Toward precision physics tests with future COHERENT detectors

TL;DR

This work provides a comprehensive sensitivity projection for future CE$\nu$NS detectors by COHERENT, focusing on CryoCsI and Ar-750 setups. It combines a detailed CE$\nu$NS cross section framework that includes neutron radii and neutrino charge radii with realistic detector models, backgrounds, and a robust Asimov-based $\chi^2$ analysis. The results show substantial gains: precise measurements of the low-energy weak mixing angle $\sin^2\vartheta_W$, improved knowledge of neutron distribution radii, competitive constraints on neutrino charge radii and electromagnetic properties, and enhanced sensitivity to new light mediators and NSIs. Systematic uncertainties, particularly on the neutrino flux, remain the limiting factor, underscoring the importance of flux calibration initiatives like the $\mathrm{D_2O}$ detector for the next precision era of CE$\nu$NS.

Abstract

We present a comprehensive sensitivity study of future CE$ν$NS detectors, focusing on a cryogenic cesium iodide detector and a tonne-scale liquid argon one, currently being developed by the COHERENT Collaboration. These setups will enable precision measurements of the weak mixing angle at low energies and allow accurate extraction of the neutron nuclear distribution radius. We also demonstrate that next-generation detectors will place constraints on the neutrino charge radius comparable to or better than current global fits. In addition, we explore the sensitivity to non standard neutrino electromagnetic properties, such as magnetic moments and millicharges, as well as new mediators. These findings reinforce the role of CE$ν$NS experiments in the upcoming precision era, with future detectors playing a key role in advancing our understanding of neutrino interactions and electroweak physics at low energies.

Figures (6)

• Figure 1: Asimov data for the COH-CryoCsI I (left) and COH-Ar 750 detectors (right) as a function of the recoil energy compared to the expected CE$\nu$NS rates for different physics scenarios. In blue the event rate for a variation of the weak mixing angle, in green for a different value of the neutron nuclear radius and in red considering the effect of a BSM light mediator universally coupling with the SM fermions, considering the effect of two different mediator masses.
• Figure 2: Left: allowed contours at $1\sigma$ CL in the plane of the weak mixing angle and the average neutron radius of cesium and iodine from the current CsI dataset AtzoriCorona:2023ktl compared to the expected sensitivity for the COH-CryoCsI I and COH-CryoCsI II detectors. Right: sensitivity for the future COH-Ar-750 detector assuming two different systematic uncertainties on the CE$\nu$NS signal. The black cross depicts the reference values employed for both parameters, namely $R_n(\textrm{CsI})=5.06 \,\textrm{fm}$, $R_n(\textrm{Ar})=3.55 \,\textrm{fm}$ and $\sin^2\vartheta_W=0.23863$.
• Figure 3: Relative precision on the determination of $\sin^2\theta_W$ as a function of the CE$\nu$NS systematic uncertainty ($\sigma_{\mathrm{CE\nu NS}}$), for the COH-CryoCsI I and II detectors achievable within 1 SNS year of data taking. The results are compared with the relative uncertainties obtained from the current CsI detector AtzoriCorona:2023ktl and atomic parity violation on cesium ParticleDataGroup:2024cfk.
• Figure 4: Running of $\sin^{2}{\theta_W}(Q^2)$ with the energy scale Q as predicted by the SM (dotted blue curve), together with experimental determination from atomic parity violation (APV) on cesium doi:10.1126/science.275.5307.1759PhysRevLett.109.203003, Møller scattering (E158) PhysRevLett.95.081601, deep inelastic scattering of polarized electrons on deuterons (PVDIS) Wang2014 the result from the proton's weak charge ($Q_\mathrm{weak}$) 2018 and the combined analysis of COHERENT CsI and Ar data sets DeRomeri:2022twgAtzoriCorona:2025xgj. In purple (magenta), our result for the COH-CryoCsI I (COH-CryoCsI II) detector is shown, while the darker cyan (azure) data point corresponds to the COH-Ar-750 detector result in the conservative (optimistic) scenario.
• Figure 5: Allowed contours at $90\%$ CL in the plane of the muon and electron neutrino charge radii obtained by our sensitivity study for the COH-CryoCsI I, COH-CryoCsI II and Ar-750 detectors, compared to the combined result from the current COHERENT CsI and Ar data (orange) AtzoriCorona:2024rtv, and the result from a recent global fit of CE$\nu$NS and neutrino-electron scattering data (green contour) AtzoriCorona:2025xwr. The black cross depicts the SM prediction.