Probing Vacuum Polarization Effects with High-Intensity Lasers

Abstract

These notes provide a pedagogical introduction to the theoretical study of vacuum polarization effects in strong electromagnetic fields as provided by state-of-the-art high-intensity lasers. Quantum vacuum fluctuations give rise to effective couplings between electromagnetic fields, thereby supplementing Maxwell's linear theory of classical electrodynamics with nonlinearities. Resorting to a simplified laser pulse model allowing for explicit analytical insights, we demonstrate how to efficiently analyze all-optical signatures of these effective interactions in high-intensity laser experiments. Moreover, we highlight several key features relevant for the accurate planning and quantitative theoretical analysis of quantum vacuum nonlinearities in the collision of high-intensity laser pulses.

Large N external-field quantum electrodynamics

“…and gamma matrices γ µ ; see refs. [3][4][5][6][7][8][9][10][11][12][13] for pertinent reviews of standard external-field QED. Here, the scalings e 2 ∼ N −1 and e F ∼ e Ā ∼ N 0 and the notation ψ(•)ψ = N i=1 ψ(i) (•)ψ (i) , where i labels the fermion flavors, are implicitly understood in eq.…”

Photon–photon physics at the LHC and laser beam experiments, present and future

“…Regarding the value obtained in the optical domain (prediction of Eq. ( 8)), we understand that this will be extremely difficult to observe light-by-light scattering in its full glory through collisions of laser beams [37,38,39,40]. In principle, the experiment could be done by focusing two laser beams on the same point in space.…”

“…Let us also recall that in the context light-by-light scattering, we are at the edge of observing the process in its full glory through collisions of laser beams [37,38,39,40]. Figure extracted from Ref.…”

Vacuum Birefringence at the Gamma Factory

“…Our next goal is to construct the effective theory describing the dynamics and interactions of macroscopic electromagnetic fields in the quantum vacuum. Here, we focus on the limit of $$\lbrace E/E_{\rm cr},B/B_{\rm cr}\rbrace \ll 1$$ relevant for laboratory experiments; compared to the recent reviews [ 10–13 ] and references therein. Correspondingly, a perturbative expansion of the vacuum‐fluctuation‐mediated effective interactions of the applied electromagnetic fields in powers of E and B , or – resorting to a covariant and gauge invariant formulation – in powers of the field strength tensor $$F^{\mu \nu }$$ and its dual $${}^*\!F^{\mu \nu } =\frac{1}{2}\epsilon ^{\mu \nu \rho \sigma }F_{\rho \sigma }$$, can be truncated at low orders; $$\epsilon ^{\mu \nu \rho \sigma }$$ is the Levi–Civita symbol.…”