共查询到20条相似文献,搜索用时 31 毫秒
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It is shown that quantum fields for massive particles with braid group statistics (Plektons) in three-dimensional space-time cannot be free, in a quite elementary sense: They must exhibit elastic two-particle scattering into every solid angle, and at every energy. This also implies that for such particles there cannot be any operators localized in wedge regions which create only single particle states from the vacuum and which are well-behaved under the space-time translations (so-called temperate polarization- free generators). These results considerably strengthen an earlier “NoGo-theorem for ’free’ relativistic Anyons”. 相似文献
3.
The Green’s function for a spinless relativistic particle subjected to the action of an electromagnetic plane wave, with local
gauge, is determined according to the stochastic quantum mechanics of G. Parisi and Wu. The evaluation was done in two steps:
first the classical action is extracted and next the fluctuation factor is calculated. The treatment has been carried out
in the phase and configuration spaces. 相似文献
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We calculate zero temperature Green’s function, the density–density correlations and expectation values of a one-dimensional quantum particle which interacts with a Fermi-sea via a δ-potential. The eigenfunctions of the Bethe-Ansatz solvable model can be expressed as a determinant. This allows us to obtain a compact expression for the Green’s function of the extra particle. In the hardcore limit the resulting expression can be analyzed further using Painlevé V transcendents. It is found that depending on the extra particles momentum its Green’s function undergoes a transition of that for hardcore Bosons to that of free Fermions. 相似文献
6.
A relativistic quantum exchange protocol enabling “coin tossing at a distance” between two participants is proposed. The exchange
protocol is based on the fact that to distinguish a pair of orthogonal states with certainty in relativistic quantum mechanics
requires a finite time that depends on the structure of the states themselves.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 10, 684–689 (25 November 1999) 相似文献
7.
Massimo Marino 《Annals of Physics》2002,301(2):85-127
A simple mathematical procedure is introduced which allows redefining in an exact way divergent integrals and limits that appear in the basic equations of classical electrodynamics with point charges. In this way all divergences are at once removed without affecting the locality and the relativistic covariance of the theory, and with no need for mass renormalization. The procedure is first used to obtain a finite expression for the electromagnetic energy-momentum of the system. We show that the relativistic Lorentz-Dirac equation can be deduced from the conservation of this electromagnetic energy-momentum plus the usual mechanical term. Then we derive a finite lagrangian, which depends on the particle variables and on the actual electromagnetic potentials at a given time. From this lagrangian the equations of motion of both particles and fields can be derived via Hamilton's variational principle. The hamiltonian formulation of the theory can be obtained in a straightforward way. This leads to an interesting comparison between the resulting divergence-free expression of the hamiltonian functional and the standard renormalization rules for perturbative quantum electrodynamics. 相似文献
8.
We show that the recently discovered double-valley splitting of the Landau levels in the quantum Hall effect in graphene can be explained as the perturbative orbital interaction of intravalley and intervalley microscopic orbital currents with a magnetic field. This effect is facilitated by the translationally noninvariant terms that correspond to graphene's crystallographic honeycomb symmetry but do not exist in the relativistic theory of massless Dirac fermions in quantum electrodynamics. We discuss recent data in view of these findings. 相似文献
9.
H. Pan Y.-H. Zhao 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,70(2):185-191
The π-junction transition of a T-shaped double quantum dot
system is investigated theoretically by using the nonequilibrium
Green’s function method. It is found that the π-junction
transition can occur with increasing the spin-flip strength.
Furthermore, the π-junction in the system can be controlled by
tuning the system parameters, such as the two quantum dot energy
levels and the interdot coupling. These controlled π-junction
transitions are interpreted in the picture of current-carrying
density of states. When the main contributions to supercurrent is
changed between the positive discrete spectrum and the negative
continuous spectrum, the π-junction transitions can happen. 相似文献
10.
