bluuebunny/crossref_metadata_2025 huggingface dataset:
OPTICAL PROPERTIES OF UNDOPED AND Ni-DOPED SbSBr AND BiSBr SINGLE CRYSTALS
Authors: JIN MOON-SEOG , SONG HO-JUN , KIM YONG-GEUN , KIM HYUNG-GON , KOH JEONG-DAE , KIM WHA-TEK
Published: November 2004

SbSBr, BiSBr, SbSBr:Ni, and BiSBr:Ni single crystals were grown by the Bridgman technique. The grown single crystals crystallized in an orthorhombic structure and have an indirect band structure. The temperature dependence of their optical energy gap shows an anomalous property at the first order phase transition temperature and at the second order one. Nickel doped as an impurity site at the T d symmetry point in the host single crystals as Ni 2+ ion. The impurity optical absorption peaks appeared by the electron transitions between the energy levels of these ions.
ONE-DIMENSIONAL STATISTICAL MECHANICS FOR IDENTICAL PARTICLES: THE CALOGERO AND ANYON CASES
Authors: DE VEIGY ALAIN DASNIÈRES , OUVRY STÉPHANE
Published: November 2004

The thermodynamic of particles with intermediate statistics interpolating between Bose and Fermi statistics is addressed in the simple case where there is one quantum number per particle. Such systems are essentially one-dimensional. As an illustration, one considers the anyon model restricted to the lowest Landau level of a strong magnetic field at low temperature, the generalization of this model to several particles species, and the one-dimensional Calogero model. One reviews a unified algorithm to compute the statistical mechanics of these systems. It is pointed out that Haldane's generalization of the Pauli principle can be deduced from the anyon model in a strong magnetic field at low temperature.
INTEGRATION FORMULAS AND EXACT CALCULATIONS IN THE CALOGERO–SUTHERLAND MODEL
Authors: FORRESTER P. J.
Published: November 2004

Some integration formulas which either occur or are implicit in Ha's recent exact calculation of some correlations in the Calogero–Sutherland model are discussed. These integration formulas include the calculation of the inner product <0|ρ(0)|κ> between the density operator acting on an excited state and the ground state, and a generalization of the Selberg integral due to Dotsenko and Fateev.
QUANTUM NOISE REDUCTION BY ELECTRO-OPTICAL MODULATION OF A COHERENT LIGHT FIELD
Authors: SILVA A. LUZIA S. , BASEIA B. , ZILIO S. C.
Published: November 2004

We employ a time-dependent Hamiltonian and a time-dependent canonical transformation to investigate the possibility of reduction of quantum noise below the vacuum limit by electro-optical modulation of a coherent light field. It is shown that the amount of noise reduction depends on the time variation of the bias field in the electro-optical effect. Some illustrative examples yielding explicit results are considered, the present scenery constituting a practical realization of some theoretical models in the literature.
SECOND ORDER APPROXIMATION FOR OPTICAL POLARON IN THE STRONG COUPLING CASE
Authors: BOGOLUBOV N. N.
Published: November 2004

Here we propose a method of constructing a second order approximation for ground state energy for a class of model Hamiltonian with linear type interaction on bose operators in the strong coupling case. For the application of the above method we have considered polaron model and propose constructing a set of nonlinear differential equations for definition ground state energy in the strong coupling case. We have considered also radial symmetry case.
CALOGERO MODELS FOR DISTINGUISHABLE PARTICLES
Authors: FURTLEHNER CYRIL , OUVRY STÉPHANE
Published: November 2004

Motivated by topological bidimensional quantum models for distinguishable particles, and by Haldane's definition of mutual statistics for different species of particles, we propose a new class of one-dimensional [Formula: see text] Calogero model with coupling constants gij depending on the labels of the particles. We solve the ground state problem, and show how to build some classes of excited states.
STRUCTURE AND STABILITY OF THE DX CENTERS IN GaAs AND InP
Authors: CHANG K. J. , CHEONG BYOUNG-HO
Published: November 2004

We review some of the recent theoretical studies on the atomic structure, the stability, and the vibrational modes of donor-induced defect levels in GaAs and InP. For Si and S donors, the microscopic origin of the DX center is investigated and a review is given of the shallow-to-deep DX level transition under hydrostatic pressure. We also discuss the band structure and the chemical bonding effects on the stability of donor impurities, which are associated with broken-bond and breathing-mode lattice relaxations.
DERIVATION OF THE LAMB SHIFT FORMULA FOR NON-S-STATES WITHOUT APPLYING THE CONCEPT OF RELATIVISTIC QUANTUM ELECTRODYNAMICS
Authors: SEKE J.
Published: November 2004

It is shown, for the first time to our knowledge, that the standard Lamb shift formula for non-S-states of hydrogenic atoms can be derived by applying the methods of nonrelativistic quantum electrodynamics and without using the Dirac equation and the second quantization for the electron.
MACROSCOPIC QUANTUM NUCLEATION: WKB ANALYSIS OF 3+2−3 MODEL
Authors: NAKAMURA TAKASHI , TAKAGI SHIN
Published: November 2004

The Lifshitz–Kagan model of macroscopic quantum nucleation is re-examined. The nucleation rate originally proposed by Lifshitz and Kagan is shown to be inapplicable to ordinary laboratory experiments. This problem is circumvented by removing some of the unnecessary assumptions within the WKB approximation. It is also shown that fairly tight bounds on relevant physical parameters may be established without substantial assumptions.
FEEDBACK IN OPEN QUANTUM SYSTEMS
Authors: WISEMAN H. M.
Published: November 2004

