Reaching supercritical field strengths with intense lasers

Abstract

It is conjectured that all perturbative approaches to quantum electrodynamics (QED) break down in the collision of a high-energy electron beam with an intense laser, when the laser fields are boosted to 'supercritical' strengths far greater than the critical field of QED. As field strengths increase toward this regime, cascades of photon emission and electron-positron pair creation are expected, as well as the onset of substantial radiative corrections. Here we identify the important role played by the collision angle in mitigating energy losses to photon emission that would otherwise prevent the electrons reaching the supercritical regime. We show that a collision between an electron beam with energy in the tens of GeV and a laser pulse of intensity -10 W cm 24 2 at oblique, or even normal, incidence is a viable platform for studying the breakdown of perturbative strong-field QED. Our results have implications for the design of near-term experiments as they predict that certain quantum effects are enhanced at oblique incidence.

Radiation reaction in electron–beam interactions with high-intensity lasers

“…The beam-beam geometry proposed by Yakimenko et al [130] exploits the Lorentz contraction of the Coulomb field of a compressed (100 nm), ultrarelativistic (100 GeV) electron beam, which is probed another beam of the same energy. In the laser-electronbeam scenario considered by Blackburn et al [131], collisions at oblique incidence are proposed for reaching χ 100, exploiting the fact that the diameter of a laser focal spot is typically much smaller than the duration of its temporal profile. Even higher χ is reached in the combined laserplasma, laser-beam interaction proposed by Baumann and Pukhov [132].…”

Absorption cross section in an intense plane wave background

“…A number of upcoming experiments aim to probe quantum processes in intense laser fields, including pair production [1], vacuum birefringence [2], and conjectured regimes where all current perturbative approaches to QED break down [3][4][5][6]. However, a series of theoretical investigations [7][8][9], as well as recent comparisons of theory with laser experiments [10,11], have highlighted shortcomings of existing models and simulations.…”

Backreaction in strong field QED: A toy model

“…Here we have defined the dimensionless detuning Δ ¼ ðω − ω a Þ=2jgj, in the notation used in (1). As for zero detuning, we expand the sine in its power series, displace ea ↦ ea þ ξ, normal order using (21), identify a variable l corresponding to the number of loops, and take the initial and final photonic states to be j0i and jni, respectively, using (23). After using the binomial theorem and a change of summation variables, we arrive at…”

“…Investigating this conjectured behavior is a target of future experiments [21][22][23][24]. However, questions remain.…”