M. Vogel 《Contemporary Physics》2013,54(3):437-452
The value of the electron's magnetic moment is a fundamental quantity in physics. Its deviation from the value expected from Dirac theory has given enormous impetus to the field of quantum theory and especially to quantum electrodynamics (QED) as the relativistic quantum field theory of electrodynamics. In fact, the measured values both for free and for bound electrons are explained by corresponding QED calculations on the part per trillion and part per billion level of accuracy, respectively. This agreement is amongst the best known in physics today. In turn, it allows highly precise determinations of related fundamental constants like the fine structure constant α or the electron mass. The present article discusses the application of the continuous Stern–Gerlach effect to the precise measurement of magnetic moments, especially of the electron bound in highly charged ions and possible tests of calculations in the framework of QED of bound states. Also, a test of QED in a more general approach by the comparison of values for the fine structure constant derived from different measurements, will be discussed. 相似文献
11.
Ruth E. Kastner 《Foundations of Physics》2012,42(8):1094-1113
A recent ontological variant of Cramer’s Transactional Interpretation, called “Possibilist Transactional Interpretation” or
PTI, is extended to the relativistic domain. The present interpretation clarifies the concept of ‘absorption,’ which plays
a crucial role in TI (and in PTI). In particular, in the relativistic domain, coupling amplitudes between fields are interpreted
as amplitudes for the generation of confirmation waves (CW) by a potential absorber in response to offer waves (OW), whereas
in the nonrelativistic context CW are taken as generated with certainty. It is pointed out that solving the measurement problem
requires venturing into the relativistic domain in which emissions and absorptions take place; nonrelativistic quantum mechanics
only applies to quanta considered as ‘already in existence’ (i.e., ‘free quanta’), and therefore cannot fully account for
the phenomenon of measurement, in which quanta are tied to sources and sinks. 相似文献
12.
A. N. Serdyukov 《Physics of Particles and Nuclei Letters》2011,8(2):78-89
A theory of gravitational interaction in classical electrodynamics is developed on the basis of an earlier-proposed minimal
relativistic model of gravitation. From the variation principle, a system of gaugeinvariant equations of the interacting electromagnetic
and gravitational fields is deduced and their common energy-momentum tensor is constructed. A rigorous solution to the problem
of regularizing the field mass of a point charge is given with consideration for the coupling energy of the gravitational
interaction. The propagation of electromagnetic waves in the gravitational field is discussed. It is shown that, under the
condition of the existing resonant ratio 2: 3 for the periods of Mercury’s orbital revolution and daily rotation, tidal forces
cause a regular shift in the planet’s perihelion in an observable forward direction. 相似文献
13.
A bound state in a continuum (BIC) might appear in open quantum dots for the variation in the dot’s shape. By means of the
equations of motion of the Green’s functions, we investigate the effect of strong intradot Coulomb interactions on that phenomenon
within the framework of the impurity Anderson model. The equation that the imaginary part of the poles of the Green’s function
equals zero yields the condition for BICs. As a result, we show that the Coulomb interactions replicate the single-electron
BICs into two-electron ones.
The text was submitted by the authors in English. 相似文献
14.
Mercedes Gimeno-Segovia Felipe J. Llanes-Estrada 《The European Physical Journal C - Particles and Fields》2008,56(4):557-569
We present an elementary method to obtain Green’s functions in non-perturbative quantum field theory in Minkowski space from
Green’s functions calculated in Euclidean space. Since in non-perturbative field theory the analytical structure of amplitudes
often is unknown, especially in the presence of confined fields, dispersive representations suffer from systematic uncertainties.
Therefore, we suggest to use the Cauchy–Riemann equations, which perform the analytical continuation without assuming global
information on the function in the entire complex plane, but only in the region through which the equations are solved. We
use as example the quark propagator in Landau gauge quantum chromodynamics, which is known from lattice and Dyson–Schwinger
studies in Euclidean space. The drawback of the method is the instability of the Cauchy–Riemann equations against high-frequency
noise,which makes it difficult to achieve good accuracy. We also point out a few curious details related to the Wick rotation. 相似文献
15.
