730 research outputs found

    A General Relativistic Rotating Evolutionary Universe

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    We show that when we work with coordinate cosmic time, which is not proper time, Robertson-Walker's metric, includes a possible rotational state of the Universe. An exact formula for the angular speed and the temporal metric coefficient, is found.Comment: 5 pages including front cover. Publishe

    The Pioneer Anomaly and a Machian Universe

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    We discuss astronomical and astrophysical evidence, which we relate to the principle of zero-total energy of the Universe, that imply several relations among the mass M, the radius R and the angular momentum L of a "large" sphere representing a Machian Universe. By calculating the angular speed, we find a peculiar centripetal acceleration for the Universe. This is an ubiquituous property that relates one observer to any observable. It turns out that this is exactly the anomalous acceleration observed on the Pioneers spaceships. We have thus, shown that this anomaly is to be considered a property of the Machian Universe. We discuss several possible arguments against our proposal.Comment: 6 pages including front page. Publishe

    Gaussian queues in light and heavy traffic

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    In this paper we investigate Gaussian queues in the light-traffic and in the heavy-traffic regime. The setting considered is that of a centered Gaussian process X≡{X(t):t∈R}X\equiv\{X(t):t\in\mathbb R\} with stationary increments and variance function σX2(⋅)\sigma^2_X(\cdot), equipped with a deterministic drift c>0c>0, reflected at 0: QX(c)(t)=sup⁡−∞<s≀t(X(t)−X(s)−c(t−s)).Q_X^{(c)}(t)=\sup_{-\infty<s\le t}(X(t)-X(s)-c(t-s)). We study the resulting stationary workload process QX(c)≡{QX(c)(t):t≄0}Q^{(c)}_X\equiv\{Q_X^{(c)}(t):t\ge0\} in the limiting regimes c→0c\to 0 (heavy traffic) and c→∞c\to\infty (light traffic). The primary contribution is that we show for both limiting regimes that, under mild regularity conditions on the variance function, there exists a normalizing function ÎŽ(c)\delta(c) such that QX(c)(ÎŽ(c)⋅)/σX(ÎŽ(c))Q^{(c)}_X(\delta(c)\cdot)/\sigma_X(\delta(c)) converges to a non-trivial limit in C[0,∞)C[0,\infty)

    Search for the decay K+→π+ΜΜˉK^+\to \pi^+ \nu \bar\nu in the momentum region Pπ<195 MeV/cP_\pi < 195 {\rm ~MeV/c}

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    We have searched for the decay K+→π+ΜΜˉK^+ \to \pi^+ \nu \bar\nu in the kinematic region with pion momentum below the K+→π+π0K^+ \to \pi^+ \pi^0 peak. One event was observed, consistent with the background estimate of 0.73±0.180.73\pm 0.18. This implies an upper limit on B(K+→π+ΜΜˉ)<4.2×10−9B(K^+ \to \pi^+ \nu \bar\nu)< 4.2\times 10^{-9} (90% C.L.), consistent with the recently measured branching ratio of (1.57−0.82+1.75)×10−10(1.57^{+1.75}_{-0.82}) \times 10^{-10}, obtained using the standard model spectrum and the kinematic region above the K+→π+π0K^+ \to \pi^+ \pi^0 peak. The same data were used to search for K+→π+X0K^+ \to \pi^+ X^0, where X0X^0 is a weakly interacting neutral particle or system of particles with 150<MX0<250 MeV/c2150 < M_{X^0} < 250 {\rm ~MeV/c^2}.Comment: 4 pages, 2 figure

    THE TIGHT-BINDING APPROACH TO THE DIELECTRIC RESPONSE IN THE MULTIBAND SYSTEMS

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    Starting from the random phase approximation for the weakly coupled multiband tightly-bounded electron systems, we calculate the dielectric matrix in terms of intraband and interband transitions. The advantages of this representation with respect to the usual plane-wave decomposition are pointed out. The analysis becomes particularly transparent in the long wavelength limit, after performing the multipole expansion of bare Coulomb matrix elements. For illustration, the collective modes and the macroscopic dielectric function for a general cubic lattice are derived. It is shown that the dielectric instability in conducting narrow band systems proceeds by a common softening of one transverse and one longitudinal mode. Furthermore, the self-polarization corrections which appear in the macroscopic dielectric function for finite band systems, are identified as a combined effect of intra-atomic exchange interactions between electrons sitting in different orbitals and a finite inter-atomic tunneling.Comment: 20 pages, LaTeX, no figure

