Conveners
Strong Field QED
- Naser Ahmadiniaz (Helmholtz-Zentrum Dresden-Rossendorf (HZDR))
- Holger Gies (University of Jena)
Strong Field QED
- Felix Karbstein (Helmholtz Institut Jena)
Strong Field QED
- Katarzyna Krajewska (University of Warsaw)
- Felix Karbstein (Helmholtz Institut Jena)
Strong Field QED
- Tom Blackburn (University of Gothenburg)
Strong Field QED
- Daniel Seipt (Helmholtz Institut Jena)
Strong Field QED
- Christian Kohlfuerst (Helmholtz-Zentrum Dresden Rossendorf)
A major computational challenge in the physics of intense fields is the ability to do reliable non-perturbative computations for fields that are both strong and have large gradients. In this talk I discuss the use of ideas from resurgence to make precise resummations and analytic continuations into the intense field regime beginning with modest amounts of perturbative weak-field information....
We study electron-positron pair creation induced by the field of two colliding (transversal and linearly polarized) laser pulses ranging from the Sauter-Schwinger regime at small laser frequencies to the Breit-Wheeler regime at large photon energies.
On the basis of a generalized WKB approach, we find that the pair creation rate along the symmetry axis (where one would expect the maximum...
We discuss spatially- and temporally-resolved, non-perturbative pair production in colliding, linearly polarized laser pulses on the basis of two numerical approaches; a generalized WKB approach culminating in solving a modified Riccati equation and large-scale simulations based on the Dirac-Heisenberg-Wigner formalism.
We discuss how Dirac-Heisenberg-Wigner (quantum kinetic theory) as well...
There is a renewed interest in the physics of radiation reaction (RR), largely driven by high-power laser systems where particles are subject to RR forces at least as strong as the Lorentz force. The Lorentz-Abraham Dirac (LAD) equation of motion with RR has, however, unphysical runaway solutions. The Landau-Lifshitz (LL) equation obtained from the Lorentz-Abraham-Dirac equation through...
The quantum vacuum nonlinearity allows for the effect of laser photon merging in the collision of two (or more) laser beams. As the merged photons origin from a manifestly inelastic process, their energy differs significantly from the background photons of the driving lasers, making them accessible for experiments. However, the number of merged photons is typically considered to be very small....
The most general QED four-photon amplitude that has been computed, so far, is the one with two photons on-shell and two off-shell. The generalization of this work to a fully off-shell calculation is presently still lacking. Here we present the result of such a calculation, although still with at least one of the legs taken in the low-energy limit, unifying the scalar and spinor QED cases....
The standard formalism for calculating the S-matrix in quantum field theory is based on path integrals over field configurations, and can be formulated as a diagrammatic perturbative method. Alternative to this approach is the Worldline formalism, based on first-quantized relativistic point particle path integrals. Recently, a novel representation of the fermion propagator dressed with an...
In this talk, we consider the scattering of an x-ray free-electron laser (XFEL) beam on the superposition of a strong magnetic field $B_{\textrm{ext}}$ with the Coulomb field $E_{\textrm{ext}}$ of a nucleus with charge number $Z$. In contrast to Delbrück scattering (Coulomb field only), the magnetic field $B_{\textrm{ext}}$ introduces an asymmetry (i.e., polarization dependence) and renders...
Strong fields are ubiquitous in physics, occurring on scales from quarks to the entire universe, and encompassing all fundamental interactions. Insights gained from one area of strong field physics can be of great value in other areas. This is (relatively) straightforward with vector and scalar forces, but the very different nature of gravity can make it hard to translate results from one...
We derive a quantum kinetic theory for QED based on Kadanoff-Baym equation [1]. It generalizes the well-known classical kinetic theory to the polarized case, with spin polarization entering in the next order of gradient expansion. We also discuss generalization to QCD. We use this framework to study polarization of probe massive fermion in QED plasma with shear [2]. We find new collisional...
The Euler-Heisenberg Lagrangian is discussed in homogeneous electromagnetic fields with a constant axial gauge coupling, to one-loop order. Two special configurations, namely a magnetic field with chiral chemical potential as well as an electric field with spatial axial gauge, are argued to possess an exact eigenspectrum, whose sum leads to a defining Lagrangian.
In the case of an electric...
