An improved direct limit on the muon electric dipole moment

Abstract

A limit on the permanent electric dipole moment (EDM) of the positive muon is presented based on data from the Fermilab Muon g-2 Experiment taken between 2019 and 2020. The tracking detectors measure the average vertical decay angle of positrons from muon decays, enabling a search for an interaction between a possible muon EDM $d_{\mu }$ and the lab-frame magnetic field. The result, $d_{\mu }=(-0.35\pm 0.19_{\mathrm{stat}}\pm 0.34_{\mathrm{sys}})\times 10^{-19}e\cdot$cm, is consistent with zero and sets a new direct limit on the muon EDM of $|d_{\mu }|<1.10\times 10^{-19}e\cdot$cm at the 95 percent confidence level.

8 pages, 3 figures