Open quantum systems continually lose information to their surroundings. In some cases this information can be readily retrieved from the environment and put to good use by engineering a feedback loop to control the system dynamics. Two cases are distinguished: one where the feedback mechanism involves a measurement of the environment, and the other where no measurement is made. It is shown that the latter case can always replicate the former, but not vice versa. This emphasizes the quantum nature of the information being fed back. Two approaches are used to describe the feedback: quantum trajectories (which apply only for feedback based on measurement) and quantum Langevin equations (which can be used in either case), and the results are shown to be equivalent. The obvious applications for the theory are in quantum optics, where the information is lost by radiation damping and can be retrieved by photodetection. A few examples are discussed, one of which is particularly interesting as it has no classical counterpart.
SUPERCONDUCTING IN THE NEAR HALF-FILLING HUBBARD MODEL
Authors: TUAN HOANG ANH , THANG NGUYEN TOAN , THUAN NGUYEN NGOC
Published: November 2004

The Hubbard model of strongly correlated electron systems is considered near half-filling within the framework of a new functional integral method without slave bosons. A dynamical system of equations determining the superconducting phase of the Hubbard model is derived. Both singlet and triplet Cooper pairings are studied.
AN INDIRECT INTERFERENTIAL METHOD FOR MEASURING THE DEFORMATIONS OF STRUCTURES IN TEMPERATURE
Authors: GIARETTO V. , RUSCICA G. , MIRALDI E.
Published: November 2004

The dimensional stability of a base of ceramic glass, designed to constitute a stable reference frame, has been determined with interferometric measurements in flowing air with variable temperature. An interferometric arrangement composed by one beam splitter and two mirrors was assembled directly on the base. The irradiance I(t) as a function of temperature at constant pressure was collected in the highest order of the interference pattern, I(t) shows a cyclic behavior, due to the superposition of the air refractivity variations and of the mechanical stretching of the frame. The component of the signal due to the air refractivity alone can be regarded as the reference signal, with a valuable periodicity in the inverse-temperature space, i.e. in the expansion coefficients space. The remaining component corresponding to the deformations of the supporting structure can be evaluated as a phase modulation of the reference signal. Preliminary results of measurements show that an equivalent thermal expansion coefficient of the order of magnitude of ±2·10–8 °C–1 can be probed. The theoretical and actual resolving power of the method, the unavoidable effects due to the presence of air, and some algorithms useful for noise reduction are discussed.
QUANTAL OVERLAPPING RESONANCE CRITERION: THE PULLEN–EDMONDS MODEL
Authors: GRAFFI S. , MANFREDI V. R. , SALASNICH L.
Published: November 2004

In order to highlight the onset of chaos in the Pullen–Edmonds model a quantal analog of the resonance overlap criterion has been examined. A quite good agreement between analytical and numerical results is obtained.
NONLINEAR SCHRÖDINGER EQUATION FOR SUPERCONDUCTORS
Authors: AO PING , THOULESS DAVID J. , ZHU X.-M.
Published: November 2004

Using the Hartree–Fock–Bogoliubov factorization of the density matrix and the Born–Oppenheimer approximation we show that the motion of a superconducting condensate satisfies a Schrödinger equation at zero temperature. The Galilean invariance of the equation is explicitly manifested. This equation gives a unified description of the condensate dynamics, such as Josephson effects, vortex dynamics and the Bogoliubov–Anderson mode.
EXAMINATION OF WAVE-PARTICLE DUALITY VIA TWO-SLIT INTERFERENCE
Authors: RABINOWITZ MARIO
Published: November 2004

The wave-particle duality is the main point of demarcation between quantum and classical physics, and is the quintessential mystery of quantum mechanics. Young's two-slit interference experiment is the arch prototype of actual and gedanken experiments used as a testing ground of this duality. Quantum mechanics predicts that any detector capable of determining the path taken by a particle through one or the other of a two-slit plate will destroy the interference pattern. We will examine both the experimental and theoretical attempts to test this assertion, including a new kind of experiment, and to grasp the underlying truth behind this mystery from the earliest days to the present. Where positions differ, the views of both sides are presented in a balanced approach.
SPIN WAVES AND THE STRONG COUPLING LIMIT IN POLYMERIC HUBBARD CHAINS
Authors: RAPOSO E. P. , COUTINHO-FILHO M. D.
Published: November 2004

We derive the strong-coupling limit of the Hubbard Hamiltonian in a class of polymeric chains displaying a ferrimagnetic structure. The derived Heisenberg Hamiltonian is used to calculate the spin-wave spectrum of the system. It is shown that there is a critical value for an external applied magnetic field above which the ferrimagnetic ordering becomes unstable.
DYNAMICS OF GENERALIZED COHERENT STATES
Authors: DE MARTINO SALVATORE , DE SIENA SILVIO , ILLUMINATI FABRIZIO
Published: November 2004

We show that generalized coherent states follow Schrödinger dynamics in time-dependent potentials. The normalized wave-packets follow a classical evolution without spreading; in turn, the Schrödinger potential depends on the state through the classical trajectory. This feedback mechanism with continuous dynamical re-adjustment allows the packets to remain coherent indefinitely.
DENSITY FUNCTIONALS AND SMALL INTERPARTICLE SEPARATIONS IN ELECTRONIC SYSTEMS
Authors: BURKE KIERON , PERDEW JOHN P.
Published: November 2004

We review some recent results concerning the probability that two electrons will be found close together in any interacting electronic system, and why this probability is usually well approximated by local (LSD) and semilocal spin density functional theories. The success of these approximations for the energy in "normal" systems is explained by the usual sum rule arguments on the system- and spherically-averaged exchange-correlation hole density , coupled with the nearly correct, but not exact, behavior of these approximations as the interelectronic separation u → 0. We argue that the accuracy of the LSD on-top hole density in "normal" systems is due to its accuracy in the noninteracting, weakly-interacting, and strongly-interacting limits.
EXACT THEORY OF SPONTANEOUS EMISSION OF TWO LEVEL ATOM IN ONE-DIMENSIONAL CAVITY
Authors: CHELTSOV V. F.
Published: November 2004

