18,388 research outputs found

    Statistical Mechanics of Relativistic One-Dimensional Self-Gravitating Systems

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    We consider the statistical mechanics of a general relativistic one-dimensional self-gravitating system. The system consists of NN-particles coupled to lineal gravity and can be considered as a model of NN relativistically interacting sheets of uniform mass. The partition function and one-particle distitrubion functions are computed to leading order in 1/c1/c where cc is the speed of light; as cc\to\infty results for the non-relativistic one-dimensional self-gravitating system are recovered. We find that relativistic effects generally cause both position and momentum distribution functions to become more sharply peaked, and that the temperature of a relativistic gas is smaller than its non-relativistic counterpart at the same fixed energy. We consider the large-N limit of our results and compare this to the non-relativistic case.Comment: latex, 60 pages, 22 figure

    Numerical modeling of dynamic powder compaction using the Kawakita equation of state

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    Dynamic powder compaction is analyzed using the assumption that the powder behaves, while it is being compacted, like a hydrodynamic fluid in which deviatoric stress and heat conduction effects can be ignored throughout the process. This enables techniques of computational fluid dynamics such the equilibrium flux method to be used as a modeling tool. The equation of state of the powder under compression is assumed to be a modified version of the Kawakita loading curve. Computer simulations using this model are performed for conditions matching as closely as possible with those from experiments by Page and Killen [Powder Metall. 30, 233 (1987)]. The numerical and experimental results are compared and a surprising degree of qualitative agreement is observed

    Geologic evidence for the prolongation of active normal faults of the Mona Rift into northwestern Puerto Rico.

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    Topography, bathymetry, regional structural observations, and fault slip measurements support the idea that the Mona rift is an active, offshore extensional structure separating a colliding area (eastern Hispaniola) from a subducting area (northwestern Puerto Rico). Near the city of Aguadilla in northwestern Puerto Rico, paleostress reconstruction through fault slip analysis demonstrates that the Mona rift is opening in an E-W direction. Fault slip analysis also indicates that this opening is oblique in the southern part of the rift. We propose that oblique rifting results from accommodation of E-W extension by oblique right-lateral reactivation of previously mapped, northwest-trending Eocene basement convergent structures (Aguadilla faults, Cerro-Goden fault). The evolution of the stress field during the Miocene and the present E-W opening of the Mona rift support the assumption that the Miocene 25° counterclockwise rotation of Puerto Rico has stopped and that this island is presently moving to the east relative to the colliding Hispaniola

    Unified model for network dynamics exhibiting nonextensive statistics

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    We introduce a dynamical network model which unifies a number of network families which are individually known to exhibit qq-exponential degree distributions. The present model dynamics incorporates static (non-growing) self-organizing networks, preferentially growing networks, and (preferentially) rewiring networks. Further, it exhibits a natural random graph limit. The proposed model generalizes network dynamics to rewiring and growth modes which depend on internal topology as well as on a metric imposed by the space they are embedded in. In all of the networks emerging from the presented model we find q-exponential degree distributions over a large parameter space. We comment on the parameter dependence of the corresponding entropic index q for the degree distributions, and on the behavior of the clustering coefficients and neighboring connectivity distributions.Comment: 11 pages 8 fig

    Phenomenology in the Zee Model with the A_4 Symmetry

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    The Zee model generates neutrino masses at the one-loop level by adding charged SU(2)_L-singlet and extra SU(2)_L-doublet scalars to the standard model of particle physics. As the origin of the nontrivial structure of the lepton flavor mixing, we introduce the softly broken A_4 symmetry to the Zee model. This model is compatible with the tribimaximal mixing which agrees well with neutrino oscillation measurements. Then, a sum rule m_1 e^{i alpha_12} + 2 m_2 + 3 m_3 e^{i alpha_32} = 0 is obtained and it results in Delta m^2_31 < 0 and m_3 > 1.8*10^{-2}eV. The effective mass |(M_nu)_{ee}| for the neutrinoless double beta decay is predicted as | (M_\nu)_{ee} | > 1.7*10^{-2}eV. The characteristic particles in this model are SU(2)_L-singlet charged Higgs bosons s^+_alpha (alpha=xi,eta,zeta) which are made from a 3-representation of A_4. Contributions of s^+_alpha to the lepton flavor violating decays of charged leptons are almost forbidden by an approximately remaining Z_3 symmetry; only BR(tau to ebar mu mu) can be sizable by the flavor changing neutral current interaction with SU(2)_L-doublet scalars. Therefore, s^+_alpha can be easily light enough to be discovered at the LHC with satisfying current constraints. The flavor structures of BR(s^-_alpha to ell nu) are also discussed.Comment: 26 pages, 4 figures, version accepted by PR

