Schwinger effect for non-Abelian gauge bosons

A gauge theory involves two kinds of particles, those which carry ‘charge’ and those which ‘mediate’ interactions between currents by coupling directly to charge. In the former class are the fundamental fermions and nonabelian gauge bosons, whereas the latter consists solely of gauge bosons, both abelian and nonabelian. The physical nature of charge depends on the specific theory. Three such kinds of charge, called color, weak isospin, and weak hypercharge, appear in the Standard Model. The values of these charges are not predicted from the gauge symmetry, but must rather be determined experimentally for each particle. The strength of coupling between a gauge boson and a particle is determined by the particle's charge, e.g. the electron-photon coupling constant is –e, whereas the u -quark and photon couple with strength 2e/3. Because nonabelian gauge bosons are both charge carriers and mediators, they undergo self-interactions. These produce substantial nonlinearities and make the solution of nonabelian gauge theories a formidable mathematical problem. Gauge symmetry does not generally determine particle masses. A fermion mass term, although violating chiral symmetry, is consistent with gauge invariance. Although gauge-boson mass would seem to be at odds with the principle of gauge symmetry, the Weinberg-Salam model contains a dynamical procedure, the Higgs mechanism, for generating mass for both gauge bosons and fermions alike. Quantum Electrodynamics Historically, the first of the gauge field theories was electrodynamics. Its modern version, Quantum Electrodynamics (QED) , is the most thoroughly verified physical theory yet constructed.

We examine a time-dependent, three-dimensional rotation of magnetic ellipsoidal particles in a two-dimensional, simple shear flow and a uniform magnetic field. We consider that the particles have paramagnetic and ferromagnetic properties, and we compare their rotational dynamics due to the strengths and directions of the applied uniform magnetic field. We determine the critical magnetic field strength that can pin the particles’ rotations. Above the critical field strength, the particles’ stable steady angles were determined. In a weak magnetic regime (below the critical field strength), a paramagnetic particle’s polar angle will oscillate toward the magnetic field plane while its azimuthal angle will execute periodic rotations. A ferromagnetic particle’s rotation depends on its initial angles and the magnetic field strength and direction. Even when it is exposed to a critical magnetic field strength, its rotational dynamics will either be pinned in or out of the magnetic field plane. In a weak magnetic regime, a ferromagnetic particle will either execute out-of-plane rotations or will oscillate toward the magnetic field plane and perform periodic rotations. For both particles, we analytically determine the peaks and troughs of their oscillations and study their time-dependent rotations through analytical and numerical analyses.

The phenomenon of partial discharge of soil that occurs when a lightning current enters the ground through a ground electrode poses a threat to the safety of personnel and equipment. The strength of partial discharge and the formation of soil discharge channels are closely related to the magnitude of the critical breakdown field strength. Therefore, how to accurately obtain the variation law of the critical breakdown field strength of typical soil is the key to realize the safe operation of the grounding device and the cable in the ground and ensure the safety of personnel and equipment. In this paper, a simulation experiment of soil impact characteristics is used to study the variation law of typical soil critical breakdown field strength with soil properties. X-ray transmission imaging technology is used to obtain the morphology of the discharge channel, and its non-intrusive observation method will not disturb the discharge channel itself, making the measurement more accurate. This paper first selects a variety of typical soils to study the influence of soil moisture, salt content, compactness and other factors on the discharge channel morphology, and then studies the calculation method of the critical breakdown field strength of the soil under different discharge channel morphologies. And further explore the reasons for the influence of typical soil media factors on the critical breakdown field strength. The experimental results show that under the same conditions, the relationship between the critical breakdown field strength values of different soils is: Ec of sandy soil <; Ec of loam soil <; Ec of pastoral soil; It is precisely because of the different reasons that different factors of the soil medium affect the critical breakdown field strength, the content of water and air inside the soil and the conductivity of the soil are different, so that the variation law of the critical breakdown field strength is different.

The Schwinger effect, a non-perturbative mechanism for particle production in strong fields, plays a crucial role in understanding quantum vacuum decay and high-energy phenomena, including heavy-ion collisions (HIC). Although holographic quantum chromodynamics (QCD) models have been widely used to study this effect, most treatments assume isotropy or consider only a single type of anisotropy, neglecting the interplay between spatial and magnetic anisotropies that arise in realistic HIC scenarios. A unified framework accounting for both anisotropies is needed to accurately model particle production. We investigate the Schwinger effect in a twice anisotropic holographic QCD model incorporating both spatial and magnetic anisotropies. Using the anti-de Sitter/conformal field theory correspondence, we compute the total potential of a particle-antiparticle pair to quantify how these anisotropies influence pair production. Our results show that the magnetic field (parameterized by and ) enhances the Schwinger effect by lowering and narrowing the potential barrier, while increasing spatial anisotropy (controlled by ) suppresses the process by raising and widening the barrier. These findings demonstrate that magnetic and spatial anisotropies exert competing effects on particle production, emphasizing the necessity of treating both concurrently in holographic models. This work advances the theoretical description of the Schwinger effect in anisotropic environments, with implications for understanding non-equilibrium dynamics in HIC and other strongly coupled systems.