The exact theory of the spontaneous emission of a motionless two level atom in a one-dimensional cavity at zero temperature is presented. In the damped cavity case, using the theory of quasistationary systems and a novel algorithm in operating casual ζ-functions, the theory predicts a hidden-triplet form of emission spectrum which turns abruptly to a singlet when the cavity passive linewidth Γ c /2 becoming equal to twice the coupling constant.
OBSERVATION OF MULTIPHOTON PROCESS IN LIQUID CS2 USING PULSED PHOTOACOUSTIC TECHNIQUE
Authors: HARILAL S. S. , ISSAC RIJU C. , BINDHU C. V. , VARIER GEETHA K. , NAMPOORI V. P. N. , VALLABHAN C. P. G.
Published: November 2004

Pulsed photoacoustic measurements have been carried out in liquid CS 2 using 532 nm radiation from a frequency doubled Nd:YAG laser. Variation of signal amplitude with laser fluence clearly indicates the role of multiphoton processes in the generation of photoacoustic effect. It is also shown that four photon induced dissociation and five photon induced ionization are likely processes in CS 2 and 532 nm radiation.
PHOTOEMISSION CALCULATION USING LEED TYPE WAVEFUNCTIONS AND A SPATIALLY VARYING PHOTON FIELD
Authors: DAS PRANATI , KAR NIKHILES
Published: November 2004

A method for calculating the photoemission matrix element with the inclusion of spatial variation of the photon field is presented. The initial and final states are taken to be the same as in the time-reversed LEED formalism, and the vector potential of the photon field is assumed to be local and to vary only along the direction normal to the surface.
VORTEX INTERACTIONS NEAR A PLANAR SURFACE OF UNIAXIAL ANISOTROPIC SUPERCONDUCTOR
Authors: SAIF A.G.
Published: November 2004

The properties of the curved vortex lattice near an uniaxial anisotropic superconducting planar surface are studied. The distributions of the fields inside and outside the sample as well as the current density are calculated. Using the current density, the forces on the vortex segments are completely determined. Moreover, the Gibbs free energy of the system is calculated. In the isotropic limit an agreement with the previous results is found.
USE OF SOLID STATE NUCLEAR TRACK DETECTORS CR-39 TO STUDY CHARGED PARTICLES EMISSION FROM A 3 kJ PLASMA FOCUS
Authors: ZAKAULLAH M. , AHMAD IMTIAZ , REHMAN KHAIRUR , MURTAZA G.
Published: November 2004

The CR-39 solid state nuclear track detectors are employed to investigate the fluence anisotropy of charged particles (protons, deuterons and tritons) emitted from the focus region of a low energy Mather-type plasma focus energized by a single 32 μF, 15 kV (3.6 kJ) capacitor. The charged particle flux is the highest in the axial direction, and decreases towards the radial direction. The radial charged particles flux is six times smaller than the flux in the axial direction.
STUDIES ON ORIENTED DOMAIN POLYSTYRENE-TGS COMPOSITE FILMS
Authors: MATHUR S.C. , RAWAT D.S. , YADAV H.O. , DUBE D.C. , BHALLA A.S.
Published: November 2004

Polymer ferroelectric films were prepared by dispersing TGS powder in polystyrene. Permittivity versus temperature plots exhibit a peak at around the transition temperature of TGS. The peak gets suppressed with increasing frequency and the trend continues up to microwave frequencies. We observed that the dielectric constant of films at microwave frequency stays close to the dielectric constant of polystyrene. The domain structure of TGS crystals essentially seems to affect their dielectric properties. Single domain films exhibit a higher spontaneous polarization and a higher coercive field.
TRANSPORT PROPERTIES OF CuO IN YBCO/CuO/YBCO JUNCTION
Authors: OGUSHI T. , HIROSE M. , KOBA S. , HIGO S. , KAWANO I.
Published: November 2004

The zero resistance behavior of a CuO film sandwiched with YBa 2 Cu 3 O 7–δ films has been examined. The CuO is of tenorite C2/c structure which is a deformed NaCl-type lattice structure without being separated by an alkaline earth, and it forms a bulk in which copper is surrounded by nearly a square of Oxygen. The transition temperature Tce (R=0) in the fabricated sandwiched-type-CuO optimally increases over that of YBa 2 Cu 3 O 7–δ film-electrodes.
DISAPPEARANCE OF THE INFRARED CATASTROPHE IN D>1 INTERACTING FERMION SYSTEMS
Authors: LI Y.M.
Published: November 2004

Within a consistent bosonization treatment in which all the physically-relevant excitations are taken into account, we show explicitly and non-perturbatively for the first time that, for regular interactions, the infrared catastrophe is eliminated by the zero-frequency particle-hole-pair excitations so that the Luttinger liquid state does not appear in dimensions higher than one. The infrared catastrophe is scarce even for systems with singular interactions due to these excitations. We find that the system remains in a Fermi liquid state for the case of unscreened Coulomb interaction.
THEORY OF OPTICAL ABSORPTION IN HIGH-TEMPERATURE SUPERCONDUCTORS
Authors: MATTIS DANIEL C. , WHEATLEY JOSEPH M.
Published: November 2004

We review the optical absorption spectrum of a high-temperature superconductor and present a simple theory which explains it in some detail. An experiment is proposed to determine the averaged spectral density and wave function renormalization functions of the charge carriers in the normal and in the superconducting states. This might help measure the superconducting gap.
CRYSTAL STRUCTURE AND BAND GAP OF RUBIDIUM HYDRIDE TO 120 GPa
Authors: GHANDEHARI KOUROS , LUO HUAN , RUOFF ARTHUR L. , TRAIL STEVEN S. , DISALVO FRANCIS J.
Published: November 2004

