$\sin^2\theta_W$ and neutrino electromagnetic interactions in CE$\bar{\nu}_e$NS with different quenching factors

Recently, evidence for the observation of about 2 keV and below nuclearrecoils from the coherent scattering of reactor anti-neutrinos off thegermanium nuclei has been reported. We analyze the observed data to estimatethe value of the weak mixing angle and constrain the neutrino millicharge,magnetic moment, charge radius and anapole moment contributing to the coherentscattering process. Currently, there is no definite model available for thequenching factor at such low energies. To this end, we consider various modelsof the quenching factor and show how it affects the interpretation of theobtained results. We find that the bounds obtained are stronger in some caseswhile comparable or weaker in other cases which show a strong dependence on thechoice and accuracy of a particular quenching factor model. The results are thefirst at such low-energy nuclear recoils. We present an exhaustive list ofanalytical functions for the different quenching factors corresponding to theexisting models and to the data from various experiments. Such functions willbe useful for any new physics study using the nuclear recoils due to thereactor neutrinos.