Elastic neutrino-electron scattering perspectives at nuclear reactors

Abstract

The determination of the weak mixing angle, $\sin^2θ_W$, at low momentum transfers remains a powerful test of the Standard Model and its potential new physics extensions. In this paper, we explore some physics opportunities at present and future reactor neutrino experiments through elastic neutrino-electron scattering (E$ν$ES). We assess the expected sensitivity to the weak mixing angle considering the CLOUD, TAO, and DANSS experimental configurations. We find that both CLOUD and TAO may achieve a precision that surpasses the current global fit from reactor experiments, while DANSS alone is expected to surpass the benchmark precision set by TEXONO measurement of the weak mixing angle. Additionally, we derive projected upper limits for the non-standard neutrino interactions (NSI), effective neutrino magnetic moment ($μ_ν$) and translate these into constraints on the neutrino transition magnetic moments ($Λ_i$). Our results demonstrate the physics potential of the E$ν$ES channel at current and upcoming reactor-based neutrino experiments.

Figures (6)

• Figure 1: Expected reconstructed signal and background event rates for the corresponding reactor setups. Signal events are shown in solid lines for the CLOUD (green), TAO (blue), and DANSS (red) configurations. Similarly, expected background events are shown in dashed lines. These projections assume a 10-year exposure time, which includes a duty factor of $11/12$ for all configurations. See the text for details.
• Figure 2: The expected sensitivities ($\Delta \chi^2$) at the CLOUD setup. The left panel displays the sensitivity to the weak mixing angle ($\sin^2 \theta_W$), while the right panel shows the sensitivity to the effective neutrino magnetic moment ($\mu_\nu$). The solid lines consider the case of conservative systematic assumptions while dashed lines represent the case of optimistic systematics. See the text for a detailed explanation.
• Figure 3: The projected sensitivities ($\Delta \chi^2$) at the TAO configuration. The left panel shows the sensitivity to the weak mixing angle ($\sin^2 \theta_W$), while the right panel displays the sensitivity to the effective neutrino magnetic moment ($\mu_\nu$). The solid lines consider the case of conservative systematic assumptions while dashed lines represent the case of optimistic systematics. See the text for a detailed explanation.
• Figure 4: The expected sensitivities ($\Delta \chi^2$) at the DANSS setup. The left panel displays the sensitivity to the weak mixing angle ($\sin^2 \theta_W$), while the right panel shows the sensitivity to the effective neutrino magnetic moment ($\mu_\nu$). The solid lines consider the case of conservative systematic assumptions while dashed lines represent the case of optimistic systematics. See the text for a detailed explanation.
• Figure 5: Scale dependence $\mu$ [GeV] of $\sin^2 \theta_W$ in the $\overline{\mathrm{MS}}$ renormalization scheme Erler:2017knjParticleDataGroup:2024cfk. We present our expected 1$\sigma$ precision sensitivities of the weak mixing angle at CLOUD (green), TAO (blue), and DANSS (red). For comparison, we also show the results from TEXONO TEXONO:2009knm (purple), global fit reactors Canas:2016vxp (maroon), as well as CONUS$+$Ackermann:2025obxAlpizar-Venegas:2025wor (cyan) via coherent elastic neutrino-nucleus scattering (CE$\nu$NS). Furthermore, we also display the results from solar neutrino interactions via CE$\nu$NS processes in dark matter direct detection experiments: PANDAX-4T, XENONnT, and LUX-ZEPLIN (LZ) Maity:2024ajiDeRomeri:2024iawLZ:2025igz. See the text for details.