14,200 research outputs found

    Subcritical Superstrings

    Get PDF
    We introduce the Liouville mode into the Green-Schwarz superstring. Like massive supersymmetry without central charges, there is no kappa symmetry. However, the second-class constraints (and corresponding Wess-Zumino term) remain, and can be solved by (twisted) chiral superspace in dimensions D=4 and 6. The matter conformal anomaly is c = 4-D < 1. It thus can be canceled for physical dimensions by the usual Liouville methods, unlike the bosonic string (for which the consistency condition is c = D <= 1).Comment: 9 pg., compressed postscript file (.ps.Z), other formats (.dvi, .ps, .ps.Z, 8-bit .tex) available at http://insti.physics.sunysb.edu/~siegel/preprints/ or at ftp://max.physics.sunysb.edu/preprints/siege

    Linear stability analysis of resonant periodic motions in the restricted three-body problem

    Full text link
    The equations of the restricted three-body problem describe the motion of a massless particle under the influence of two primaries of masses 1−μ1-\mu and μ\mu, 0≤μ≤1/20\leq \mu \leq 1/2, that circle each other with period equal to 2π2\pi. When μ=0\mu=0, the problem admits orbits for the massless particle that are ellipses of eccentricity ee with the primary of mass 1 located at one of the focii. If the period is a rational multiple of 2π2\pi, denoted 2πp/q2\pi p/q, some of these orbits perturb to periodic motions for μ>0\mu > 0. For typical values of ee and p/qp/q, two resonant periodic motions are obtained for μ>0\mu > 0. We show that the characteristic multipliers of both these motions are given by expressions of the form 1±C(e,p,q)μ+O(μ)1\pm\sqrt{C(e,p,q)\mu}+O(\mu) in the limit μ→0\mu\to 0. The coefficient C(e,p,q)C(e,p,q) is analytic in ee at e=0e=0 and C(e,p,q)=O(e^{\abs{p-q}}). The coefficients in front of e^{\abs{p-q}}, obtained when C(e,p,q)C(e,p,q) is expanded in powers of ee for the two resonant periodic motions, sum to zero. Typically, if one of the two resonant periodic motions is of elliptic type the other is of hyperbolic type. We give similar results for retrograde periodic motions and discuss periodic motions that nearly collide with the primary of mass 1−μ1-\mu

    Considerations on Super Poincare Algebras and their Extensions to Simple Superalgebras

    Get PDF
    We consider simple superalgebras which are a supersymmetric extension of \fspin(s,t) in the cases where the number of odd generators does not exceed 64. All of them contain a super Poincar\'e algebra as a contraction and another as a subalgebra. Because of the contraction property, some of these algebras can be interpreted as de Sitter or anti de Sitter superalgebras. However, the number of odd generators present in the contraction is not always minimal due to the different splitting properties of the spinor representations under a subalgebra. We consider the general case, with arbitrary dimension and signature, and examine in detail particular examples with physical implications in dimensions d=10d=10 and d=4d=4.Comment: 16 pages, AMS-LaTeX. Version to appear in the Reviews in Mathematical Physic

    The Strange and Spooky Battle over Bats and Black Dresses: The Commodification of Whitby Goth Weekend and the Loss of a Subculture

    Get PDF
    From counterculture to subculture to the ubiquity of every black-clad wannabe vampire hanging around the centre of Western cities, Goth has transcended a musical style to become a part of everyday leisure and popular culture. The music’s cultural terrain has been extensively mapped in the first decade of this century. In this article, we examine the phenomenon of the Whitby Goth Weekend, a modern Goth music festival, which has contributed to (and has been altered by) the heritage-tourism marketing of Whitby as the holiday resort of Dracula (the place where Bram Stoker imagined the Vampire Count arriving one dark and stormy night). We examine marketing literature and websites that sell Whitby as a spooky town, and suggest that this strategy has driven the success of the Goth festival. We explore the development of the festival and the politics of its ownership, and its increasing visibility as a mainstream tourist destination for those who want to dress up for the weekend. By interviewing Goths from the north of England, we suggest that the mainstreaming of the festival has led to it becoming less attractive to those more established, older Goths who see the subculture’s authenticity as being rooted in the post-punk era, and who believe that Goth subculture should be something one lives full-time

    Absence of squirt singularities for the multi-phase Muskat problem

    Get PDF
    In this paper we study the evolution of multiple fluids with different constant densities in porous media. This physical scenario is known as the Muskat and the (multi-phase) Hele-Shaw problems. In this context we prove that the fluids do not develop squirt singularities.Comment: 16 page

    Spectroscopy of a fractional Josephson vortex molecule

    Full text link
    In long Josephson junctions with multiple discontinuities of the Josephson phase, fractional vortex molecules are spontaneously formed. At each discontinuity point a fractional Josephson vortex carrying a magnetic flux ∣Φ∣<Φ0|\Phi|<\Phi_0, Φ0≈2.07×10−15\Phi_0\approx 2.07\times 10^{-15} Wb being the magnetic flux quantum, is pinned. Each vortex has an oscillatory eigenmode with a frequency that depends on Φ/Φ0\Phi/\Phi_0 and lies inside the plasma gap. We experimentally investigate the dependence of the eigenfrequencies of a two-vortex molecule on the distance between the vortices, on their topological charge ℘=2πΦ/Φ0\wp=2\pi\Phi/\Phi_0 and on the bias current γ\gamma applied to the Josephson junction. We find that with decreasing distance between vortices, a splitting of the eigenfrequencies occurs, that corresponds to the emergence of collective oscillatory modes of both vortices. We use a resonant microwave spectroscopy technique and find good agreement between experimental results and theoretical predictions.Comment: submitted to Phys. Rev.

    The natural science of cosmology

    Full text link
    The network of cosmological tests is tight enough now to show that the relativistic Big Bang cosmology is a good approximation to what happened as the universe expanded and cooled through light element production and evolved to the present. I explain why I reach this conclusion, comment on the varieties of philosophies informing searches for a still better cosmology, and offer an example for further study, the curious tendency of some classes of galaxies to behave as island universes.Comment: Keynote lecture at the seventh International Conference on Gravitation and Cosmology, Goa India, December 201

    Air entrainment through free-surface cusps

    Get PDF
    In many industrial processes, such as pouring a liquid or coating a rotating cylinder, air bubbles are entrapped inside the liquid. We propose a novel mechanism for this phenomenon, based on the instability of cusp singularities that generically form on free surfaces. The air being drawn into the narrow space inside the cusp destroys its stationary shape when the walls of the cusp come too close. Instead, a sheet emanates from the cusp's tip, through which air is entrained. Our analytical theory of this instability is confirmed by experimental observation and quantitative comparison with numerical simulations of the flow equations
    • …
    corecore