3,922 research outputs found

    Predictions from the Fritzsch-Type Lepton Mass Matrices

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    We revisit the Fritzsch-type lepton mass matrix models confronted with new experiments for neutrino mixings. It is shown that the model is viable and leads to a rather narrow range of free parameters. Using empirical mixing information between νe\nu_e and νμ\nu_\mu, and between νμ\nu_\mu and ντ\nu_\tau, it is predicted that the mixing angle between nuenu_e and ντ\nu_\tau is in the range 0.04<U13<0.200.04<|U_{13}|<0.20, consistent with the CHOOZ experiment and the lightest neutrino mass is 0.0004<m1<0.00300.0004<m_1<0.0030 eV. The range of the effective mass measured in double beta decay is 0.002<0.0070.002<0.007 eV.Comment: Latex file with 13 pages, 6 eps file

    Volume dependence of light hadron masses in full lattice QCD

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    The aim of the GRAL project is to simulate full QCD with standard Wilson fermions at light quark masses on small to medium-sized lattices and to obtain infinite-volume results by extrapolation. In order to establish the functional form of the volume dependence we study systematically the finite-size effects in the light hadron spectrum. We give an update on the status of the GRAL project and show that our simulation data for the light hadron masses depend exponentially on the lattice size.Comment: 3 pages, 1 figure, Lattice2003(spectrum

    How natural is a small but nonzero cosmological constant?

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    Based on our previous attempt, we propose a better way to understand a small but nonzero cosmological constant, as indicated by a number of recent observational studies. We re-examine the assumptions of our model of two scalar fields, trying to explain the basic mechanism resulting in a series of mini-inflations occuring nearly periodically with respect to lnt\ln t with tt the cosmic time. We also discuss how likely the solution of this type would be, depending on the choice of the parameters.Comment: 12 pages, latex, 5 figures as epsf files included, compressed uuencode

    Matter Distribution around Galaxies

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    We explore the mass distribution of material associated with galaxies from the observation of gravitational weak lensing for the galaxy mass correlation function with the aid of NN-body simulations of dark matter. The latter is employed to unfold various contributions that contribute to the integrated line of sight mass density. We conclude that galaxies have no definite edges of the matter distribution, extending to the middle to neighbouring galaxies with the density profile roughly r2.4r^{-2.4} beyond the virial radius. The mass distributed beyond the virial radius (gravitationally bound radius) explains the gap seen in the mass density estimates, the global value Ωm0.27\Omega_m\sim 0.27 and typically Ωgal0.15\Omega_{\rm gal} \sim 0.15 from the luminosity density multiplied by the mass to light ratio. We suggest to use a physical method of gravitational lensing to characterise galaxy samples rather than characterise them with photometric means.Comment: 16 pages, 5 figures. ApJ accepte