Schwinger Mechanism Research Articles

Spontaneous pair production near magnetized Reissner-Nordstrom black holes

We investigate the pair production near a (near) extremal magnetized Reissner-Nordstrom black hole. The pair production is shown to exist in the extremal state, which can be interpreted as the Schwinger effect due to the strong field under consideration. To show a correspondence between the growth of the external magnetic field and the scalar absorption, some numerical examples are provided.

Gravitational Pair Production and Black Hole Evaporation.

We present a new avenue to black hole evaporation using a heat-kernel approach analogous as for the Schwinger effect. Applying this method to an uncharged massless scalar field in a Schwarzschild spacetime, we show that spacetime curvature takes a similar role as the electric field strength in the Schwinger effect. We interpret our results as local pair production in a gravitational field and derive a radial production profile. The resulting emission peaks near the unstable photon orbit. Comparing the particle number and energy flux to the Hawking case, we find both effects to be of similar order. However, our pair production mechanism itself does not explicitly make use of the presence of a black hole event horizon.

Dynamic entanglement for continuous variables in an electric field background

Quantum entanglement is a typical nonclassical correlation. Here, we use this concept to analyze quantum entanglement for continuous variables generated by the Schwinger pair production for constant and pulsed electric fields. An initial two-mode entangled state evolves into a three-mode entangled state through a Gaussian channel of the Schwinger effect, which encodes the information about the Schwinger effect. By detecting the entanglement of the output three-mode state, we obtain the optimal parameters for easier to generate particle–antiparticle pairs. We find that the generated 1 → 2 entanglement is more sensitive to the parameters than the generated 1 → 1 entanglement. Therefore, we should choose the generated 1 → 2 entanglement to extract information. We argue that extracting the optimal parameters from quantum entanglement may guide future experiments.

Superconductors in strong electric fields: Quantum Electrodynamics meets Superconductivity

A static electric field has always been thought to play little role in the physics of ideal conductors, since the screening effects of mobile carriers prevent it from penetrating deep into the bulk of a metal. Very recently however, experimental evidence has been obtained which indicates that static electric fields can be used to manipulate the superconductive properties of metallic BCS superconducting thin films, weakening the critical current. In this paper I will show how possible explanations to this striking effect can be found relying on the analogy between Superconductivity and Quantum Electrodynamics noticed by Nambu and Iona-Lasinio in the sixties. I will show that, following this parallelism, it is possible to predict a new phenomenon: the superconducting Schwinger effect. Secondly I will explain how this new microscopic effect can be connected to a modified Gizburg-Landau theory where additional couplings between electric field and the superconductive condensate are taken into account. Eventually I will connect these theoretical predictions to the experiments, proposing them as a possible explanation of the weakening of superconductivity due to an external electric field.

Mining the quantum vacuum: quantum tunnelling and particle creation

Particle production from the vacuum is a remarkable aspect of particle physics. Prime examples are the Schwinger process of particle production in strong electric fields and the Hawking process of particle production from black holes. These processes can be viewed as quantum tunnelling of particles from the vacuum. The tunnelling approach, and the closely related instanton or complex path approaches, are reviewed here with emphasis on paths in the complex coordinate plane. The method is applied to particle production from a black hole in a magnetic field, where ultra-high energy charged particles are produced.

Evidence of the Schwinger Mechanism from Lattice QCD

In quantum chromodynamics (QCD), gluons acquire a mass scale through the action of the Schwinger mechanism. This mass emerges as a result of the dynamical formation of massless bound-states of gluons which manifest as longitudinally coupled poles in the vertices. In this contribution, we show how the presence of these poles can be determined from lattice QCD results for the propagators and vertices. The crucial observation that allows this determination is that the Schwinger mechanism poles induce modifications, called “displacements”, to the Ward identities (WIs) relating two- and three-point functions. Importantly, the displacement functions correspond precisely to the Bethe–Salpeter amplitudes of the massless bound-states. We apply this idea to the case of the three-gluon vertex in pure Yang–Mills SU(3). Using lattice results in the corresponding WI, we find an unequivocal displacement and show that it is consistent with the prediction based on the Bethe–Salpeter equation.

