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 $m_a\simeq 2.27\mathrm{e}\mathrm{V}$. No excess was observed. We thus set a $95\mathrm{\%}$ C.L.\ upper limit on the pseudoscalar two-photon coupling, with a minimum sensitivity of $g\mathrm{/}M\simeq 4.2\times {10}^{-10}{\mathrm{G}\mathrm{e}\mathrm{V}}^{-1}$ at $m_a=2.27\mathrm{e}\mathrm{V}$. 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.