    Accurate determination of the Lagrangian bias for the dark matter halos

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    We use a new method, the cross power spectrum between the linear density field and the halo number density field, to measure the Lagrangian bias for dark matter halos. The method has several important advantages over the conventional correlation function analysis. By applying this method to a set of high-resolution simulations of 256^3 particles, we have accurately determined the Lagrangian bias, over 4 magnitudes in halo mass, for four scale-free models with the index n=-0.5, -1.0, -1.5 and -2.0 and three typical CDM models. Our result for massive halos with MMM \ge M_* (MM_* is a characteristic non-linear mass) is in very good agreement with the analytical formula of Mo & White for the Lagrangian bias, but the analytical formula significantly underestimates the Lagrangian clustering for the less massive halos $M < M_*. Our simulation result however can be satisfactorily described, with an accuracy better than 15%, by the fitting formula of Jing for Eulerian bias under the assumption that the Lagrangian clustering and the Eulerian clustering are related with a linear mapping. It implies that it is the failure of the Press-Schechter theories for describing the formation of small halos that leads to the inaccuracy of the Mo & White formula for the Eulerian bias. The non-linear mapping between the Lagrangian clustering and the Eulerian clustering, which was speculated as another possible cause for the inaccuracy of the Mo & White formula, must at most have a second-order effect. Our result indicates that the halo formation model adopted by the Press-Schechter theories must be improved.Comment: Minor changes; accepted for publication in ApJ (Letters) ; 11 pages with 2 figures include

    Stocking rate and rate of superphosphate in a higher rainfall area

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    In its virgin state the area carried a forest association of red-gum and jarrah, and the soils are typical of large areas in the south-west of Western Australia. These gravelly soils have a high requirement for phosphate during their first years under pasture, and this trial was designed to investigate the relationship between rate of phosphate, stocking rate and pasture production over a number of seasons

    Electroweak Symmetry Breaking and Proton Decay in SO(10) SUSY-GUT with TeV W_R

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    In a recent paper, we proposed a new class of supersymmetric SO(10) models for neutrino masses where the TeV scale electroweak symmetry is SU(2)_L\times SU(2)_R\times U(1)_{B-L} making the associated gauge bosons W_R and Z' accessible at the Large Hadron Collider. We showed that there exists a domain of Yukawa coupling parameters and symmetry breaking patterns which give an excellent fit to all fermion masses including neutrinos. In this sequel, we discuss an alternative Yukawa pattern which also gives good fermion mass fit and then study the predictions of both models for proton lifetime. Consistency with current experimental lower limits on proton life time require the squark masses of first two generations to be larger than ~ 1.2 TeV. We also discuss how one can have simultaneous breaking of both SU(2)_R\times U(1)_{B-L} and standard electroweak symmetries via radiative corrections.Comment: 31 pages, 5 figures, 4 tables

    Quantum scalar field on three-dimensional (BTZ) black hole instanton: heat kernel, effective action and thermodynamics

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    We consider the behaviour of a quantum scalar field on three-dimensional Euclidean backgrounds: Anti-de Sitter space, the regular BTZ black hole instanton and the BTZ instanton with a conical singularity at the horizon. The corresponding heat kernel and effective action are calculated explicitly for both rotating and non-rotating holes. The quantum entropy of the BTZ black hole is calculated by differentiating the effective action with respect to the angular deficit at the conical singularity. The renormalization of the UV-divergent terms in the action and entropy is considered. The structure of the UV-finite term in the quantum entropy is of particular interest. Being negligible for large outer horizon area A+A_+ it behaves logarithmically for small A+A_+. Such behaviour might be important at late stages of black hole evaporation.Comment: 28 pages, latex, 2 figures now include

    Eguchi-Hanson Solitons in Odd Dimensions

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    We present a new class of solutions in odd dimensions to Einstein's equations containing either a positive or negative cosmological constant. These solutions resemble the even-dimensional Eguchi-Hanson-(A)dS metrics, with the added feature of having Lorentzian signatures. They are asymptotic to (A)dSd+1/Zp_{d+1}/Z_p. In the AdS case their energy is negative relative to that of pure AdS. We present perturbative evidence in 5 dimensions that such metrics are the states of lowest energy in their asymptotic class, and present a conjecture that this is generally true for all such metrics. In the dS case these solutions have a cosmological horizon. We show that their mass at future infinity is less than that of pure dS.Comment: 26 pages, Late
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