First Quantisation for Physics in Strong Fields

Session

Talk

24 Feb 2025, 13:30

Higgs Centre Seminar Room (4305) (James Clerk Maxwell Building )

Conveners

Talk

• James Edwards (University of Plymouth)

Talk

• James Edwards (University of Plymouth)

Talk

• Anton Ilderton (UoE)

Talk

• Anton Ilderton (UoE)

Talk

• Patrick Copinger (University of Plymouth)

Talk

• Patrick Copinger (University of Plymouth)

Talk

• Karthik Rajeev

Talk

• Karthik Rajeev

Talk: Plenary Address

• James Edwards (University of Plymouth)

Talk

• Riccardo Gonzo (University of Edinburgh)

Talk

• Riccardo Gonzo (University of Edinburgh)

Talk

• Anton Ilderton (UoE)

10. Unified Worldline treatment of a Dirac particle with (pseudo)scalar and (axial)vector couplings

Olindo Corradini (Università di Modena e Reggio Emilia)

24/02/2025, 13:30

General Talk

We present a worldline representation of the one-loop effective action for a Dirac particle coupled to external scalar, pseudoscalar, vector and axialvector fields, which allows one to treat the real and the imaginary parts of the effective action in a unified manner, at the price of having a non-Hermitian Hamiltonian. Unlike other existing worldline representations, our new worldline action...

11. Low-energy master formulae on the loop and line in a homogeneous electromagnetic field

Patrick Copinger (University of Plymouth)

24/02/2025, 14:15

General Talk

An $N-$photon dressed propagator in (s)QED at tree level and effective action to one-loop in an arbitrary homogeneous electromagnetic field are examined in a photon low-energy limit. On the line, in a Fock-Schwinger gauge for the $N-$photons, it is discussed how the photons resemble a superposition of homogeneous fields, in addition to the background field. On the loop and on the line, in both...

7. The Worldline Formalism and the Gauge/Gravity Correspondence

Adi Armoni (Swansea University)

25/02/2025, 09:15

General Talk

The worldline formalism is a powerful tool to explore the strong coupling regime of QCD. Together with the AdS/CFT correspondence it leads to powerful results, in particular about meson correlators and meson scattering.
Another application of the worldline formalism that I hope to report is the relation between 2d QCD and the string worldsheet.

12. Magnetic monopole pair production in strong magnetic fields

Arttu Rajantie (Imperial College London)

25/02/2025, 10:00

General Talk

If magnetic monopoles exist, they are produced in strong magnetic fields by the electromagnetic dual of the Schwinger pair creation process. This phenomenon can be described non-perturbatively using the worldline instanton approach, and therefore it avoids the problems the strength of the magnetic charge required by the Dirac quantisation condition poses to any perturbative calculations. I...

4. Worldline instantons for the momentum spectrum of strong-field-QED processes in space-time dependent fields

Greger Torgrimsson (Umeå university)

25/02/2025, 13:45

General Talk

Affleck et al used worldline instantons to obtain an all-orders-in-$\alpha$ result for Schwinger pair production by a constant electric field.
Dunne and Schubert et al showed how to use instantons to obtain the probability for non-constant fields.
In both cases, and in most subsequent papers, the instantons are closed loops, which give probabilities integrated over particle momenta (and...

15. Boundary conditions and proper-time contours for worldline path integrals

Karthik Rajeev

25/02/2025, 14:30

General Talk

In standard uses of the worldline path integral formalism, Dirichlet or periodic boundary conditions are typically employed to calculate relevant quantities. However, when representing wave functions via path integrals, mixed boundary conditions emerge, where one end adheres to a Dirichlet or Neumann condition, while the other satisfies the opposite. Through straightforward examples from...

2. Worldline approach for spinning bound binaries

Riccardo Gonzo (University of Edinburgh)

26/02/2025, 09:15

General Talk

We will discuss how to use the wordline formalism to compute scattering and bound observables for the classical two-body problem in general relativity, with particular emphasis on the case of Kerr black hole solutions. First, new classical Dirac brackets will be introduced to streamline the calculation of scattering observables for spinning binaries. Then, we will study the geodesic solution...

6. Gravitational Waves from Worldline Quantum Field Theory

Gustav Mogull (Queen Mary University of London)

26/02/2025, 10:00

General Talk

The Worldline Quantum Field Theory (WQFT) formalism has proven itself a powerful tool for perturbatively calculating the physical observables involved in two-body gravitational scattering events — change in momentum, scattering angles, radiated energy and angular momentum. In this talk I will review the WQFT formalism and summarise this progress. In particular, I will discuss recent work on...

8. Worldline approach to QED in external fields

Christian Schubert (Facultad de Ciencias Físico-Matemáticas, Universidad Michoacana de San Nicolas de Hidalgo)

27/02/2025, 09:15

General Talk

The worldline formalism has been found particularly suitable for calculations in QED in external fields, including effective actions, amplitudes as well as Schwinger pair-creation rates. Here I will give a short summary of what has been achieved in this context, focussing mostly on constant and plane-wave fields.

9. Classical worldlines from scattering amplitudes

Dr Mao Zeng (The University of Edinburgh)

27/02/2025, 10:00

General Talk

The rapid advance in gravitational wave detectors has spurred renewed interest in the two-body problem in general relativity. Two perturbative approaches based on quantum field theory have emerged, one based on scattering amplitudes and the other based on worldlines. We argue that the two approaches are equivalent at an intimate level. By systematic algebraic manipulations through the...

13. Tadpole contribution to magnetic photon-graviton conversion

Naser Ahmadiniaz (Helmholtz-Zentrum Dresden - Rossendorf (HZDR))

27/02/2025, 11:15

General Talk

In this talk, I will provide a brief review of the reducible contributions
to QED amplitudes in a constant background field from the worldline
perspective. The focus will be on the missing piece in photon-graviton
conversion in a magnetic field. This process is typically studied at tree
level, but one-loop corrections involving scalars and spinors have also been
calculated. Unlike the...

14. Flying focus, self-duality and scattering

Tim Adamo (University of Edinburgh)

27/02/2025, 14:15

General Talk

Flying focus beams are exact solutions of the Maxwell equations with spatial focussing, a feature which is absent in plane waves. In the first instance, these flying focus solutions are complex-valued; unfortunately, taking the real part of this field results in background-coupled wave equations for particles interacting with the real background field that are complicated PDEs. In this talk,...