Vacuum polarization in a background magnetic field in (2 + 1)-dimensional QED

1995 ◽  
Vol 73 (7-8) ◽  
pp. 458-462
Author(s):  
D. G. C. McKeon
Keyword(s):  
Magnetic Field ◽  
Path Integral ◽  
Vacuum Polarization ◽  
Quantum Mechanical ◽  
Matrix Elements ◽  
Integral Technique ◽  
Background Magnetic Field ◽  
The One

The one-loop vacuum polarization in the presence of a background magnetic field is computed in (2 + 1)-dimensional electrodynamics in which the spinor mass is parity violating. The quantum-mechanical path-integral technique is used to compute matrix elements arising in the context operator regularization.

RADIATIVE EFFECTS IN A CONSTANT MAGNETIC FIELD USING THE QUANTUM MECHANICAL PATH-INTEGRAL

1994 ◽  
Vol 09 (23) ◽  
pp. 2167-2178 ◽  
Author(s):  
D.G.C. MCKEON ◽  
T.N. SHERRY
Keyword(s):  
Magnetic Field ◽  
Field Theory ◽  
Quantum Field Theory ◽  
Path Integral ◽  
Constant Magnetic Field ◽  
Quantum Mechanical ◽  
Quantum Field ◽  
Matrix Elements ◽  
Loop Momentum ◽  
Background Magnetic Field

It has been shown how evaluation of matrix elements of the form <x| exp −iHt|y> using the quantum mechanical path-integral allows one to determine radiative corrections in quantum field theory without encountering loop momentum integrals. In this paper we show how this technique can be applied when there is a constant background magnetic field contributing to the “Hamiltonian” H.

Thermal Vacuum Polarization Using the Quantum Mechanical Path Integral

1997 ◽  
Vol 12 (30) ◽  
pp. 5387-5396 ◽  
Author(s):  
D. G. C. Mckeon
Keyword(s):  
Path Integral ◽  
Vacuum Polarization ◽  
Thermal Field ◽  
Quantum Mechanical ◽  
Loop Order ◽  
Thermal Vacuum ◽  
One Dimensional ◽  
Loop Expansion ◽  
High Temperature Expansion ◽  
The One

It has been shown how the quantum mechanical path integral can be used to do perturbative calculations in both quantum and thermal field theory to any order of the loop expansion. However, it is not readily apparent how gauge invariance is made manifest in this approach; in this paper we demonstrate how the vacuum polarization in electrodynamics at one-loop order is in fact transverse. We employ the one-dimensional Green's function [Formula: see text] in conjunction with an integration-by-parts procedure akin to that used by Strassler and Bern and Kosower. Surface terms in this approach are all zero. We obtain the high temperature expansion for the vacuum polarization in the static limit.

FICTON THEORY OF DYNAMICAL SYSTEMS WITH NOISY PARAMETERS

1965 ◽  
Vol 43 (4) ◽  
pp. 619-639 ◽  
Author(s):  
R. C. Bourret
Keyword(s):  
Magnetic Field ◽  
Exact Solution ◽  
Dynamical Systems ◽  
Approximate Solutions ◽  
Frequency Parameter ◽  
Time Dependent ◽  
Quantum Mechanical ◽  
Graphical Comparison ◽  
The One ◽  
Random Fluctuations

The theory of randomly perturbed waves described previously (Bourret 1962a, b) is presented in a form applicable to purely time-dependent systems, classical or quantum mechanical. It is then applied to the problem of a spin-[Formula: see text] dipole in a magnetic field with random fluctuations. One- and two-ficton processes are taken into account and a "renormalization" approximation is given also. Graphical comparison of the approximate solutions with the exact solution is presented. As a classical example, the harmonic oscillator with a noisy frequency parameter is analyzed in both the one- and two-ficton approximations.

scholarly journals Dynamically important magnetic fields near the event horizon of Sgr A*

2020 ◽  
Vol 643 ◽  
pp. A56
Author(s):  
◽  
A. Jiménez-Rosales ◽  
J. Dexter ◽  
F. Widmann ◽  
M. Bauböck ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Near Infrared ◽  
Emission Region ◽  
Compact Region ◽  
Background Magnetic Field ◽  
Field Geometry ◽  
Sgr A ◽  
The One ◽  
Linear Polarisation

