Physics Department Colloquium: Tuesday, February 25, 2019 - Modern tests of Quantum Electrodynamics in the high-intensity regime

Event Date: 

Tuesday, February 25, 2020 - 3:45pm

Event Date Details: 

Refreshments served at 3:30pm.

Event Location: 

  • Broida 1640
  • Physics Department Colloquium

Quantum electrodynamics (QED) is a well established physical theory and its predictions have been confirmed experimentally in various regimes and with extremely high accuracy. However, there are still areas of QED that deserve theoretical and experimental investigation, especially when physical processes occur in the presence of intense background electromagnetic fields, i.e., of the order of the so-called “critical” field of QED [1]. In the presence of electromagnetic fields of such a high strength even the vacuum becomes unstable and electron-positron pair production spontaneously occurs.

After a broad introduction on strong-field QED, I describe different regimes of this theory and introduce present and upcoming experimental efforts to test it under such extreme conditions. As a prominent theoretical example of open problems, I focus on the so-called “radiation reaction” problem [2], which recently has been also addressed experimentally [3, 4]. The problem of radiation reaction in QED is intimately related to the behavior of the theory at short distances, i.e., at high energies. According to the so-called Ritus-Narozhny (RN) conjecture, strong-field QED in an intense plane wave, unlike QED in vacuum, should become a strongly coupled theory already at moderately high energies [5]. After reviewing the RN conjecture, I show how this tension between strong-field QED and QED in vacuum has been recently resolved [6].

 

[1] A. Di Piazza, C. M ̈uller, K. Z. Hatsagortsyan, and C. H. Keitel, Rev. Mod. Phys. 84, 1177 (2012).
[2] J. D. Jackson, Classical Electrodynamics (Wiley, New York, 1975).
[3] T. N. Wistisen, A. Di Piazza, H. V. Knudsen, and Ulrik I. Uggerhøj, Nat. Commun. 9, 795 (2018).
[4] K. Poder, M. Tamburini, G. Sarri, A. Di Piazza, S. Kuschel, C. D. Baird, K. Behm, S. Bohlen, J. M.
Cole, M. Duff, E. Gerstmayr, C. H. Keitel, K. Krushelnick, S. P. D. Mangles, P. McKenna, C. D. Murphy,
Z. Najmudin, C. P. Ridgers, G. M. Samarin, D. Symes, A. G. R. Thomas, J. Warwick, and M. Zepf,
Phys. Rev. X 8, 031004 (2018).
[5] V. I. Ritus, J. Sov. Laser Res. 6, 497 (1985).
[6] T. Podszus and A. Di Piazza, Phys. Rev. D 99, 076004 (2019).

Antonino Di Piazza, Max Plank Institute for Nuclear Physics