Electro-coalescence of two charged droplets under pulsed direct current electric fields with various waveforms: A molecular dynamics study

The external field induced paranematic–nematic phase separation of hard spherocylinder systems is studied using the Onsager and Parsons free-energy functionals. A bifurcation analysis is carried out in the context of the Onsager theory at an infinitesimal external field. The bifurcation concentration is found to decrease with increasing field strength. Below the critical field strength, van der Waals-like loops are found. The molecular aspect ratio dependence of the phase coexistence curves of hard spherocylinders also is investigated. The critical field strength is found to decrease with decreasing aspect ratio. The external field dependence of the order parameter along the paranematic–nematic phase equilibrium curve is also studied.

We discuss gluon production by the Schwinger mechanism in collinear color-electric and magnetic fields which may be realized in pre-equilibrium stages of ultra-relativistic heavy-ion collisions. Fluctuations of non-Abelian gauge fields around a purely color-magnetic field contain exponentially growing unstable modes in a longitudinally soft momentum region, which is known as the Nielsen–Olesen instability. With a color-electric field imposed parallelly to the color-magnetic field, we can formulate this instability as the Schwinger mechanism. This is because soft unstable modes are accelerated by the electric fields to escape from the instability condition. Effects of instability remain in the transverse spectrum of particle modes, leading to an anomalously intense Schwinger particle production.

This paper studies the production of charged particles from the vacuum by a strong electric field and vibrating plates. The author shows that the Schwinger mechanism by the strong electric field and the dynamical Casimir effect by the vibrating plates assist with each other and enhance the production number.

Critical electric field strength for partial coalescence of droplets on oil–water interface under DC electric field

Dynamic behaviors and self-cleaning property of droplet on superhydrophobic coating in uniform DC electric field

Dielectrical and electro-mechanical behavior of NBR at high electric field strength

Field limit for ion evaporation from charged thermospray droplets

Active control of viscous fingering (VF) is of critical importance for many industrial and experimental systems. Here, we numerically study the electrokinetic control of miscible VF using an externally applied electric field. Simulations for three intrinsically hydrodynamically unstable mobility ratios are carried out using two different configurations for each: case I where the high-viscosity resident fluid has higher electroosmotic mobility than the invading low-viscosity fluid and case II where the resident fluid has a lower electroosmotic mobility than the invading fluid. For both cases, the theoretical critical electric field value required to (de)-stabilize the interface is computed and electric fields around this value are applied in simulations. Qualitative results show that VF can be fully suppressed if an electric field is applied with an absolute value above the critical field strength. For case I, this means an electric field in the direction of the pressure-driven flow, while for case II, a field in opposite direction is required. Our quantitative analysis using interfacial and mixing lengths was used to support the qualitative findings. Even though any field strength applied in the right direction will reduce the instability, full suppression is only achieved if the absolute field strength is higher than the required critical field strength. The results from this work provide useful insights that can be applied to electrokinetically enhanced oil recovery, spreading of pollution zones in aquifers, band broadening in liquid chromatography, and electrokinetic soil remediation.

The SF6/N2 gas mixture is a key eco-friendly alternative to SF6 in power equipment. However, its insulation and decomposition behaviors under realistic conditions of varying pressure and electric field non-uniformity remain insufficiently studied. This study establishes an experimental platform to systematically investigate the power–frequency breakdown and decomposition characteristics of a 3:7 SF6/N2 mixture. Breakdown tests and critical field strength calculations were conducted under different pressures and electric field uniformities, followed by gas composition analysis. Results demonstrate that the proposed critical breakdown field strength method effectively predicts the mixture’s breakdown voltage. Furthermore, a range of decomposition products, including NF3, SOF2, CO2, and C2F6, were identified, whose concentrations generally decreased with rising pressure. These findings provide valuable experimental data and a predictive tool for optimizing the insulation design and condition monitoring of SF6/N2 gas-insulated equipment.

Wide bandgap semiconductors like silicon carbide (SiC) are currently being developed for high‐power/high‐temperature applications. Silicon carbide (SiC) is ideally suited for power switching because of its high saturated drift velocity, its high critical field strength, its excellent thermal conductivity, and its mechanical strength. For power devices, the 10‐fold increase in critical field strength of SiC relative to Si allows high‐voltage blocking layers to be fabricated significantly thinner than those of comparable Si devices. This reduces device ON‐state resistance and the associated conduction and switching losses, while maintaining the same high‐voltage blocking capability. The specific ON‐state resistance of 4H‐SiC is approximately 400 times lower than that of Si at a given breakdown voltage. This allows for high current operation at relatively low forward voltage drop. In addition, the wide bandgap of SiC allows operation at high temperatures where conventional Si devices fail.In this article, we will review the SiC single‐implant no epitaxial regrowth vertical channel junction field‐effect transistor (JFET). The feasibility of efficient 1200 V normally OFF JFET operation will be investigated. The all‐SiC JFET‐based cascode switch will be introduced and aspects of its operation evaluated. High‐temperature direct‐current (dc) characteristics of JFETs and 1200 V normally OFF cascode switches will be discussed. Large‐area high‐current JFETs and their current sharing and switching performances will be presented. Aspects of JFET fabrication, including their edge termination, will be provided. JFET wafer yields and parameter uniformities will be presented. Hard and unclamped inductive JFET switching evaluations will be introduced. Finally, a 9‐kV JFET will be introduced and its reliability under bipolar stress will be examined.