In recent years, the sole light-based interaction with the spin of a free electron (polarization and spin detection) has been discussed for the case of electron diffraction in counterpropagating laser beams [1,2]. The quantum dynamics of the electron in such a standing light wave of the so-called Kapitza-Dirac effect [3,4] is commonly solved for the approximation of two counterpropagating...
There is a famous $\alpha \chi^{2/3} \sim 1$ problem of a perturbation theory for QED in a strong electromagnetic field. It leads to the situation when radiation losses of highly energetic electrons in a sufficiently high intensity electromagnetic wave cannot be calculated reliably in the frame of the perturbation theory because of divergence of its series at $\alpha \chi^{2/3} \sim 1$. We...
The acceleration of spin-polarized particle beams from laser-plasma interaction has gained a lot of interest in recent years due to the availability of high-intensity lasers and their applications for investigating strong-field phenomena. In particular, probing the nuclear structure of protons and neutrons requires polarized particle beams [1]. In this talk, we will present a setup consisting...
New laser facilities will reach intensities of $10^{23} \textrm{W cm}^{-2}$. This advance enables novel experimental setups in the study of laser-plasma interaction. In these setups with extreme fields quantum electrodynamic (QED) effects like photon emission via non-linear Compton scattering and Breit-Wheeler pair production become important.
We study high-intensity lasers grazing the...
Creation of electrons and positrons via binary photon collisions, i.e. the linear Breit-Wheeler (BW) process, is a basic prediction of quantum electrodynamics, but it is yet to be observed in the laboratory. Motivated by experimental capabilities of newly constructed laser facilities and by recent developments in target fabrication, we have performed PIC simulations supplemented by a...
We show that an all-optical configuration of the laser-electron collision in the $\lambda^3$ configuration based on 10 PW-class lasers presents a viable platform for reaching the range of parameters where a perturbative QED in strong external electromagnetic field breaks. This case is contingently referred to as a case of the non-perturbative QED, and this range of parameters is the intriguing...
We investigate the optimization of photon polarization to increase the yield of Breit-Wheeler pair production in arbitrarily polarized plane wave backgrounds. We show that the optimized photon polarization can improve the positron yield by more than $20\%$ compared to the unpolarized case, in the intensity regime of current laser-particle experiments.
The seed photon optimal polarization...
We consider the scattering of probe particles on an ultraboosted beam of charge, in the case that the fields of the beam are strong and must be treated nonperturbatively.
We show that the fields of the ultraboosted beam act as stochastic plane waves-scattering amplitudes (of elastic scattering, nonlinear Compton and nonlinear Breit-Wheeler) are obtained without approximation by averaging...
The locally constant crossed field approximation (LCFA) is a powerful tool for studies of various strong field QED phenomena. It is common that numerical codes for simulating strong laser-matter interaction rely on LCFA for taking into account QED effects, and therefore it is crucial to establish the limits of applicability of the approximation and develop possible extensions.
We explore...
In the presence of an electromagnetic background plane-wave field, electron, positron, and photon states are not stable, because electrons and positrons emit photons and photons decay into electron-positron pairs. This decay of the particle states leads to an exponential damping term in the probabilities of single nonlinear Compton scattering and nonlinear Breit-Wheeler pair production [1]. We...
Accounting for loop radiative corrections, such as photon polarization and electron mass operators, become essential as the strength of the external field reaches the limit of ~1600 Sauter-Schwinger fields in the reference frame of a particle, namely, $\alpha\chi^{2/3}\sim 1$ where $\chi$ denotes the (dimensionless) field. It is sufficient to consider just 1-loop corrections below the limit...
Quantum electrodynamics (QED) is a theory of the interacting fermionic electron-positron and electromagnetic fields. However, it may be expedient to isolate or neglect contributions of spin effects. Also, there do exist charged scalar particles. Therefore, it is worth studying a scalar version of QED as well. At first glance, such a theory should be simpler due to the absence of spin...
Experimental efforts toward the detection of the nonperturbative strong-field regime of the Breit-Wheeler pair creation process plan to combine incoherent sources of GeV $\gamma$ quanta and the coherent fields of tightly focussed optical laser pulses. This endeavour calls for a theoretical understanding of how the pair yields depend on the applied laser field profile. We provide estimates...
