We conduct the first ``light-shining-through-wall" (LSW) search for dark photons using two state-of-the-art high quality-factor superconducting radio frequency (SRF) cavities and report the results of its pathfinder run. Our new experimental setup enables improvements in sensitivity over previous searches and covers new dark photon parameter space. We design delicate calibration and measurement protocols to utilize the high-Q setup at Dark SRF. Using cavities operating at 1.3GHz, we establish a new exclusion limit for kinetic mixing as small as {ϵ=1.6×10−9} and provide the world's best constraints on dark photons in the 2.1×10−7eV−5.7×10−6eV mass range. Our result is the first proof-of-concept for the enabling role of SRF cavities in LSW setups, with ample opportunities for further improvements. In addition, our data sets a competitive lab-based limit on the Standard Model photon mass by searching for longitudinal photon polarization.
@article{arxiv.2301.11512,
title = {New Exclusion Limit for Dark Photons from an SRF Cavity-Based Search (Dark SRF)},
author = {A. Romanenko and R. Harnik and A. Grassellino and R. Pilipenko and Y. Pischalnikov and Z. Liu and O. S. Melnychuk and B. Giaccone and O. Pronitchev and T. Khabiboulline and D. Frolov and S. Posen and A. Berlin and A. Hook},
journal= {arXiv preprint arXiv:2301.11512},
year = {2023}
}