Pair Production Rate Research Articles

Empirical Model of SSUSI‐Derived Auroral Ionization Rates

AbstractWe present an empirical model for auroral (90–150 km) electron–ion pair production rates, ionization rates for short, derived from Special Sensor Ultraviolet Spectrographic Imager electron energy and flux data. Using the Fang et al. (2010, https://doi.org/10.1029/2010gl045406) parametrization for mono‐energetic electrons, and the NRLMSISE‐00 neutral atmosphere model (Picone et al., 2002, https://doi.org/10.1029/2002ja009430), the calculated ionization rate profiles are binned in 2‐hr magnetic local time and 3.6°geomagnetic latitude to yield time series of ionization rates at 5‐km altitude steps. We fit each of these time series to the geomagnetic indices Kp, PC, and Ap, the 81‐day averaged solar radio flux index, and a constant term. The resulting empirical model can easily be incorporated into coupled chemistry–climate models to include particle precipitation effects.

A Model for Pair Production Limit Cycles in Pulsar Magnetospheres

It was recently proposed that the electric field oscillation as a result of self-consistent e ± pair production may be the source of coherent radio emission from pulsars. Direct particle-in-cell simulations of this process have shown that the screening of the parallel electric field by this pair cascade manifests as a limit cycle, as the parallel electric field is recurrently induced when pairs produced in the cascade escape from the gap region. In this work, we develop a simplified time-dependent kinetic model of e ± pair cascades in pulsar magnetospheres that can reproduce the limit-cycle behavior of pair production and electric field screening. This model includes the effects of a magnetospheric current, the escape of e ±, as well as the dynamic dependence of pair production rate on the plasma density and energy. Using this simple theoretical model, we show that the power spectrum of electric field oscillations averaged over many limit cycles is compatible with the observed pulsar radio spectrum.

Enhanced vacuum pair production by combination of two spatially separated electric fields

The effective enhancement of the pair production rate using a subcritical electromagnetic field is an active area of interest in quantum electrodynamics. Enhanced pair production was investigated using the Dirac–Heisenberg–Wigner (DHW) formalism with spatially separated electric fields. Symmetric and asymmetric combinations of two separate electric fields with the same temporal shape were considered. The interplay and dynamical assistance between the fields were examined from a numerical perspective to elucidate the effects of the spatial distance and asymmetry of the field on the pair production efficiency. For the symmetric combination, the total particle number was reduced with an increase in the distance between the two fields up to one Compton length and then remained constant with distance. For the asymmetric combination, the total number of created pairs increased significantly up to a distance of one Compton length. It was also determined that not only was the separation distance crucial for enhancing pair production, but the spatial field asymmetries were also important, both of which had nontrivial effects on the particle momentum distribution. Finally, we have studied the validity of the DHW and analytical approximation in the spatially separated two electric fields. We found that the analytical approximation could almost estimate the DHW results.

Thermal dilepton production in heavy-ion collisions at beam-energy-scan (BES) energies

The lepton pair production rate at finite temperature and at nextto-leading-order (NLO) is calculated for quark-gluon plasma at non-zero net baryon density. Yields are obtained using a (3+1)D multicomponent simulation capable of reproducing hadronic observables measured in the RHIC Beam Energy Scan (BES). Spectra of intermediate invariant mass dileptons are compared with measurements from the STAR collaboration. The result of a study where the temperature information obtained from the dilepton spectrum from heavyion collisions performed at different energies and centralities is presented.

The open string pair production, its enhancement and the physics behind

Why adding a collinear magnetic field to the electric one on a D3 brane in a system of two parallel separated D3 branes can enhance the open string pair production? How is the open string pair production rate related to the QED ones in the weak field limit? We answer these questions and report the somehow expected but still remarkable relation between the weak field non-perturbative stringy rate and the corresponding QED ones in this letter.

