Schwinger effect in an instanton background with electric and magnetic fields via holography

2018 ◽  
Vol 33 (25) ◽  
pp. 1850144
Author(s):  
Maryam Gholizadeh Arashti ◽  
Majid Dehghani
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Production Rate ◽  
Pair Creation ◽  
Zero Temperature ◽  
Expectation Value ◽  
Background Magnetic Field ◽  
Electric And Magnetic Fields ◽  
Schwinger Effect ◽  
Horizon Limit

The Schwinger effect in the presence of instantons and background magnetic field was considered to study the dependence of critical electric field on instanton density and magnetic field using AdS/CFT conjecture. The gravity side is the near horizon limit of D3[Formula: see text]D(−[Formula: see text]1) background with electric and magnetic fields on the brane. Our approach is based on the potential analysis for particle–antiparticle pair at zero and finite temperatures, where the zero temperature case is a semi-confining theory. We find that presence of instantons suppresses the pair creation effect, similar to a background magnetic field. Then, the production rate will be obtained numerically using the expectation value of circular Wilson loop. The obtained production rate in a magnetic field is in agreement with previous results.

scholarly journals Axion assisted Schwinger effect

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Valerie Domcke ◽  
Yohei Ema ◽  
Kyohei Mukaida
Keyword(s):  
Electric Field ◽  
Production Rate ◽  
Strong Electric Field ◽  
Background Field ◽  
Chiral Anomaly ◽  
Fermion Mass ◽  
Anomaly Equation ◽  
Electric And Magnetic Fields ◽  
Schwinger Effect ◽  
Momentum Transverse

Abstract We point out an enhancement of the pair production rate of charged fermions in a strong electric field in the presence of time dependent classical axion-like background field, which we call axion assisted Schwinger effect. While the standard Schwinger production rate is proportional to $$ \exp \left(-\pi \left({m}^2+{p}_T^2\right)/E\right) $$ exp − π m 2 + p T 2 / E , with m and pT denoting the fermion mass and its momentum transverse to the electric field E, the axion assisted Schwinger effect can be enhanced at large momenta to exp(−πm2/E). The origin of this enhancement is a coupling between the fermion spin and its momentum, induced by the axion velocity. As a non-trivial validation of our result, we show its invariance under field redefinitions associated with a chiral rotation and successfully reproduce the chiral anomaly equation in the presence of helical electric and magnetic fields. We comment on implications of this result for axion cosmology, focussing on axion inflation and axion dark matter detection.

scholarly journals Holographic Schwinger effect with a deformed AdS background

2017 ◽  
Vol 32 (10) ◽  
pp. 1750045 ◽  
Author(s):  
J. Sadeghi ◽  
B. Pourhassan ◽  
S. Tahery ◽  
F. Razavi
Keyword(s):  
Pair Production ◽  
Production Rate ◽  
Electrostatic Potential ◽  
Deformation Parameter ◽  
Zero Temperature ◽  
Test Particles ◽  
Schwinger Effect

In this paper, we consider a deformed AdS background and study the effect of deformation parameter on the pair production rate of the Schwinger effect. The electrostatic potential is important for the pair production in the holographic Schwinger effect. In this paper, we analyze the electrostatic potential in a deformed AdS background and investigate the effect of deformation parameter which may be useful to test the AdS/QCD. In the case of zero temperature, we find that the larger value of the deformation parameter leads to a smaller value of separation length of the test particles on the probe. Also, we find a finite maximum of separation length in the presence of modification parameter.

scholarly journals Pair creation for bosons in electric and magnetic fields

2013 ◽  
Vol 87 (2) ◽  
Author(s):  
Q. Z. Lv ◽  
A. C. Su ◽  
M. Jiang ◽  
Y. J. Li ◽  
R. Grobe ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Pair Creation ◽  
Electric And Magnetic Fields

Modified Morris-Lecar neuron model: Effects of very low frequency electric fields and of magnetic fields on the local and network dynamics of an excitable media

