The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform
Supriya Kar - One of the best experts on this subject based on the ideXlab platform.
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Quintessence and Effective AdS brane geometries
International Journal of Modern Physics A, 2015Co-Authors: K. Priyabrat Pandey, Abhishek K Singh, Sunita Singh, Supriya KarAbstract:A geometric torsion dynamics leading to an Effective Curvature in a second-order formalism on a D4-brane is revisited with a renewed interest. We obtain two Effective AdS 4 brane geometries on a vacuum created pair of [Formula: see text]-brane. One of them is shown to describe an AdS Schwarzschild spinning black hole and the other is shown to describe a spinning black hole bound state. It is argued that a D-instanton in a vacuum created anti-D3-brane within a pair may describe a quintessence. It may seem to incorporate a varying vacuum energy density in a brane universe. We consider the Effective Curvature scalar on S1 × S1 to analyze torsionless geometries on a vacuum created pair of [Formula: see text]-brane. The emergent AdS 3 brane is shown to describe a Schwarzschild and a Reissner–Nordstrom (RN) geometries in the presence of extra dimension(s).
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Discrete Torsion, (Anti) de Sitter D4-Brane and Tunneling
2014Co-Authors: Abhishek K Singh, Sunita Singh, Pratibha Pandey, Supriya KarAbstract:Abstract We obtain quantum geometries on a vacuum created pair of a ( D D ¯ ) 3 -brane, at a Big Bang singularity, by a local two form on a D 4 -brane. In fact our analysis is provoked by an established phenomenon leading to a pair creation by a gauge field at a black hole horizon by Stephen Hawking in 1975. Importantly, the five dimensional microscopic black holes are described by an Effective non-perturbative Curvature underlying a discrete torsion in a second order formalism. In the case for a non-propagating torsion, the Effective Curvature reduces to Riemannian, which in a low energy limit may describe Einstein vacuum in the formalism. In particular, our analysis suggests that a non-trivial space begin with a hot de Sitter brane-Universe underlying a nucleation of a vacuum pair of ( D D ¯ ) -instanton at a Big Bang. A pair of instanton nucleats a D-particle which in turn combines with an anti D-particle to describe a D-string and so on. The nucleation of a pair of higher dimensional pair of brane/anti-brane from a lower dimensional pair may be viewed via an expansion of the brane-Universe upon time. It is in conformity with the conjecture of a branes within a brane presumably in presence of the non-zero modes of two form. Interestingly, we perform a thermal analysis underlying various emergent quantum de Sitter vacua on a D 4 -brane and argue for the plausible tunneling geometries underlying a thermal equilibrium. It is argued that a de Sitter Schwarzschild undergoes quantum tunneling to an AdS-brane Schwarzschild via Nariai and de Sitter topological black hole.
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Quintessence and Effective AdS brane geometries
arXiv: High Energy Physics - Theory, 2014Co-Authors: K. Priyabrat Pandey, Abhishek K Singh, Sunita Singh, Supriya KarAbstract:A geometric torsion dynamics leading to an Effective Curvature in a second order formalism on a D4-brane is revisited with a renewed interest. We obtain two Effective $AdS_4$ brane geometries on a vacuum created pair of $(D{\bar D})_3$-brane. One of them is shown to describe an AdS Schwarzschild spinning black hole and the other is shown to describe a spinning black hole bound state. It is argued that a D-instanton in a vacuum created anti D3-brane within a pair may describe a quintessence. It may seen to incorporate a varying vacuum energy density in a brane universe. We consider the Effective Curvature scalar on $S^1\times S^1$ to analyze torsion-less geometries on a vacuum created pair of $(D{\bar D})_2$-brane. The emergent $AdS_3$ brane is shown to describe a Schwarzschild and a Reissner-Nordstrom (RN) geometries in presence of extra dimension(s).
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Emergent Schwarzschild and Reissner-Nordstrom black holes in four dimensions: An Effective Curvature sourced by a B 2 -field on a D 4 -brane
Physical Review D, 2013Co-Authors: Abhishek K Singh, Sunita Singh, K. Priyabrat Pandey, Supriya KarAbstract:We obtain a Schwarzschild and Reissner-Nordstrom emergent black holes by exploring the torsion dynamics in a generalized Curvature formulation, underlying an Effective ${D}_{4}$-brane on ${S}^{1}$. It is shown that a constant Effective metric, sourced by a background fluctuation in ${B}_{2}$ potential, on a ${D}_{3}$-brane receives a dynamical quantum correction in the presence of an electric charge.
