Single-Point Search for eV-Scale Axion-Like Particles with Variable-Angle Three-Beam-Stimulated Resonant Photon Collider

We report a laboratory search for axion-like particles (ALPs) in the eV mass range using a variable-angle three-beam-stimulated resonant photon collider. The scheme independently focuses and collides three laser beams, providing a cosmology- and astrophysics-independent test. By varying the angles of incidence, the center-of-mass energy can be scanned continuously across the eV range. In this work, we operated the collider in a vacuum chamber at a large-angle configuration, verified the spacetime overlap of the three short pulses, and performed a first search centered at ma≃2.27eV. No excess was observed. Thus, we set a 95% C.L. upper limit on the pseudoscalar two-photon coupling, with a minimum sensitivity of g/M≃4.2×10−10GeV−1 at ma=2.27eV. This provides the first model-independent upper limit on the coupling that reaches the KSVZ benchmark in the eV regime and demonstrates the feasibility of eV-scale mass scans in the near future.