Afterglow of the dynamical Schwinger process: Soft photons amass
AbstractWe consider the conversion of an electric field into photons as a secondary probe of the dynamical Schwinger process. In spatially homogeneous electric fields, quantum fluctuations of electron-positron (e+e-) pairs are lifted on the mass shell leaving asymptotically a small finite pair density. The e+e- dynamics, in turn, couples to the quantized photon field and drives its on-shell mode occupation. The spectral properties of the emerging asymptotic photons accompanying the Schwinger process are calculated in lowest-order perturbation theory. Soft photons in the optical range are produced amass in the subcritical region, thus providing a promising discovery avenue, e.g. for laser parameters of the Extreme Light Initiative (ELI-NP) to be put in operation soon.