Global Monopole Spacetime Research Articles

Kaluza–Klein magnetic monopole in five-dimensional global monopole spacetime

In this paper we present a solution for the Kaluza–Klein magnetic monopole in a five-dimensional global monopole spacetime. This new solution is a generalization of the previous ones, obtained by Gross and Perry (1983 Nucl. Phys. B 226 29), containing a magnetic monopole in a Ricci-flat formalism, and by Banerjee et al (1996 Class. Quantum Grav. 13 3141) for a global monopole in a five-dimensional spacetime, setting the specific integration constant equal to zero. Also we analyse the classical motion of a massive charged test particle on this manifold and present the equation for the classical trajectory obeyed by this particle.

Spinor Casimir densities for a spherical shell in the global monopole spacetime

We investigate the vacuum expectation values of the energy–momentum tensor and the fermionic condensate associated with a massive spinor field obeying the MIT bag boundary condition on a spherical shell in the global monopole spacetime. In order to do that, we use the generalized Abel–Plana summation formula. As we shall see, this procedure allows us to extract from the vacuum expectation values the contribution coming from the unbounded spacetime and to explicitly present the boundary induced parts. As regards the boundary induced contribution, two distinct situations are examined: the vacuum average effects inside and outside the spherical shell. The asymptotic behaviour of the vacuum densities is investigated near the sphere centre and near the surface, and at large distances from the sphere. In the limit of strong gravitational field corresponding to small values of the parameter describing the solid angle deficit in the global monopole geometry, the sphere induced expectation values are exponentially suppressed. We discuss, as a special case, the fermionic vacuum densities for the spherical shell on the background of the Minkowski spacetime. Previous approaches to this problem within the framework of the QCD bag models have been global and our calculation is a local extension of these contributions.

Reply to “Comment on ‘Gravitating magnetic monopole in the global monopole spacetime’ ”

In this Reply I present some arguments in favor of the stability of the topological defect composed by global and magnetic monopoles.Received 31 March 2003DOI:https://doi.org/10.1103/PhysRevD.68.088702©2003 American Physical Society

Vacuum polarization effects in the global monopole spacetime in the presence of the Wu–Yang magnetic monopole

In this paper, we consider the presence of the Wu–Yang magnetic monopole in the global monopole spacetime and their influence on the vacuum polarization effects around these two monopoles placed together. According to Wu and Yang (1976 Nucl. Phys. B 107 365) the solution of the Klein–Gordon equation in such an external field will not be an ordinary function but, instead, a section. Because of the peculiar radial symmetry of the global monopole spacetime, it is possible to cover its space section by two overlapping regions, needed to define the singularity-free vector potential, and to study the quantum effects due to a charged scalar field in this system. In order to develop this analysis, we construct the explicit Euclidean scalar Green section associated with a charged massless field in a global monopole spacetime in the presence of the Abelian Wu–Yang magnetic monopole. Using this Green section, it is possible to study the vacuum polarization effects. We explicitly calculate the renormalized vacuum expectation value ⟨Φ(x)*Φ(x)⟩Ren., associated with a charged scalar field operator and the respective energy–momentum tensor, ⟨Tμν(x)⟩Ren., which are expressed in terms of the parameter which codifies the presence of the global and magnetic monopoles.

Critical phenomena of gravitating monopoles in the spacetime of a global monopole

We present a numerical study of critical phenomena (including the Lue-Weinberg phenomenon) arising for gravitating monopoles in a global monopole spacetime. The equations of this model have been recently studied by Spinelly, de Freitas, and Bezerra in a domain of parameter space away from the critical points.

Gravitating magnetic monopole in the global monopole spacetime

In this paper we study the regular self-gravitating 't Hooft--Polyakov magnetic monopole in a global monopole spacetime. We show that, for the large distance, the structure of the manifold corresponds to the Reissner-Nordstr\"om spacetime with a solid angle deficit factor. Although we analyze static and spherically symmetric solutions, it is not possible to solve analytically the system of coupled differential equations and only numerical evaluations can provide detailed information about the behavior of this system at the neighborhood of the defect's core. So, for this reason we solve numerically the set of differential equations for the metric tensor and for the matter fields for different values of the Higgs field vacuum expectation value \ensuremath{\eta} and the self-coupling constant \ensuremath{\lambda}.

