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Stringy Models of Modified Gravity: Space-time defects and Structure Formation

Starting from microscopic models of space-time foam, based on brane universes propagating in bulk space-times populated by D0-brane defects ("D-particles"), we arrive at effective actions used by a low-energy observer on the brane world to describe his/her observations of the Universe. The...

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Detalles Bibliográficos
Autores principales: Mavromatos, Nick E., Sakellariadou, Mairi, Yusaf, Muhammad Furqaan
Lenguaje:eng
Publicado: 2012
Materias:
Acceso en línea:https://dx.doi.org/10.1088/1475-7516/2013/03/015
http://cds.cern.ch/record/1493104
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author Mavromatos, Nick E.
Sakellariadou, Mairi
Yusaf, Muhammad Furqaan
author_facet Mavromatos, Nick E.
Sakellariadou, Mairi
Yusaf, Muhammad Furqaan
author_sort Mavromatos, Nick E.
collection CERN
description Starting from microscopic models of space-time foam, based on brane universes propagating in bulk space-times populated by D0-brane defects ("D-particles"), we arrive at effective actions used by a low-energy observer on the brane world to describe his/her observations of the Universe. These actions include, apart from the metric tensor field, also scalar (dilaton) and vector fields, the latter describing the interactions of low-energy matter on the brane world with the recoiling point-like space-time defect (D-particle). The vector field is proportional to the recoil velocity of the D-particle and as such it satisfies a certain constraint. The vector breaks locally Lorentz invariance, which however is assumed to be conserved on average in a space-time foam situation, involving the interaction of matter with populations of D-particle defects. In this paper we demonstrate that, already at the end of the radiation era, the (constrained) vector field associated with the recoil of the defects provides the seeds for a growing mode in the evolution of the Universe. Such a growing mode survives during the matter dominated era, provided the variance of the D-particle recoil velocities on the brane is larger than a critical value.
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spelling cern-14931042023-10-04T08:51:10Zdoi:10.1088/1475-7516/2013/03/015http://cds.cern.ch/record/1493104engMavromatos, Nick E.Sakellariadou, MairiYusaf, Muhammad FurqaanStringy Models of Modified Gravity: Space-time defects and Structure FormationParticle Physics - TheoryStarting from microscopic models of space-time foam, based on brane universes propagating in bulk space-times populated by D0-brane defects ("D-particles"), we arrive at effective actions used by a low-energy observer on the brane world to describe his/her observations of the Universe. These actions include, apart from the metric tensor field, also scalar (dilaton) and vector fields, the latter describing the interactions of low-energy matter on the brane world with the recoiling point-like space-time defect (D-particle). The vector field is proportional to the recoil velocity of the D-particle and as such it satisfies a certain constraint. The vector breaks locally Lorentz invariance, which however is assumed to be conserved on average in a space-time foam situation, involving the interaction of matter with populations of D-particle defects. In this paper we demonstrate that, already at the end of the radiation era, the (constrained) vector field associated with the recoil of the defects provides the seeds for a growing mode in the evolution of the Universe. Such a growing mode survives during the matter dominated era, provided the variance of the D-particle recoil velocities on the brane is larger than a critical value.Starting from microscopic models of space-time foam, based on brane universes propagating in bulk space-times populated by D0-brane defects (``D-particles''), we arrive at effective actions used by a low-energy observer on the brane world to describe his/her observations of the Universe. These actions include, apart from the metric tensor field, also scalar (dilaton) and vector fields, the latter describing the interactions of low-energy matter on the brane world with the recoiling point-like space-time defect (D-particle). The vector field is proportional to the recoil velocity of the D-particle and as such it satisfies a certain constraint. The vector breaks locally Lorentz invariance, which however is assumed to be conserved on average in a space-time foam situation, involving the interaction of matter with populations of D-particle defects. In this paper we clarify the role of fluctuations of the vector field on structure formation and galactic growth. In particular we demonstrate that, already at the end of the radiation era, the (constrained) vector field associated with the recoil of the defects provides the seeds for a growing mode in the evolution of the Universe. Such a growing mode survives during the matter dominated era, provided the variance of the D-particle recoil velocities on the brane is larger than a critical value. We note that in this model, as a result of specific properties of D-brane dynamics in the bulk, there is no issue of overclosing the brane Universe for large defect densities. Thus, in these models, the presence of defects may be associated with large-structure formation. Although our string inspired models do have (conventional, from a particle physics point of view) dark matter components, nevertheless it is interesting that the role of ``extra'' dark matter is also provided by the population of massive defects. This is consistent with the weakly interacting character of the D-particle defects, which predominantly interact only gravitationally.Starting from microscopic models of space-time foam, based on brane universes propagating in bulk space-times populated by D0-brane defects ("D-particles"), we arrive at effective actions used by a low-energy observer on the brane world to describe his/her observations of the Universe. These actions include, apart from the metric tensor field, also scalar (dilaton) and vector fields, the latter describing the interactions of low-energy matter on the brane world with the recoiling point-like space-time defect (D-particle). The vector field is proportional to the recoil velocity of the D-particle and as such it satisfies a certain constraint. The vector breaks locally Lorentz invariance, which however is assumed to be conserved on average in a space-time foam situation, involving the interaction of matter with populations of D-particle defects. In this paper we demonstrate that, already at the end of the radiation era, the (constrained) vector field associated with the recoil of the defects provides the seeds for a growing mode in the evolution of the Universe. Such a growing mode survives during the matter dominated era, provided the variance of the D-particle recoil velocities on the brane is larger than a critical value.arXiv:1211.1726KCL-PH-TH-2012-27LCTS-2012-30KCL-PH-TH-2012-27LCTS-2012-30oai:cds.cern.ch:14931042012-11-09
spellingShingle Particle Physics - Theory
Mavromatos, Nick E.
Sakellariadou, Mairi
Yusaf, Muhammad Furqaan
Stringy Models of Modified Gravity: Space-time defects and Structure Formation
title Stringy Models of Modified Gravity: Space-time defects and Structure Formation
title_full Stringy Models of Modified Gravity: Space-time defects and Structure Formation
title_fullStr Stringy Models of Modified Gravity: Space-time defects and Structure Formation
title_full_unstemmed Stringy Models of Modified Gravity: Space-time defects and Structure Formation
title_short Stringy Models of Modified Gravity: Space-time defects and Structure Formation
title_sort stringy models of modified gravity: space-time defects and structure formation
topic Particle Physics - Theory
url https://dx.doi.org/10.1088/1475-7516/2013/03/015
http://cds.cern.ch/record/1493104
work_keys_str_mv AT mavromatosnicke stringymodelsofmodifiedgravityspacetimedefectsandstructureformation
AT sakellariadoumairi stringymodelsofmodifiedgravityspacetimedefectsandstructureformation
AT yusafmuhammadfurqaan stringymodelsofmodifiedgravityspacetimedefectsandstructureformation