    Aspects of hairy black holes in spontaneously-broken Einstein-Yang-Mills systems: Stability analysis and Entropy considerations

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    We analyze (3+1)-dimensional black-hole space-times in spontaneously broken Yang-Mills gauge theories that have been recently presented as candidates for an evasion of the scalar-no-hair theorem. Although we show that in principle the conditions for the no-hair theorem do not apply to this case, however we prove that the `spirit' of the theorem is not violated, in the sense that there exist instabilities, in both the sphaleron and gravitational sectors. The instability analysis of the sphaleron sector, which was expected to be unstable for topological reasons, is performed by means of a variational method. As shown, there exist modes in this sector that are unstable against linear perturbations. Instabilities exist also in the gravitational sector. A method for counting the gravitational unstable modes, which utilizes a catastrophe-theoretic approach is presented. The r\^ole of the catastrophe functional is played by the mass functional of the black hole. The Higgs vacuum expectation value (v.e.v.) is used as a control parameter, having a critical value beyond which instabilities are turned on. The (stable) Schwarzschild solution is then understood from this point of view. The catastrophe-theory appproach facilitates enormously a universal stability study of non-Abelian black holes, which goes beyond linearized perturbations. Some elementary entropy considerations are also presented...Comment: Latex file, 50 pages, 2 figures (included as PS files at the end: plot1.ps, plot2.ps

    Quark-Squark Alignment Revisited

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    We re-examine the possibility that the solution to the supersymmetric flavor problem is related to small mixing angles in gaugino couplings induced by approximate horizontal Abelian symmetries. We prove that, for a large class of models, there is a single viable structure for the down quark mass matrix with four holomorphic zeros. Consequently, we are able to obtain both lower and upper bounds on the supersymmetric mixing angles and predict the contributions to various flavor changing neutral current processes. We find that the most likely signals for alignment are ΔmD\Delta m_D close to the present bound, significant CP violation in D0−D0ˉD^0-\bar{D^0} mixing, and shifts of order a few percent in various CP asymmetries in B0B^0 and BsB_s decays. In contrast, the modifications to radiative B decays, to Ï”â€Č/Ï”\epsilon^\prime/\epsilon and to K→πΜΜˉK\to\pi\nu\bar\nu decays are small. We further investigate a new class of alignment models, where supersymmetric contributions to flavor changing processes are suppressed by both alignment and RGE-induced degeneracy.Comment: 20 pages, 3 figure

    Preanalytical, Analytical, and Computational Factors Affect Homeostasis Model Assessment Estimates

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    OBJECTIVE—We investigated how ÎČ-cell function and insulin sensitivity or resistance are affected by the type of blood sample collected or choice of insulin assay and homeostatis model assessment (HOMA) calculator (http://www.dtu.ox.ac.uk)

    No hair for spherical black holes: charged and nonminimally coupled scalar field with self--interaction

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    We prove three theorems in general relativity which rule out classical scalar hair of static, spherically symmetric, possibly electrically charged black holes. We first generalize Bekenstein's no--hair theorem for a multiplet of minimally coupled real scalar fields with not necessarily quadratic action to the case of a charged black hole. We then use a conformal map of the geometry to convert the problem of a charged (or neutral) black hole with hair in the form of a neutral self--interacting scalar field nonminimally coupled to gravity to the preceding problem, thus establishing a no--hair theorem for the cases with nonminimal coupling parameter Ο<0\xi<0 or Ο≄12\xi\geq {1\over 2}. The proof also makes use of a causality requirement on the field configuration. Finally, from the required behavior of the fields at the horizon and infinity we exclude hair of a charged black hole in the form of a charged self--interacting scalar field nonminimally coupled to gravity for any Ο\xi.Comment: 30 pages, RevTeX. Sec.IV corrected, simplified and shortened. Corrections to Sec.IIA between Eqs. 2.7 and Eq.2.1. First two paragraphs of Sec. VC new. To appear Phys. Rev. D, Oct. 15, 199

    Cancellation of Global Anomalies in Spontaneously Broken Gauge Theories

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    We discuss the generalization to global gauge anomalies of the familiar procedure for the cancellation of local gauge anomalies in effective theories of spontaneously broken symmetries. We illustrate this mechanism in a recently proposed six-dimensional extension of the standard model.Comment: 5 pages; v2: version to appear in Phys. Rev.
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