5,930 research outputs found

    A homotopy-theoretic view of Bott-Taubes integrals and knot spaces

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    We construct cohomology classes in the space of knots by considering a bundle over this space and "integrating along the fiber" classes coming from the cohomology of configuration spaces using a Pontrjagin-Thom construction. The bundle we consider is essentially the one considered by Bott and Taubes, who integrated differential forms along the fiber to get knot invariants. By doing this "integration" homotopy-theoretically, we are able to produce integral cohomology classes. We then show how this integration is compatible with the homology operations on the space of long knots, as studied by Budney and Cohen. In particular we derive a product formula for evaluations of cohomology classes on homology classes, with respect to connect-sum of knots.Comment: 32 page

    Optical, gravitational, and kinesthetic determinants of judged eye level

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    Subjects judged eye level, defined in three distinct ways relative to three distinct reference planes: a gravitational horizontal, giving the gravitationally referenced eye level (GREL); a visible surface, giving the surface-referenced eye level (SREL); and a plane fixed with respect to the head, giving the head-referenced eye level (HREL). The information available for these judgements was varied by having the subjects view an illuminated target that could be placed in a box which: (1) was pitched at various angles, (2) was illuminated or kept in darkness, (3) was moved to different positions along the subject's head-to-foot body axis, and (4) was viewed with the subjects upright or reclining. The results showed: (1) judgements of GREL made in the dark were 2.5 deg lower than in the light, with a significantly greater variability; (2) judged GREL was shifted approximately half of the way toward SREL when these two eye levels did not coincide; (3) judged SREL was shifted about 12 percent of the way toward HREL when these two eye levels did not coincide, (4) judged HREL was shifted about half way toward SREL when these two eye level did not coincide and when the subject was upright (when the subject was reclining, HREL was shifted approx. 90 percent toward SREL); (5) the variability of the judged HREL in the dark was nearly twice as great with the subject reclining than with the subject upright. These results indicate that gravity is an important source of information for judgement of eye level. In the absence of information concerning the direction of gravity, the ability to judge HREL is extremely poor. A visible environment does not seem to afford precise information as to judgements of direction, but it probably does afford significant information as to the stability of these judgements

    Diffusion Enhances Spontaneous Electroweak Baryogenesis

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    We include the effects of diffusion in the electroweak spontaneous baryogenesis scenario and show that it can greatly enhance the resultant baryon density, by as much as a factor of 1/αw41061/\alpha_w^4 \sim 10^6 over previous estimates. Furthermore, the baryon density produced is rather insensitive to parameters characterizing the first order weak phase transition, such as the width and propagation velocity of the phase boundary.Comment: 15 pages, uses harvmac and epsf macro

    Editorial

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    Strong Sphalerons and Electroweak Baryogenesis

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    We analyze the spontaneous baryogenesis and charge transport mechanisms suggested by Cohen, Kaplan and Nelson for baryon asymmetry generation in extended versions of electroweak theory. We find that accounting for non-perturbative chirality-breaking transitions due to strong sphalerons reduces the baryonic asymmetry by the factor (mt/πT)2(m_t/\pi T)^2 or αW\alpha_W, provided those processes are in thermal equilibrium.Comment: CERN-TH.7080/9

    Representation theory for the Kriz model

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    The natural action of the symmetric group on the configuration spaces F(X; n) induces an action on the Kriz model E(X; n). The represen- tation theory of this DGA is studied and a big acyclic subcomplex which is Sn-invariant is described.Comment: 25 page

    With missing title of the paper. Overrelaxation Algorithm for coupled Gauge-Higgs systems

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    In this letter we extent the overrelaxation algorithm, known to be very efficient in gauge theories, to coupled gauge-Higgs systems with a particular emphasis on the update of the radial mode of the Higgs field. Our numerical tests of the algorithm show that the autocorrelation times can be reduced substantially.Comment: 10pages, DESY-95-04

    On the multiplicity of non-iterated periodic billiard trajectories

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    We introduce the iteration theory for periodic billiard trajectories in a compact and convex domain of the Euclidean space, and we apply it to establish a multiplicity result for non-iterated trajectories.Comment: 21 pages, 2 figures; v3: final version, as publishe
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