1,197 research outputs found

    Protogalactic Extension of the Parker Bound

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    We extend the Parker bound on the galactic flux F\cal F of magnetic monopoles. By requiring that a small initial seed field must survive the collapse of the protogalaxy, before any regenerative dynamo effects become significant, we develop a stronger bound. The survival and continued growth of an initial galactic seed field ≤10−9\leq 10^{-9}G demand that F≤5×10−21(m/1017GeV)cm−2sec−1sr−1{\cal F} \leq 5 \times 10^{-21} (m/10^{17} {GeV}) {cm}^{-2} {sec}^{-1} {sr}^{-1}. For a given monopole mass, this bound is four and a half orders of magnitude more stringent than the previous `extended Parker bound', but is more speculative as it depends on assumptions about the behavior of magnetic fields during protogalactic collapse. For monopoles which do not overclose the Universe (Ωm<1\Omega_m <1), the maximum flux allowed is now 8×10−198 \times 10^{-19} cm^{-2} s^{-1} sr^{-1}, a factor of 150 lower than the maximum flux allowed by the extended Parker bound.Comment: 9 pages, 1 eps figur

    Quantum carpet interferometry for trapped atomic Bose-Einstein condensates

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    We propose an ``interferometric'' scheme for Bose-Einstein condensates using near-field diffraction. The scheme is based on the phenomenon of intermode traces or quantum carpets; we show how it may be used in the detection of weak forces.Comment: 4 figures. Submitted to Phys. Rev.

    Reconciling inflation with openness

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    It is already understood that the increasing observational evidence for an open Universe can be reconciled with inflation if our horizon is contained inside one single huge bubble nucleated during the inflationary phase transition. In this frame of ideas, we show here that the probability of living in a bubble with the right Ω0\Omega_0 (now the observations require Ω0≈.2\Omega_0 \approx .2) can be comparable with unity, rather than infinitesimally small. For this purpose we modify both quantitatively and qualitatively an intuitive toy model based upon fourth order gravity. As this scheme can be implemented in canonical General Relativity as well (although then the inflation driving potential must be designed entirely ad hoc), inferring from the observations that Ω0<1\Omega_0 < 1 not only does not conflict with the inflationary paradigm, but rather supports therein the occurrence of a primordial phase transition.Comment: 4 pages, one postscript figure, to be published on Physical Review D PACS: 98.80. C

    Design, performance, and calibration of the CMS hadron-outer calorimeter

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    The outer hadron calorimeter (HCAL HO) of the CMS detector is designed to measure the energy that is not contained by the barrel (HCAL HB) and electromagnetic (ECAL EB) calorimeters. Due to space limitation the barrel calorimeters do not contain completely the hadronic shower and an outer calorimeter (HO) was designed, constructed and inserted in the muon system of CMS to measure the energy leakage. Testing and calibration of the HO was carried out in a 300 GeV/c test beam that improved the linearity and resolution. HO will provide a net improvement in missing E T measurements at LHC energies. Information from HO will also be used for the muon trigger in CMS

    Subjective Expected Utility with Non-Increasing Risk Aversion

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    It is shown that assumptions about risk aversion, usually studied under the pre-supposition of expected utility maximization, have a surprising extra merit at an earlier stage of the measurement work: together with the sure-thing principle, these assumptions imply subjective expected utility maximization for monotonic continuous weak orders

    Expansion of a Bose-Einstein Condensate in an atomic waveguide

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    The expansion of a Bose-Einstein condensate in an atomic waveguide is analyzed. We study different regimes of expansion, and identify a transient regime between one-dimensional and three-dimensional dynamics, in which the properties of the condensate and its further expansion can be well explained by reducing the transversal dynamics to a two-level system. The relevance of this regime in current experiments is discussed.Comment: 4 pages, 3 figs, Accepted for publication in Phys. Rev.

    Standard Model baryogenesis through four-fermion operators in braneworlds

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    We study a new baryogenesis scenario in a class of braneworld models with low fundamental scale, which typically have difficulty with baryogenesis. The scenario is characterized by its minimal nature: the field content is that of the Standard Model and all interactions consistent with the gauge symmetry are admitted. Baryon number is violated via a dimension-6 proton decay operator, suppressed today by the mechanism of quark-lepton separation in extra dimensions; we assume that this operator was unsuppressed in the early Universe due to a time-dependent quark-lepton separation. The source of CP violation is the CKM matrix, in combination with the dimension-6 operators. We find that almost independently of cosmology, sufficient baryogenesis is nearly impossible in such a scenario if the fundamental scale is above 100 TeV, as required by an unsuppressed neutron-antineutron oscillation operator. The only exception producing sufficient baryon asymmetry is a scenario involving out-of-equilibrium c quarks interacting with equilibrium b quarks.Comment: 39 pages, 5 figures v2: typos, presentational changes, references and acknowledgments adde

    Turbulence Modeling Using Fractional Derivatives

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    We propose a new turbulence model in this work. The main idea of the model is that the shear stresses are considered to be random variables and we assume that their differences with respect to time are Lévy-type distributions. This is a generalization of the classical Newton’s law of viscosity. We tested the model on the classical backward facing step benchmark problem. The simulation results are in a good accordance with real measurements

    Hadronic properties of the S_{11}(1535) studied by electroproduction off the deuteron

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    Properties of excited baryonic states are investigated in the context of electroproduction of baryon resonances off the deuteron. In particular, the hadronic radii and the compositeness of baryon resonances are studied for kinematic situations in which their hadronic reinteraction is the dominant contribution. Specifically, we study the reaction d(e,e′S11)Nd(e,e'S_{11})N at Q2≥1GeV2Q^2\ge 1 GeV^2 for kinematics in which the produced hadronic state reinteracts predominantly with the spectator nucleon. A comparison of constituent quark model and effective chiral Lagrangian calculations of the S11S_{11} shows substantial sensitivity to the structure of the produced resonance.Comment: 24 pages, 5 figure

    Long time dynamics and coherent states in nonlinear wave equations

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    We discuss recent progress in finding all coherent states supported by nonlinear wave equations, their stability and the long time behavior of nearby solutions.Comment: bases on the authors presentation at 2015 AMMCS-CAIMS Congress, to appear in Fields Institute Communications: Advances in Applied Mathematics, Modeling, and Computational Science 201
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