Femtosecond formation of collective modes due to meanfield fluctuations

TL;DR

This paper derives an analytical formula describing the femtosecond formation of collective modes in a plasma, simplifying the understanding of quasiparticle features in interacting systems following intense laser excitation.

Contribution

It introduces a new analytical formula for the dielectric function's time evolution, capturing universal features of collective mode formation in plasmas after femtosecond laser pulses.

Findings

The formula reproduces experimental features of collective mode formation.

It simplifies the theoretical description of quasiparticle dynamics.

Numerical treatments can now focus on effects beyond the formula's scope.

Abstract

Starting from a quantum kinetic equation including the mean field and a conserving relaxation-time approximation we derive an analytic formula which describes the time dependence of the dielectric function in a plasma created by a short intense laser pulse. This formula reproduces universal features of the formation of collective modes seen in recent experimental data of femtosecond spectroscopy. The presented formula offers a tremendous simplification for the description of the formation of quasiparticle features in interacting systems. Numerical demanding treatments can now be focused on effects beyond these gross features found here to be describable analytically.