Energy dispersive x ray diffraction measurements were performed on RbH to 120 GPa. RbH was observed to transform from the B2 phase to the orthorhombic, CrB, phase at 85 GPa. The equation of state for the B2 phase and the CrB phase are reported. Transmission measurements were made to 120 GPa to determine the band gap versus pressure in RbH. We report here the first measurement of the band gap of RbH at zero pressure at 4.91 eV. At 120 GPa, the band gap closed to 2.68 eV. Extrapolating the present band gap data leads to a zero gap at about 310 GPa.
A SIMPLE GEOMETRICAL BOUND FOR REPLICA SYMMETRY STABILITY IN NEURAL NETWORKS MODELS
Authors: BRUNEL NICOLAS , ZECCHINA RICCARDO
Published: November 2004

In the statistical mechanics framework of formal neural networks learning theory, we discuss a very simple geometrical interpretation of the stability line (the AT-line) for the replica symmetric phase. The geometrical bound on the maximal fraction of patterns storable on hyperplanes — which depends only on the local fields distribution — is shown to coincide with the AT-line both for single layer models and for a simple toy model of multilayer net.
JAYNES-CUMMINGS MODEL WITH INTENSITY-INDEPENDENT INTERACTION VIA THE PHASE OPERATORS
Authors: BASEIA B. , MARQUES G.C. , CHABA A.N. , de BRITO A.L. , DUARTE S.B.
Published: November 2004

We introduce a new version of the JC-Model using the (non-Hermitian) phase operators [Formula: see text] in the interaction Hamiltonian, which becomes independent of the excitation number or the field intensity, thus being able to describe properties of the atom in the saturation regime. We employ the “dressed-states” formalism to find an exact solution for our system. As applications we investigate the occurrence of nonclassical effects in the field (squeezing and sub-Poissonian statistics) and in the atom (collapses and revivals of Rabi oscillations and population trapping).
GENERATION AND TRANSFERENCE OF NONCLASSICAL EFFECTS IN COUPLED OSCILLATOR
Authors: SILVA A. LUZIA , BASEIA B. , MARQUES G.C.
Published: November 2004

It is known from the recent literature that a quadratic oscillator (QO), in terms of the ladder operators â e â+ may exhibit various nonclassical effects, whereas a linear oscillator (LO) does not exhibit them. In this paper we find exact solutions for the system constituted by a LO coupled to a QO and show that nonclassical effects generated in the QO may contaminate the LO. The influence of the involved parameters of the system upon the generation and transference of different nonclassical effects, from the QO to the LO, is investigated. The analytical results are plotted numerically for various situations.
IDENTIFICATION OF THE NATURAL TERMINATION LAYER ON THE SURFACES OF As-PREPARED Nd1Ba2Cu3Oy SINGLE CRYSTALS AND SURFACE DEFECT STRUCTURES
Authors: TING WU , EGI T. , ITTI R. , KURODA K. , KOSHIZUKA N. , TANAKA S.
Published: November 2004

The natural termination layer has been identified to be the CuO chain layer on the surfaces of as-prepared high quality Nd 1 Ba 2 Cu 3 O 7−y (Nd123) single crystals, employing an ultrahigh vacuum scanning tunneling microscope (UHV-STM) system. It is found that the oxygen atoms of the CuO chain layer are unstable in the environment of UHV (~10−8 Pa). Oxygen loss occurs in some areas of the surfaces of Nd123 single crystals, leading to some localized surface defect structures. Such defect structures may be responsible for the poor reproducibility of the superconducting gap structure observed on the surface of Y 1 Ba 2 Cu 3 O y from low temperature tunneling measurements.
THE OBSERVATION OF A NEW HIGH PRESSURE PHASE TRANSITION IN TETRAMETHYLAMMONIUM TETRABROMOCUPRATE
Authors: LORENZ BERND , HOCHHEIMER HANS DIETER , HÖNLE WOLFGANG
Published: November 2004

We have found an unusual narrow transmission window in the blue in the absorption spectrum of tetramethylammonium tetrabromocuprate, { N ( CH 3)4}2 CuBr 4. This transmission window disappears at about 2.5 GPa when pressure is applied, indicating the occurrence of an until-now unknown phase transition at this pressure.
COEXISTENCE OF BUBBLES AND STRIPE DOMAINS IN THIN MAGNETIC FILMS WITH PERPENDICULAR ANISOTROPY
Authors: ZABLOTSKII V. A. , MAMALUI YU. A.
Published: November 2004

The possibility of coexistence of a magnetic bubble lattice (MBL) and a stripe domain structure (SDS) as two domain phases of a thin magnetic film at various temperatures has been studied from the point of view of the balance their magnetostatic pressures. It is shown that such two-phase structures respond to increasing the film temperature by the phase boundary advance from the MBL to the SDS. This advance is a reversible one until the temperature of the phase transition in the MBL phase.
THE SINGLE-PARTICLE DENSITY OF STATES AND THE RESONANCE IN THE AHARONOV–BOHM POTENTIAL
Authors: MOROZ ALEXANDER
Published: November 2004

The single-particle densitity of states (DOS) for the Pauli and the Schrödinger Hamiltonians in the presence of an Aharonov–Bohm potential is calculated for different values of the particle magnetic moment. The DOS is a symmetric and periodic function of the flux. The Krein–Friedel formula can be applied to this long-ranged potential when regularized with the zeta function. We have found that whenever a bound state is present in the spectrum it is always accompanied by a resonance. The shape of the resonance is not of the Breit-Wigner type. The differential scattering cross section is asymmetric if a bound state is present and gives rise to the Hall effect. As an application, propagation of electrons in a dilute vortex limit is considered and the Hall resistivity is calculated.
XYZ TECHNIQUES APPLIED TO A TWISTED XXX CHAIN
Authors: R-MONTEIRO M.
Published: November 2004

We show that the techniques developed by Baxter to solve the eight-vortex model can be applied to study a spin-1/2 twisted XXX chain.
COMPUTER SIMULATION STUDY OF ONE-DIMENSIONAL LATTICE SPIN MODELS WITH LONG-RANGE INHOMOGENEOUS INTERACTIONS
Authors: ROMANO S.
Published: November 2004

