Conducting walls have a very small, but observable effect on measurements of electron $g-2$. We compute it from first principles with quantum field theory, and show how it can be accounted for in future measurements.
Intrinsically quantum effects of axion dark matter are always highly suppressed, and in practice undetectable. Thus, even though the axion may be in a nonclassical state, it can still be treated as a classical field.
The heterodyne approach to axion detection enhances the axion signal power. A prototype cavity was designed and tested, with a novel geometry that maximizes signal, suppresses noise, and allows a wide tuning range.
Light dark matter particles could couple directly to electron spin. Since the same is true for neutrons, existing neutron scattering data can accurately predict the signal rate of a dark matter experiment.
Oscillating forces, torques, and mass shifts from dark matter average to zero, but can yield a nonzero second order effect enhanced at low frequency, analogous to the ponderomotive force or gravitational wave memory.
The axion-fermion coupling induces spin-dependent forces and torques, which can lead to macroscopic currents. "Magnetized multilayer" setups can use these currents to probe orders of magnitude beyond existing bounds.
Observed long-range forces are traditionally assumed to be mediated by fields with exactly zero spin scale. We present the first theory of matter particles interacting with "continuous spin" fields with arbitrary $\rho$, and show that there are calculable, universal, observable $\rho$-dependent modifications from familiar gauge theories.
QCD axion dark matter induces oscillating EDMs, yielding physical currents that can be amplified in a microwave cavity. This setup has the unique ability to test whether a cavity haloscope signal arises from the QCD axion.
Electron beam fixed target experiments such as NA64 and LDMX can improve constraints on invisible light vector meson decays by $5$ orders of magnitude, enhancing their sensitivity to dark matter of mass $m_\chi \gtrsim 0.1 \ \mathrm{GeV}$.
When macroscopic dark matter passes through a star, the resulting shock waves cause a distinctive UV transient. Existing telescopes could probe orders of magnitude in dark matter mass in one week of observation.