Localisation in worldline pair production and lightfront zero-modes

Ilderton, Anton

doi:10.1007/jhep09(2014)166

Cited by 44 publications

(48 citation statements)

References 58 publications

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“…(The same is seen in the calculation of helicity flip in a plane wave [65]. For related simplifications in pair production see [71], and also [72,73].) In order to keep track of factors of s, it is simplest to leave the integral over (4.11) unevaluated, for now, and to set δy + → 0 in the rest of the amplitude.…”

Section: Coordinate Integralsmentioning

confidence: 97%

Reducible contributions to quantum electrodynamics in external fields

Ahmadiniaz

Edwards

Ilderton

2019

J. High Energ. Phys.

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We consider one-particle reducible (1PR) contributions to QED and scalar QED processes in external fields, at one-loop and two-loop order. We investigate three cases in detail: constant crossed fields, constant magnetic fields, and plane waves. We find that 1PR tadpole contributions in plane waves and constant crossed fields are non-zero, but contribute only divergences to be renormalised away. In constant magnetic fields, on the other hand, tadpole contributions give physical corrections to processes at one loop and beyond. Our calculations are exact in the external fields and we give strong and weak field expansions in the magnetic case. arXiv:1901.09416v2 [hep-th] 11 May 2019making such instances of great theoretical and phenomenological interest. This is possible if the field configuration is simple, or highly symmetric.This area of field theory was pioneered by Euler and Heisenberg who, taking a constant electromagnetic background, calculated the one-loop effective Lagrangian for QED [1] (see the calculations of Schwinger and Weisskopf [2, 3] for the corresponding calculations in scalar QED, and [4] for a review of these results). As is well known, one physical consequence revealed by the Euler-Heisenberg Lagrangian (EHL) is the instability of the vacuum to the application of strong electric fields, which leads to particle / anti-particle pair creation (the Schwinger mechanism). This effect has recently received renewed attention [5][6][7][8][9] due to the prospects of investigating pair creation using future laser facilities. For the status of current and future laser facilities, making study of these backgrounds of great experimental interest for the coming years see, for example, the information at [10-13]).Related results now exist for the effective action at two-and three loops [14,15] in a constant background, (anti-)self-dual backgrounds [16][17][18] and at one-loop order for various non-constant backgrounds such as Sauter pulses [19][20][21] and a pulsed Hermite and Laguerre-Gaussian laser beam [22]. See also [23] for the full mass range analysis of the QED effective action for a nontrivial background with some special symmetry. These have been used to study low energy photon amplitudes [24,25] and the structure of the quantum vacuum, see [26] for a recent review. Aside from this, the particle propagator can also be constructed exactly (non-perturbatively) in the presence of constant fields, plane waves, and other symmetric fields, allowing the calculation of a variety of electron-seeded and photon-seeded processes, see [26][27][28][29] for reviews.Recently, however, it was found that historical calculations had overlooked the possibility of one particle reducible (1PR) contributions to processes in constant background fields [30][31][32]. These contributions involve a tadpole, displayed in figure 1, attached somewhere in the corresponding Feynman diagram describing the process. The tadpole is linear in the exchanged (off-shell) photon momentum, k µ , and momentum conservation implies that it can be ...

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Section: Coordinate Integralsmentioning

confidence: 97%

Reducible contributions to quantum electrodynamics in external fields

Ahmadiniaz

Edwards

Ilderton

2019

J. High Energ. Phys.

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“…e.g. [40,48,71]. On the other hand, if > 1 and γ ω → 0, there will be no critical value present for γ k .…”

Section: A Analytical Approximationsmentioning

confidence: 98%

Quantum tunnelling from vacuum in multidimensions

Akal

Moortgat‐Pick²

2017

Phys. Rev. D

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The tunnelling of virtual matter-antimatter pairs from the quantum vacuum in multidimensions is studied. We consider electric backgrounds as a linear combination of a spatial Sauter field and, interchangeably, certain weaker time dependent fields without poles in the complex plane such as the sinusoidal and Gaussian cases. Based on recent geometric considerations within the worldline formalism, we employ the relevant critical points in order to analytically estimate a characteristic threshold for the temporal inhomogeneity. We set appropriate initial conditions and apply additional symmetry constraints in order to determine the classical periodic paths in spacetime. Using these worldline instantons, we compute the corresponding leading order exponential factors showing large dynamical enhancement in general. We work out the main differences caused by the analytic structure of such composite backgrounds and also discuss the case with a strong temporal variation of Sauter-type.

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“…In contrast to the parallel scenarios discussed in [12][13][14][15][16][17], we consider the case of a transversal plane wave propagating perpendicular to the strong field E…”

Section: Introductionmentioning

confidence: 99%

Sauter-Schwinger pair creation dynamically assisted by a plane wave

2018

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We study electron-positron pair creation by a strong and constant electric field superimposed with a weaker transversal plane wave which is incident perpendicularly (or under some angle). Comparing the fully nonperturbative approach based on the world-line instanton method with a perturbative expansion into powers of the strength of the weaker plane wave, we find good agreement-provided that the latter is carried out to sufficiently high orders. As usual for the dynamically assisted Sauter-Schwinger effect, the additional plane wave induces an exponential enhancement of the pair-creation probability if the combined Keldysh parameter exceeds a certain threshold.

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Localisation in worldline pair production and lightfront zero-modes

Cited by 44 publications

References 58 publications

Reducible contributions to quantum electrodynamics in external fields

Reducible contributions to quantum electrodynamics in external fields

Quantum tunnelling from vacuum in multidimensions

Sauter-Schwinger pair creation dynamically assisted by a plane wave

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