Probing scalar-neutrino and scalar-dark-matter interactions with PandaX-4T

TL;DR

This paper uses PandaX-4T double beta-decay data to set new limits on scalar-mediated neutrino and dark matter interactions, impacting cosmological models addressing the Hubble Tension.

Contribution

First direct spectral search for scalar-mediated neutrino and dark matter interactions using PandaX-4T data, providing the most stringent limits to date.

Findings

Set new limits on scalar-mediated neutrino self-interactions for mediators below 2 MeV/c^2.

Placed constraints on dark matter-scalar interactions consistent with cosmological bounds.

Provided implications for models addressing the Hubble Tension.

Abstract

Scalar-mediated interactions may exist among neutrinos, dark matter particles, or between the two. Double $\beta$-decay experiments provide a powerful tool to probe such exotic interactions. Using $^{136}$Xe double $\beta$-decay data from PandaX-4T, we perform the first direct spectral search in the energy range of 20 to 2800~keV, setting the most stringent limits to date on scalar-mediated neutrino self-interactions for mediator masses below 2~MeV$/c^2$. These results place significant constraints on models invoking such interactions to alleviate the Hubble Tension. Assuming the same scalar also mediates dark matter self-interactions, constraints on the dark matter-scalar interactions can be placed in conjunction with cosmological constraints.