Constraints on General Light Mediators from PandaX-II Electron Recoil Data

TL;DR

This paper uses PandaX-II electron recoil data to set new constraints on general light mediators (vector, axial-vector, scalar, pseudoscalar) affecting neutrino-electron scattering, improving limits on their couplings for masses below 30 keV.

Contribution

It derives the first constraints on various light mediator couplings from PandaX-II data, extending previous bounds to lower mass ranges and multiple interaction types.

Findings

Constraints on vector mediator coupling: g_{V'} extless 32×10^{-7} for extless 10 keV mass.

Constraints on axial-vector mediator coupling: g_{A'} extless 34×10^{-7} for extless 10 keV mass.

Constraints on scalar and pseudoscalar couplings: g_{S} extless 49×10^{-7} (20 keV), g_{P} extless 67×10^{-7} (30 keV).

Abstract

PandaX-II has analyzed their complete data set of the electron recoil energy spectrum and has confirmed the XENON1T (1-7) keV excess, although the excess was also found compatible with the total background. Treating the background as well known, in which case it provides a good fit to the observed spectrum, one can expect stronger constraints on any new physics model with this data. With this motivation, we derive constraints on the new general vector (V), axial-vector (A), scalar (S) and pseudoscalar (P) interactions if any of them contribute to the neutrino-electron elastic scattering. The derived constraints on the couplings at $90\%$ C.L., respectively, are $g_{V^{^{\prime }}} \lesssim 32 \times 10^{-7}$ for the mediator mass ${\lesssim 10}$ keV, $g_{A^{^{\prime }}} \lesssim 34 \times 10^{-7}$ for mass ${\lesssim 10}$ keV, $g_{S}\lesssim 49 \times 10^{-7}$ for mass ${\lesssim 20}$ keV and $g_{P} \lesssim 67 \times 10^{-7}$ for mass ${\lesssim 30}$ keV.