VACUUM POLARIZATION IN THE GLOBAL MONOPOLE SPACETIME AT FINITE TEMPERATURE

In this paper we calculate the thermal Green functions associated with massless scalar and spin-1/2 fields in the pointlike global monopole spacetime. The thermal average values of their respective energy-momentum tensors are formally presented and explicit calculations are performed for specific values of the parameter α which codify the presence of the monopole. Moreover their high-temperature limit behaviors are explicitly exhibited by numerical analysis.

Euclidean scalar Green function in a higher dimensional global monopole space–time

We construct the explicit Euclidean scalar Green function associated with a massless field in a higher dimensional global monopole space–time, i.e., a (1+d)-space–time with d⩾3 which presents a solid angle deficit. Our result is expressed in terms of an infinite sum of products of Legendre functions with Gegenbauer polynomials. Although this Green function cannot be expressed in a closed form, for the specific case where the solid angle deficit is very small, it is possible to develop the sum and obtain the Green function in a more workable expression. Having this expression it is possible to calculate the vacuum expectation value of some relevant operators. As an application of this formalism, we calculate the renormalized vacuum expectation value of the square of the scalar field, 〈Φ2(x)〉Ren, and the energy-momentum tensor, 〈Tμν(x)〉Ren, for the global monopole space–time with spatial dimensions d=4 and d=5.

Vacuum polarization for a massless spin-1/2 field in the global monopole spacetime at nonzero temperature

In this paper we present the effects produced by temperature in the renormalized vacuum expectation value of the zero–zero component of the energy–momentum tensor associated with a massless left-handed spinor field in the point-like global monopole spacetime. In order to develop this calculation we had to obtain the Euclidean thermal Green function in this background. Because the expression obtained for the thermal energy density cannot be expressed in a closed form, its explicit dependence on temperature is not completely evident. So, in order to obtain concrete information about its thermal behaviour, we develop a numerical analysis of our result in the high-temperature limit for specific values of the parameter α which codify the presence of the monopole.

GLOBAL MONOPOLES AND SCALAR FIELDS AS THE ELECTROGRAVITY DUAL OF SCHWARZSCHILD SPACE–TIME

We prove that both global monopole and minimally coupled static zero mass scalar field are electrogravity dual of the Schwarzschild solution or flat space and they share the same equation of state, [Formula: see text]. This property was however known for the global monopole space–time while it is for the first time being established for the scalar field. In particular, it turns out that the Xanthopoulos–Zannias scalar field solution is dual to flat space.

Physics in the Global Monopole Spacetime

In this paper we review some important aspects of the global monopole spacetime and present how this manifold modifies, at classical and quantum points of view, the movement of a charged particle. The explicit calculations of the renormalized vacuum expectation values of the energy-momentum tensors, aTmn(x)nRen., associated with massless bosonic and fermionic fields are also presented. Moreover the effect of the nonzero temperature in this previous formalism is analyzed. Finally, we briefly present other applications of this manifold in the topological inflation and condensed matter system.

Vacuum polarization for amassless scalar field in the global monopole spacetime at finitetemperature

In this paper we calculate the effects produced by the temperature in therenormalized vacuum expectation value of the square of the masslessscalar field in the pointlike global monopole spacetime. In order todevelop this calculation, we had to construct the Euclidean thermal Greenfunction associated with this field in this background. We also calculatethe high-temperature limit for the thermal average of the zero-zerocomponent of the energy-momentum tensor.

Vacuum polarization of a massless spinor field in global monopole spacetime

We calculate the renormalized vacuum average of the energy-momentum tensor of massless left-handed spinor field in the pointlike global monopole spacetime using point-separation approach. The general structure of the vacuum average of the energy-momentum tensor is obtained and expressed in terms of $<T^0_0>^{ren}$ component, explicit form of which is analyzed in great details for arbitrary solid angle deficit.

Quasi-asymptotically flat spacetimes and their ADM mass

We define spacetimes that are asymptotically flat, except for a deficit solid angle and present a definition of their `ADM' mass, which is finite for this class of spacetimes, and, in particular, coincides with the value of the parameter M of the global monopole spacetime studied by Vilenkin and Barriola. Moreover, we show that the definition is coordinate independent, and explain why it can, in some cases, be negative.