2,515 research outputs found

    Exactly solvable model of the 2D electrical double layer

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    We consider equilibrium statistical mechanics of a simplified model for the ideal conductor electrode in an interface contact with a classical semi-infinite electrolyte, modeled by the two-dimensional Coulomb gas of pointlike ±\pm unit charges in the stability-against-collapse regime of reduced inverse temperatures 0β<20\le \beta<2. If there is a potential difference between the bulk interior of the electrolyte and the grounded interface, the electrolyte region close to the interface (known as the electrical double layer) carries some nonzero surface charge density. The model is mappable onto an integrable semi-infinite sine-Gordon theory with Dirichlet boundary conditions. The exact form-factor and boundary state information gained from the mapping provide asymptotic forms of the charge and number density profiles of electrolyte particles at large distances from the interface. The result for the asymptotic behavior of the induced electric potential, related to the charge density via the Poisson equation, confirms the validity of the concept of renormalized charge and the corresponding saturation hypothesis. It is documented on the non-perturbative result for the asymptotic density profile at a strictly nonzero β\beta that the Debye-H\"uckel β0\beta\to 0 limit is a delicate issue.Comment: 14 page

    Renormalized effective actions for the O(N) model at next-to-leading order of the 1/N expansion

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    A fully explicit renormalized quantum action functional is constructed for the O(N)-model in the auxiliary field formulation at next-to-leading order (NLO) of the 1/N expansion. Counterterms are consistently and explicitly derived for arbitrary constant vacuum expectation value of the scalar and auxiliary fields. The renormalized NLO pion propagator is exact at this order and satisfies Goldstone's theorem. Elimination of the auxiliary field sector at the level of the functional provides with order N^0 accuracy the renormalized effective action of the model in terms of the original variables. Alternative elimination of the pion and sigma propagators provides the renormalized NLO effective potential for the expectation values of the N-vector and of the auxiliary field with the same accuracy.Comment: RevTeX4, 19 pages, 3 figures. Version published Phys. Rev.

    Classical Physics and Quantum Loops

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    The standard picture of the loop expansion associates a factor of h-bar with each loop, suggesting that the tree diagrams are to be associated with classical physics, while loop effects are quantum mechanical in nature. We discuss examples wherein classical effects arise from loop contributions and display the relationship between the classical terms and the long range effects of massless particles.Comment: 15 pages, 3 figure

    Zurek-Kibble Mechanism for the Spontaneous Vortex Formation in NbAl/Alox/NbNb-Al/Al_{ox}/Nb Josephson Tunnel Junctions: New Theory and Experiment

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    New scaling behavior has been both predicted and observed in the spontaneous production of fluxons in quenched NbAl/Alox/NbNb-Al/Al_{ox}/Nb annular Josephson tunnel junctions as a function of the quench time, τQ\tau_{Q}. The probability f1f_{1} to trap a single defect during the N-S phase transition clearly follows an allometric dependence on τQ\tau_{Q} with a scaling exponent σ=0.5\sigma = 0.5, as predicted from the Zurek-Kibble mechanism for {\it realistic} JTJs formed by strongly coupled superconductors. This definitive experiment replaces one reported by us earlier, in which an idealised model was used that predicted σ=0.25\sigma = 0.25, commensurate with the then much poorer data. Our experiment remains the only condensed matter experiment to date to have measured a scaling exponent with any reliability.Comment: Four pages, one figur

    Optimized perturbation theory for charged scalar fields at finite temperature and in an external magnetic field

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    Symmetry restoration in a theory of a self-interacting charged scalar field at finite temperature and in the presence of an external magnetic field is examined. The effective potential is evaluated nonperturbatively in the context of the optimized perturbation theory method. It is explicitly shown that in all ranges of the magnetic field, from weak to large fields, the phase transition is second order and that the critical temperature increases with the magnetic field. In addition, we present an efficient way to deal with the sum over the Landau levels, which is of interest especially in the case of working with weak magnetic fields.Comment: 18 pages, 7 eps figures. References added and some small improvements to the tex

    From toothpick legs to dropping vaginas: Gender and sexuality in Joan Rivers' stand-up comedy performance

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    This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2011 Intellect.This article employs sociocultural analysis to examine Joan Rivers’ stand-up comedy performances in order to reveal how she successfully operates in a sphere of artistic expression that has been, and continues to be, male-dominated. The analysis uncovers how Rivers’ stand-up comedy performance involves a complex combination of elements and how it fuses features that are regarded as ‘traditionally masculine’, such as aggression, with features frequently used by other female stand-up comedians, such as self-deprecating comedy and confessional comedy. Furthermore, the analysis exposes the complex ways in which constructions of gender and sexuality are negotiated and re-negotiated in Rivers’ stand-up comedy performance, and illustrates how dominant ideological identity constructions can be simultaneously reinforced and subverted within the same comic moment

    Combination structural support and thermal protection system

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    A combination structural support and thermal protection system is provided. A cured preceramic polymer matrix reinforced with carbon fibers can be used alone or in a multiple component system

    More on Gribov copies and propagators in Landau-gauge Yang-Mills theory

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    Fixing a gauge in the non-perturbative domain of Yang-Mills theory is a non-trivial problem due to the presence of Gribov copies. In particular, there are different gauges in the non-perturbative regime which all correspond to the same definition of a gauge in the perturbative domain. Gauge-dependent correlation functions may differ in these gauges. Two such gauges are the minimal and absolute Landau gauge, both corresponding to the perturbative Landau gauge. These, and their numerical implementation, are described and presented in detail. Other choices will also be discussed. This investigation is performed, using numerical lattice gauge theory calculations, by comparing the propagators of gluons and ghosts for the minimal Landau gauge and the absolute Landau gauge in SU(2) Yang-Mills theory. It is found that the propagators are different in the far infrared and even at energy scales of the order of half a GeV. In particular, also the finite-volume effects are modified. This is observed in two and three dimensions. Some remarks on the four-dimensional case are provided as well.Comment: 23 pages, 16 figures, 6 tables; various changes throughout most of the paper; extended discussion on different possibilities to define the Landau gauge and connection to existing scenarios; in v3: Minor changes, error in eq. (3) & (4) corrected, version to appear in PR
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