Searching for Beyond the Standard Model Particles at the ALPS II Experiment

The Any Light Particle Search II (ALPS II) experiment has completed its first science runs searching for pseudoscalar and scalar beyond the standard model particles. ALPS II is a "light-shining-through-a-wall" experiment located at DESY in Hamburg, Germany. The experiment consists of two 120 m strings of straightened 5.3 T HERA dipoles separated by an opaque wall and containing high-finesse optical cavities. Axions or axion-like particles that are generated by photons in the production optical cavity pass through the wall into the regeneration optical cavity where some will regenerate photons identical to those in the production cavity. The regenerated photons will be detected with a heterodyne readout scheme during the initial configuration after which the experiment will be reconfigured to use a transition-edge single-photon detector.

The first ALPS II science runs were conducted in a reduced sensitivity configuration with the regeneration cavity only commissioned. The collaboration plans to implement the production cavity before the next science run begins. Science runs, searches for both pseudoscalar and scalar particles, began in 2023 and concluded during 2024. In this talk, I will report on the science data analysis and current results, the current status of the experiment, and the outlook for 2025 and beyond.