I. Ţifrea M. Crisan I. Grosu 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,79(4):455-464
We consider the transport and the noise characteristic in the case of a triple quantum dots T-shape system where two of the
dots form a two-level system and the other works in a detector-like setup. Our theoretical results are obtained using the
equation of motion method for the case of zero and finite on-site Coulomb interaction in the detector dot. We present analytic
results for the electronic Green’s functions in the system’s component quantum dots, and we used numerical calculations to
evaluate the system’s transport properties. The transport trough the T-shaped system can be controlled by varying the coupling
between the two-level system dots or the coupling between the detector dot and the exterior electrodes. The system’s conductance
presents Fano dips for both strong (fast detector) and weak coupling (slow detector) between the detector dot and the external
electrodes. Due to stronger electronic correlations the noise characteristics in the case of a slow detector are much higher.
This setup may be of interest for the practical realization of qubit states in quantum dots systems. 相似文献
16.
Jae-Weon Lee 《Foundations of Physics》2012,42(9):1153-1164
It was recently suggested that quantum field theory is not fundamental but emerges from the loss of phase space information about matter crossing causal horizons. Possible connections between this formalism and Verlinde’s entropic gravity and Jacobson’s thermodynamic gravity are proposed. The holographic screen in Verlinde’s formalism can be identified as local Rindler horizons and its entropy as that of the bulk fields beyond the horizons. This naturally resolves some issues on entropic gravity. The quantum fluctuation of the fields is the origin of the thermodynamic nature of entropic gravity. It is also suggested that inertia is related to dragging Rindler horizons. 相似文献
17.
A. G. Sotnikov 《Optics and Spectroscopy》2011,111(4):639-646
We study theoretically the linear response of a gas in the state with Bose-Einstein condensate to the perturbation by an external
electromagnetic field (weak laser pulse). The Green’s functions formalism is used to study the dispersion characteristics
of a system at finite temperatures. It is shown that the group velocity of the near-resonant pulses in condensate in some
cases can strongly depend on the temperature. Basing on the account of the Zeeman splitting of the magnetic states we study
also a possibility to filter light pulses by the condensate with several occupied quantum states. 相似文献
18.
The heating rate and conservative—dissipative forces in a system of two parallel plates moving at a nonrelativistic velocity
with respect to each other have been calculated in terms of the fluctuation electromagnetic electrodynamics for the first
time. It has been demonstrated that the recently proposed relativistic theory of fluctuation electromagnetic interactions
in the configuration under consideration offers fundamental disadvantages. 相似文献
19.
Giampiero Esposito 《Foundations of Physics》2002,32(9):1459-1483
This paper proves that it is possible to build a Lagrangian for quantum electrodynamics which makes it explicit that the photon mass is eventually set to zero in the physical part on observational ground. Gauge independence is achieved upon considering the joint effect of gauge-averaging term and ghost fields. It remains possible to obtain a counterterm Lagrangian where the only non-gauge-invariant term is proportional to the squared divergence of the potential, while the photon propagator in momentum space falls off like k
–2 at large k which indeed agrees with perturbative renormalizability. The resulting radiative corrections to the Coulomb potential in QED are also shown to be gauge-independent. The experience acquired with quantum electrodynamics is used to investigate properties and problems of the extension of such ideas to non-Abelian gauge theories. 相似文献
20.
The phenomenon of quantum superposition, which allows a physical system to exist in different states ‘simultaneously’, is
one of the most bizarre notions in physics. Here we illustrate an even more bizarre example of it: a superposed state of a
physical system consisting of both an ‘older’ version and a ‘younger’ version of that system. This can be accomplished by
exploiting the special relativistic effect of time dilation featuring in Einstein’s famous twin paradox. 相似文献