Spin-dependent axion generation with controllable emission angles in strong-laser fields

We investigate axion production in the collision between a spin-polarized relativistic electron beam and an ultraintense laser pulse. A spin-resolved Monte Carlo framework is developed to model axion-electron and axion-photon couplings in arbitrary electromagnetic fields, using quantum emission probabilities under the local constant field approximation. Owing to spin-dependent asymmetries in the radiation probability, the emitted axions acquire a characteristic angular deflection correlated with the initial electron polarization, enabling control of the axion emission via the polarizations of the electron beam and laser field. Simulations demonstrate that a dense ( ∼ 10 10 g a e 2 ) and highly collimated axion beam with a tunable milliradian-scale deflection can be produced within tens of femtoseconds using current laser technology. The polarization-tagged angular asymmetry, combined with femtosecond time gating, provides enhanced signal-background discrimination. These results establish a spin-dependent mechanism for manipulating axion trajectories and open a promising route toward laboratory-based searches for the axion-electron coupling.