We have considered a classical spin system, consisting of n-component unit vectors (n = 2, 3), associated with a semi-infinite lattice in one dimension {uk, k ∈ N+}, and interacting via inhomogeneous pair potentials, anisotropic in spin space, and of the long-range ferromagnetic form [Formula: see text] here ∊ is a positive constant setting energy and temperature scales (i.e. T* = k B T/∊), a > 0, b ≥ 0, and the symbols uj,α denote Cartesian components of the spins. On the basis of available theoretical results, one can prove the existence of an ordering transition at a finite temperature for n ≥ 2, b = 0, as well as upper and lower bounds on the transition temperatures. We have studied the two cases n = 2, 3, b = 0, by computer simulation, and made a comparison with the Mean Field treatment.
UNIFICATION OF LINEAR AND NONLINEAR WAVE OPTICS
Authors: SNYDER ALLAN W. , MITCHELL D. JOHN , KIVSHAR YURI S.
Published: November 2004

A new conceptual approach unifies the seemingly disparate fields of linear and nonlinear waves. Linear physics is shown to be the natural way to approach nonlinear wave optics. It generates the fundamental equations, allows for unforeseen generalizations and, through physical insight, motivates novel phenomena.
EFFECT OF Ce3+ ION ON THE X-RAY INDUCED FLUORESCENCE EMISSION FROM CaS
Authors: JOSEPH JAMES , ANANTHAKRISHNAN T. R. , NAMPOORI V. P. N. , WARIER M. K. RUDRA , KARANJIKAR N. P. , KAMAT M. J.
Published: November 2004

The effect of Ce 3+ on the fluorescence emission from CaS:Ce 3+ phosphor is studied using X-ray excitation. Apart from the emission in the visible region, the phosphor also shows fluorescence emission in the ultraviolet region. Variation in wavelengths and intensities of these emissions due to change in dopant concentration is also analysed.
NONPERTURBATIVE THEORY OF CAVITY-CONTROLLED SPONTANEOUS EMISSION OF TWO LEVEL ATOM
Authors: CHELTSOV VLADISLAV F.
Published: November 2004

Cavity-controlled spontaneous emission spectrum of two level atom coupled to two lossless symmetrically detuned modes has been found rigorously to be a function of the system's energy eigenvalues and displays triplet, doublet or single form depending on detuning, natural linewidth and coupling constant.
KINETIC ENERGY AND PHASE SEPARATION IN A DOPED ANTIFERROMAGNET
Authors: XU XIN , SONG YUN , FENG SHIPING
Published: November 2004

The ground-state kinetic energy of the t-J model is studied within the mean field approximation by using the fermion-spin transformation, the results show that the mean field ground-state kinetic energy is close to the numerical result at under dopings, and roughly consistent with the numerical result at optimal dopings.

It is also shown that the frustration term J′ is favourable to diminish the range of the phase seperation in the t-J model.
MODIFIED HUBBARD DECOUPLING FOR THE EMERY MODEL
Authors: GEHLHOFF LEW
Published: November 2004

We consider a version of the Emery model with large spin degeneracy N and use the X-operator formulation and the equation-of-motion method to determine the single-particle Green’s functions. We propose a modified Hubbard decoupling technique for the higher-order Green’s functions appearing in this equation of motion. By applying it to the above model in the limit N→∞ we obtain the exact results.
ANISOTROPY IN THE MAGNETIC SUSCEPTIBILITY OF THE QUASI-ONE-DIMENSIONAL CONDUCTOR Nb3Te4
Authors: JIANG YIN , AO-CHUAN DOU , MIN ZHU , ZHI-GUO LIU
Published: November 2004

We have measured the temperature dependence of the magnetic susceptibility of Nb 3 Te 4 single crystals along the chain direction (c-axis) and perpendicular to the chain direction. Two anomalies were observed, one around 110 K and the other around 50 K, and the anisotropy in the magnetic susceptibility of Nb 3 Te 4 single crystals is obvious.
TRANSPORT AND THERMAL STUDY OF THE PHASE TRANSITION OF BLUE BRONZE K0.3MoO3 AROUND 180 K
Authors: JIANG YIN , AO-CHUAN DOU , ZHI-GUO LIU
Published: November 2004

We present results on the normalized resistivity log (R(T)/R(235 K )), nonlinear conductivity, and the excess specific heat ΔCp of K0.3 MoO 3 near the Peierls transition at 180 K. The results indicate that below 180 K the single crystal K0.3 MoO 3 has a semiconductor gap Δ=1320 K (0.114 eV), and that the transition at 180 K is of second order.
ENERGETIC EFFECT IN LIQUID ANTIMONY-INDIUM ALLOYS
Authors: SINGH R.N. , SINGH K.K.
Published: November 2004

The complex formation model has been used to extract the atomic level interactions in liquid Sb-In alloys. The phase diagram, the concentration fluctuations and the chemical short range order parameter indicate that the chemical complexes of the equiatomic composition (SbIn) exist in the liquid phase. The nature of interactions between Sb, In and the complexes (SbIn) in the liquid phase are attractive. The observed concentration dependent behaviour of activity, HM, GxsSxs and Scc(0) have been successfully explained.
CHARACTERIZATION OF POTASSIUM DOPED GdBa2Cu3O7−δ USING RAMAN SPECTROSCOPY AND X-RAY DIFFRACTION
Authors: THOMAS PREETHI CICILY , K. MANOJ KUMAR , NAYAR V. UNNIKRISHNAN , V. VIDYALAL , VALLABHAN C.P.G.
Published: November 2004

Potassium doped and undoped GdBa 2 Cu 3 O 7−δ have been prepared and superconducting transition temperatures between 92 K and 100 K have been determined from resistivity measurements. Raman spectra of doped and undoped samples are identical and they contain bands corresponding to both the superconducting orthorhombic phase and nonsuperconducting tetragonal phase. XRD patterns also reveal both the phases. Raman spectra recorded at 92 K of undoped GdBa 2 Cu 3 O 7−δ and doped GdBa 2 Cu 3 O 7−δ with weight percentages 0.75, 1.00, 1.25 and 1.50 of K shows a softening of the band at 338 cm−1.
RELATIVISTIC TRANSITION MATRIX ELEMENTS IN THE CASE OF HYDROGENIC ATOMS
Authors: SEKE J.
Published: November 2004

