Light-shinning-through-thin-wall radio frequency cavities for probing dark photon

We address the radio frequency (RF) cavity experiment for probing dark photons, which is a modification of the light-shining-through-thin-wall (LSthinW) setup with a relatively thin conducting barrier between cylindrical emitter and hollow We address the radio frequency (RF) cavity experiment for probing dark photons, which is a modification of the light-shining-through-thin-wall (LSthinW) setup with a relatively thin conducting barrier between a cylindrical emitter and a hollow receiver. The experimental facility allows for the effective probing of dark photons even in the off-shell regime, i.e., when the dark photon mass exceeds the driving frequency of the emitter cavity, which is pumped by an electromagnetic mode. We compare the sensitivity of two specific setup configurations: (i) two adjacent cylindrical cavities placed end-to-end with an end-cap separating them, and (ii) a nested geometry in which the cylindrical receiver is encapsulated within the emitter. We demonstrate that, for a certain range of dark photon masses, the nested configuration with the $\mbox{TM}_{010}$ pump mode can provide enhanced sensitivity compared to an adjacent emitter setup. Remarkably, for the $\mbox{TE}_{011}$ pump mode, both the nested and adjacent cavity configurations can yield comparable expected reaches for the specific geometry type.