Breaking of adiabatic invariance in the creation of particles by electromagnetic backgrounds

Beltrán-Palau, Pau; Ferreiro, Antonio; Navarro-Salas, José; Pla, Silvia

doi:10.1103/physrevd.100.085014

Cited by 12 publications

(20 citation statements)

References 38 publications

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“…Finally, in section V, we provide an explicit example of the application of the procedure developed in the previous sections to the scalar Schwinger effect in a concrete external potential, the Sauter pulse [1]. In particular, we show explicitly how our method allows for a well defined particle number density of created particles via Schwinger effect at any instant of time, which also agrees in the asymptotic limit with the one obtained in previous works using the asymptotic approach [8,29]. We conclude in section VI with a recap of the main results achieved in this paper.…”

Section: Introductionsupporting

confidence: 72%

“…Substitution of this solution (5.5) into (4.37) gives an explicit expression for |β k (t)| 2 as a function of time in terms of hypergeometric functions (indeed, since the derivative of a hypergeometric function is proportional to other hypergeometric function). Thus, using the asymptotic properties of these functions [34], it is straightforward to check that in the asymptotic future t → ∞, when the electric field vanishes, we recover the result of [8,29]:…”

Section: Schwinger Effectmentioning

confidence: 99%

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Unitary quantization of a scalar charged field and Schwinger effect

Garay

Martín-Caro

Martín-Benito

2020

J. High Energ. Phys.

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Quantum field theory in curved spacetimes suffers in general from an infinite ambiguity in the choice of Fock representation and associated vacuum. In cosmological backgrounds, the requirement of a unitary implementation of the field dynamics in the physical Hilbert space of the theory is a good criterion to ameliorate such ambiguity. Indeed, this criterion, together with a unitary implementation of the symmetries of the equations of motion, leads to a unique equivalence class of Fock representations. In this work, we apply the procedure developed for fields in cosmological settings to analyze the quantization of a scalar field in the presence of an external electromagnetic classical field in a flat background. We find a natural Fock representation that admits a unitary implementation of the quantum field dynamics. It automatically allows to define a particle number density at all times in the evolution with the correct asymptotic behavior, when the electric field vanishes. Moreover we show the unitary equivalence of all the quantizations that fulfill our criteria. Although we perform the field quantization in a specific gauge, we also show the equivalence between the procedures taken in different gauges.

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Section: Introductionsupporting

confidence: 72%

Section: Schwinger Effectmentioning

confidence: 99%

Unitary quantization of a scalar charged field and Schwinger effect

Garay

Martín-Caro

Martín-Benito

2020

J. High Energ. Phys.

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“…The above arguments make it necessary to reconsider the problem of adiabatic regularization for fermions in timevarying electric backgrounds in four dimensions. We will adopt the view of considering A μ of adiabatic order 1, as advocated in [31,35,36,38], and in contrast to the view adopted in [34]. The main reasons, as exposed above, are (i) expected agreement with the Schwinger-DeWitt adiabatic expansion of the two-point function at coincidence; (ii) consistency with the covariant conservation of the energy-momentum tensor when gravity is turned on.…”

Section: A Adiabatic Regularization For Fermions In Two-dimensionsmentioning

confidence: 99%

“…In this context, the most important physical local expectation value is the electric current hj μ i, which also possesses ultraviolet divergences and has to be renormalized in a proper way. Recent discussions on foundational issues related to the particle number density of the created particles, adiabatic invariance, and unitary evolution can be seen in [29][30][31].…”

Section: Introductionmentioning

confidence: 99%

“…The argument was reinforced in [36,37] on the basis of the covariant conservation of the energy-momentum tensor. The adiabatic regularization of two-dimensional fermions incorporating the adiabatic order assignment 1 for A μ has been further reanalyzed in [31,35,38]. Other renormalization methods have been generalized to incorporate an electromagnetic background, as for instance the Hadamard point-splitting method for complex scalar fields [39,40], with results in agreement with [35].…”

Section: Introductionmentioning

confidence: 99%

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Adiabatic regularization for Dirac fields in time-varying electric backgrounds

2020

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The adiabatic regularization method was originally proposed by Parker and Fulling to renormalize the energy-momentum tensor of scalar fields in expanding universes. It can be extended to renormalize the electric current induced by quantized scalar fields in a time-varying electric background. This can be done in a way consistent with gravity if the vector potential is considered as a variable of adiabatic order one. Assuming this, we further extend the method to deal with Dirac fields in four spacetime dimensions. This requires a self-consistent ansatz for the adiabatic expansion, in presence of a prescribed time-dependent electric field, which is different from the conventional expansion used for scalar fields. Our proposal is consistent, in the massless limit, with the conformal anomaly. We also provide evidence that our proposed adiabatic expansion for the fermionic modes parallels the Schwinger-DeWitt adiabatic expansion of the two-point function. We give the renormalized expression of the electric current and analyze, using numerical and analytical tools, the pair production induced by a Sauter-type electric pulse. We also analyze the scaling properties of the current for a large field strength.

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States of low energy in the Schwinger effect

Álvarez-Domínguez

Garay

Martín-Benito

et al. 2023

J. High Energ. Phys.

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States of low energy in cosmology minimise the energy density when smeared in a chosen time interval. We extend such construction to generic homogeneous (possibly anisotropic) particle creation settings. Focusing on the Schwinger effect, we study the role played by the support of the smearing function and identify the vacua obtained in the limiting cases of small and large time intervals. We also analyse the spectral properties of the power spectrum and the number of created particles, which are complementary in characterising the vacuum, and investigate the multipolar contributions coming from the anisotropies.

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Breaking of adiabatic invariance in the creation of particles by electromagnetic backgrounds

Cited by 12 publications

References 38 publications

Unitary quantization of a scalar charged field and Schwinger effect

Unitary quantization of a scalar charged field and Schwinger effect

Adiabatic regularization for Dirac fields in time-varying electric backgrounds

States of low energy in the Schwinger effect

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