Atomic scatterin G by a resonant standing light wave

The theory of atomic scattering by a resonant standing light wave is developed. It is shown that, if the natural width of atomic transition is larger than the recoil energy and the interaction time exeeds the spontaneous decay time, the atomic motion is described by the kinetic equation for atomic distribution function. The latter is a Fokker-Planck type equation and includes the light pressure force and momentum diffusion tensor. It is found that in a strong wave the maximum value of the force is limited, whereas the diffusion tensor increases proportional to wave intensity. It is concluded that for high intensities of a standing wave, it is the atomic momentum diffusion that is responsible for scattering.     

A New Approach to the 3D Faddeev Equation for Three-body Scattering

A novel approach to solve the Faddeev equation for three-body scattering at arbitrary energies is proposed. This approach disentangles the complicated singularity structure of the free three-nucleon propagator leading to the moving and logarithmic singularities in standard treatments. The Faddeev equation is formulated in momentum space and directly solved in terms of momentum vectors without employing a partial wave decomposition. In its simplest form the Faddeev equation for identical bosons, which we are using, is an integral equation in five variables, magnitudes of relative momenta and angles. The singularities of the free propagator and the deuteron propagator are now both simple poles in two different momentum variables, and thus can both be integrated with standard techniques.     

On the Diagonalization of the Bethe–Salpeter Equation for the Imaginary Part of the Scattering Amplitude

The Bethe–Salpeter (BS) equation for the imaginary part of the scattering amplitude is examined in the ladder approximation of scalar quantum electrodynamics (QED). Asymptotic solutions of the BS equation derived for the imaginary part of the scattering amplitude are shown to exhibit the Regge amplitude behavior for small momentum transfer and scattering in the forward direction and at arbitrary angles.     

Influence of degeneracy on momentum relaxation times in semiconductors

We have studied the effect of degeneracy on momentum relaxation times under ohmic as well as non-ohmic conditions. We find that a proper momentum relaxation time, within the framework of the Boltzmann transport equation, can no longer be defined for isotropic but inelastic scattering when the carriers are hot whereas under ohmic conditions it can be defined and is appreciably altered by degeneracy. For elastic scattering the momentum relaxation time is found to be unaffected by degeneracy for both ohmic and non-ohmic regimes.     

Resonance States in Scattering of Slow Particles with Nonzero Orbital Angular Momentum by the Pöschl-Teller Potential

The scattering of slow particles with nonzero orbital angular momentum in the field of a finite potential is considered. The respective scattering problem is solved in the Pais approximation. The inverse problem is solved for the Pöschl-Teller equation, and a general scheme for Pais resonances and a procedure for calculating scattering cross sections for resonance particles are formulated.

     

Universal Physics of 2+1 Particles with Non-Zero Angular Momentum

The zero-energy universal properties of scattering between a particle and a dimer that involves an identical particle are investigated for arbitrary scattering angular momenta. For this purpose, we derive an integral equation that generalises the Skorniakov?CTer-Martirosian equation to the case of non-zero angular momentum. As the mass ratio between the particles is varied, we find various scattering resonances that can be attributed to the appearance of universal trimers and Efimov trimers at the collisional threshold.     

Relaxation of hot quasiparticles in a d-wave superconductor

Motivated by recent pump-probe experiments we consider the processes by which "hot" quasiparticles produced near the antinodes of a d-wave superconductor can relax. We show that in a large region of momentum space processes which break Cooper pairs are forbidden by energy and momentum conservation. Equilibration then occurs by scattering with thermal quasiparticles: Umklapp scattering is exponentially suppressed at low temperatures, but small-angle scattering leads to power-law behavior. By solving the Boltzmann equation analytically we make detailed predictions for the temperature and intensity dependence of these processes, which we compare with experiment.     

Quantum scattering by nonspherical objects

The problem of scattering by spherically asymmetric potentials is considered where angular momentum not only ceases to be a conserved quantity but is also not a convenient basis for the expansion of wave functions and scattering amplitudes. Numerical solutions of the two-dimensional differential equation for the scattering amplitude of a particle and a coupled pair on a semitransparent disc of finite thickness are obtained. The effect of resonant diffraction is shown. A numerical scheme can be used to describe the scattering of a particle by deformed atomic nuclei.     

Angular momentum analysis of a composite particle scattering problem and its cross channel analog

We investigate the solutions, by a determinental method, for a partial wave Bethe-Salpeter equation describing composite particle scattering and for its cross channel analog. We compare the behavior at s = ?∞ of the leading angular momentum singularity from the Bethe-Salpeter equation with that of the leading Regge singularity of the cross channel equation. We mention the effect of the general properties of the kernel of the Bethe-Salpeter equation on the angular momentum structure of the solution.     

Interrelations between soluble model Boltzmann equations

It is shown that the Boltzmann equation for the energy distribution function of several soluble models may be interpreted as having a deterministic (with momentum conservation) or a stochastic (without momentum conservation) scattering law, and that whole families of models with different dimensionality can be solved from the same set of moment equations.     

Single-Photon Momentum Displacement in Resonator Array with Optomechanics

We present the single-photon scattering in a resonator array system with optomechanical by solving the Lippmann-Schwinger equation iteratively. Up to the first order of the radiation pressure interaction, the single-photon transport is formulated as a three-channel scattering process. We calculate the scattering currents in different channels and obtain the transmission spectrum which shows a momentum displacement effect.     

