New limits on Bosonic Dark Matter, Solar Axions, Pauli Exclusion Principle Violation, and Electron Decay from the Majorana Demonstrator

TL;DR

This paper reports new experimental limits on exotic keV-scale physics phenomena, including dark matter, solar axions, Pauli exclusion principle violation, and electron decay, based on data from the Majorana Demonstrator with improved sensitivity.

Contribution

It provides the most stringent constraints to date on several exotic physics models using 478 kg·day of data from the Majorana Demonstrator.

Findings

Limits on bosonic dark matter coupling constants at 11.8 keV mass.

Constraints on solar axion couplings at 14.4 keV.

Lower bound on electron lifetime exceeding 10^24 years.

Abstract

We present new limits on exotic keV-scale physics based on 478 kg d of MAJORANA DEMONSTRATOR commissioning data. Constraints at the 90% confidence level are derived on bosonic dark matter (DM) and solar axion couplings, Pauli exclusion principle violating (PEPV) decay, and electron decay using monoenergetic peak signal-limits above our background. Our most stringent DM constraints are set for 11.8 keV mass particles, limiting $g_{Ae} <4.5\times 10^{-13}$ for pseudoscalars and $\frac{\alpha'}{\alpha} < 9.7\times 10^{-28}$ for vectors. We also report a 14.4 keV solar axion coupling limit of $g_{AN}^{\mathrm{eff}}\times g_{Ae}~<~3.8 \times 10^{-17}$, a $\frac{1}{2}\beta^2~<~8.5\times10^{-48}$ limit on the strength of PEPV electron transitions, and a lower limit on the electron lifetime of $\tau_e > 1.2 \times 10^{24}\;$yr for $e^- \rightarrow$ invisible.