Efficient vacuum pair production in frequency chirped electric fields with spatiotemporal inhomogeneity

Vacuum pair production under intense electromagnetic fields is an intriguing prediction in quantum electrodynamics (QED), and has become a topic of considerable interest with the rapid advancements in laser technologies. The pair production efficiency can be enhanced using chirped electric fields. In this study, the effects of electric field chirping on electron–positron pair production in different oscillating electric fields were investigated using the Dirac–Heisenberg–Wigner (DHW) formalism. We primarily considered quadratic and sinusoidal chirped electric fields. The results revealed that chirping significantly influences the momentum spectra of the generated particles in an electric field dominated by low-frequency tunneling effects, resulting in pronounced oscillations of the momentum spectrum, particularly in a sinusoidal chirped field. However, multiphoton processes gradually emerge as the chirp parameter increases. Consequently, in a high-frequency electric field dominated by multiphoton processes, the number density of the generated particles increases with the chirping parameter in a quadratic chirped field, whereas the momentum distribution remains relatively symmetric. However, in a sinusoidal chirped electric field, introducing a chirp parameter immediately alters the momentum distribution and enhances pair production rate. Moreover, there exists an optimal chirp parameter and the total particle number is enhanced approximately more than an order of magnitude with optimal chirping in a sinusoidal chirped electric field. These findings provide valuable insights into the intricate dynamics of pair production under the influence of chirping in different oscillating electric fields, and offer potential directions for future research in this domain.

Applicability of the Klein-Gordon equationfor pair production in vacuum and plasma.

In this paper, a phase-space description of electron-positron pair creation will be applied, based on a Wigner transformation of the Klein-Gordon equation. The resulting theory is similar in many respects to the equationsfrom the Dirac-Heisenberg-Wigner formalism. However, in the former case, all physics related to particle spin is neglected. In the present paper we compare the pair-production rate in vacuum and plasmas, with and without spin effects, in order to evaluate the accuracy and applicability of the spinless approximation. It is found that for modest frequencies of the electromagnetic field the pair production rate of the Klein-Gordon theory is a good approximation to the Dirac theory, provided the matter density is small enough for Pauli blocking to be neglected, and a factor of 2 related to the difference in the vacuum energy density is compensated for.

Understanding the open string pair production of the Dp/D0 system

Consider a system consisting of Dp and Dp′, placed parallel at a separation and with p − p′ = 2n (assuming p ≥ p′, the integer n ≥ 0 and p′ > 0). When either Dp or Dp′ carries a worldvolume electric flux, one in general expects a non-vanishing open string pair production due to the pair of virtual open string/anti open string connecting the two D branes under the action of the applied flux. However, this will not be true for p′ = 0 and p = 2, 4, 6 when the Dp carries a pure electric flux. In this note, we will explore the case for which a finite non-vanishing open string pair production rate can indeed be produced when a certain worldvolume flux is applied to the Dp brane and understand the physics behind.

Stability and pair production of scalars in the charged Einstein–ModMax black hole spacetime

This study has established the stability of Reissner–Nordström black holes within a specific parameter range against charged scalar perturbations. Additionally, the near-extremal Reissner–Nordström black holes exhibit a phenomenon known as the Schwinger effect for black holes, involving the production of charged scalar particles. This paper explores the stability and Schwinger effect in the context of static charged black holes within the Einstein–ModMax theory. Our approach closely aligns with the existing literature methods. We aim to investigate how the nonlinearity inherent in the theory may impact both the stability regime and the rate of charged scalar pair production by the black hole.

Contribution of the Photonic Component to the Ionization of the Atmosphere by Earth Crust Nuclides and Radioactive Emanations

Abstract—We investigate the contribution of gamma radiation of natural radionuclides constituting the Earth crust, radioactive emanations, and their decay product in the ground to the intensity of production of ion pairs in the atmosphere against the background of ionization of the atmosphere by radioactive gases flowing to the atmosphere from the ground and propagating together with their short-lived daughter products. The density of the radon flux to the atmosphere is estimated by three methods: the reservoir method, the integration of altitude profiles of volume activity of radon, based on gamma spectroscopic observation and diffusion model. The distribution of the gamma dose rate dose from the earth radionuclides in the soil and in the atmosphere is calculated using Gleant4 software. The propagation of the radon isotopes and their decay products in the atmosphere is calculated using large eddy simulations supplemented with kinematic simulations of the subgrid transport of a passive scalar. It is shown that depending on the specific activity of nuclides in the ground and the turbulent regime of the atmosphere, the total contribution of the γ-radiation to the ion pair production rate in the atmospheric boundary layer is approximately from 1% to 20% and increases upon a decrease in the penetrability of the upper ground layer for radioactive emanations.

