35,876 research outputs found

    Analogy between turbulence and quantum gravity: beyond Kolmogorov's 1941 theory

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    Simple arguments based on the general properties of quantum fluctuations have been recently shown to imply that quantum fluctuations of spacetime obey the same scaling laws of the velocity fluctuations in a homogeneous incompressible turbulent flow, as described by Kolmogorov 1941 (K41) scaling theory. Less noted, however, is the fact that this analogy rules out the possibility of a fractal quantum spacetime, in contradiction with growing evidence in quantum gravity research. In this Note, we show that the notion of a fractal quantum spacetime can be restored by extending the analogy between turbulence and quantum gravity beyond the realm of K41 theory. In particular, it is shown that compatibility of a fractal quantum-space time with the recent Horava-Lifshitz scenario for quantum gravity, implies singular quantum wavefunctions. Finally, we propose an operational procedure, based on Extended Self-Similarity techniques, to inspect the (multi)-scaling properties of quantum gravitational fluctuations.Comment: Sliglty modified version of the article about to appear in IJMP

    Gravitational Theory with a Dynamical Time

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    A gravitational theory involving a vector field χμ\chi^{\mu}, whose zero component has the properties of a dynamical time, is studied. The variation of the action with respect to χμ\chi^{\mu} gives the covariant conservation of an energy momentum tensor T(χ)μν T^{\mu \nu}_{(\chi)}. Studying the theory in a background which has killing vectors and killing tensors we find appropriate shift symmetries of the field χμ\chi^{\mu} which lead to conservation laws. The energy momentum that is the source of gravity T(G)μν T^{\mu \nu}_{(G)} is different but related to T(χ)μν T^{\mu \nu}_{(\chi)} and the covariant conservation of T(G)μν T^{\mu \nu}_{(G)} determines in general the vector field χμ\chi^{\mu}. When T(χ)μν T^{\mu \nu}_{(\chi)} is chosen to be proportional to the metric, the theory coincides with the Two Measures Theory, which has been studied before in relation to the Cosmological Constant Problem. When the matter model consists of point particles, or strings, the form of T(G)μν T^{\mu \nu}_{(G)}, solutions for χμ\chi^{\mu} are found. For the case of a string gas cosmology, we find that the Milne Universe can be a solution, where the gas of strings does not curve the spacetime since although T(χ)μν0 T^{\mu \nu}_{(\chi)} \neq 0, T(G)μν=0 T^{\mu \nu}_{(G)}= 0, as a model for the early universe, this solution is also free of the horizon problem. There may be also an application to the "time problem" of quantum cosmology.Comment: 21 pages, discussions extended, some more explicit proofs included, more references include

    Reactor Searches for Neutrino Magnetic Moment as a Probe of Extra Dimensions

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    We present calculations of the magnetic moment contribution to neutrino electron scattering in large extra dimension brane-bulk models (LED) with three bulk neutrinos. We discuss the cases with two and three large extra dimensions of sizes RR. The calculations are done using reactor flux from Uranium, 235U^{235}U as the neutrino source. We find that if the electron neutrino mass is chosen to be in the range of one eV, the differential cross section for νˉe\bar{\nu}-e scattering for low electron recoil energy can be of the same order as the presently explored values in reactor experiments. Furthermore the spectral shape for the LED models is different from the four dimensional case. Future higher precision reactor experiments can therefore be used to provide new constraints on a class of large extra dimension theories.Comment: 8 pages; 3 figure

    Kinetic modeling of Secondary Organic Aerosol formation: effects of particle- and gas-phase reactions of semivolatile products

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    The distinguishing mechanism of formation of secondary organic aerosol (SOA) is the partitioning of semivolatile hydrocarbon oxidation products between the gas and aerosol phases. While SOA formation is typically described in terms of partitioning only, the rate of formation and ultimate yield of SOA can also depend on the kinetics of both gas- and aerosol-phase processes. We present a general equilibrium/kinetic model of SOA formation that provides a framework for evaluating the extent to which the controlling mechanisms of SOA formation can be inferred from laboratory chamber data. With this model we examine the effect on SOA formation of gas-phase oxidation of first-generation products to either more or less volatile species, of particle-phase reaction (both first- and second-order kinetics), of the rate of parent hydrocarbon oxidation, and of the extent of reaction of the parent hydrocarbon. The effect of pre-existing organic aerosol mass on SOA yield, an issue of direct relevance to the translation of laboratory data to atmospheric applications, is examined. The importance of direct chemical measurements of gas- and particle-phase species is underscored in identifying SOA formation mechanisms

    Spontaneous Symmetry Breaking through Mixing

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    We discuss a model, in which the negative mass square needed in the Higgs mechanism is generated by mixing with a heavy scalar. We have two scalar doublets in the standard model. Phenomenological properties of the heavy new scalar are discussed. The heavy scalar can be detected by the LHC.Comment: 4 page

    The Ammann-Beenker tilings revisited

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    This paper introduces two tiles whose tilings form a one-parameter family of tilings which can all be seen as digitization of two-dimensional planes in the four-dimensional Euclidean space. This family contains the Ammann-Beenker tilings as the solution of a simple optimization problem.Comment: 7 pages, 4 figure

    Factors of Entrepreneurial Personality Characteristics on Business Failure of SMEs

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    The purpose of this research is to identifythefactorofentrepreneurialpersonality characteristics that can lead to the business failure of Small and Medium Enterprises (SME) in Melaka, Malaysia. This research used the Big Five Personality Model or OCEAN Model as the independent variables which include openness, conscientiousness, extraversion, agreeableness, and neuroticism. The quantitative method had been conducted by the researcher to collect the data through the questionnaire that was distributed and answered by the respondent of this research. A total of 379 Small and Medium Enterprises (SME) that established and operate in the business in Melaka, Malaysia had been participating in this data collection process. The result of the analysis showed that openness, conscientiousness, extraversion, and neuroticism have significant relationship with the factors of entrepreneurial personality characteristics on business failure of Small and Medium Enterprises (SME) in Melaka, Malaysia. There is one factor of entrepreneurial personality characteristics which is agreeableness has no significant relationship with factors of entrepreneurial personality characteristics on business failure of Small and Medium Enterprises (SME) in Melaka, Malaysia. The result of this study contributes in improve the rate of business success among SME in Melaka, Malaysia by eliminating the possibility of business failure.Keywords—Entrepreneurial personality characteristics, Big Five Personality Model, business failure, Small and Medium Enterprises (SME), Melaka.
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