7,867 research outputs found

    Partition Functions, the Bekenstein Bound and Temperature Inversion in Anti-de Sitter Space and its Conformal Boundary

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    We reformulate the Bekenstein bound as the requirement of positivity of the Helmholtz free energy at the minimum value of the function L=E- S/(2\pi R), where R is some measure of the size of the system. The minimum of L occurs at the temperature T=1/(2\pi R). In the case of n-dimensional anti-de Sitter spacetime, the rather poorly defined size R acquires a precise definition in terms of the AdS radius l, with R=l/(n-2). We previously found that the Bekenstein bound holds for all known black holes in AdS. However, in this paper we show that the Bekenstein bound is not generally valid for free quantum fields in AdS, even if one includes the Casimir energy. Some other aspects of thermodynamics in anti-de Sitter spacetime are briefly touched upon.Comment: Latex, 32 page

    On two dimensional coupled bosons and fermions

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    We study complex bosons and fermions coupled through a generalized Yukawa type coupling in the large-N_c limit following ideas of Rajeev [Int. Jour. Mod. Phys. A 9 (1994) 5583]. We study a linear approximation to this model. We show that in this approximation we do not have boson-antiboson and fermion-antifermion bound states occuring together. There is a possibility of having only fermion-antifermion bound states. We support this claim by finding distributional solutions with energies lower than the two mass treshold in the fermion sector. This also has implications from the point of view of scattering theory to this model. We discuss some aspects of the scattering above the two mass treshold of boson pairs and fermion pairs. We also briefly present a gauged version of the same model and write down the linearized equations of motion.Comment: 25 pages, no figure

    Conductivity, weak ferromagnetism and charge instability in αMnS\alpha-MnS single crystal

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    The temperature dependence of resistivity, magnetization and electron-spin resonance of the αMnS\alpha- MnS single crystal were measured in temperature range of 5K<T<550K5 K < T < 550 K. Magnetization hysteresis in applied magnetic field up to 0.7 T at T=5K,77K,300KT=5 K, 77 K, 300 K, irreversible temperature behavior of magnetization and resistivity were found . The obtained data were explained in terms of degenerate tight binding model using random phase approximation. The contribution of holes in t2gt_{2g} and ege_g bands of manganese ions to the conductivity, optical absorbtion spectra and charge instability in αMnS\alpha -MnS were studied. Charge susceptibility maxima resulted from the competition of the on-site Coulomb interaction between the holes in different orbitals and small hybridization of sub-bands were calculated at T=160K,250K,475KT=160 K, 250 K, 475 K.Comment: 6 pages, 12 figure

    Turbulent Friction in Rough Pipes and the Energy Spectrum of the Phenomenological Theory

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    The classical experiments on turbulent friction in rough pipes were performed by J. Nikuradse in the 1930's. Seventy years later, they continue to defy theory. Here we model Nikuradse's experiments using the phenomenological theory of Kolmog\'orov, a theory that is widely thought to be applicable only to highly idealized flows. Our results include both the empirical scalings of Blasius and Strickler, and are otherwise in minute qualitative agreement with the experiments; they suggest that the phenomenological theory may be relevant to other flows of practical interest; and they unveil the existence of close ties between two milestones of experimental and theoretical turbulence.Comment: Accepted for publication in PRL; 4 pages, 4 figures; revised versio

    On Duality in the Born-Infeld Theory

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    The SL(2,R)SL(2,R) duality symmetric action for the Born-Infeld theory in terms of two potentials, coupled with non-trivial backgroud fields in four dimensions is established. This construction is carried out in detail by analysing the hamiltonian structure of the Born-Infeld theory. The equivalence with the usual Born-Infeld theory is shown.Comment: revtex, 4 page

    The local symmetries of M-theory and their formulation in generalised geometry

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    In the doubled field theory approach to string theory, the T-duality group is promoted to a manifest symmetry at the expense of replacing ordinary Riemannian geometry with generalised geometry on a doubled space. The local symmetries are then given by a generalised Lie derivative and its associated algebra. This paper constructs an analogous structure for M-theory. A crucial by-product of this is the derivation of the physical section condition for M-theory formulated in an extended space.Comment: 20 pages, v2: Author Name corrected, v3: typos correcte

    On Effective Action of Multiple M5-branes and ABJM Action

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    We calculate the fluctuations from the classical multiple M5-brane solution of ABJM action which we found in the previous paper. We obtain D4-brane-like action but the gauge coupling constant depends on the spacetime coordinate. This is consistent with the expected properties of M5-brane action, although we will need to take into account the monopole operators in order to fully understand M5-branes. We also see that the Nambu-Poisson bracket is hidden in the solution.Comment: 21 pages; v2:version to appear in JHE

    Rotating Hairy Black Holes

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    We construct stationary black holes in SU(2) Einstein-Yang-Mills theory, which carry angular momentum and electric charge. Possessing non-trivial non-abelian magnetic fields outside their regular event horizon, they represent non-perturbative rotating hairy black holes.Comment: 13 pages, including 4 eps figures, LaTex forma

    Androidal Fat Dominates in Predicting Cardiometabolic Risk in Postmenopausal Women

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    We hypothesized that soy isoflavones would attenuate the anticipated increase in androidal fat mass in postmenopausal women during the 36-month treatment, and thereby favorably modify the circulating cardiometabolic risk factors: triacylglycerol, LDL-C, HDL-C, glucose, insulin, uric acid, C-reactive protein, fibrinogen, and homocysteine. We collected data on 224 healthy postmenopausal women at risk for osteoporosis (45.8–65 y, median BMI 24.5) who consumed placebo or soy isoflavones (80 or 120 mg/d) for 36 months and used longitudinal analysis to examine the contribution of isoflavone treatment, androidal fat mass, other biologic factors, and dietary quality to cardiometabolic outcomes. Except for homocysteine, each cardiometabolic outcome model was significant (overall P-values from ≤.0001 to .0028). Androidal fat mass was typically the strongest covariate in each model. Isoflavone treatment did not influence any of the outcomes. Thus, androidal fat mass, but not isoflavonetreatment, is likely to alter the cardiometabolic profile in healthy postmenopausal women

    Super-Yang-Mills and M5-branes

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    We uplift 5-dimensional super-Yang-Mills theory to a 6-dimensional gauge theory with the help of a space-like constant vector ηM\eta^M, whose norm determines the Yang-Mills coupling constant. After the localization of ηM\eta^M the 6D gauge theory acquires Lorentzian invariance as well as scale invariance. We discuss KK states, instantons and the flux quantization. The 6D theory admits extended solutions like 1/2 BPS `strings' and monopoles.Comment: 15 pages; minor changes, to appear in JHE
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