Papers by Flávio Takakura
Proceedings of International Workshop on Astroparticle and High Energy Physics — PoS(AHEP2003), 2003
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The Tenth Marcel Grossmann Meeting, 2006
ABSTRACT We obtain a new self-similar solution to the Einstein's equations in four-dimens... more ABSTRACT We obtain a new self-similar solution to the Einstein's equations in four-dimensions, representing the collapse of a spherically symmetric, minimally coupled, massless, scalar field. Depending on the value of certain parameters, this solution represents the formation of naked singularities and black holes. The black holes are identified as the Schwarzschild ones.
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We obtain a new self-similar solution to the Einstein's equations in four-dimensions, represe... more We obtain a new self-similar solution to the Einstein's equations in four-dimensions, representing the collapse of a spherically symmetric, minimally coupled, massless, scalar field. Depending on the value of certain parameters, this solution represents the formation of naked singularities and black holes. Since the black holes are identified as the Schwarzschild ones, one may naturally see how these black holes are produced as remnants of the scalar field collapse.
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Physical Review E, 1995
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Physical Review B, 1998
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Physical Review E, 1998
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Physical Review E, 2001
We study the nonequilibrium dynamics of a charge interacting with its own radiation, which origin... more We study the nonequilibrium dynamics of a charge interacting with its own radiation, which originates the radiation damping. The real-time equation of motion for the charge and the associated Langevin equation is found in classical limit. The equation of motion for the charge allows one to obtain the frequency-dependent coefficient of friction. In the lowest order we find that although the coefficient of static friction vanishes, there is dynamical dissipation represented by a non-Markovian dissipative kernel.
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Physics Letters A, 2010
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Physical Review D, 1992
ABSTRACT Quantum corrections to the tachyon amplitude are computed perturbatively using Polyakov&... more ABSTRACT Quantum corrections to the tachyon amplitude are computed perturbatively using Polyakov's method of quantization for the bosonic string. The tachyonic pole is eliminated for dimension {ital D}{ge}13.
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Physical Review D, 1998
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Optics Communications, 1999
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Nuclear Physics B - Proceedings Supplements, 2004
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Nuclear Physics B - Proceedings Supplements, 2004
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Nuclear Physics B, 2003
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Modern Physics Letters A, 2008
Improving the beginning steps of a previous work, we settle the dual embedding method (DEM) as an... more Improving the beginning steps of a previous work, we settle the dual embedding method (DEM) as an alternative and efficient method for obtaining dual equivalent actions also in D = 3. We show that we can obtain dual equivalent actions which were previously obtained in the literature using the gauging iterative Noether dualization method (NDM). We believe that, with the arbitrariness property of the zero mode, the DEM is more profound since it can reveal a whole family of dual equivalent actions. The result confirms the one obtained previously which is important since it has the same structure that appears in the Abelian Higgs model with an anomalous magnetic interaction.
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Journal of Physics A: Mathematical and General, 2005
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Journal of Physics A: Mathematical and General, 2005
... 0 = ˜ν(0) ˜θ ∂ ˜V (0)(ai,pi, η) ∂ ˜ξ(0) ˜θ = µθ ∂V (0)(ai,pi) ∂ξ(0)θ + µθ ∂G(1)(ai,pi, η) ∂ξ(... more ... 0 = ˜ν(0) ˜θ ∂ ˜V (0)(ai,pi, η) ∂ ˜ξ(0) ˜θ = µθ ∂V (0)(ai,pi) ∂ξ(0)θ + µθ ∂G(1)(ai,pi, η) ∂ξ(0)θ + µθ ∂G(2)(ai,pi, η) ∂ξ(0)θ + ··· + G(1)(ai,pi, η) ∂η + ∂G(2)(ai,pi, η) ∂η + ··· , 21) ... For a quadratic correction term, we get µθ ∂G(1)(ai,pi, η) ∂ξ(0)θ + ∂G(2)(ai,pi, η) ∂η = 0. (23) ...
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Journal of Mathematical Physics, 2005
The Wyman solution depends on two parameters, the mass M and the scalar charge Σ. If one fixes M ... more The Wyman solution depends on two parameters, the mass M and the scalar charge Σ. If one fixes M to a positive value, say M0, and lets Σ2 take values along the real line, we show that this solution exhibits a type of critical behavior, in analogy with the nonstatic massless scalar field solutions. For Σ2>0 the space-times have naked singularities, for Σ2=0 one has a Schwarzschild black hole of mass M0 and finally for −M02⩽Σ2<0 one has “wormhole-like” solutions. We also show that the Wyman solution is not self-similar, i.e., it does not admit a homothetic Killing vector.
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International Journal of Modern Physics A, 2006
In this paper we define a noncommutative (NC) metafluid dynamics.1,2 We applied the Dirac's q... more In this paper we define a noncommutative (NC) metafluid dynamics.1,2 We applied the Dirac's quantization to the metafluid dynamics on NC spaces. First class constraints were found which are the same obtained in Ref. 4. The gauge covariant quantization of the nonlinear equations of fields on noncommutative spaces were studied. We have found the extended Hamiltonian which leads to equations of motion in the gauge covariant form. In addition, we show that a particular transformation3 on the usual classical phase space (CPS) leads to the same results as of the ⋆-deformation with ν = 0. Besides, we have shown that an additional term is introduced into the dissipative force due to the NC geometry. This is an interesting feature due to the NC nature induced into model.
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International Journal of Modern Physics A, 2007
In this work we show that we can obtain dual equivalent actions following the symplectic formalis... more In this work we show that we can obtain dual equivalent actions following the symplectic formalism with the introduction of extra variables which enlarge the phase space. We show that the results are equal as the one obtained with the recently developed gauging iterative Noether dualization method. We believe that, with the arbitrariness property of the zero mode, the symplectic embedding method is more profound since it can reveal a whole family of dual equivalent actions. We illustrate the method demonstrating that the gauge-invariance of the electromagnetic Maxwell Lagrangian broken by the introduction of an explicit mass term and a topological term can be restored to obtain the dual equivalent and gauge-invariant version of the theory.
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Papers by Flávio Takakura