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Can quantum effects due to a massless conformally coupled field avoid gravitational singularities?
dc.contributor.author | Haro Cases, Jaume |
dc.contributor.other | Universitat Politècnica de Catalunya. Departament de Matemàtica Aplicada I |
dc.date.accessioned | 2012-09-20T08:50:09Z |
dc.date.created | 2012-04 |
dc.date.issued | 2012-04 |
dc.identifier.citation | Haro, J. Can quantum effects due to a massless conformally coupled field avoid gravitational singularities?. "Theoretical and mathematical physics", Abril 2012, vol. 171, núm. 1, p. 563-574. |
dc.identifier.issn | 0040-5779 |
dc.identifier.uri | http://hdl.handle.net/2117/16532 |
dc.description.abstract | Using quantum corrections from massless fields conformally coupled to gravity, we study the possibility of avoiding singularities that appear in the flat Friedmann–Robertson–Walker model. We assume that the universe contains a barotropic perfect fluid with the state equation p = ωρ, where p is the pressure and ρ is the energy density. We study the dynamics of the model for all values of the parameter ω and also for all values of the conformal anomaly coefficients α and β. We show that singularities can be avoided only in the case where α > 0 and β < 0. To obtain an expanding Friedmann universe at late times with ω > −1 (only a one-parameter family of solutions, but no a general solution, has this behavior at late times), the initial conditions of the nonsingular solutions at early times must be chosen very exactly. These nonsingular solutions consist of a general solution (a two-parameter family) exiting the contracting de Sitter phase and a one-parameter family exiting the contracting Friedmann phase. On the other hand, for ω < −1 (a phantom field), the problem of avoiding singularities is more involved because if we consider an expanding Friedmann phase at early times, then in addition to fine-tuning the initial conditions, we must also fine-tune the parameters α and β to obtain a behavior without future singularities: only a oneparameter family of solutions follows a contracting Friedmann phase at late times, and only a particular solution behaves like a contracting de Sitter universe. The other solutions have future singularities. |
dc.format.extent | 12 p. |
dc.language.iso | eng |
dc.rights | Attribution-NonCommercial-NoDerivs 3.0 Spain |
dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/3.0/es/ |
dc.subject | Àrees temàtiques de la UPC::Matemàtiques i estadística |
dc.subject.other | conformal anomaly |
dc.subject.other | cosmological singularity avoidance |
dc.subject.other | semiclassical approximation |
dc.title | Can quantum effects due to a massless conformally coupled field avoid gravitational singularities? |
dc.type | Article |
dc.subject.lemac | Quàntums, Teoria dels |
dc.contributor.group | Universitat Politècnica de Catalunya. EGSA - Equacions Diferencials, Geometria, Sistemes Dinàmics i de Control, i Aplicacions |
dc.identifier.doi | 10.1007/s11232-012-0055-0 |
dc.description.peerreviewed | Peer Reviewed |
dc.relation.publisherversion | http://www.springerlink.com/content/w22566572x2705kx/fulltext.pdf |
dc.rights.access | Restricted access - publisher's policy |
local.identifier.drac | 10507635 |
dc.description.version | Postprint (published version) |
dc.date.lift | 10000-01-01 |
local.citation.author | Haro, J. |
local.citation.publicationName | Theoretical and mathematical physics |
local.citation.volume | 171 |
local.citation.number | 1 |
local.citation.startingPage | 563 |
local.citation.endingPage | 574 |
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