Constraining exotic spin dependent interactions of muons and electrons

Abstract

AbstractMany experiments have been performed to search for the exotic spin-dependent interactions in ranges from $$\sim \upmu $$∼μm to astrophysical range which corresponds to the energy scale of less than $$\sim $$∼10 eV. At present, nearly all known experiments searching for these new interactions at the macroscopic range are for protons, neutrons, and electrons. Constraints at this range for other fermions such as muons are scarce, though muons might be the most suspicious particles which might take part in new interactions, considering their involvement of several well-known puzzles of modern physics. We use the anomalous magnetic moment and electric dipole moment (EDM) to study the exotic spin-dependent interactions for muons and electrons. The muon’s magnetic moment might indicate existing of the pseudo-scalar–pseudo-scalar (PP) type interaction. We set up a constraint for the scalar–pseudo-scalar (SP) type interaction at the interested range for muons. For the PP type interaction of electrons, we obtained a new constraint at the range of $$\sim $$∼ nm to $$\sim $$∼ 1 mm. Since all the present experiments searching for the new forces give zero results, it is reasonable to consider that these new interactions might only couple to muons. We propose to further search for the new interactions using the muon spin rotation techniques.