Periodic waves and solitons in a nonlinear fibre with resonant impurities

We shall consider a coupled nonlinear Schrodinger equation- Bloch system of equations describing the propagation of a single pulse through a nonlinear dispersive waveguide in the presence of resonances; this could be, for example, a doped optical fibre. By making use of the integrability of the dynamic equations, we shall apply the finite-gap integration method to obtain periodic solutions for this system. Next, we consider the problem of the formation of solitons at a sharp front pulse and, by means of the Whitham modulational theory, we derive the amplitude and velocity of the largest soliton.

Formation of soliton trains in Bose-Einstein condensates as a nonlinear Fresnel diffraction of matter waves

The problem of generation of atomic soliton trains in elongated Bose-Einstein condensates is considered in framework of Whitham theory of modulations of nonlinear waves. Complete analytical solution is presented for the case when the initial density distribution has sharp enough boundaries. In this case the process of soliton train formation can be viewed as a nonlinear Fresnel diffraction of matter waves. Theoretical predictions are compared with results of numerical simulations of one- and three-dimensional Gross-Pitaevskii equation and with experimental data on formation of Bose-Einstein bright solitons in cigar-shaped traps. (C) 2003 Elsevier B.V. All rights reserved.

Stable periodic waves in coupled Kuramoto-Sivashinsky-Korteweg-de Vries equations

Periodic waves are investigated in a system composed of a Kuramoto-Sivashinsky-Korteweg-de Vries (KS-KdV) equation linearly coupled to an extra linear dissipative one. The model describes, e.g., a two-layer liquid film flowing down an inclined plane. It has been recently shown that the system supports stable solitary pulses. We demonstrate that a perturbation analysis, based on the balance equation for the net field momentum, predicts the existence of stable cnoidal waves (CnWs) in the same system. It is found that the mean value u(0) of the wave field u in the main subsystem, but not the mean value of the extra field, affects the stability of the periodic waves. Three different areas can be distinguished inside the stability region in the parameter plane (L, u(0)), where L is the wave's period. In these areas, stable are, respectively, CnWs with positive velocity, constant solutions, and CnWs with negative velocity. Multistability, i.e., the coexistence of several attractors, including the waves with several maxima per period, appears at large value of L. The analytical predictions are completely confirmed by direct simulations. Stable waves are also found numerically in the limit of vanishing dispersion, when the KS-KdV equation goes over into the KS one.

Search for Wbb(-) and WH production in pp(-) collisions at root s=1.96 TeV

We present a search for Wb (b) over bar production in p (p) over bar collisions at root s=1.96 TeV in events containing one electron, an imbalance in transverse momentum, and two b-tagged jets. Using 174 pb(-1) of integrated luminosity accumulated by the D0 experiment at the Fermilab Tevatron collider, and the standard-model description of such events, we set a 95% C.L. upper limit on Wb (b) over bar production of 6.6 pb for b quarks with transverse momenta p(T)(b)> 20 GeV and b (b) over bar separation in pseudorapidity-azimuth space Delta R-bb> 0.75. Restricting the search to optimized b (b) over bar mass intervals provides upper limits on WH production of 9.0-12.2 pb for Higgs-boson masses of 105-135 GeV.

Universal scaling in Bardeen-Cooper-Schrieffer superconductivity in two dimensions in non-s waves

The solutions of a renormalized BCS model are studied in two space dimensions for s, p and d waves for finite-range separable potentials. The gap parameter, the critical temperature T-c, the coherence length xi and the jump in specific heat at T-c as a function of the zero-temperature condensation energy exhibit universal scalings. In the weak-coupling limit, the present model yields a small xi and large T-c, appropriate for high-T-c cuprates. The specific heat, penetration depth and thermal conductivity as functions of temperature show universal scaling for p and d waves.

Z gamma production and limits on anomalous ZZ gamma and Z gamma gamma couplings in pp collisions at root s=1.96 TeV

We present a study of eey and mu mu gamma events using 1109 (1009) pb-(1) of data in the electron (muon) channel, respectively. These data were collected with the DO detector at the Fermilab Tevatron pp collider at Is = 1.96 TeV. Having observed 453 (515) candidates in the eey (jtAy) final state, we measure the Z gamma production cross section for a photon with transverse energy ET > 7 GeV, separation between the photon and leptons Delta Rey > 0.7, and invariant mass of the di-lepton pair Mee > 30 GeV/(2)(c), to be 4.96 0.30(stat. + syst.) zE 0.30(lumi.) pb, in agreement with the Standard Model prediction of 4.74 0.22 pb. This is the most precise Zy cross section measurement at a hadron collider. We set limits on anomalous trilinear Zyy and ZZy gauge boson couplings of -0.085 < h(30)(y) < 0.084, -0.0053 < h(40)(y) < 0.0054 and -0.083 < h(30)(Z) < 0.082, 30 40 30 -0.0053 < h(40)(Z) < 0.0054 at the 95% C.L. for the form-factor scale A = 1.2 TeV. 40 Published by Elsevier B.V.

The nonlinear essence of gravitational waves

A critical review of gravitational wave theory is made. It is pointed out that the usual linear approach to the gravitational wave theory is neither conceptually consistent nor mathematically justified. Relying upon that analysis it is argued that-analogously to a Yang-Mills propagating field, which must be nonlinear to carry its gauge charge-a gravitational wave must necessarily be nonlinear to transport its own charge-that is, energy-momentum.