Open string pair production from the interacting dressed-angled D-strings

We calculate the rate of the open string pair production from the interaction of two non-intersecting D-strings at angle. The D-strings have been equipped with the U(1) gauge potentials in the presence of the Kalb–Ramond field. This rate will be discussed when the D-strings intersect each other. Our computations is in the framework of the bosonic string theory.

Schwinger-Type Pair Production in Non-SUSY AdS/CFT

We study pair production of particles in the presence of an external electric field in a large N non-supersymmetric Yang-Mills theory using the holographic duality. The dual geometry we consider is asymptotically AdS and is effectively parametrized by two parameters, u 0 and − 5 / 2 < δ ≤ 0 , both of which can be related to the effective mass of quark/antiquark for non-supersymmetric theories. We numerically calculate the interquark potential profile and the effective potential to study pair production and analytically find out the threshold electric field beyond which one gets catastrophic pair creation by studying rectangular Wilson loops using the holographic method. We also find out the critical electric field from DBI analysis of a probe brane. Our initial investigations reveal that the critical electric field necessary for spontaneous pair production increases or decreases w.r.t. its non-supersymmetric value depending on the parameter δ . Ultimately, we find out the pair production rate of particles in the presence of an external electric field by evaluating circular Wilson loops using perturbative methods. From the later investigation, we note the resemblance with our earlier prediction. However, we also see that for and below another certain value of the parameter δ , the pair production rate of particle/antiparticle pairs blows up as the external electric field is taken to zero. We thus infer that the vacuum of the non-SUSY gauge theory is unstable for a range of non-supersymmetric parameter δ and that the geometry/non-SUSY field theory under consideration has quite different characteristics than earlier reported.

Pair production in the rainbow dS2 space

The study is devoted to discuss the rate of pair production in a two-dimensional de Sitter (dS2) type manifold with the help of the rainbow gravity formalism and the method of the Bogoliubov transformations. After obtaining exact analytical solutions of the Dirac equation for the selected rainbow metric, we focus on the creation rate of massive spin-1/2 particles.

( 3+1 )-dimensional Schwinger pair production with quantum computers

Real-time quantum simulation of quantum field theory in $(3+1)\mathrm{D}$ requires large quantum computing resources. With a few-qubit quantum computer, we develop a novel algorithm and experimentally study the Schwinger effect, the electron-positron pair production in a strong electric field, in $(3+1)\mathrm{D}$. The resource reduction is achieved by treating the electric field as a background field, working in Fourier space transverse to the electric field direction, and considering parity symmetry, such that we successfully map the three spatial dimension problems into one spatial dimension problems. We observe that the rate of pair production of electrons and positrons is consistent with the theoretical predication of the Schwinger effect. Our work paves the way towards exploring quantum simulation of quantum field theory beyond one spatial dimension.

Revisiting vacuum energy in compact spacetimes

We revisit the calculation of vacuum energy density in compact spacetimes. For the general case of k compact spatial dimensions in p+k dimensional Minkowski spacetime, we calculate the Casimir force on a piston placed in the presence of external electromagnetic fields. We observe that while the presence of a strong external magnetic field reduces the intensity of the Casimir force, the presence of an electric field enhances it instead. We discuss various physical cases and also derive the particle production rate in the presence of such external fields in compact spacetimes. We observe that the pair production rate is enhanced in the presence of a piston.

Schwinger pair production rate and time for some space-dependent fields via worldline instantons formalism

Schwinger pair production in some of space-dependent electromagnetic fields is studied analytically by using worldline instantons formalism for scalar quantum electrodynamics. With the increase of the modified Keldysh parameter $\gamma_{keb}$, the pair production rate decreases, the region of instanton paths expands regardless of the electromagnetic field form. We also find that all of the paths of the instantons for various electromagnetic fields are exactly in the same plane while with the different elliptical shapes. Moreover, the magnitudes of the normalized instantons action with different external electromagnetic fields are all bounded within the region from $\pi$ to $2\pi$ in spatial inhomogeneity fields. We further analytically identify and obtain two kinds of the pair-production time associated to the worldline instantons action.

