  We propose a new possibility of using the coherently enhanced neutrino pair
emission to probe light-mediator interactions between electron and neutrinos.
With typical momentum transfer at the atomic $\mathcal O(1$\,eV) scale, this
process is extremely sensitive for the mediator mass range $\mathcal O(10^{-3}
\sim 10^4$) eV. The sensitivity on the product of couplings with electron
($g^e$ or $y^e$) and neutrinos ($g^\nu$ or $y^\nu$) can touch down to $|y^e
y^\nu| < 10^{-9} \sim 10^{-19}$ for a scalar mediator and $|g^e g^\nu| <
10^{-15} \sim 10^{-26}$ for a vector one, with orders of improvement from the
existing constraints.

High Energy Physics - Phenomenology