Theory of optical dispersive shock waves in photorefractive media

The theory of optical dispersive shocks generated in the propagation of light beams through photorefractive media is developed. A full one-dimensional analytical theory based on the Whitham modulation approach is given for the simplest case of a sharp steplike initial discontinuity in a beam with one-dimensional striplike geometry. This approach is confirmed by numerical simulations, which are extended also to beams with cylindrical symmetry. The theory explains recent experiments where such dispersive shock waves have been observed.

Renomalization of the NN interaction at NNLO: Uncoupled peripheral waves

We apply the subtractive renormalization method to the nucleon-nucleon interaction at Next-to-Next-to-Leading order (NNLO). Here we show the results for some uncoupled peripheral waves.

Measurement of the pp(-)-> W gamma plus X cross section at root s=1.96 TeV and WW gamma anomalous coupling limits

The WW gamma triple gauge boson coupling parameters are studied using p (p) over bar -> l nu gamma + X(l = e, mu) events at root s = 1.96 TeV. The data were collected with the D0 detector from an integrated luminosity of 162 pb(-1) delivered by the Fermilab Tevatron Collider. The cross section times branching fraction for p (p) over bar -> W(gamma) + X -> l nu gamma + X with E-T(gamma) > 8 GeV and Delta R-l gamma > 0.7 is 14.8 +/- 1.6(stat) +/- 1.0(syst) +/- 1.0(lum) pb. The one-dimensional 95% confidence level limits on anomalous couplings are -0.88 < Delta kappa(gamma) < 0.96 and -0.20 < lambda(gamma) < 0.20.

Production of WZ events in pp(-) collisions at root s=1.96 TeV and limits on anomalous WWZ couplings

We present results from a search for WZ production with subsequent decay to l nu l'(l) over bar'(l and l' = e or mu) using 0.30 fb(-1) of data collected by the D0 experiment between 2002 and 2004 at the Fermilab Tevatron. Three events with WZ decay characteristics are observed. With an estimated background of 0.71 +/- 0.08 events, we measure the WZ production cross section to be 4.5(-2.6)(+3.8) pb, with a 95% C.L. upper limit of 13.3 pb. The 95% C.L. limits for anomalous WWZ couplings are found to be -2.0 ppa(Z)< 2.4 for form factor scale Lambda=1 TeV, and -0.48

Study Z gamma events and limits on anomalous ZZ gamma and Z gamma gamma couplings in pp(-) collisions at root s=1.96 Tev

We present a measurement of the Z gamma production cross section and limits on anomalous ZZ gamma and Z gamma gamma couplings for form-factor scales of Lambda=750 and 1000 GeV. The measurement is based on 138 (152) candidates in the ee gamma (mu mu gamma) final state using 320(290) pb(-1) of p (p) over bar collisions at root s=1.96 TeV. The 95% C.L. limits on real and imaginary parts of individual anomalous couplings are vertical bar h(10,30)(Z)vertical bar < 0.23, vertical bar h(20,40)(Z)vertical bar < 0.020, vertical bar h(10,30)(gamma)vertical bar < 0.23, and vertical bar h(20,40)(gamma)vertical bar < 0.019 for Lambda=1000 GeV.

PP-wave light-cone free string field theory at finite temperature

In this paper, a real-time formulation of light-cone pp-wave string field theory at finite temperature is presented. This is achieved by developing the thermo field dynamics (TFD) formalism in a second quantized string scenario. The equilibrium thermodynamic quantities for a pp-wave ideal string gas are derived directly from expectation values on the second quantized string thermal vacuum. Also, we derive the real-time thermal pp-wave closed string propagator. In the flat space limit it is shown that this propagator can be written in terms of Theta functions, exactly as the zero temperature one. At the end, we show how superstrings interactions can be introduced, making this approach suitable to study the BMN dictionary at finite temperature.

gamma p and gamma gamma scattering from (p)over-bar-p, pp forward amplitudes in a QCD eikonal model with a dynamical gluon mass

We examine the gamma p photoproduction and the hadronic gamma gamma total cross sections by means of a QCD eikonal model with a dynamical infrared mass scale. In this model, where the dynamical gluon mass is the natural regulator for the tree level gluon-gluon scattering, the gamma p and gamma gamma total cross sections are derived from the pp and (p) over barp forward scattering amplitudes assuming vector meson dominance and the additive quark model. We show that the validity of the cross section factorization relation sigma(pp)/sigma(gamma p)=sigma(gamma p)/sigma(gamma gamma) is fulfilled depending on the Monte Carlo model used to unfold the hadronic gamma gamma cross section data, and we discuss in detail the case of sigma(gamma gamma -> hadrons) data with W-gamma gamma> 10 GeV unfolded by the Monte Carlo generators PYTHIA and PHOJET. The data seems to favor a mild dependence with the energy of the probability (P-had) that the photon interacts as a hadron.

BCS superconductivity in the van Hove scenario in s and d waves

The effect of including a van Hove singularity in the density of state of a renormalized BCS equation in s and d waves and its appropriateness in describing some properties of high-Tc cuprates in the weak-coupling region are studied in two space dimensions. The specific heat and knight shift as a function of temperature exhibit scaling below the critical temperature in d wave. We also study the jump in the specific heat at the critical temperature Tc in s and d waves, which can have values significantly higher than the standard BCS values and which increases with Tc, as experimentally observed in many d-wave high-Tc materials. The experimental results on the specific heat and knight shift of the Y-123 system are compared with the theoretical predictions.