Schwinger mechanism for gluons from lattice QCD

Continuum and lattice analyses have revealed the existence of a mass-scale in the gluon two-point Schwinger function. It has long been conjectured that this expresses the action of a Schwinger mechanism for gauge boson mass generation in quantum chromodynamics (QCD). For such to be true, it is necessary and sufficient that a dynamically-generated, massless, colour-carrying, scalar gluon+gluon correlation emerges as a feature of the dressed three-gluon vertex. Working with results on elementary Schwinger functions obtained via the numerical simulation of lattice-regularised QCD, we establish with an extremely high level of confidence that just such a feature appears; hence, confirm the conjectured origin of the gluon mass scale.

Ultrafast optical generation of antiferromagnetic meron-antimeron pairs with conservation of topological charge

We propose a new mechanism to produce a meron-antimeron pair in a two dimensional antiferromagnet with an ultrafast laser pulse via thermal Schwinger mechanism. Unlike ultrafast skyrmion nucleation, this process conserves total topological charge. We systematically show different stages of the dynamics and define proper topological invariants to characterise the configurations. The emergent structure can retain its topological structure for up to 100 ps. By introducing a topological structure factor we show that pair formation is robust against any random choice of initial magnetic configuration and can survive against disorder. Our findings demonstrate that the rich world of spin textures, which goes beyond conventional skyrmions, can be reached optically.

Pair production as a probe for the dynamics of nuclear fission and α decay

Electron-positron pairs can be produced via the Schwinger mechanism in the presence of strong electric fields. In particular, the fields involved in $\alpha$ decay and nuclear fission are strong enough to produce them. The energy of the $e^+e^-$ pair is related to the relative distance and velocity of the daughter nuclei. Thus, the energy distribution of the produced pairs can give information about the dynamics of the fission and $\alpha$ decay processes. A neck model of nuclear fission is used to illustrate how the pairs can be used as a probe of the dynamics.

Euler-Heisenberg Lagrangian under an axial gauge field

Augmentations to the Euler-Heisenberg Lagrangian (QED one-loop effective action in homogeneous electromagnetic fields) under a constant background axial gauge are examined. Two special configurations admit an exact eigendecomposition, and hence effective action as a spectral sum, of the augmented Dirac operator: one with a magnetic field with chiral chemical potential, and the other with an electric field with spatial axial gauge, which resembles an emergent vorticity. An enhancement to Schwinger pair production is found for the latter, which is more fully analyzed using the worldline instanton formalism. There it is found the overall enhancement is due to the spatial axial gauge serving as a negative mass shift. Finally, we remark on the exactly solvable massless case for arbitrary electromagnetic and axial gauges.

Dyon production from near-extremal Kerr–Newman–(anti-)de Sitter black holes

Using the enhanced symmetry in the near-horizon region of the near-extremal dyonic Kerr–Newman (KN) black hole in the (A)dS space, we find the exact solutions for dyonic charged scalar field in terms of the hypergeometric function and explicitly compute the Schwinger effect for the emission of electric and/or magnetic charges. The emission formula confirms a universal factorization of the Schwinger formula in the AdS_2 and another Schwinger formula in the two-dimensional Rindler space determined by the effective temperature and the Hawking temperature with the chemical potentials of electric and/or magnetic charges and the angular momentum. The emission of the same species of charges from the KN black hole is enhanced in the AdS boundary while it is suppressed in the dS boundary. In addition, the dragging of particles in the KN black hole diminishes the emission of charges in both AdS and dS spaces. The AdS geometry of near-horizon gives the Breitenloher–Freedman (BF) bound, within which the stability of dyonic KN black holes is guaranteed against both the emission of charges and Hawking radiation.