Holographic Schwinger effect and electric instability with anisotropy

According to the gauge-gravity duality, we systematically study the Schwinger effect and electric instability with anisotropy in a top-down holographic approach. The anisotropic black brane and bubble (soliton) background in IIB supergravity are employed and the dual theories in these backgrounds are expected to be anisotropic theory at finite temperature and anisotropic theory with confinement respectively. Then performing the potential analysis, we find due to the anisotropy, the potential barrier behaves oppositely with parallel and perpendicular electric fields, and this behavior agrees with the previous study about the quark potential with anisotropy in this system. Afterwards, we evaluate the pair production rate by solving the equation of motion for a fundamental string numerically which reveals the consistent behavior with the potential analysis. Furthermore, the probe D7-brane as flavor is introduced into the bulk in order to investigate the electric instability. The vacuum decay rate can be obtained by evaluating the imaginary part of the D7-brane action which again agrees with our potential analysis. Solving the associated constraint of gauge field strength on the flavor brane, we finally obtain the V-A curve displaying the distinct behavior of the conductivity in parallel and perpendicular direction which is in agreement with some bottom-up and phenomenologically holographic approaches in anisotropic fluid. Accordingly, we believe this work may be remarkable to study the electric features in strongly coupled anisotropic system.

What are the Composition and Power of the Jet in Cyg X-1?

We calculate the electron–positron pair production rate at the base of the jet of Cyg X-1 by collisions of photons from its hot accretion flow using the measurement of its average soft gamma-ray spectra by the Compton Gamma Ray Observatory and INTEGRAL satellites. We have found that this rate approximately equals the flow rate of the leptons emitting the observed synchrotron radio-to-IR spectrum of the jet, calculated using an extended jet model following that of Blandford & Königl. This coincidence shows the jet composition is likely to be pair dominated. The same coincidences were found before in the microquasar MAXI J1820+070 and in the radio galaxy 3C 120, which shows that the considered mechanism can be universal for at least some classes of relativistic jets. Furthermore, we recalculate the jet power of Cyg X-1. The presence of pairs can strongly reduce the power in the bulk motion of ions, which then limits the parameter space at which the jet can power the ∼5 pc nebular structure present in its vicinity.

On Schwinger pair production between D3 branes

We study the open string pair production between two D3 branes, which will give rise to similar effect as Schwinger pair production for observers on one of the D3 branes. The D3 branes are placed parallel at a distance, and they are carrying world-volume electromagnetic fluxes that take a general form. We derive the pair production rate by computing the interaction amplitude between the D3 branes. We discussed how to maximize the pair production rate in this general case. We also mentioned that the general result can be used to describe other system such as D3–D1, where the pair production is ultra large compared to original Schwinger pair production, making it hopeful to observe pair production in experiments.

Multiphoton absorption and Rabi oscillations in armchair graphene nanoribbons

We present an analytical approach to the problem of the multiphoton absorption and Rabi oscillations in an armchair graphene nanoribbon (AGNR) in the presence of a time-oscillating strong electric field induced by a light wave directed parallel to the ribbon axis. The two-dimensional Dirac equation for the massless electron subject to the ribbon confinement is employed. In the resonant approximation the electron-hole pair production rate, associated with the electron transitions between the valence and conduction size-quantized subbands, the corresponding multiphoton absorption coefficient and the frequency of the Rabi oscillations are obtained in an explicit form. We trace the dependencies of the above quantities on the ribbon width and electric field strength for both the multiphoton assisted and tunneling regimes relevant to the time-oscillating and practically constant electric field, respectively. A significant enhancement effect of the oscillating character of the electric field on the intersubband transitions is encountered. Our analytical results are in qualitative agreement with those obtained for the graphene layer by numerical methods. Estimates of the expected experimental values for the typically employed AGNR and laser parameters show that both the Rabi oscillations and multiphoton absorption are accessible in the laboratory. The data relevant to the intersubband tunneling makes the AGNR a 1D condensed matter analog in which the quantum electrodynamic vacuum decay can be detected by applying an external laboratory electric field.