Stimulated Raman backscattering of laser radiation in deep plasma channels

Stimulated Raman backscattering (RBS) of intense laser radiation confined by a single-mode plasma channel with a radial variation of plasma frequency greater than a homogeneous-plasma RBS bandwidth is characterized by a strong transverse localization of resonantly-driven electron plasma waves (EPW). The EPW localization reduces the peak growth rate of RBS and increases the amplification bandwidth. The continuum of non-bound modes of backscattered radiation shrinks the transverse field profile in a channel and increases the RBS growth rate. Solution of the initial-value problem shows that an electromagnetic pulse amplified by the RBS in the single-mode deep plasma channel has a group velocity higher than in the case of homogeneous-plasma Raman amplification. Implications to the design of an RBS pulse compressor in a plasma channel are discussed.Comment: 11 pages, 3 figures; submitted to Physics of Plasma

Cold Quark Matter, Quadratic Corrections and Gauge/String Duality

We make an estimate of the quadratic correction in the pressure of cold quark matter using gauge/string duality.Comment: 7 pages; v.2: reference added; v.3: reference and comments added, version to appear in PRD; v4. final version to appear in PRD; v.5: key reference adde

Generating Functional for Gauge Invariant Actions: Examples of Nonrelativistic Gauge Theories

We propose a generating functional for nonrelativistic gauge invariant actions. In particular, we consider actions without the usual magnetic term. Like in the Born-Infeld theory, there is an upper bound to the electric field strength in these gauge theories.Comment: 14 pages, 2 figures; v2: misprints correcte

Non-divergent pseudo-potential treatment of spin-polarized fermions under 1D and 3D harmonic confinement

Atom-atom scattering of bosonic one-dimensional (1D) atoms has been modeled successfully using a zero-range delta-function potential, while that of bosonic 3D atoms has been modeled successfully using Fermi-Huang's regularized s-wave pseudo-potential. Here, we derive the eigenenergies of two spin-polarized 1D fermions under external harmonic confinement interacting through a zero-range potential, which only acts on odd-parity wave functions, analytically. We also present a divergent-free zero-range potential treatment of two spin-polarized 3D fermions under harmonic confinement. Our pseudo-potential treatments are verified through numerical calculations for short-range model potentials.Comment: 9 pages, 4 figures (subm. to PRA on 03/15/2004

Tunneling into d-wave superconductors: Effects of interface spin-orbit coupling

Tunneling conductance of a clean normal metal/d-wave superconductor junction is studied by using the extended Blonder-Tinkham-Klapwijk formalism. We show that the conductance is significantly affected by the interface spin-orbit coupling of the Rashba type, which is inevitably present due to the asymmetry of the junction.Comment: 4 pages, 4 figure

Nonlinear evolution of the plasma beatwave: Compressing the laser beatnotes via electromagnetic cascading

The near-resonant beatwave excitation of an electron plasma wave (EPW) can be employed for generating the trains of few-femtosecond electromagnetic (EM) pulses in rarefied plasmas. The EPW produces a co-moving index grating that induces a laser phase modulation at the difference frequency. The bandwidth of the phase-modulated laser is proportional to the product of the plasma length, laser wavelength, and amplitude of the electron density perturbation. The laser spectrum is composed of a cascade of red and blue sidebands shifted by integer multiples of the beat frequency. When the beat frequency is lower than the electron plasma frequency, the red-shifted spectral components are advanced in time with respect to the blue-shifted ones near the center of each laser beatnote. The group velocity dispersion of plasma compresses so chirped beatnotes to a few-laser-cycle duration thus creating a train of sharp EM spikes with the beat periodicity. Depending on the plasma and laser parameters, chirping and compression can be implemented either concurrently in the same, or sequentially in different plasmas. Evolution of the laser beatwave end electron density perturbations is described in time and one spatial dimension in a weakly relativistic approximation. Using the compression effect, we demonstrate that the relativistic bi-stability regime of the EPW excitation [G. Shvets, Phys. Rev. Lett. 93, 195004 (2004)] can be achieved with the initially sub-threshold beatwave pulse.Comment: 13 pages, 11 figures, submitted to Physical Review

Two-photon correlations as a sign of sharp transition in quark-gluon plasma

The photon production arising due to time variation of the medium has been considered. The Hamilton formalism for photons in time-variable medium (plasma) has been developed with application to inclusive photon production. The results have been used for calculation of the photon production in the course of transition from quark-gluon phase to hadronic phase in relativistic heavy ion collisions. The relative strength of the effect as well as specific two- photon correlations have been evaluated. It has been demonstrated that the opposite side two-photon correlations are indicative of the sharp transition from the quark-gluon phase to hadrons.Comment: 23 pages, 2 figure

A quantum hydrodynamics approach to the formation of new types of waves in polarized two-dimension systems of charged and neutral particles

In this paper we explicate a method of quantum hydrodynamics (QHD) for the study of the quantum evolution of a system of polarized particles. Though we focused primarily on the two-dimension physical systems, the method is valid for three-dimension and one-dimension systems too. The presented method is based upon the Schr\"{o}dinger equation. Fundamental QHD equations for charged and neutral particles were derived from the many-particle microscopic Schr\"{o}dinger equation. The fact that particles possess the electric dipole moment (EDM) was taken into account. The explicated QHD approach was used to study dispersion characteristics of various physical systems. We analyzed dispersion of waves in a two-dimension (2D) ion and hole gas placed into an external electric field which is orthogonal to the gas plane. Elementary excitations in a system of neutral polarized particles were studied for 1D, 2D and 3D cases. The polarization dynamics in systems of both neutral and charged particles is shown to cause formation of a new type of waves as well as changes in the dispersion characteristics of already known waves. We also analyzed wave dispersion in 2D exciton systems, in 2D electron-ion plasma and 2D electron-hole plasma. Generation of waves in 3D system neutral particles with EDM by means of the beam of electrons and neutral polarized particles is investigated.Comment: 15 pages, 7 figure

Physical Mechanism of the d->d+is Transition

We discuss the basic physical mechanism of the d->d+is transition, which is the currently accepted explanation for the results of tunneling experiments into $ab$ planes. Using the first-order perturbation theory, we show that the zero-bias states drive the transition. We present various order-of-magnitude estimates and consistency checks that support this picture.Comment: 7 pages, 2 figure