44,473 research outputs found

    QCD color interactions between two quarks

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    We study the QCD color interactions between static two heavy quarks at zero temperature in a quenched SU(3) lattice gauge simulation: in addition to the standard singlet qqˉq\bar{q} potentials, we calculate octet qqˉq\bar{q} potentials, symmetric and antisymmetric qqqq potentials. It is shown that the antisymmetric qqqq channel behaves as a linearly rising potential at large quark separations. We further find that the qqˉq\bar{q} octet and qqqq symmetric channels have the complex dependence on the distance; at short distances they are repulsive forces, while at large distances, they show linearly rising feature. Ratio of string tensions between qqˉq\bar{q} singlet and qqqq antisymmetric potentials is described in terms of the Casimir factor

    Gluon Propagators and Confinement

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    We present SU(3) gluon propagators calculated on 48*48*48*N_t lattices at beta=6.8 where N_t=64 (corresponding the confinement phase) and N_t=16 (deconfinement) with the bare gauge parameter,alpha, set to be 0.1. In order to avoid Gribov copies, we employ the stochastic gauge fixing algorithm. Gluon propagators show quite different behavior from those of massless gauge fields: (1) In the confinement phase, G(t) shows massless behavior at small and large t, while around 5<t<15 it behaves as massive particle, and (2) effective mass observed in G(z) becomes larger as z increases. (3) In the deconfinement phase, G(z) shows also massive behavior but effective mass is less than in the confinement case. In all cases, slope masses are increasing functions of t or z, which can not be understood as addtional physical poles.Comment: 6 pages in Postscrip

    A Case Report of Folie\u27a Deux: Husband-and-Wife

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    Shared paranoid disorder is a relatively rare psychiatric disorder in which paranoid delusions are transferred from one individual to one or more other susceptible person(s) in close association. Folie a deux describes a shared paranoid disorder involving two people and is characterized by a complex dependant relationship between the involved individuals. Provided there is no additional underlying psychopathology, there is a good prognosis for the submissive partner. Here we present a case report and discussion off folie a deux involving a husband and wife. Although folie a deux is a relatively uncommon disorder, it is important to recognize such cases due to the potential for recovery in the submissive partner

    Determining the Equation of State of the Expanding Universe Using a New Independent Variable

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    To determine the equation of state of the universe, we propose to use a new independent variable R(H0/c)(dL(z)/(1+z))R\equiv (H_0/c)(d_L(z)/(1+z)), where H0H_0 and dL(z)d_L(z) are the present Hubble parameter and the luminosity distance, respectively. For the flat universe suggested from the observation of the anisotropy of cosmic microwave background, the density and the pressure are expressed as ρ/ρ0=4(df/dR)2/f6\rho/\rho_0=4(df/dR)^2/f^6 and p/ρ0=4/3(d2f/dR2)/f5p/\rho_0=-4/3(d^2f/dR^2)/f^5 where ρ0\rho_0 is the present density and f(R)=1/1+z(R)f(R)=1/\sqrt{1+z(R)}. In (R,f)(R, f) plane the sign as well as the strength of the pressure is in proportion to the curvature of the curve f(R)f(R). We propose to adopt a Pade-like expression of f(R)=1/uf(R)=1/\sqrt{u} with u1+n=1NunRnu\equiv 1+\sum\limits_{n=1}^{N}u_nR^n. For flat Λ\Lambda model the expansion up to N=7 has at most an error <0.2< 0.2% for z<1.7z < 1.7 and any value of Λ\Lambda. We also propose a general method to determine the equation of state of the universe which has N1N-1 free parameters. If the number of parameters are smaller than N1N-1, there is a consistency check of the equation of state so that we may confirm or refute each model.Comment: 12 pages, to be published in the Astrophysical Journa