Probing Light Mediators in the Radiative Emission of Neutrino Pair

Abstract

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 ($g^{\hat{I}}½$ or $y^{\hat{I}}½$) can touch down to $|y^e{y}^{\hat{I}}½|<10^{-9}\sim 10^{-19}$ for a scalar mediator and $|g^e{g}^{\hat{I}}½|<10^{-15}\sim 10^{-26}$ for a vector one, with orders of improvement from the existing constraints.

13 pages, 4 figures, 1 table