HR4049: signature of nova nucleosynthesis ?

The post-Asymptotic Giant Branch (AGB) star HR4049 is in an eccentric binary system with a relatively short period probably surrounded by a dusty circumbinary disk. Extremely anomalous oxygen isotopic ratios, O16/O17 ~ O16/O18 ~ 7, have been measured from CO_2 molecules likely residing in the disk. Such a composition cannot be explained in the framework of AGB and post-AGB evolution while it can be qualitatively associated with the nucleosynthesis occurring during nova outbursts. We discuss nova models, the presence of a white dwarf companion to HR4049 and possible scenarios for the dynamical evolution of this binary system. Circumbinary disks in which mixing occurs between red-giant and nova material may also be invoked as the site of formation of some rare types of meteoritic presolar grains.Comment: 4 pages, 2 figures, submitted for the proceedings of the 8th Nuclei in the Cosmos symposium (Vancouver, Canada, 19-23 July 2004

Frequency dependence of acoustic waves in marine sediments

In situ techniques provide the most reliable method of examining the geoacoustical properties of marine sediments. In the past, individual in situ surveys have only been able to examine compressional waves over a maximum frequency range of 100 Hz to 50 kHz. A new in situ acoustic device, the Sediment Probing Acoustic Detection Equipment, or SPADE, has been developed, which can emit a variety of pulses, e.g. tonal and swept-frequency, over a continuous frequency range of 10 - 100 kHz. Data from a recent field trial are analysed to obtain the in situ velocity and attenuation over frequency increments of 5 kHz between 10 - 75 kHz. Results imply that scattering is a dominant attenuation mechanism from 10-75 kHz and the media is dispersive for frequencies between 60 and 70 kHz and below 20 kHz. Biot theory cannot accurately model the observed velocity and attenuation

Five-loop \sqrt\epsilon-expansions for random Ising model and marginal spin dimensionality for cubic systems

The \sqrt\epsilon-expansions for critical exponents of the weakly-disordered Ising model are calculated up to the five-loop order and found to possess coefficients with irregular signs and values. The estimate n_c = 2.855 for the marginal spin dimensionality of the cubic model is obtained by the Pade-Borel resummation of corresponding five-loop \epsilon-expansion.Comment: 9 pages, TeX, no figure

Anomalous Charge Dynamics in the Superconducting State of Underdoped Cuprates

We present fermi liquid expressions for the low temperature behavior of the superfluid stiffness, explain why they differ from those suggested recently by Lee and Wen, and discuss their applicability to data on high-$T_c$ superconductors. We find that a consistent description requires a strong, doping dependent anisotropy, which affects states near the zone corners much more strongly than those near the zone diagonals

Cross section of the processes e++e−→e++e−(γ)e^++e^-\to e^++e^-(\gamma), →π++π−(γ)\to \pi^++\pi^-(\gamma), μ++μ−(γ) \mu^++\mu^-(\gamma), γ+γ(γ) \gamma+\gamma(\gamma) in the energy region 200 MeV ≤2E≤\le 2E\le 3 GeV

The cross section for different processes induced by $e^+e^-$ annihilation, in the kinematical limit $\beta_{\mu}\approx\beta_{\pi}=(1-m_{\pi}^2/\epsilon^2)^{1/2}\sim 1$, is calculated taking into account first order corrections to the amplitudes and the corrections due to soft emitted photons, with energy $\omega\le\Delta E\le \epsilon$ in the center of mass of the $e^+e^-$ colliding beams. The results are given separately for charge--odd and charge--even terms in the final channels $\pi^+\pi^-(\gamma)$ and $\mu^+\mu^-(\gamma)$. In case of pions, form factors are taken into account. The differential cross sections for the processes: $e^++e^-\to e^++e^-(+\gamma)$, $\to \pi^++\pi^-(\gamma)$, $\to \mu^++\mu^-(\gamma),\to \gamma\gamma(\gamma)$ have been calculated and the corresponding formula are given in the ultrarelativistic limit $\sqrt{s}/2= \epsilon \gg m_{\mu}\sim m_{\pi}$ . For a quantitative evaluation of the contribution of higher order of the perturbation theory, the production of $\pi^+\pi^-$, including radiative corrections, is calculated in the approach of the lepton structure functions. This allows to estimate the precision of the obtained results as better than 0.5% outside the energy region corresponding to narrow resonances. A method to integrate the cross section, avoiding the difficulties which arise from singularities is also described.Comment: 25 pages 3 firgur