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Discrete torsion, de Sitter tunneling vacua and AdS brane: U(1) gauge theory on D _4-brane and an Effective Curvature
Journal of High Energy Physics, 2013Co-Authors: Abhishek K Singh, Sunita Singh, K. Priyabrat Pandey, Supriya KarAbstract:The U(1) gauge dynamics on a D _4-brane is revisited, with a two form, to construct an Effective Curvature theory in a second order formalism. We exploit the local degrees in a two form, and modify its dynamics in a gauge invariant way, to incorporate a non-perturbative metric fluctuation in an Effective D _4-brane. Interestingly, the near horizon D _4-brane is shown to describe an asymptotic Anti de Sitter (AdS) in a semi-classical regime. Using Weyl scaling(s), we obtain the emergent rotating geometries leading to primordial de Sitter (dS) and AdS vacua in a quantum regime. Under a discrete transformation, we re-arrange the mixed dS patches to describe a Schwazschild-like dS (SdS) and a topological-like dS (TdS) black holes. We analyze SdS vacuum for Hawking radiations to arrive at Nariai geometry, where a discrete torsion forms a condensate. We perform thermal analysis to identify Nariai vacuum with a TdS. Investigation reveals an AdS patch within a thermal dS brane, which may provide a clue to unfold dS/CFT. In addition, the role of dark energy, sourced by a discrete torsion, in the dS vacua is investigated using Painleve geometries. It is argued that a D-instanton pair is created by a discrete torsion, with a Big Bang/Crunch, at the past horizon in a pure dS. Nucleation, of brane/anti-brane pair(s), is qualitatively analyzed to construct an Effective space-time on a D _4-brane and its anti brane. Analysis re-assures the significant role played by a non-zero mode, of NS-NS two form, to generalize the notion of branes within a brane.
Abhishek K Singh - One of the best experts on this subject based on the ideXlab platform.
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Quintessence and Effective AdS brane geometries
International Journal of Modern Physics A, 2015Co-Authors: K. Priyabrat Pandey, Abhishek K Singh, Sunita Singh, Supriya KarAbstract:A geometric torsion dynamics leading to an Effective Curvature in a second-order formalism on a D4-brane is revisited with a renewed interest. We obtain two Effective AdS 4 brane geometries on a vacuum created pair of [Formula: see text]-brane. One of them is shown to describe an AdS Schwarzschild spinning black hole and the other is shown to describe a spinning black hole bound state. It is argued that a D-instanton in a vacuum created anti-D3-brane within a pair may describe a quintessence. It may seem to incorporate a varying vacuum energy density in a brane universe. We consider the Effective Curvature scalar on S1 × S1 to analyze torsionless geometries on a vacuum created pair of [Formula: see text]-brane. The emergent AdS 3 brane is shown to describe a Schwarzschild and a Reissner–Nordstrom (RN) geometries in the presence of extra dimension(s).
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Discrete Torsion, (Anti) de Sitter D4-Brane and Tunneling
2014Co-Authors: Abhishek K Singh, Sunita Singh, Pratibha Pandey, Supriya KarAbstract:Abstract We obtain quantum geometries on a vacuum created pair of a ( D D ¯ ) 3 -brane, at a Big Bang singularity, by a local two form on a D 4 -brane. In fact our analysis is provoked by an established phenomenon leading to a pair creation by a gauge field at a black hole horizon by Stephen Hawking in 1975. Importantly, the five dimensional microscopic black holes are described by an Effective non-perturbative Curvature underlying a discrete torsion in a second order formalism. In the case for a non-propagating torsion, the Effective Curvature reduces to Riemannian, which in a low energy limit may describe Einstein vacuum in the formalism. In particular, our analysis suggests that a non-trivial space begin with a hot de Sitter brane-Universe underlying a nucleation of a vacuum pair of ( D D ¯ ) -instanton at a Big Bang. A pair of instanton nucleats a D-particle which in turn combines with an anti D-particle to describe a D-string and so on. The nucleation of a pair of higher dimensional pair of brane/anti-brane from a lower dimensional pair may be viewed via an expansion of the brane-Universe upon time. It is in conformity with the conjecture of a branes within a brane presumably in presence of the non-zero modes of two form. Interestingly, we perform a thermal analysis underlying various emergent quantum de Sitter vacua on a D 4 -brane and argue for the plausible tunneling geometries underlying a thermal equilibrium. It is argued that a de Sitter Schwarzschild undergoes quantum tunneling to an AdS-brane Schwarzschild via Nariai and de Sitter topological black hole.