Mesoscopic Klein-Schwinger effect in graphene

Strong electric field annihilation by particle–antiparticle pair creation, also known as the Schwinger effect, is a non-perturbative prediction of quantum electrodynamics. Its experimental demonstration remains elusive, as threshold electric fields are extremely strong and beyond current reach. Here, we propose a mesoscopic variant of the Schwinger effect in graphene, which hosts Dirac fermions with an approximate electron–hole symmetry. Using transport measurements, we report on universal one-dimensional Schwinger conductance at the pinchoff of ballistic graphene transistors. Strong pinchoff electric fields are concentrated within approximately 1 μm of the transistor’s drain and induce Schwinger electron–hole pair creation at saturation. This effect precedes a collective instability towards an ohmic Zener regime, which is rejected at twice the pinchoff voltage in long devices. These observations advance our understanding of current saturation limits in ballistic graphene and provide a direction for further quantum electrodynamic experiments in the laboratory.

Dymnikova-Schwinger traversable wormholes

In this paper, we obtain new d-dimensional and asymptotically flat wormhole solutions by assuming a specific form of the energy density distribution. This is addressed by considering the generalization of the so-called Dymnikova model, originally studied in the context of regular black holes. In this way, we find constraints for the involved parameters, namely, the throat radius, the scale associated to the matter distribution, and the spacetime dimension, to build those wormholes. Following, we study the properties of the obtained solutions, namely, embedding diagrams as well as Weak and Null Energy Conditions (WEC and NEC). We show that the larger the dimension, the larger the flatness of the wormhole and the more pronounced the violation of these energy conditions. We also show that the corresponding fluid behaves as phantom-like for d ≥ 4 in the neighborhood of the wormhole throat. In addition, we specialize the employed model for d = 4 spacetime, associating it with the gravitational analog of the Schwinger effect in a vacuum and correcting the model by introducing a minimal length via Generalized Uncertainty Principle (GUP). Thus, we obtain a novel traversable and asymptotically flat wormhole solution by considering that the minimal length is very tiny. The associated embedding diagram shows us that the presence of this fundamental quantity increases the slope of the wormhole towards its throat compared with the case without it. That correction also attenuates the WEC (and NEC) violations nearby the throat, with the fluid ceasing to be a phantom-type at the Planck scale, unlike the case without the minimal length.

The alteration of the Schwinger effect on radiatively corrected Higgs inflationary magneto-genesis by axial coupling

We study the alteration of the Schwinger effect on radiatively corrected Higgs inflationary magneto-genesis by axial coupling function. The conformal invariance of Maxwell action should be broken by axial coupling with the inflaton field. We use the potential of [M. Kamarpour, Gen. Relativ. Gravit. 53 (2021) 53, doi:10.1007/s10714-021-02824-0; M. Kamarpour, Gen. Relativ. Gravit. 54 (2022) 32, doi:10.1007/s10714-022-02920-9] with the simplest coupling function [Formula: see text] in which [Formula: see text] is a dimensionless coupling parameter. In comparison to our previous work (in which we used curvature-based coupling or so-called nonminimal coupling function to gravity to break conformal invariance of action) of [M. Kamarpour, Gen. Relativ. Gravit. 54 (2022) 32, doi:10.1007/s10714-022-02920-9] we find that the Schwinger effect does alter magneto-genesis and is considerable. In fact, in comparison to our previous work of [M. Kamarpour, Gen. Relativ. Gravit. 54 (2022) 32, doi:10.1007/s10714-022-02920-9] we obtain that for some certain values of coupling parameter [Formula: see text] the Schwinger effect does alter magneto-genesis (see [M. Kamarpour, Gen. Relativ. Gravit. 53 (2021) 53, doi:10.1007/s10714-021-02824-0]) and the energy density of created charged particles during the Schwinger effect becomes considerable and of course comparable to the energy density of inflaton field. Therefore, the Schwinger effect decreases the value of the electric field, so that it helps to finish the inflation stage. Then the universe enters the stage of preheating. The Schwinger effect produces charged particles, imposing the Schwinger reheating framework even before the ending of last oscillations of the inflaton field.

