30,026 research outputs found

    The Forced Non-Linear Schroedinger Equation with a Potential on the Half-Line

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    In this paper we prove that the initial-boundary value problem for the forced non-linear Schroedinger equation with a potential on the half-line is locally and (under stronger conditions) globally well posed, i.e. that there is a unique solution that depends continuously on the force at the boundary and on the initial data. We allow for a large class of unbounded potentials. Actually, for local solutions we have no restriction on the grow at infinity of the positive part of the potential, and for global solutions very mild assumptions that allow, for example, for exponential grow.Comment: 23 page

    WγW\gamma and ZγZ\gamma production and limits on anomalous WWγWW\gamma, ZZγZZ\gamma and ZγγZ\gamma\gamma couplings with D0 detector

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    The recent D0 results on Wgamma and Zgamma production are presented. First, the cross section and the difference in rapidities between photons and charged leptons for inclusive Wgamma production in egamma and mugamma final states are discussed, then are the cross section and differential cross section as a function of photon transverse momentum for Zgamma process. Finally, I present the limits on anomalous WWgamma, ZZgamma and Zgammagamma couplings.Comment: 18 pages, 16 figures, review articl

    On the convective instability of hot radiative accretion flows

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    How many fraction of gas available at the outer boundary can finally fall onto the black hole is an important question. It determines the observational appearance of accretion flows, and is also related with the evolution of black hole mass and spin. Previous two-dimensional hydrodynamical simulations of hot accretion flows find that the flow is convectively unstable because of its inward increase of entropy. As a result, the mass accretion rate decreases inward, i.e., only a small fraction of accretion gas can fall onto the black hole, while the rest circulates in the convective eddies or lost in convective outflows. Radiation is usually neglected in these simulations. In many cases, however, radiative cooling is important. In the regime of the luminous hot accretion flow (LHAF), radiative cooling is even stronger than the viscous dissipation. In the one dimensional case, this implies that the inward increase of entropy will become slower or the entropy even decreases inward in the case of an LHAF. We therefore expect that convective instability becomes weaker or completely disappears when radiative cooling is important. To examine the validity of this expectation, in this paper we perform two-dimensional hydrodynamical simulations of hot accretion flows with strong radiative cooling. We find that compared to the case of negligible radiation, convection only becomes slightly weaker. Even an LHAF is still strongly convectively unstable, its radial profile of accretion rate correspondingly changes little. We find the reason is that the entropy still increases inward in the two-dimensional case.Comment: moderately revised, one figure added; 11 pages, 10 figures; accepted by MNRA

    1+1-dimensional p-wave superconductors from intersecting D-branes

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    In this work we explore 1+1 dimensional p-wave superconductors using the probe D-brane construction. Specifically, we choose three intersecting D-brane models: D1/D5, D2/D4 and D3/D3 systems. According to the dilaton running behavior, we denote the former two systems as nonconformal models and the last system as conformal. We find that all three models are qualitatively similar in describing superconducting condensate as well as some basic features (such as the gap formation and DC superconductivity) of superconducting conductivity. There also exist some differences among the three models as far as the AC conductivity is concerned. Specifically, for D3/D3 model there is no peak at nonzero frequency for the imaginary part of the conductivity, which is present in the nonconformal models; their asymptotic behaviors are different-for D1/D5 the real part of the AC conductivity approaches one at large frequency limit, for D2/D4 it slowly goes to a certain nonzero constant smaller than one and for D3/D3 it goes to zero. We find the profile of the AC conductivity for the D1/D5 system is very similar to that of higher dimensional p-wave superconductors.Comment: v2: matched with the published versio
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