Constraints on active-sterile neutrino transition magnetic moments from low-energy electronic recoils at direct detection experiments

Sterile neutrinos can potentially be produced through neutrino transition magnetic moments in neutrino-electron scattering. In this work, we investigate this dipole portal by analyzing low-energy electronic recoil data from the PandaX-4T (Run0 and Run1) and XENONnT experiments. We focus on the up-scattering of solar neutrinos into sterile states via the transition magnetic moment. By performing a comprehensive analysis, we derive robust exclusion limits on the neutrino flavor-independent and flavor-dependent transition magnetic moments for fixed sterile neutrino masses as well as on the mass-coupling parameter space. We demonstrate that, since they can detect solar neutrino-induced processes, direct detection experiments offer a unique framework for studying all possible neutrino flavors. The obtained limits extend the sensitivity to previously unexplored regions of the parameter space.