1,582 research outputs found

    Heat flow method to Lichnerowicz type equation on closed manifolds

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    In this paper, we establish existence results for positive solutions to the Lichnerowicz equation of the following type in closed manifolds -\Delta u=A(x)u^{-p}-B(x)u^{q},\quad in\quad M, where p>1,q>0p>1, q>0, and A(x)>0A(x)>0, B(x)0B(x)\geq0 are given smooth functions. Our analysis is based on the global existence of positive solutions to the following heat equation {ll} u_t-\Delta u=A(x)u^{-p}-B(x)u^{q},\quad in\quad M\times\mathbb{R}^{+}, u(x,0)=u_0,\quad in\quad M with the positive smooth initial data u0u_0.Comment: 10 page

    Localisation of Fermions to brane: Codimension d2d \geq 2

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    We investigate 4+d4+d dimensional fermionic models in which the system in codimension-dd supports a topologically stable solution, and in which the fermion may be localised to the brane, with power law in 'instanton' backgrounds and exponentially in 'soliton' backgrounds. When the fermions are isoscalars, the mechanism fails, while for isospinor fermions it is successful. As backgrounds we consider instantons of Yang--Mills and sigma models in even codimensions, solitons of sigma models in odd codimensions, as well as solitons of Higgs and Goldstone models in all codimensions.Comment: 20 pages latex; expande

    A Microscale Quadrupole Mass Spectrometer for Ion Species Analysis

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77363/1/AIAA-2004-3444-418.pd

    Finite Volume Effect of Nucleons and the Formation of the Quark-Gluon Plasma

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    We study a thermodynamically consistent implementation of the nucleon volume in the mean field theory, and find that this volume has large consequences on the properties of hadronic matter under extreme conditions such as in astrophysical objects and high energy heavy-ion collisions. It is shown that we can reproduce the critical temperature Tc200T_{c}\simeq 200 MeV predicted by lattice QCD calculations for the phase transition from hadronic matter to quark-gluon plasma, by using parameters which are adjusted to fit all empirical data for normal nuclear matter.Comment: 11 Latex pages, 4 figures upon reques

    A HIERARCHY OF GAUGED GRASSMANIAN MODELS IN 4p4p DIMENSIONS WITH SELF-DUAL INSTANTONS

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    We present a hierarchy of gauged Grassmanian models in 4p4p dimensions, where the gauge field takes its values in the 22p1×22p12^{2p- 1}\times 2^{2p-1} chiral representation of SO(4p). The actions of all these models are absolutely minimised by a hierarchy of self-duality equations, all of which reduce to a single pair of coupled ordinary differential equations when subjected to 4p4p dimensional spherical symmetry.Comment: latex file, 13 page

    Self-consistent description of nuclear compressional modes

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    Isoscalar monopole and dipole compressional modes are computed for a variety of closed-shell nuclei in a relativistic random-phase approximation to three different parametrizations of the Walecka model with scalar self-interactions. Particular emphasis is placed on the role of self-consistency which by itself, and with little else, guarantees the decoupling of the spurious isoscalar-dipole strength from the physical response and the conservation of the vector current. A powerful new relation is introduced to quantify the violation of the vector current in terms of various ground-state form-factors. For the isoscalar-dipole mode two distinct regions are clearly identified: (i) a high-energy component that is sensitive to the size of the nucleus and scales with the compressibility of the model and (ii) a low-energy component that is insensitivity to the nuclear compressibility. A fairly good description of both compressional modes is obtained by using a ``soft'' parametrization having a compression modulus of K=224 MeV.Comment: 28 pages and 10 figures; submitted to PR

    A Gaussian Theory of Superfluid--Bose-Glass Phase Transition

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    We show that gaussian quantum fluctuations, even if infinitesimal, are sufficient to destroy the superfluidity of a disordered boson system in 1D and 2D. The critical disorder is thus finite no matter how small the repulsion is between particles. Within the gaussian approximation, we study the nature of the elementary excitations, including their density of states and mobility edge transition. We give the gaussian exponent η\eta at criticality in 1D and show that its ratio to η\eta of the pure system is universal.Comment: Revtex 3.0, 11 pages (4 figures will be sent through airmail upon request

    Non-Gaussianity from Inflation

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    Correlated adiabatic and isocurvature perturbation modes are produced during inflation through an oscillation mechanism when extra scalar degrees of freedom other than the inflaton field are present. We show that this correlation generically leads to sizeable non-Gaussian features both in the adiabatic and isocurvature perturbations. The non-Gaussianity is first generated by large non-linearities in some scalar sector and then efficiently transferred to the inflaton sector by the oscillation process. We compute the cosmic microwave background angular bispectrum, providing a characteristic feature of such inflationary non-Gaussianity,which might be detected by upcoming satellite experiments.Comment: Revised version accepted for publication in Phys. Rev. D. 19 pages, LaTeX fil

    Nuclear matter incompressibility coefficient in relativistic and nonrelativistic microscopic models

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    We systematically analyze the recent claim that nonrelativistic and relativistic mean field (RMF) based random phase approximation (RPA) calculations for the centroid energy E_0 of the isoscalar giant monopole resonance yield for the nuclear matter incompressibility coefficient, K_{nm}, values which differ by about 20%. For an appropriate comparison with the RMF based RPA calculations, we obtain the parameters for the Skyrme force used in the nonrelativistic model by adopting the same procedure as employed in the determination of the NL3 parameter set of an effective Lagrangian used in the RMF model. Our investigation suggest that the discrepancy between the values of K_{nm} predicted by the relativistic and nonrelativistic models is significantly less than 20%.Comment: Revtex file (13 pages), appearing in PRC-Rapid Com
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