New constraints on neutrino electric millicharge from elastic neutrino-electron scattering and coherent elastic neutrino-nucleus scattering
The neutrino electromagnetic properties have been studied since this particle was first postulated by Wolfgang Pauli in 1930. In different extensions of the Standard Model of Particle Physics (SMPP), the neutrino has electric millicharge and charge radius, as well as electric and magnetic dipole moments, the latter being the most studied property in the literature. However, the possibility that neutrino be a millicharged particle has also been a subject of study in different theoretical and experimental works. Additionally, several experimental constraints on the neutrino electric millicharge (NEM) have been reported from reactors, accelerators, and astrophysical measurements. In this work, we first carry out a statistical analysis using data from reactor neutrino experiments, which include elastic neutrino-electron scattering (ENES) processes, in order to obtain both individual and combined limits on the neutrino electric millicharge. Then we perform a similar calculation, but this time employing data from several future experimental proposals involving coherent elastic neutrino-nucleus scattering (CE$\nu$NS). In the first case, the limit of NEM achieved from the combined results of different experiments is $q_{\nu} \lesssim 1.5\times 10^{-12} e$ at $90\%$ C.L., and in the second scenario the bound corresponds to $q_{\nu} \lesssim 3.5\times 10^{-13} e$ ($90\%$ C.L.). The outcomes indicate CE$\nu$NS experimental proposals might be a suitable alternative to improve the current limits of NEM.