Search for New Physics in Electronic Recoil Data from XENONnT

TL;DR

This paper reports a low-background electronic recoil search in the XENONnT experiment, setting new limits on dark matter and axion models with the lowest background levels achieved.

Contribution

It presents the first analysis of XENONnT data with novel background reduction techniques, achieving unprecedented sensitivity in electronic recoil searches.

Findings

No excess above background observed.

Set new limits on solar axions and neutrino magnetic moments.

Achieved the lowest background in a dark matter detector.

Abstract

We report on a blinded analysis of low-energy electronic-recoil data from the first science run of the XENONnT dark matter experiment. Novel subsystems and the increased 5.9 tonne liquid xenon target reduced the background in the (1, 30) keV search region to $(15.8 \pm 1.3)$ events/(tonne$\times$year$\times$keV), the lowest ever achieved in a dark matter detector and $\sim$5 times lower than in XENON1T. With an exposure of 1.16 tonne-years, we observe no excess above background and set stringent new limits on solar axions, an enhanced neutrino magnetic moment, and bosonic dark matter.