150 research outputs found
Hamiltonian Formulation of Two Body Problem in Wheeler-Feynman electrodynamics
A Hamiltonian formulation for the classical problem of electromagnetic
interaction of two charged relativistic particles is found.Comment: 22 pages, 8 Uuencoded Postscript figure
Effects of fault transmissivity on the potential of fault reactivation and induced seismicity : Implications for understanding induced seismicity at Pohang EGS
Funding Information: The project leading to part of the results in this article received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 691728 .Peer reviewedPublisher PD
Quantum-classical crossover in electrodynamics
A classical field theory is proposed for the electric current and the
electromagnetic field interpolating between microscopic and macroscopic
domains. It represents a generalization of the density functional for the
dynamics of the current and the electromagnetic field in the quantum side of
the crossover and reproduces standard classical electrodynamics on the other
side. The effective action derived in the closed time path formalism and the
equations of motion follow from the variational principle. The polarization of
the Dirac-see can be taken into account in the quadratic approximation of the
action by the introduction of the deplacement field strengths as in
conventional classical electrodynamics. Decoherence appears naturally as a
simple one-loop effect in this formalism. It is argued that the radiation time
arrow is generated from the quantum boundary conditions in time by decoherence
at the quantum-classical crossover and the Abraham-Lorentz force arises from
the accelerating charge or from other charges in the macroscopic or the
microscopic side, respectively. The functional form of quantum renormalization
group, the generalization of the renormalization group method for the density
matrix, is proposed to follow the scale dependence through the
quantum-classical crossover in a systematical manner.Comment: new references added, few sign errors fixed, to appear in Physical
Review
Hamiltonian Formalism for Space-time Non-commutative Theories
Space-time non-commutative theories are non-local in time. We develop the
Hamiltonian formalism for non-local field theories in d space-time dimensions
by considering auxiliary d+1 dimensional field theories which are local with
respect to the evolution time. The Hamiltonian path integral quantization is
considered and the Feynman rules in the Lagrangian formalism are derived. The
case of non-commutative \phi^3 theory is considered as an example.Comment: 6 pages, A new section is added with other comments and references.
To appear in PR
Harmonic Pulse Testing for Well Monitoring: application to a fractured geothermal reservoir
Harmonic Pulse Testing (HPT) has been developed as a type of well testing applicable during ongoing field operations because a pulsed signal is superimposed on background pressure trend. Its purpose is to determine well and formation parameters such as wellbore storage, skin, permeability and boundaries within the investigated volume. Compared to conventional well testing, HPT requires more time to investigate the same reservoir volume. The advantage is that it does not require the interruption of well and reservoir injection/production before and/or during the test because it allows the extraction of an interpretable periodic signal from measured pressure potentially affected by interference. This makes it an ideal monitoring tool. Interpretation is streamlined through diagnostic plots mimicking conventional well test interpretation methods. To this end, analytical solutions in the frequency domain are available.
The methodology was applied to monitor stimulation operations performed at an Enhanced Geothermal System (EGS) site in Pohang, Korea. The activities were divided into two steps: first a preliminary sequence of tests, injection/fall‐off and two HPTs, characterized by low injection rates and dedicated to estimate permeability prior to stimulation operations; then stimulation sequence characterized by higher injection rate. During the stimulation operations other HPTs were performed to monitor formation properties behavior. The interpretation of HPT data through the derivative approach implemented in the frequency domain provided reliable results in agreement with the injection test. Moreover, it provided an estimation of hydraulic properties without cessation of stimulation operations, thus confirming the effectiveness of HPT application for monitoring purposes
A relativistic action-at-a-distance description of gravitational interactions?
It is shown that certain aspects of gravitation may be described using a
relativistic action-at-a-distance formulation. The equations of motion of the
model presented are invariant under Lorentz transformations and agree with the
equations of Einstein's theory of General Relativity, at the first
Post-Newtonian approximation, for any number of interacting point masses
Stochastic Gravity
Gravity is treated as a stochastic phenomenon based on fluctuations of the
metric tensor of general relativity. By using a (3+1) slicing of spacetime, a
Langevin equation for the dynamical conjugate momentum and a Fokker-Planck
equation for its probability distribution are derived. The Raychaudhuri
equation for a congruence of timelike or null geodesics leads to a stochastic
differential equation for the expansion parameter in terms of the
proper time . For sufficiently strong metric fluctuations, it is shown that
caustic singularities in spacetime can be avoided for converging geodesics. The
formalism is applied to the gravitational collapse of a star and the
Friedmann-Robertson-Walker cosmological model. It is found that owing to the
stochastic behavior of the geometry, the singularity in gravitational collapse
and the big-bang have a zero probability of occurring. Moreover, as a star
collapses the probability of a distant observer seeing an infinite red shift at
the Schwarzschild radius of the star is zero. Therefore, there is a vanishing
probability of a Schwarzschild black hole event horizon forming during
gravitational collapse.Comment: Revised version. Eq. (108) has been modified. Additional comments
have been added to text. Revtex 39 page
ADM canonical formalism for gravitating spinning objects
In general relativity, systems of spinning classical particles are
implemented into the canonical formalism of Arnowitt, Deser, and Misner [1].
The implementation is made with the aid of a symmetric stress-energy tensor and
not a 4-dimensional covariant action functional. The formalism is valid to
terms linear in the single spin variables and up to and including the
next-to-leading order approximation in the gravitational spin-interaction part.
The field-source terms for the spinning particles occurring in the Hamiltonian
are obtained from their expressions in Minkowski space with canonical variables
through 3-dimensional covariant generalizations as well as from a suitable
shift of projections of the curved spacetime stress-energy tensor originally
given within covariant spin supplementary conditions. The applied coordinate
conditions are the generalized isotropic ones introduced by Arnowitt, Deser,
and Misner. As applications, the Hamiltonian of two spinning compact bodies
with next-to-leading order gravitational spin-orbit coupling, recently obtained
by Damour, Jaranowski, and Schaefer [2], is rederived and the derivation of the
next-to-leading order gravitational spin(1)-spin(2) Hamiltonian, shown for the
first time in [3], is presented.Comment: REVTeX4, 18 pages. v1: published version. v2: corrected misprints in
(8.4) and (9.3), updated reference
Stochastic thermodynamics of holonomic systems
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