Elastic neutrino-electron scattering perspectives at nuclear reactors

The determination of the weak mixing angle, $\sin^2\theta_W$, 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$\nu$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 ($\mu_\nu$) and translate these into constraints on the neutrino transition magnetic moments ($\Lambda_i$). Our results demonstrate the physics potential of the E$\nu$ES channel at current and upcoming reactor-based neutrino experiments.