scholarly journals VACUUM POLARIZATION OF A CHARGED MASSLESS FERMIONIC FIELD BY A MAGNETIC FLUX IN THE COSMIC STRING SPACETIME

2004 ◽  
Vol 13 (04) ◽  
pp. 607-624 ◽  
Author(s):  
J. SPINELLY ◽  
E. R. BEZERRA DE MELLO
Keyword(s):  
Magnetic Flux ◽  
Cosmic String ◽  
Energy Momentum Tensor ◽  
Finite Thickness ◽  
Momentum Tensor ◽  
Homogeneous Field ◽  
Physical Systems ◽  
Left Handed ◽  
Spinor Fields ◽  
Fermionic Fields

We calculate the vacuum averages of the energy–momentum tensor associated with a massless left-handed spinor fields due to magnetic fluxes on idealized cosmic string spacetime. In this analysis three distinct configurations of magnetic fields are considered: (i) a homogeneous field inside the tube, (ii) a magnetic field proportional to 1/r, and (iii) a cylindrical shell with δ-function. In these three cases the axis of the infinitely long tubes of radius R coincides with the cosmic string. In order to proceed with these calculations we explicitly obtain the Euclidean Feynman propagators associated with these physical systems. As we shall see, these propagators possess two distinct parts. The first are the standard ones, i.e. corresponding to the spinor Green's functions associated with the massless fermionic fields on the idealized cosmic string spacetime with a magnetic flux running through the line singularity. The second parts are new, they are due to the finite thickness of the radius of the tubes. As we shall see these extra parts provide relevant contributions to the vacuum averages of the energy–momentum tensor.

scholarly journals Quantum Effects in the Spacetime of a Magnetic Flux Cosmic String

2003 ◽  
Vol 18 (12) ◽  
pp. 2093-2098 ◽  
Author(s):  
M. E. X. Guimarães ◽  
A. L. N. Oliveira
Keyword(s):  
Scalar Field ◽  
Magnetic Flux ◽  
Cosmic String ◽  
Energy Momentum Tensor ◽  
Vacuum Expectation ◽  
Momentum Tensor ◽  
Expectation Values ◽  
Charged Scalar ◽  
Average Value ◽  
Charged Scalar Field

In this work we compute the vacuum expectation values of the energy-momentum tensor and the average value of a massive, charged scalar field in the presence of a magnetic flux cosmic string for both zero- and finite-temperature cases.

scholarly journals VACUUM POLARIZATION BY FERMIONIC FIELDS IN HIGHER DIMENSIONAL COSMIC STRING SPACE-TIME

2009 ◽  
Vol 24 (08n09) ◽  
pp. 1481-1488 ◽  
Author(s):  
J. SPINELLY ◽  
E. R. BEZERRA DE MELLO
Keyword(s):  
Magnetic Flux ◽  
Cosmic String ◽  
Vacuum Polarization ◽  
Fractional Part ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Momentum Tensor ◽  
Closed Expression ◽  
Fermionic Fields ◽  
Tensor Formula

In this paper we investigate vacuum polarization effects associated with charged massive quantum fermionic fields in a six-dimensional cosmic string space-times considering the presence of a magnetic flux running along its core. We have shown that for specific values of the parameters which codify the presence of the cosmic string, and the fractional part of the ratio of the magnetic flux by the quantum one, a closed expression for the respective Green function is obtained. Adopting this result, we explicitly calculate the renormalized vacuum expectation value of the energy-momentum tensor, [Formula: see text], and analyse this result in some limiting cases.

scholarly journals LOCAL COSMIC STRING AND C-FIELD

2006 ◽  
Vol 21 (18) ◽  
pp. 3727-3732 ◽  
Author(s):  
F. RAHAMAN ◽  
R. MONDAL ◽  
M. KALAM
Keyword(s):  
Cosmic String ◽  
Energy Momentum Tensor ◽  
Momentum Tensor ◽  
Einstein’S Equations ◽  
Einstein's Equations

We investigate a local cosmic string with a phenomenological energy–momentum tensor as prescribed by Vilenkin, in the presence of C-field. The solutions of full nonlinear Einstein's equations for exterior and interior regions of such a string are presented.

scholarly journals VACUUM POLARIZATION IN A COSMIC STRING SPACETIME INDUCED BY FLAT BOUNDARY

2011 ◽  
Vol 03 ◽  
pp. 434-445
Author(s):  
EUGÊNIO R. BEZERRA DE MELLO ◽  
ARAM A. SAHARIAN
Keyword(s):  
Cosmic String ◽  
Vacuum Polarization ◽  
Energy Momentum Tensor ◽  
Neumann Boundary ◽  
Vacuum Expectation ◽  
Momentum Tensor ◽  
Massive Scalar ◽  
Expectation Values ◽  
Massive Scalar Field ◽  
Higher Dimensional

In this paper we analyze the vacuum expectation values of the field squared and the energy-momentum tensor associated to a massive scalar field in a higher dimensional cosmic string spacetime, obeying Dirichlet or Neumann boundary conditions on the surface orthogonal to the string.

scholarly journals VACUUM POLARIZATION IN THE SPACE–TIME OF A SCALAR–TENSOR COSMIC STRING

2001 ◽  
Vol 16 (24) ◽  
pp. 1565-1571 ◽  
Author(s):  
V. B. BEZERRA ◽  
R. M. TEIXEIRA FILHO ◽  
G. GREBOT ◽  
M. E. X. GUIMARÃES
Keyword(s):  
Cosmic String ◽  
Polarization Effect ◽  
Vacuum Polarization ◽  
Energy Momentum Tensor ◽  
Vacuum Expectation ◽  
Momentum Tensor ◽  
Space Time ◽  
Scalar Tensor Theory ◽  
Expectation Values ◽  
Tensor Theory

We study the vacuum polarization effect in the space–time generated by a magnetic flux cosmic string in the framework of a scalar–tensor theory of gravity. The vacuum expectation values of the energy–momentum tensor of a conformally coupled scalar field are calculated and the dilaton's contribution to the vacuum polarization effect is shown.

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