Photon Recoil in Light Scattering by a Bose–Einstein Condensate of a Dilute Gas

Photon recoil upon light scattering by a Bose–Einstein condensate (BEC) of a dilute atomic gas is analyzed theoretically accounting for a weak interatomic interaction. Our approach is based on the Gross–Pitaevskii equation for the condensate, which is coupled to the Maxwell equation for the field. The dispersion relations of recoil energy and momentum are calculated, and the effect of weak nonideality of the condensate on the photon recoil is ubraveled. A good agreement between the theory and experiment [7] on the measurement of the photon recoil momentum in a dispersive medium is demonstrated.     

On the QCD pomeron at large momentum transfer

We investigate the asymptotics of the QCD scattering amplitude with vacuum quantum number exchange in the region where the energy is large and the momentum transfer is much smaller than the energy but large compared to the hadronic scale. The appropriate modification of the QCD pomeron partial wave equation is derived. The singularities in the angular momentum which arise at relatively large momentum transfer are studied in double logarithmic approximation.     

Acoustic beams with angular momentum

A family of exact solutions of the Helmholtz equation is used to represent transversely bounded helicoidal sound beams. Simple results are obtained for the energy content per unit length, the momentum content per unit length, and the angular momentum content per unit length. The analysis is restricted to lossless media; scattering and viscous damping are neglected. The energy, momentum, and angular momentum are calculated to second order in the velocity potential. The angular momentum content is always equal to m/omega times the energy content, where m (an integer) is the topological charge and omega is the angular frequency.     

Multi-patch model for transport properties of cuprate superconductors

A number of normal state transport properties of cuprate superconductors are analyzed in detail using the Boltzmann equation. The momentum dependence of the electronic structure and the strong momentum anisotropy of the electronic scattering are included in a phenomenological way via a multi-patch model. The Brillouin zone and the Fermi surface are divided in regions where scattering between the electrons is strong and the Fermi velocity is low (hot patches) and in regions where the scattering is weak and the Fermi velocity is large (cold patches). We present several motivations for this phenomenology starting from various microscopic approaches. A solution of the Boltzmann equation in the case of N patches is obtained and an expression for the distribution function away from equilibrium is given. Within this framework, and limiting our analysis to the two patches case, the temperature dependence of resistivity, thermoelectric power, Hall angle, magnetoresistance and thermal Hall conductivity are studied in a systematic way analyzing the role of the patch geometry and the temperature dependence of the scattering rates. In the case of Bi-based cuprates, using ARPES data for the electronic structure, and assuming an inter-patch scattering between hot and cold states with a linear temperature dependence, a reasonable agreement with the available experiments is obtained. Received 3 August 2001 and Received in final form 1st November 2001     

A new combination of scattering mechanisms for transverse runaway (TR) of hot electrons

A new combination of energy and momentum scattering mechanisms has been found at which the transverse runaway (TR) of hot electrons takes place. Up to now only two combinations of scattering mechanisms at which TR occurred have been known. These two combinations were obtained by analytical solution of a complex integral equation at certain approximations. In the present work, using modern numerical methods, with no above-mentioned approximations, a solution of the integral equation for a new combination of scattering mechanisms has been found.In the work physical conditions responsible for dominance of corresponding scattering mechanisms are also analyzed.     

Elastic pion-deuteron scattering in the resonance region as a three-body problem

We study elastic pion-deuteron scattering in the Δ(1236) energy region by means of the three-body Faddeev equations. We present a compact angular momentum reduction of the Faddeev integral equation for separable amplitudes, neglecting the nucleon spin, and solve the resulting coupled integral equations. We examine the dependence of the elastic scattering amplitude on the deuteron structure, on the pion-nucleon scattering amplitude, and on the various orders of multiple scattering. The differential cross section is very sensitive to multiple scattering effects at backward angles. We find that a number of conventional approximations do not well reproduce these multiple scattering effects in the resonance region.     

Nonlocal corrections to the Boltzmann equation for dense Fermi systems

A kinetic equation which combines the quasiparticle drift of Landau's equation with a dissipation governed by a nonlocal and noninstant scattering integral in the spirit of Snider's equation for gases is derived. Consequent balance equations for the density, momentum and energy include quasiparticle contributions and the second-order quantum virial corrections. The medium effects on binary collisions are shown to mediate the latent heat, i.e. an energy conversion between correlation and thermal energy. An implementation to heavy ion collisions is discussed.     

Topology of the superconducting order under pairing repulsion

The superconducting state with a large momentum of a pair in a doped insulator is controlled by the features of Coulomb pairing associated with the suppression of small momentum transfers during scattering owing to electron-phonon interaction and of large transfers due to redistribution of the spectral weight among the superconducting or the insulating branches of the elementary excitation spectrum. Superconductivity emerges when the characteristic energy of the pairing interaction has an upper bound. The solutions obtained for a self-consistent equation with a simple structure of the degenerate kernel are antisymmetric and symmetric relative to inversion of the momentum of relative motion of a pair. The orbital symmetry of the singlet superconducting order is analyzed.