Stability of critical behaviour of weakly disordered systems with respect to the replica symmetry breaking

A field-theoretic description of the critical behaviour of the weakly disordered systems is given. Directly, for three- and two-dimensional systems a renormalization analysis of the effective Hamiltonian of model with replica symmetry breaking (RSB) potentials is carried out in the two-loop approximation. For case with 1-step RSB the fixed points (FP's) corresponding to stability of the various types of critical behaviour are identified with the use of the Pade-Borel summation technique. Analysis of FP's has shown a stability of the critical behaviour of the weakly disordered systems with respect to RSB effects and realization of former scenario of disorder influence on critical behaviour.Comment: 10 pages, RevTeX. Version 3 adds the $\beta$ functions for arbitrary dimension of syste

Storing and releasing light in a gas of moving atoms

We propose a scheme of storing and releasing pulses or cw beams of light in a moving atomic medium illuminated by two stationary and spatially separated control lasers. The method is based on electromagnetically induced transparency (EIT) but in contrast to previous schemes, storage and retrieval of the probe pulse can be achieved at different locations and without switching off the control laser.Comment: 4 pages, 3 figures, revised versio

Five-loop renormalization-group expansions for the three-dimensional n-vector cubic model and critical exponents for impure Ising systems

The renormalization-group (RG) functions for the three-dimensional n-vector cubic model are calculated in the five-loop approximation. High-precision numerical estimates for the asymptotic critical exponents of the three-dimensional impure Ising systems are extracted from the five-loop RG series by means of the Pade-Borel-Leroy resummation under n = 0. These exponents are found to be: \gamma = 1.325 +/- 0.003, \eta = 0.025 +/- 0.01, \nu = 0.671 +/- 0.005, \alpha = - 0.0125 +/- 0.008, \beta = 0.344 +/- 0.006. For the correction-to-scaling exponent, the less accurate estimate \omega = 0.32 +/- 0.06 is obtained.Comment: 11 pages, LaTeX, no figures, published versio

Adiabatic following criterion, estimation of the nonadiabatic excitation fraction and quantum jumps

An accurate theory describing adiabatic following of the dark, nonabsorbing state in the three-level system is developed. An analytical solution for the wave function of the particle experiencing Raman excitation is found as an expansion in terms of the time varying nonadiabatic perturbation parameter. The solution can be presented as a sum of adiabatic and nonadiabatic parts. Both are estimated quantitatively. It is shown that the limiting value to which the amplitude of the nonadiabatic part tends is equal to the Fourier component of the nonadiabatic perturbation parameter taken at the Rabi frequency of the Raman excitation. The time scale of the variation of both parts is found. While the adiabatic part of the solution varies slowly and follows the change of the nonadiabatic perturbation parameter, the nonadiabatic part appears almost instantly, revealing a jumpwise transition between the dark and bright states. This jump happens when the nonadiabatic perturbation parameter takes its maximum value.Comment: 33 pages, 8 figures, submitted to PRA on 28 Oct. 200

Vortex Dynamics and the Hall-Anomaly: a Microscopic Analysis

We present a microscopic derivation of the equation of motion for a vortex in a superconductor. A coherent view on vortex dynamics is obtained, in which {\it both} hydrodynamics {\it and} the vortex core contribute to the forces acting on a vortex. The competition between these two provides an interpretation of the observed sign change in the Hall angle in superconductors with mean free path $l$ of the order of the coherence length $\xi$ in terms of broken particle-hole symmetry, which is related to details of the microscopic mechanism of superconductivity.Comment: 12 pages, late