Interaction of a neutral cloud moving through a magnetized plasma

Current collection by outgassing probes in motion relative to a magnetized plasma may be significantly affected by plasma processes that cause electron heating and cross field transport. Simulations of a neutral gas cloud moving across a static magnetic field are discussed. The authors treat a low-Beta plasma and use a 2-1/2 D electrostatic code linked with the authors' Plasma and Neutral Interaction Code (PANIC). This study emphasizes the understanding of the interface between the neutral gas cloud and the surrounding plasma where electrons are heated and can diffuse across field lines. When ionization or charge exchange collisions occur a sheath-like structure is formed at the surface of the neutral gas. In that region the crossfield component of the electric field causes the electron to E times B drift with a velocity of the order of the neutral gas velocity times the square root of the ion to electron mass ratio. In addition a diamagnetic drift of the electron occurs due to the number density and temperature inhomogeneity in the front. These drift currents excite the lower-hybrid waves with the wave k-vectors almost perpendicular to the neutral flow and magnetic field again resulting in electron heating. The thermal electron current is significantly enhanced due to this heating

Hot Nuclear Matter Equation of State with a Three-body Force

The finite temperature Brueckner-Hartree-Fock approach is extended by introducing a microscopic three-body force. In the framework of the extended model, the equation of state of hot asymmetric nuclear matter and its isospin dependence have been investigated. The critical temperature of liquid-gas phase transition for symmetric nuclear matter has been calculated and compared with other predictions. It turns out that the three-body force gives a repulsive contribution to the equation of state which is stronger at higher density and as a consequence reduces the critical temperature of liquid-gas phase transition. The calculated energy per nucleon of hot asymmetric nuclear matter is shown to satisfy a simple quadratic dependence on asymmetric parameter $\beta$ as in the zero-temperature case. The symmetry energy and its density dependence have been obtained and discussed. Our results show that the three-body force affects strongly the high-density behavior of the symmetry energy and makes the symmetry energy more sensitive to the variation of temperature. The temperature dependence and the isospin dependence of other physical quantities, such as the proton and neutron single particle potentials and effective masses are also studied. Due to the additional repulsion produced by the three-body force contribution, the proton and neutron single particle potentials are correspondingly enhanced as similar to the zero-temperature case.Comment: 16 pages, 8 figure

Continuum Electromechanical Modeling of Protein-Membrane Interaction

A continuum electromechanical model is proposed to describe the membrane curvature induced by electrostatic interactions in a solvated protein-membrane system. The model couples the macroscopic strain energy of membrane and the electrostatic solvation energy of the system, and equilibrium membrane deformation is obtained by minimizing the electro-elastic energy functional with respect to the dielectric interface. The model is illustrated with the systems with increasing geometry complexity and captures the sensitivity of membrane curvature to the permanent and mobile charge distributions.Comment: 5 pages, 12 figure

Effects of frequency correlation in linear optical entangling gate operated with independent photons

Bose-Einstein coalescence of independent photons at the surface of a beam splitter is the physical process that allows linear optical quantum gates to be built. When distinct parametric down-conversion events are used as an independent photon source, distinguishability arises form the energy correlation of each photon with its twin. We find that increasing the pump bandwidth may help in improving the visibility of non-classical interference and reaching a level of near perfect indistinguishability. PACS: 03.67.Mn, 42.65.Lm, 42.50.St.Comment: Replaced with published versio

The discrete contribution to ψ′→J/ψ+γγ\psi^{\prime}\to J/\psi+\gamma\gamma

The decay mode $\psi(2S)\to J/\psi+\gamma\gamma$ is proposed in order to experimentally identify the effects of the coupling of charmonium states to the continuum $D\bar D$ states. To have a better understanding of such a two-photon decay process, in this work we restrict ourselves to investigate the contribution of the discrete part, in which the photons are mainly produced via the intermediate states $\chi_{cJ}(nP)$. Besides calculating the resonance contributions of $\chi_{cJ}(1P)\; (J=0,1,2)$, we also take into account the contributions of the higher excited states $\chi_{cJ}(2P)$ and the interference effect among the 1P and 2P states. We find that the contribution of the 2P states and the interference terms to the total decay width is very tiny. However, for specific regions of the Dalitz plot, off the resonance peaks, we find that these contributions are sizable and should also be accounted for. We also provide the photon spectrum and study the polarization of $J/\psi$.Comment: 19 pages, 5 figures, minor changes, references added, accepted version in PR

New angles on D-branes

A low-energy background field solution is presented which describes several D-membranes oriented at angles with respect to one another. The mass and charge densities for this configuration are computed and found to saturate the BPS bound, implying the preservation of one-quarter of the supersymmetries. T-duality is exploited to construct new solutions with nontrivial angles from the basic one.Comment: Latex, 12 pages, still no figures, references update