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

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 𝑔𝐴⁢𝑒 <4.5 ×10^-13 for pseudoscalars and (𝛼′/𝛼)<9.7×10^-28 for vectors. We also report a 14.4 keV solar axion coupling limit of 𝑔eff𝐴⁢𝑁 ×𝑔𝐴⁢𝑒 <3.8 ×10^-17, a 1/2⁢𝛽² <8.5 ×10^-48 limit on the strength of PEPV electron transitions, and a lower limit on the electron lifetime of 𝜏𝑒 >1.2 ×1⁢0²⁴  yr for 𝑒− → invisible.