Search results for "IC framework"
showing 10 items of 268 documents
Vortex-liquid entanglement inBi2Sr2CaCu2O8+δfilms in the presence of quenched disorder
1998
We have investigated the thermally activated behavior of the in-plane electrical resistivity of ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\mathrm{\ensuremath{\delta}}}$ films for magnetic fields $Bl~{10}^{4}\mathrm{G}$ applied parallel to the $c$ axis. The activation energy in the vortex-liquid state changes suddenly at a crossover field ${B}_{\mathrm{cr}}.$ The anisotropy reduction generated by oxygen annealing leads to the increase of the crossover field. For $Bl{B}_{\mathrm{cr}},$ the activation energy $U$ is weakly magnetic-field dependent. For $Bg{B}_{\mathrm{cr}},$ $U(B,T)\ensuremath{\sim}(1\ensuremath{-}{T/T}_{c0}{)/B}^{1/2},$ which corresponds to an entan…
Close packing of clusters: Application toAl100
2003
The lowest energy configurations of close-packed clusters up to N=110 atoms with stacking faults are studied using the Monte Carlo method with Metropolis algorithm. Two types of contact interactions, a pair-potential and a many-atom interaction, are used. Enhanced stability is shown for N=12, 26, 38, 50, 59, 61, 68, 75, 79, 86, 100 and 102, of which only the sizes 38, 75, 79, 86, and 102 are pure FCC clusters, the others having stacking faults. A connection between the model potential and density functional calculations is studied in the case of Al_100. The density functional calculations are consistent with the experimental fact that there exist epitaxially grown FCC clusters starting from…
Pairing based cooling of Fermi gases
2007
We propose a pairing-based method for cooling an atomic Fermi gas. A three component (labels 1, 2, 3) mixture of Fermions is considered where the components 1 and 2 interact and, for instance, form pairs whereas the component 3 is in the normal state. For cooling, the components 2 and 3 are coupled by an electromagnetic field. Since the quasiparticle distributions in the paired and in the normal states are different, the coupling leads to cooling of the normal state even when initially $T_{paired}\geq T_{normal}$ (notation $T_S\geq T_N$). The cooling efficiency is given by the pairing energy and by the linewidth of the coupling field. No superfluidity is required: any type of pairing, or ot…
Observational effects of varying speed of light in quadratic gravity cosmological models
2017
We study different manifestations of the speed of light in theories of gravity where metric and connection are regarded as independent fields. We find that for a generic gravity theory in a frame with locally vanishing affine connection, the usual degeneracy between different manifestations of the speed of light is broken. In particular, the space-time causal structure constant ([Formula: see text]) may become variable in that local frame. For theories of the form [Formula: see text], this variation in [Formula: see text] has an impact on the definition of the luminosity distance (and distance modulus), which can be used to confront the predictions of particular models against Supernovae t…
Feynman diagrams as a weight system: four-loop test of a four-term relation
1996
At four loops there first occurs a test of the four-term relation derived by the second author in the course of investigating whether counterterms from subdivergence-free diagrams form a weight system. This test relates counterterms in a four-dimensional field theory with Yukawa and $\phi^4$ interactions, where no such relation was previously suspected. Using integration by parts, we reduce each counterterm to massless two-loop two-point integrals. The four-term relation is verified, with $ = 0 - 3\zeta_3 + 6\zeta_3 - 3\zeta_3 = 0$, demonstrating non-trivial cancellation of the trefoil knot and thus supporting the emerging connection between knots and counterterms, via transcendental number…
An invariant analytic orthonormalization procedure with applications
2007
We apply the orthonormalization procedure previously introduced by two of us and adopted in connection with coherent states to Gabor frames and other examples. For instance, for Gabor frames we show how to construct $g(x)\in L^2(\Bbb{R})$ in such a way the functions $g_{\underline n}(x)=e^{ian_1x}g(x+an_2)$, $\underline n\in\Bbb{Z}^2$ and $a$ some positive real number, are mutually orthogonal. We discuss in some details the role of the lattice naturally associated to the procedure in this analysis.
Zerfallende Zustände als physikalisch nichtisolierbare Teilsysteme
1976
Presently the investigations of decaying quantum mechanical systems lack a well-founded concept, which is reflected by several formal difficulties of the corresponding mathematical treatment. In order to clarify in some respect the situation, we investigate, within the framework of nonrelativistic quantum mechanics, the resonant scattering of an initially well localized partial wave packet ϕl(r, t). If the potential decreases sufficiently fast for r ∞, ϕl(r, t) can be expressed at sufficiently long time after the scattering has taken place, as ϕl(r, t) = I(r, t) + ∑ Niϕl(Ki, r) exp {–iKi2t/2M} × Θ(ki – γi – Mr/t), ϕl(Ki, r) being the resonant solution with complex “momentum” Ki = ki – iγi. …
Connection between certain massive and massless diagrams
1996
A useful connection between two-loop massive vacuum integrals and one-loop off-shell triangle diagrams with massless internal particles is established for arbitrary values of the space-time dimension {ital n}. {copyright} {ital 1996 The American Physical Society.}
Wave functions of composite hadron states and relationship to couplings of scattering amplitudes for general partial waves
2012
In this paper we present the connection between scattering amplitudes in momentum space and wave functions in coordinate space, generalizing previous work done for $s$-waves to any partial wave. The relationship to the wave function of the residues of the scattering amplitudes at the pole of bound states or resonances is investigated in detail. A sum rule obtained for the couplings provides a generalization to coupled channels, any partial wave and bound or resonance states, of Weinberg's compositeness condition, which was only valid for weakly bound states in one channel and $s$-wave. An example, requiring only experimental data, is shown for the $\ensuremath{\rho}$ meson indicating that i…
A realistic model of neutrino masses with a large neutrinoless double beta decay rate
2011
The minimal Standard Model extension with the Weinberg operator does accommodate the observed neutrino masses and mixing, but predicts a neutrinoless double beta ($0\nu\beta\beta$) decay rate proportional to the effective electron neutrino mass, which can be then arbitrarily small within present experimental limits. However, in general $0\nu\beta\beta$ decay can have an independent origin and be near its present experimental bound; whereas neutrino masses are generated radiatively, contributing negligibly to $0\nu\beta\beta$ decay. We provide a realization of this scenario in a simple, well defined and testable model, with potential LHC effects and calculable neutrino masses, whose two-loop…