A general formula for exact transition matrix elements in relativistic hydrogenic atoms is derived. By using the obtained formula an explicit evaluation for different electric dipole transition matrix elements is carried out analytically and numerically.
ORDERED PHASES IN PURE AND MIXED DICHROIC MONOLAYERS
Authors: FLAMENT CYRILLE , GALLET FRANÇOIS
Published: November 2004

We synthesise the results of different experiments concerning the structure of 2D crystalline phases and smectic phases in Langmuir films fully or partially made of dichroic amphiphiles. We develop an experimental procedure and the related theory to deduce the local order of absorption dipoles from measurements of the light intensity reflected by the film. Together with conventional techniques, this procedure is applied to determine the crystalline structure in films made of pure dyes. The phase diagram of a binary mixture, showing several mesophases, is also explored as a function of the film composition. The same optical technique is used to measure the mean square amplitude of the fluctuations of the dipolar order parameter. We infer the elastic constant K associated to the dipolar order in the mixed film, close to the smectic/isotropic transition. K decreases when approaching the isotropic phase, and jumps to zero at the transition, in agreement with the Kosterlitz-Thouless prediction.
RYDBERG ELECTRON DYNAMICS IN EXTERNAL FIELDS
Authors: WALS J. , FIELDING H.H. , VAN DEN HEUVELL H.B. VAN LINDEN
Published: November 2004

We review the role which classical trajectories play in quantum-mechanical systems in a more or less chronological order guided by experimental observations. The onset of a renewed interest in classical dynamics was catalysed by the observation of unknown features in the absorption spectra of atoms in the presence of external magnetic and electric fields. Although the most dominant features in these spectra can be accounted for by the simple quantisation conditions for classical electrons, the finer details require a more sophisticated approach. Starting from the Feynman path-integral formalism, Gutzwiller’s periodic-orbit theory is introduced, which is then transformed into the closed-orbit theory developed by Delos et al. Applying this semiclassical theory enabled atomic physicists to understand complicated quantum spectra as a coherent sum of classical trajectories. Newly observed features such as core-scattered orbits and ghost orbits, necessitated adjustments to the standard closed-orbit theory in order to be able to reproduce these new features. Recent results from both scaled-energy experiments and wave-packet experiments are presented to demonstrate the classical dynamics underlying the quantum system as it is currently understood.
ANALYSIS OF A NEW MODEL FOR TUMOR-IMMUNE SYSTEM COMPETITION INCLUDING LONG-TIME SCALE EFFECTS
Authors: DERBEL LOBNA
Published: November 2004

This paper deals with the competition between the immune system and an agressive host such as tumor. We are particularly interested in the asymptotic behavior of the system when the time goes to infinity: we prove that this competition will absolutely finish either by the suppression of the harmful substances or by the inhibition of the immune system. The model which we introduce is suitable to describe the disease evolution for a long time scale, because it takes the capacity of the body to repair cells damage into account: body cells produce new cells to replace dead ones. We also examine the evolution of the solutions if we assume that the immune system has a normal healthy state that it always tries to reach.
NETWORKS OF RESONANT GRAVITATIONAL WAVE ANTENNAS
Authors: FRASCA S. , PAPA M.A.
Published: November 2004

There are many reasons, other than that of excluding local disturbances, for using more gravitational antennas at the same time. In fact a network of resonant antennas allows

— the detection of radiation coming from any direction and in any polarization state (sky coverage problem).

— the estimate of some parameters of the source (information gain).

— the verification of the predictions of general relativity regarding the features of gravitational waves (e.g. their propagation velocity, their quadrupole nature etc.) and the existence of celestial objects which cannot be observed other than through the gravitational effects they produce (e.g. black holes).

— the enhancement of the noise rejection capability of the instrument thus enhancing its sensitivity (network filtering). Regarding this feature, some very interesting characteristics are exhibited by local networks of equal antennas (gravitational arrays).

In this paper the major issues related to these problems will be presented and discussed and the experimental and theoretical results will briefly be reviewed. Some new ideas will also be introduced.
OBSERVABLE TIME IN QUANTUM COSMOLOGY
Authors: PERVUSHIN V. , TOWMASJAN T.
Published: November 2004

We show that the first principles of quantization and the experience of relativistic quantum mechanics can lead to the definition of observable time in quantum cosmology as a global quantity which coincides with the constrained action of the reduced theory up to the energy factor. The latter is fixed by the correspondence principle once one considers the limit of the “dust filled” Universe. The “global time” interpolates between the proper time for dust dominance and the conformal time for radiation dominance.
LARGE SCALE ANISOTROPY OF MICROWAVE BACKGROUND RADIATION IN ROTATING COSMOLOGIES
Authors: PAVELKIN V.N. , PANOV V.F.
Published: November 2004

The background radiation temperature distribution as a function of observation position angles for Gödel type cosmologies with expansion, rotation and shear is studied in the geometric optics approach. Null geodesic equations in the relevant metrics are solved for some particular cases and the background radiation temperature anisotropy for two directions is evaluated in terms of the values of rotation and shear.
CAUSALITY PROPERTIES OF TOPOLOGICALLY NONTRIVIAL SPACE-TIME MODELS
Authors: KONSTANTINOV M. YU.
Published: November 2004

The causality properties of space-time models with traversable wormholes are considered. It is shown that the relativity principle cannot be applied to the motion of the wormhole’s mouths in the outer space and the dynamical wormhole transformation into the time machine is impossible. The examples of both causal and noncausal space-time models with traversable wormholes are also considered. Some properties of space-time models with causality violation are briefly discussed.
GENERALIZED BRANS-DICKE COSMOLOGY
Authors: GONG YUNGUI , ZHANG YUAN ZHONG
Published: November 2004

The generalized Brans-Dicke cosmology is studied. We find that the difference in the evolution of the universe is significant between the generalized Brans-Dicke cosmology and the standard cosmology during the radiation-dominated era and the inflationary era, though the difference is negligible during the matter-dominated era. The consequences arising from the differences remain to be studied in detail.
NEUTRON STARS AND THE COHERENT NUCLEAR INTERACTION
Authors: GIUDICE E. DEL , MELE R. , PREPARATA G. , GUALDI C. , MANGANO G. , MIELE G.
Published: November 2004

In the framework of a novel approach to the dynamics of nuclei and large collections of nucleons, which fully exploits the coherent interaction among π’s, nucleons and Δ’s, we derive a new equation of state for neutronic matter.

