EXCESS workshop: Descriptions of rising low-energy spectra

TL;DR

The paper summarizes the findings of the EXCESS Workshop, where ten rare event search collaborations shared data and insights on unexplained low-energy spectral rises, aiming to understand their origins and implications for dark matter and neutrino research.

Contribution

It provides a comprehensive overview of different experimental observations of low-energy excesses, sharing data and analysis methods to facilitate collective understanding.

Findings

Shared spectra data from ten collaborations

Identification of common features and differences in excess signals

Publicly available data and visualization tools

Abstract

Many low-threshold experiments observe sharply rising event rates of yet unknown origins below a few hundred eV, and larger than expected from known backgrounds. Due to the significant impact of this excess on the dark matter or neutrino sensitivity of these experiments, a collective effort has been started to share the knowledge about the individual observations. For this, the EXCESS Workshop was initiated. In its first iteration in June 2021, ten rare event search collaborations contributed to this initiative via talks and discussions. The contributing collaborations were CONNIE, CRESST, DAMIC, EDELWEISS, MINER, NEWS-G, NUCLEUS, RICOCHET, SENSEI and SuperCDMS. They presented data about their observed energy spectra and known backgrounds together with details about the respective measurements. In this paper, we summarize the presented information and give a comprehensive overview of the similarities and differences between the distinct measurements. The provided data is furthermore publicly available on the workshop's data repository together with a plotting tool for visualization.