Search results for "electrodynamics"
showing 10 items of 820 documents
Polarization observables for elastic electron scattering off a moving nucleon
2019
General expressions for all parity-conserving polarization observables of elastic electron-nucleon scattering in the one-photon exchange approximation are derived for a general frame of reference, i.e.\ not assumming scattering off a nucleon at rest and not specializing to a specific system of coordinates. Essentially, the given expressions are also valid for the inverse process, i.e.\ nucleon scattering off electrons.
Magnetic moment of the Roper resonance
2012
The magnetic moment of the Roper resonance is calculated in the framework of a low-energy effective field theory of the strong interactions. A systematic power-counting procedure is implemented by applying the complex-mass scheme.
EPM calculations of E2/M1 mixing ratios for even samarium isotopes 146–152Sm
1987
Abstract The M1 operator and the E2/M1 mixing ratios, Δ (E2/M1), are discussed in the framework of the extended phonon projection model (EPM). The model is applied to 146, 148, 150, 152 Sm to describe their M1 properties. Comparison is made between the EPM, the consistent- Q formalism (CQF) of the basic interacting-boson approximation (IBA-1) and the experimental Δ(E2/M1) data. Both theoretical approaches give reasonably good results and parameter systematics.
Study of thepd→pdηreaction
2007
A study of the pd{yields}pd{eta} reaction in the energy range where the recent data from Uppsala are available is done in the two-step model of {eta} production including the final state interaction. The {eta}-d final state interaction is incorporated through the solution of the Lippmann Schwinger equation using an elastic scattering matrix element, T{sub {eta}}{sub d{yields}}{sub {eta}}{sub d}, which is required to be half off-shell. It is written in a factorized form, with an off-shell form factor multiplying an on-shell part given by an effective range expansion up to the fourth power in momentum. The parameters of this expansion have been taken from an existing recent relativistic Fadde…
Relativistic scattering theory of charged spinless particles
1986
In the context of a relativistic quantum mechanics we discuss the scattering of two and three charged spinless particles. The corresponding transition operators are shown to satisfy four-dimensional Lippmann-Schwinger and eight-dimensional Faddeev-type equations, respectively. A simplified model of two particles with Coulomb interaction can be solved exactly. We calculate: (i) The partial waveS-matrix from which we extract the bound state spectrum. The latter agrees with a fourth-order result of Schwinger, (ii) The full scattering amplitude which in the weakfield limit coincides with the expression derived by Fried et al. from eikonalized QED.
DYNAMIC STRUCTURE FUNCTION OF QUANTUM BOSE SYSTEMS: CONDENSATE FRACTION AND MOMENTUM DISTRIBUTION
2008
We present results on the behavior of the dynamic structure function in the short wave length limit using the equation of motion method. Within this framework we study the linear response of a quantum system to an infinitesimal external perturbation by direct minimization of the action integral. As a result we get a set of coupled continuity equations which define the self-energy. We evaluate the self-energy and the dynamic structure function in the short wavelength limit and show that sum rules up to the third moment are fulfilled. This implies, for instance, that the self-energy at short wavelengths and zero frequency is proportional to the kinetic energy per particle. An essential featu…
Stopping a slow-light soliton: an exact solution
2005
We investigate propagation of a slow-light soliton in Λ-type media such as atomic vapours and Bose–Einstein condensates. We show that the group velocity of the soliton monotonically decreases with the intensity of the controlling laser field, which decays exponentially after the laser is switched off. The shock wave of the vanishing controlling field overtakes the slow soliton and stops it, while the optical information is recorded in the medium in the form of spatially localized polarization. In the strongly nonlinear regime we find an explicit exact solution describing the whole process.
Giant collective incoherent shock waves in strongly nonlinear turbulent flows
2016
Contrary to conventional coherent shocks, we show theoretically and experimentally that nonlocal turbulent flows lead to the emergence of large-scale incoherent shock waves, which constitute a collective phenomenon of the incoherent field as a whole.
Scaling Regimes and the Singularity of Specific Heat in the 3D Ising Model
2013
AbstractThe singularity of specific heat CV of the three-dimensional Ising model is studied based on Monte Carlo data for lattice sizes L≤1536. Fits of two data sets, one corresponding to certain value of the Binder cumulant and the other — to the maximum of CV, provide consistent values of C0 in the ansatz CV(L)=C0+ALα/ν at large L, if α/ν=0.196(6). However, a direct estimation from our data suggests that α/ν, most probably, has a smaller value (e.g., α/ν= 0.113(30)). Thus, the conventional power-law scaling ansatz can be questioned because of this inconsistency. We have found that the data are well described by certain logarithmic ansatz.
Many-electron transport in Aharonov-Bohm interferometers: Time-dependent density-functional study
2012
We apply time-dependent density-functional theory to study many-electron transport in Aharonov-Bohm interferometers in a non-equilibrium situation. The conductance properties in the system are complex and depend on the enclosed magnetic flux in the interferometer, the number of interacting particles, and the mutual distance of the transport channels at the points of encounter. Generally, the electron-electron interactions do not suppress the visibility of Aharonov-Bohm oscillations if the interchannel distance -- determined by the positioning of the incompressible strips through the external magnetic field -- is optimized. However, the interactions also impose an interesting Aharonov-Bohm p…