By introducing it in the Tolman-Oppenheimer-Volkof equations we derive the masses and radii of neutron stars as a function of the central density. We obtain a maximum mass Mmax≃2.7 Mʘ and a minimum period of rotation Tmin=0.8 msec.
TIME MACHINES: THE PRINCIPLE OF SELF-CONSISTENCY AS A CONSEQUENCE OF THE PRINCIPLE OF MINIMAL ACTION
Authors: CARLINI A. , FROLOV V.P. , MENSKY M.B. , NOVIKOV I.D. , SOLENG H.H.
Published: November 2004

We consider the action principle to derive the classical, nonrelativistic motion of a self-interacting particle in a 4D Lorentzian spacetime containing a wormhole and which allows the existence of closed time-like curves. For the case of a “hard-sphere” self-interaction potential we show that the only possible trajectories (for a particle with fixed initial and final positions and which traverses the wormhole once) minimizing the classical action are those which are globally self-consistent, and that the “principle of self-consistency” (originally introduced by Novikov) is thus a natural consequence of the “principle of minimal action.”
REDUCED PHASE SPACE QUANTIZATION OF ASHTEKAR’S GRAVITY ON A DE SITTER BACKGROUND
Authors: GRIGENTCH IGNATI , VASSILEVICH D.V.
Published: November 2004

We solve perturbative constraints and eliminate gauge freedom for Ashtekar’s gravity on a de Sitter background. We show that the reduced phase space consists of transverse, traceless, symmetric fluctuations of the triad and transverse, traceless, symmetric fluctuations of the connection. A part of the gauge freedom corresponding to the conformal Killing vectors of the three-manifold can be fixed only by imposing conditions on the Lagrange multiplier. The reduced phase space is equivalent to that of ADM gravity on the same background.
HIGHER-DIMENSIONAL THEORIES, DILATON FIELDS AND SPONTANEOUS SYMMETRY BREAKING
Authors: MACÍAS A. , CAMACHO A. , MATOS T.
Published: November 2004

We consider an eight-dimensional gravitational theory, which possesses a principle fiber bundle structure, with Lorentz-scalar fields coupled to the metric. One of them plays the role of a Higgs field and the other one of a dilaton field. The effective cosmological constant is interpreted as a Higgs potential. As usual we introduce by hand the Yukawa couplings. The extra dimensions are a SU(2)L×U(1)Y×SU(2)R group manifold. A Dirac field is coupled to the metric. As a result, we obtain an effective four-dimensional theory which contains all couplings of a Weinberg-Salam-Glashow theory in a curved space-time. The true masses of the gauge bosons and of the first two fermions families are given by the theory.
GRAVITATIONAL LENSING AND CATASTROPHE THEORY
Authors: KAKIGI YUUKO , OKAMURA TAKASHI , FUKUYAMA TAKESHI
Published: November 2004

Singularities of caustics appearing in the gravitational lensing effect are discussed analytically.

The multipole expansion model of the lensing object is mainly studied since it is tractable and universal. Our analyses are confirmed by numerical calculations and applied to the multiple quasar system of PG1115+080. Consistencies with elliptical lens models are also discussed.
HEAVY-QUARK SYMMETRY AND SKYRMIONS
Authors: MIN DONG-PIL , OH YONGSEOK , PARK BYUNG-YOON , RHO MANNQUE
Published: November 2004

We review recent development on combining heavy-quark symmetry and chiral symmetry in the skyrmion structure of the baryons containing one or more heavy quarks, c (charmed) and b (bottom). We describe two approaches: One going from the chiral symmetry regime of light quarks to the heavy-quark symmetry regime which will be referred to as “bottom-up” approach and the other going down from the heavy-quark limit to the realistic finite-mass regime which will be referred to as “top-down.” A possible hidden connection between the two symmetry limits is suggested. This review is based largely on the work done — some unpublished — by the authors since several years.
AVERAGE TRAJECTORY SEMICLASSICAL THEORY OF HEAVY ION COLLISIONS
Authors: MARTA H.D. , CANTO L.F. , DONANGELO R.
Published: November 2004

The semiclassical method of Alder-Winther-de Boer is generalized to include the nuclear potential, both in the description of the relative motion of the projectile-target system and in the amplitudes for exciting collective states. We find a reasonable agreement between our results and exact quantum-mechanical coupled-channels calculations for the case of inelastic excitation of rotational levels. This approach can be easily generalized to the case of transfer reactions.
CHIRAL DYNAMICS IN NUCLEONS AND NUCLEI
Authors: BERNARD V. , KAISER N. , MEIßNER ULF-G.
Published: November 2004

We review the implications of the spontaneous chiral symmetry breaking in QCD for processes involving one, two, or more nucleons.
A Uqp(u2) ROTOR MODEL FOR ROTATIONAL BANDS OF SUPERDEFORMED NUCLEI
Authors: BARBIER R. , MEYER J. , KIBLER M.
Published: November 2004