Photon emission in the graphene under the action of a quasiconstant external electric field

Following a nonperturbative formulation of strong-field QED developed in our earlier works, and using the Dirac model of the graphene, we construct a reduced QED_{3,2} to describe one species of the Dirac fermions in the graphene interacting with an external electric field and photons. On this base, we consider the photon emission in this model and construct closed formulas for the total probabilities. Using the derived formulas, we study probabilities for the photon emission by an electron and for the photon emission accompanying the vacuum instability in the quasiconstant electric field that acts in the graphene plane during the time interval T. We study angular and polarization distribution of the emission as well as emission characteristics in a high frequency and low frequency approximations. We analyze the applicability of the presented calculations to the graphene physics in laboratory conditions. In fact, we are talking about a possible observation of the Schwinger effect in these conditions.

Gauge Sector Dynamics in QCD

The dynamics of the QCD gauge sector give rise to non-perturbative phenomena that are crucial for the internal consistency of the theory; most notably, they account for the generation of a gluon mass through the action of the Schwinger mechanism, the taming of the Landau pole, the ensuing stabilization of the gauge coupling, and the infrared suppression of the three-gluon vertex. In the present work, we review some key advances in the ongoing investigation of this sector within the framework of the continuum Schwinger function methods, supplemented by results obtained from lattice simulations.

Angular momentum inheritance from the Schwinger effect in (chromo)electromagnetic fields

Abstract The angular momentum of fermion pairs generated by the Schwinger effect is studied in homogeneous (chromo)electromagnetic fields, mimicking the early stages of a heavy-ion collision. It is demonstrated that the angular momentum density of produced pairs is proportional to that of the background fields. This is argued both heuristically in a virtual breaking condensate model by evaluating Wong’s equations, and out-of-equilibrium to one-loop using the in–in formalism.

Dynamically assisted Schwinger mechanism in spatially separated electric fields

We investigate the Schwinger pair production in combined electric fields using quantum field theoretical simulations, where static and oscillating electric fields are finitely extended and spatially separated. We find that the pair production can be dynamically assisted until the two fields are separated much farther than one Compton length. We show the signature of dynamical assistance, in the position of both static and oscillating fields, based on the position-based production rate. Moreover, we investigate the impact of spatial width on dynamical assistance to show that the production rate is suppressed when the width of any of the two fields exceeds one Compton length and potential heights are constant.

Numerical study of the Schwinger effect in axion inflation

Previous studies demonstrate that the inflaton, when coupled to the hypercharge Chern-Simons density, can source an explosive production of helical hypermagnetic fields. Then, in the absence of fermion production, those fields have the capability of preheating the Universe after inflation and triggering a successful baryogenesis mechanism at the electroweak phase transition. In the presence of fermion production, however, we expect a strong damping of the gauge fields production from the fermion backreaction, a phenomenon called Schwinger effect, thus jeopardizing their original capabilities. Using numerical methods, we study the backreaction on the generated gauge fields and revisit the processes of gauge preheating and baryogenesis in the presence of the Schwinger effect. We have found that gauge preheating is very unlikely, while still having a sizable window in the parameter space to achieve the baryon asymmetry of the Universe at the electroweak phase transition.

Membrane nucleation rates from holography

Membrane nucleation, a higher dimensional analog of the Schwinger effect, is a useful toy model for vacuum decay. While a non-perturbative effect, the computation of nucleation rates has only been accomplished at weak coupling in the field theory. Here we compute the nucleation rates of spherical membranes using AdS/CFT duality, thus naturally including the effects of strong coupling. More precisely, we consider the nucleation of spherical membranes coupled to an antisymmetric tensor field, a process which renders the vacuum unstable above a critical value of the field strength. We analyze membrane creation in flat and de Sitter space using various foliations of AdS. This is accomplished via instanton methods, where the rate of nucleation is dominated by the semi-classical on-shell Euclidean action. Our findings generalize the holographic Schwinger effect and provide a step toward holographic false vacuum decay mediated by Coleman-De Luccia instantons.