6,112 research outputs found

    Fate of Inhomogeneity in Schwarzschild-deSitter Space-time

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    We investigate the global structure of the space time with a spherically symmetric inhomogeneity using a metric junction, and classify all possible types. We found that a motion with a negative gravitational mass is possible although the energy condition of the matter is not violated. Using the result, formation of black hole and worm hole during the inflationary era is discussed.Comment: 6page

    Axionic Membranes

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    A metal ring removed from a soap-water solution encloses a film of soap which can be mathematically described as a minimal surface having the ring as its only boundary. This is known to everybody. In this letter we suggest a relativistic extension of the above fluidodynamic system where the soap film is replaced by a Kalb-Ramond gauge potential \b(x) and the ring by a closed string. The interaction between the \b-field and the string current excites a new configuration of the system consisting of a relativistic membrane bounded by the string. We call such a classical solution of the equation of motion an axionic membrane. As a dynamical system, the axionic membrane admits a Hamilton-Jacobi formulation which is an extension of the H-J theory of electromagnetic strings.Comment: 15 page

    Top Condensation without Fine-Tuning

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    Quadratic divergencies which lead to the usual fine-tuning or hierarchy problem are discussed in top condensation models. As in the Standard Model a cancellation of quadratic divergencies is not possible without the boson contributions in the radiative corrections which are absent in lowest order of an 1/Nc1/N_c-expansion. To deal with the cancellation of quadratic divergencies we propose therefore an expansion in the flavor degrees of freedom. In leading order we find the remarkable result that quadratic divergencies automatically disappear.Comment: LMU - 17/93, in LATEX, 12 pages and 3 pages of figures appended in Postscrip

    Black Objects in the Gauge Theory of P-Branes

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    Within the context of the recently formulated classical gauge theory of relativistic p-branes minimally coupled to general relativity in D-dimensional spacetimes, we obtain solutions of the field equations which describe black objects. Explicit solutions are found for two cases: D > p+1 (true p-branes) and D = p+1 (p-bags).Comment: 9 pages, REVTEX 3.

    Supersymmetry And Electron-hole Excitation in Semiconductor At Finite Temperature

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    The fermionic and bosonic electron-hole low lying excitations in a semiconductor are analyzed at finite temperature in a unified way following Nambu's quasi-supersymmetric approach for the BCS model of superconductivity. The effective lagrangian for the fermionic modes and for the bosonic low lying collective excitations in the semiconductor is no longer supersymmetric in a conventional finite temperature treatment. However the bosonic excitations don't couple directly to the heat bath and as a result, quasisupersymmetry is restored to the effective lagrangian when a redefinition of the coupling constant associated with the collective excitations is performed. Our result shows that although the mass and coupling parameters are now temperature dependent, the fermion and boson excited states pair together and can still be transmuted into one another.Comment: 23 pages with 3 independent EPS figures; to appear in Nulear Physics

    Instability of Massive Scalar Fields in Kerr-Newman Spacetime

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    We investigate the instability of charged massive scalar fields in Kerr-Newman spacetime. Due to the super-radiant effect of the background geometry, the bound state of the scalar field is unstable, and its amplitude grows in time. By solving the Klein-Gordon equation of the scalar field as an eigenvalue problem, we numerically obtain the growth rate of the amplitude of the scalar field. Although the dependence of the scalar field mass and the scalar field charge on this growth rate agrees with the result of the analytic approximation, the maximum value of the growth rate is three times larger than that of the analytic approximation. We also discuss the effect of the electric charge on the instability of the scalar field.Comment: 15 pages, 10 figures. Accepted for publication in Prog.Theor.Phy
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