oak Ridge National Laboratory, the Coherent Captain Mills (CCM) detector at Los Alamos National Laboratory, and the proposed PIP2-BD detector at Fermilabs Facility for Dark Matter Discovery (F2D2). Using realistic neutrino fluxes and detector configurations corresponding to these facilities, we evaluate event rates and sensitivities to a range of observables. Within the SM, argon-based CEvNS detectors enable precision tests of electroweak parameters, including the weak mixing angle, at momentum transfers well below the electroweak scale. We also investigate the sensitivity of these experiments to neutrino electromagnetic properties, such as the magnetic moment and effective charge radius, as well as to possible non-standard neutrino interactions with quarks. Together, these studies highlight the potential of argon-based CEvNS experiments as a clean and versatile platform for precision exploration of non-standard neutrino properties.

Figures (12)

• Figure 1: Total CEvNS cross section for $^{40}$Ar as a function of incident neutrino energy for different nuclear form factor models. The inset shows the relative variation among the models at higher energies.
• Figure 2: CEvNS event rate per day as a function of the nuclear recoil energy (left) and expected reconstructed event rate accumulated over three years for different argon-based detectors and flux source (right).
• Figure 3: (Left) Sensitivity on $\sin^2\theta_W$ showing 90%, 95%, and 99% C.L. regions for different LAr experiments and systematic assumptions. (Right) Running of $\sin^2\theta_W$ with energy scale $\mu$ shown with prediction for different LAr experiments and systematic assumptions considered in this work. The SM prediction is shown as dashed black line alongside existing experimental measurements from Atomic Parity Violation (APV) of Cs (teal), $Q_{\mathrm weak}$ from electron-proton scattering (pink), combined analysis of PandaX-4T with XENONnT (brown) and COHERENT - CsI + LAr (black). The inset provides a magnified view of $\theta_W$ and associated ranges from the different flux sources, with a small offset applied for readability.
• Figure 4: CEvNS event rate per day (for PIP2-BD at F2D2) as a function of the nuclear recoil energy due to Neutrino Magnetic moment for three different values for the moment ($\mu_\nu = 10^{-10},\,10^{-11}\,$and $10^{-12}\,\mu_B$).
• Figure 5: Sensitivity ($\Delta \chi^2 = \chi^2-\chi^2_{\rm min}$) on neutrino magnetic moment ($\mu_{\nu_e},\,\mu_{\nu_\mu}$) for different experiments: PIP2-BD at F2D2 with $\sigma_{\rm{syst}}$ = 10% and 5% (top left), CCM with $\sigma_{\rm{syst}}$ = 10% (top right), CENNS10 with $\sigma_{\rm{syst}}$ = 10% (bottom left), and CENNS750 with $\sigma_{\rm{syst}}$ = 10% and 5% (bottom right).