A search for new physics in low-energy electron recoils from the first LZ exposure

TL;DR

This paper reports on the LZ experiment's search for new physics via low-energy electron recoils, setting limits on various beyond-standard-model particles and interactions using 60 days of data.

Contribution

First search for new physics in low-energy electron recoils using LZ's initial data, providing new limits on axions, neutrino magnetic moments, millicharge, and WIMP-related signals.

Findings

No evidence for new physics found; data consistent with background.

Set new limits on axion-electron coupling and neutrino magnetic moments.

Constraints on millicharge and hidden photon interactions.

Abstract

The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on a dual-phase xenon time projection chamber. We report searches for new physics appearing through few-keV-scale electron recoils, using the experiment's first exposure of 60 live days and a fiducial mass of 5.5t. The data are found to be consistent with a background-only hypothesis, and limits are set on models for new physics including solar axion electron coupling, solar neutrino magnetic moment and millicharge, and electron couplings to galactic axion-like particles and hidden photons. Similar limits are set on weakly interacting massive particle (WIMP) dark matter producing signals through ionized atomic states from the Migdal effect.