2021 ◽  
Author(s):  
Karthikeyan Rajagopal ◽  
Irene Moroz ◽  
Balamurali Ramakrishnan ◽  
Anitha Karthikeyan ◽  
Prakash Duraisamy
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Electric Field ◽  
Neuron Model ◽  
Low Noise ◽  
Spiral Waves ◽  
Excitable Media ◽  
Field Frequency ◽  
Electric And Magnetic Fields ◽  
Electric Field Frequency

Abstract A Morris-Lecar neuron model is considered with Electric and Magnetic field effects where the electric field is a time varying sinusoid and magnetic field is simulated using an exponential flux memristor. We have shown that the exposure to electric and magnetic fields have significant effects on the neurons and have exhibited complex oscillations. The neurons exhibit a frequency-locked state for the periodic electric field and different ratios of frequency locked states with respect to the electric field frequency is also presented. To show the impact of the electric and magnetic fields on network of neurons, we have constructed different types of network and have shown the network wave propagation phenomenon. Interestingly the nodes exposed to both electric and magnetic fields exhibit more stable spiral waves compared to the nodes exhibited only to the magnetic fields. Also, when the number of layers are increased the range of electric field frequency for which the layers exhibit spiral waves also increase. Finally the noise effects on the field affected neuron network are discussed and multilayer networks supress spiral waves for a very low noise variance compared against the single layer network.

scholarly journals Dynamics of an orbital polarization of twisted electron beams in electric and magnetic fields

2019 ◽  
Vol 204 ◽  
pp. 10008
Author(s):  
Alexander J. Silenko ◽  
Pengming Zhang ◽  
Liping Zou
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Magnetic Fields ◽  
Quantum Dynamics ◽  
Electron Beams ◽  
Equations Of Motion ◽  
Vortex Beam ◽  
Dirac Particles ◽  
Electric And Magnetic Fields ◽  
Average Projection

Relativistic classical and quantum dynamics of twisted (vortex) Dirac particles in arbitrary electric and magnetic fields is constructed. The relativistic Hamiltonian and equations of motion in the Foldy-Wouthuysen representation are derived. Methods for the extraction of an electron vortex beam with a given orbital polarization and for the manipulation of such a beam are developed. The new effect of a radiative orbital polarization of a twisted electron beam in a magnetic field resulting in a nonzero average projection of the intrinsic orbital angular momentum on the field direction is predicted.

Acoustomagnetoelectric Effect in Graphene Nanoribbon in the Presence of External Electric and Magnetic Fields

2015 ◽  
Vol 4 (1) ◽  
Author(s):  
Kwadwo A. Dompreh ◽  
Samuel Y. Mensah ◽  
Sulemana S. Abukari ◽  
Raymond Edziah ◽  
Natalia G. Mensah ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Kinetic Equation ◽  
Magnetic Fields ◽  
Fermi Level ◽  
Boltzmann Kinetic Equation ◽  
Graphene Nanoribbon ◽  
Open Circuit ◽  
Energy Dispersion ◽  
Electric And Magnetic Fields ◽  
Band Index

AbstractAcoustomagnetoelectric Effect (AME) in Graphene Nanoribbon (GNR) in the presence of an external electric and magnetic fields was studied using the Boltzmann kinetic equation. On open circuit, the Surface Acoustomagnetoelectric field (ESAME) in GNR was obtained in the region ql >> 1, for energy dispersion "(p) near the Fermi level. The dependence of ESAME on the dimensional factor (ɳ), the sub-band index (pi), and the width (N) of GNR were analyzed numerically. For ESAME versus ɳ, a non-linear graph was obtained. From the graph, at ɳ < 0.62, the obtained graph qualitatively agreed with that experimentally observed in graphite. However at ɳ > 0.62, the ⃗ESAME falls rapidly to a minimum value. We observed that in GNR, the maximum ⃗ESAME was obtained at magnetic field H = 3.2Am−1. The graphs obtainedwere modulated by varying the subband index pi with an inversion observed when pi = 6. The dependence of ESAME on the width N for various pi was also studied where, ⃗ESAME decreases for increase in pi. To enhanced the understanding of ESAME on the N and ɳ, a 3D graph was plotted. This study is relevant for investigating the properties of GNR.