We study the time-variable linear polarisation of Sgr A* during a bright near-infrared flare observed with the GRAVITY instrument on July 28, 2018. Motivated by the time evolution of both the observed astrometric and polarimetric signatures, we interpret the data in terms of the polarised emission of a compact region (“hotspot”) orbiting a black hole in a fixed, background magnetic field geometry. We calculated a grid of general relativistic ray-tracing models, created mock observations by simulating the instrumental response, and compared predicted polarimetric quantities directly to the measurements. We take into account an improved instrument calibration that now includes the instrument’s response as a function of time, and we explore a variety of idealised magnetic field configurations. We find that the linear polarisation angle rotates during the flare, which is consistent with previous results. The hotspot model can explain the observed evolution of the linear polarisation. In order to match the astrometric period of this flare, the near horizon magnetic field is required to have a significant poloidal component, which is associated with strong and dynamically important fields. The observed linear polarisation fraction of ≃30% is smaller than the one predicted by our model (≃50%). The emission is likely beam depolarised, indicating that the flaring emission region resolves the magnetic field structure close to the black hole.

scholarly journals ACTION WITH ACCELERATION I: EUCLIDEAN HAMILTONIAN AND PATH INTEGRAL

2013 ◽  
Vol 28 (27) ◽  
pp. 1350137 ◽  
Author(s):  
BELAL E. BAAQUIE
Keyword(s):  
Boundary Conditions ◽  
Path Integral ◽  
Degrees Of Freedom ◽  
Similarity Transformation ◽  
Quantum Mechanical ◽  
Matrix Elements ◽  
Quantum Mechanical System ◽  
The Matrix ◽  
Correct Boundary Conditions ◽  
Acceleration Term

An action having an acceleration term in addition to the usual velocity term is analyzed. The quantum mechanical system is directly defined for Euclidean time using the path integral. The Euclidean Hamiltonian is shown to yield the acceleration Lagrangian and the path integral with the correct boundary conditions. Due to the acceleration term, the state space depends on both position and velocity — and hence the Euclidean Hamiltonian depends on two degrees of freedom. The Hamiltonian for the acceleration system is non-Hermitian and can be mapped to a Hermitian Hamiltonian using a similarity transformation; the matrix elements of the similarity transformation are explicitly evaluated.

scholarly journals Quantum resources for energy storage

2020 ◽  
Vol 230 ◽  
pp. 00003 ◽  
Author(s):  
Dario Ferraro ◽  
Michele Campisi ◽  
Gian Marcello Andolina ◽  
Vittorio Pellegrini ◽  
Marco Polini
Keyword(s):  
Energy Storage ◽  
Cavity Mode ◽  
Quantum Mechanical ◽  
Double Quantum ◽  
Level System ◽  
Close Proximity ◽  
Two Level Systems ◽  
Quantum Mechanical Effects ◽  
The One ◽  
Superradiant Phase

Recently the possibility to exploit quantum-mechanical effects to increase the performance of energy storage has raised a great interest. It consists of N two-level systems coupled to a single photonic mode in a cavity. We demonstrate the emergence of a quantum advantage in the charging power on this collective model (Dicke Quantum Battery) with respect to the one in which each two-level system is coupled to its own separate cavity mode (Rabi Quantum Battery). Moreover, we discuss the model of a Quantum Supercapacitor. This consists of two chains, one containing electrons and the other one holes, hosted by arrays of double quantum dots. The two chains are in close proximity and embedded in the same photonic cavity, in the same spirit of the Dicke model. We find the phase diagram of this model showing that, when transitioning from the ferro/antiferromagnetic to the superradiant phase, the quantum capacitance of the model is greatly enhanced.

Path integral for spinning particle in magnetic field via bosonic coherent states

1995 ◽  
Vol 36 (4) ◽  
pp. 1602-1615 ◽  
Author(s):  
T. Boudjedaa ◽  
A. Bounames ◽  
L. Chetouani ◽  
T. F. Hammann ◽  
Kh. Nouicer
Keyword(s):  
Magnetic Field ◽  
Path Integral ◽  
Coherent States ◽  
Spinning Particle

Parametric excitation of magnetoacoustic waves by a pump magnetic field in a high-β plasma

1977 ◽  
Vol 17 (1) ◽  
pp. 93-103 ◽  
Author(s):  
N. F. Cramer
Keyword(s):  
Magnetic Field ◽  
Parametric Excitation ◽  
Acoustic Waves ◽  
Magnetic Pressure ◽  
Gas Pressure ◽  
Alfven Wave ◽  
Fast Wave ◽  
Magnetoacoustic Waves ◽  
Background Magnetic Field ◽  
The Waves

The parametric excitation of slow, intermediate (Alfvén) and fast magneto-acoustic waves by a modulated spatially non-uniform magnetic field in a plasma with a finite ratio of gas pressure to magnetic pressure is considered. The waves are excited in pairs, either pairs of the same mode, or a pair of different modes. The growth rates of the instabilities are calculated and compared with the known result for the Alfvén wave in a zero gas pressure plasma. The only waves that are found not to be excited are the slow plus fast wave pair, and the intermediate plus slow or fast wave pair (unless the waves have a component of propagation direction perpendicular to both the background magnetic field and the direction of non-uniformity of the field).

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