A nonrigid rotor model is developed from the two-parameter quantum algebra Uqp(u2). (This model presents the Uqp(u2) symmetry and shall be refered to as the qp-rotor model.) A rotational energy formula as well as a qp-deformation of E2 reduced transition probabilities are derived. The qp-rotor model is applied (through fitting procedures) to twenty rotational bands of superdeformed nuclei in the A~130, 150, and 190 mass regions. Systematic comparisons between the qp-rotor model and the q-rotor model of Raychev, Roussev, and Smirnov, on one hand, and a basic three-parameter model, on the other, are performed on energy spectra, on dynamical moments of inertia and on B(E2) values. The physical significance of the deformation parameters q and p is discussed.
THE q-DEFORMED MOSZKOWSKI MODEL REVISITED
Authors: FÁVERO F.W. , SANTOS L.O.E. , MENEZES D.P.
Published: November 2004

In this paper, we have used the q-deformed Moszkowski model to study the validity of the coherent states variational method, to observe the differences arising from two different deformation procedures and, finally, to look at the evolution in time of the system by means of the time dependent variational principle.
SCATTERING AND DISSOCIATION OF DEUTERONS AND 3H-NUCLEI BY NUCLEI AT INTERMEDIATE ENERGIES
Authors: BEREZHNOY YU. A. , KORDA V. YU.
Published: November 2004

We present a closed-form description that enables us to obtain the analytical expressions for the elastic scattering and dissociation differential cross-sections of deuterons and 3H-nuclei by heavy target nuclei. The resulting expressions are used to analyze the data for the 110 MeV deuterons elastically scattered on 208Pb-nuclei. The dissociation cross-sections of deuterons and 3H-nuclei are the oscillating functions of the scattering angle of the released two- and three-nucleon-particle system center-of-mass.
THE INFLUENCE OF THE NUCLEAR MEDIUM ON THE BARYON RESONANCE EXCITATION
Authors: MOKEEV V.I. , SANTOPINTO E. , GIANNINI M.M. , RICCO G.
Published: November 2004

We have analyzed the influence of the nuclear medium on the photoexcitation of nucleon resonances, keeping separate the kinematical from the dynamical effects. We have updated the fit to the proton and neutron photoabsorption cross-sections and then evaluated the nuclear cross-section by means of a folding formula, showing that the Fermi motion alone is not able to reproduce the behavior observed in the recent Genova-Frascati experiments. The discrepancy with the data can be substantially eliminated by introducing both a quenching of the excitation strength and a broadening of the resonance widths. According to some recent theoretical works, which are also briefly discussed, the broadening can be due to a rescattering of the nucleon resonances in nuclei, while the damping of the resonances can be attributed to mechanisms involving the internal structure of the nucleon.
PHENOMENOLOGY OF NUCLEI AT VERY HIGH ANGULAR MOMENTA USING PARAMETRIZED TWO-CENTER NUCLEAR SHAPES
Authors: GUPTA RAJ K. , MALIK SHAM S. , BATRA J.S. , HESS PETER O. , SCHEID WERNER
Published: November 2004

The nuclear shapes and variation of moment of inertia with angular momentum, as well as the limiting angular momentum carried by a nucleus at its fissioning stage, are derived from the observed data of the ground-state yrast band and quadrupole deformations of these states. The necking-in of the nuclear shapes are shown to start already at J*~14+−18+. The empirical variation of moment of inertia with angular momentum is found to include the back-bending and forward-bending effects and supports the nuclear softness model of the nucleus. The fission of nuclei is shown to occur at very high angular momenta, which is different for different nuclei. The role of deformation energy is analyzed and the possibility of predicting the quadrupole deformations, or B(E2) transitions, for very high spin states is discussed. The calculations are presented for 156Dy, 158Er, and 164Hf.
Y-SCALING QUANTITIES AND NUCLEON CORRELATION EFFECTS IN NUCLEI
Authors: GAIDAROV M.K. , ANTONOV A.N. , DIMITROVA S.S. , STOITSOV M.V.
Published: November 2004

The asymptotic scaling function F(y) and the binding correction B(y), the mean kinetic 〈T〉 and removal 〈E〉 energies, as well as the occupation probabilities Sgr and Sex are calculated in the cases of the 4He, 12C, 16O and 40Ca nuclei using the nucleon momentum distributions obtained within the Jastrow correlation method and the phenomenological model which takes into account short-range and tensor nucleon-nucleon correlations. It is shown that the scaling functions F(y) differ from those obtained in the mean-field approximation but qualitatively agree with the available experimental data. The binding correction B(y) is explicitly evaluated using a model nuclear spectral function. The nucleon-nucleon correlation effects increase the values of the mean kinetic 〈T〉 and mean removal 〈E〉 energies in comparison with their values in the mean-field approximation.
INTERACTIONS OF RELATIVISTIC 24Mg NUCLEI WITH EMULSION NUCLEI AT 4.5 GeV/c PER NUCLEON
Authors: JILANY M.A. , ALLAH N.N. ABD , ABD-ELDAIM A.
Published: November 2004

Nuclear emulsions are used to investigate spallations produced by 108 GeV/c 24Mg nuclei. The main experimental characteristics (inelastic cross-sections and multiplicities of various types of secondary particles and their dependence on the masses of the colliding nuclei) in inelastic interactions of 24Mg nuclei with nuclei of nuclear emulsion at 4.5 GeV/c per nucleon have been studied. The integral multiplicity distribution of disintegrated particles from target nuclei is used to separate the inelastic interactions with the free hydrogen (H), the light (CNO), and the heavy (AgBr) nuclei. Multiplicity scaling in the shower particles obeys a scaling function of Koba-Neilsen-Olesen (KNO) type in this energy region.
A GRADIENT METHOD FOR APPLICATION OF CHEMOTHERAPY PROTOCOLS
Authors: DUDA Z.
Published: November 2004

The paper presents some properties and. related simulation results of optimal control strategies in problems arising from cancer chemotherapy. Two bilinear models of a proliferation cycle are considered. A numerical gradient method is applied to solve the problems.