Cylindrical Distribution of Matter in Longitudinal Electric and Magnetic Fields

1975 ◽  
Vol 53 (17) ◽  
pp. 1659-1663
Author(s):  
K. D. Krori ◽  
Jayantimala Chakrabarty
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Test Particles ◽  
Electric And Magnetic Fields

We have presented here some results on test particles in the field of a cylindrical distribution of matter in a longitudinal electric or magnetic field.

Photodetachment microscopy of H– ion in time-dependent electric and magnetic fields

2018 ◽  
Vol 96 (9) ◽  
pp. 961-968
Author(s):  
De-hua Wang
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Electric Field ◽  
Interference Pattern ◽  
Current Distribution ◽  
Time Dependent ◽  
Electron Current ◽  
Detector Plane ◽  
Electron Trajectories ◽  
Electric And Magnetic Fields

We examine the dynamics of electrons photodetached from the H– ion in time-dependent electric and magnetic fields for the first time. The photodetachment microscopy patterns caused by a time-dependent gradient electric field and magnetic field have been analyzed in great detail based on the semiclassical theory. The interplay of the gradient electric field and magnetic field forces causes an intricate shape of the electron wave and multiple electron trajectories generated by a fixed energy point source can arrive at a given point on the microchannel-plate detector. The interference effects between these electron trajectories cause the oscillatory structures of the electron probability density and electron current distribution, and a set of concentric interference fringes are found at the detector. Our calculation results suggest that the photodetachment microscopy interference pattern on the detector can be adjusted by the electron energy, magnetic field strength, and position of the detector plane. Under certain conditions, the interference pattern in the electron current distribution might be seen on the detector plane localized at a macroscopic distance from the photodetachment source, which can be observed in an actual photodetachment microscopy experiment. Therefore, we make predictions that our work should serve as a guide for future photodetachment microscopy experiments in time-dependent electric and magnetic fields.

scholarly journals Magnetotellurics with a remote magnetic reference

Geophysics ◽  
1979 ◽  
Vol 44 (1) ◽  
pp. 53-68 ◽  
Author(s):  
T. D. Gamble ◽  
W. M. Goubau ◽  
J. Clarke
Keyword(s):  
Magnetic Field ◽  
Standard Deviation ◽  
Magnetic Fields ◽  
Apparent Resistivity ◽  
The Other ◽  
Impedance Tensor ◽  
Free Data ◽  
Electric And Magnetic Fields ◽  
Conventional Methods ◽  
The Magnetic Field

Magnetotelluric measurements were performed simultaneously at two sites 4.8 km apart near Hollister, California. SQUID magnetometers were used to measure fluctuations in two orthogonal horizontal components of the magnetic field. The data obtained at each site were analyzed using the magnetic fields at the other site as a remote reference. In this technique, one multiplies the equations relating the Fourier components of the electric and magnetic fields by a component of magnetic field from the remote reference. By averaging the various crossproducts, estimates of the impedance tensor not biased by noise are obtained, provided there are no correlations between the noises in the remote channels and noises in the local channels. For some data, conventional methods of analysis yielded estimates of apparent resistivities that were biased by noise by as much as two orders of magnitude. Nevertheless, estimates of the apparent resistivity obtained from these same data, using the remote reference technique, were consistent with apparent resistivities calculated from relatively noise‐free data at adjacent periods. The estimated standard deviation for periods shorter than 3 sec was less than 5 percent, and for 87 percent of the data, was less than 2 percent. Where data bands overlapped between periods of 0.33 sec and 1 sec, the average discrepancy between the apparent resistivities was 1.8 percent.

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