Frequency chirp-induced enhancement of electron–positron pair production in polarized laser fields

We investigate electron–positron pair production in frequency-chirped, polarized laser fields using the Dirac–Heisenberg–Wigner formalism. A key theoretical finding is the polarization-dependent critical chirp threshold b_c(δ), which marks the transition between tunneling-dominated and multiphoton pair production regimes: b_c doubles as polarization evolves from linear (δ = 0, b_c(0) = 0.02 m²) to circular (δ = 1, b_c(1) = 0.04 m²). Above this threshold, chirp induces spectral compression with the momentum distribution width scaling as Δq ∝ b^−1/2, concentrating pairs into a smaller phase-space volume and enhancing production yields by up to three orders of magnitude, following the universal scaling law n ∝ (bτ)^3/2. Notably, non-monotonic polarization dependence is observed at intermediate chirp values, where linear polarization temporarily surpasses circular in yield before convergence at large b. These results establish chirp as a precise control parameter for optimizing EP pair production in nonperturbative quantum electrodynamics, advancing the theoretical framework for understanding quantum vacuum dynamics and providing a foundation for structured pulse engineering in strong-field quantum electrodynamics.