The XENON1T collaboration has found an excess of electron recoil events in their Science Run 1 data below ~7 keV with a spectral shape consistent with that expected from a solar-axion-induced signal. The claimed statistical significance of the solar-axion model over the null hypothesis is 3.5σ. In this work we provide evidence for mismodeling in the electron recoil data that may decrease the local significance of the axion model to as low as p≈0.1. To reach this conclusion, we search for a signal with the spectral template of the solar axion model, but shifted to higher (unphysical) energies above ~7 keV. We find that the distribution of significances found from this side-band analysis does not follow the expected chi-square distribution, which allows us to quantify the extent to which mismodeling may be affecting the interpretation of the data at energies below ~7 keV. For example, we find that there is an even higher-significance fit to the data when the solar axion model is shifted upwards in energy by ~15 keV and allowed to have a negative normalization.
@article{arxiv.2006.16220,
title = {Systematics in the XENON1T data: the 15-keV anti-axion},
author = {Christopher Dessert and Joshua W. Foster and Yonatan Kahn and Benjamin R. Safdi},
journal= {arXiv preprint arXiv:2006.16220},
year = {2020}
}
Comments
9 pages, 7 figures, supplementary code at https://github.com/joshwfoster/XenonSystematics