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Quintessence and Effective AdS brane geometries
arXiv: High Energy Physics - Theory, 2014Co-Authors: K. Priyabrat Pandey, Abhishek K Singh, Sunita Singh, Supriya KarAbstract:A geometric torsion dynamics leading to an Effective Curvature in a second order formalism on a D4-brane is revisited with a renewed interest. We obtain two Effective $AdS_4$ brane geometries on a vacuum created pair of $(D{\bar D})_3$-brane. One of them is shown to describe an AdS Schwarzschild spinning black hole and the other is shown to describe a spinning black hole bound state. It is argued that a D-instanton in a vacuum created anti D3-brane within a pair may describe a quintessence. It may seen to incorporate a varying vacuum energy density in a brane universe. We consider the Effective Curvature scalar on $S^1\times S^1$ to analyze torsion-less geometries on a vacuum created pair of $(D{\bar D})_2$-brane. The emergent $AdS_3$ brane is shown to describe a Schwarzschild and a Reissner-Nordstrom (RN) geometries in presence of extra dimension(s).
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Emergent Schwarzschild and Reissner-Nordstrom black holes in four dimensions: An Effective Curvature sourced by a B 2 -field on a D 4 -brane
Physical Review D, 2013Co-Authors: Abhishek K Singh, Sunita Singh, K. Priyabrat Pandey, Supriya KarAbstract:We obtain a Schwarzschild and Reissner-Nordstrom emergent black holes by exploring the torsion dynamics in a generalized Curvature formulation, underlying an Effective ${D}_{4}$-brane on ${S}^{1}$. It is shown that a constant Effective metric, sourced by a background fluctuation in ${B}_{2}$ potential, on a ${D}_{3}$-brane receives a dynamical quantum correction in the presence of an electric charge.
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Discrete torsion, de Sitter tunneling vacua and AdS brane: U(1) gauge theory on D _4-brane and an Effective Curvature
Journal of High Energy Physics, 2013Co-Authors: Abhishek K Singh, Sunita Singh, K. Priyabrat Pandey, Supriya KarAbstract:The U(1) gauge dynamics on a D _4-brane is revisited, with a two form, to construct an Effective Curvature theory in a second order formalism. We exploit the local degrees in a two form, and modify its dynamics in a gauge invariant way, to incorporate a non-perturbative metric fluctuation in an Effective D _4-brane. Interestingly, the near horizon D _4-brane is shown to describe an asymptotic Anti de Sitter (AdS) in a semi-classical regime. Using Weyl scaling(s), we obtain the emergent rotating geometries leading to primordial de Sitter (dS) and AdS vacua in a quantum regime. Under a discrete transformation, we re-arrange the mixed dS patches to describe a Schwazschild-like dS (SdS) and a topological-like dS (TdS) black holes. We analyze SdS vacuum for Hawking radiations to arrive at Nariai geometry, where a discrete torsion forms a condensate. We perform thermal analysis to identify Nariai vacuum with a TdS. Investigation reveals an AdS patch within a thermal dS brane, which may provide a clue to unfold dS/CFT. In addition, the role of dark energy, sourced by a discrete torsion, in the dS vacua is investigated using Painleve geometries. It is argued that a D-instanton pair is created by a discrete torsion, with a Big Bang/Crunch, at the past horizon in a pure dS. Nucleation, of brane/anti-brane pair(s), is qualitatively analyzed to construct an Effective space-time on a D _4-brane and its anti brane. Analysis re-assures the significant role played by a non-zero mode, of NS-NS two form, to generalize the notion of branes within a brane.
Nicolaos Toumbas - One of the best experts on this subject based on the ideXlab platform.
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Thermal/quantum effects and induced superstring cosmologies
Nuclear Physics, 2008Co-Authors: Tristan Catelin-jullien, Hervé Partouche, Costas Kounnas, Nicolaos ToumbasAbstract:We consider classical superstring theories on flat four-dimensional space–times, and where N=4N=4 or N=2N=2 supersymmetry is spontaneously broken. We obtain the thermal and quantum corrections at the string one-loop level and show that the back-reaction on the space–time metric induces a cosmological evolution. We concentrate on heterotic string models obtained by compactification on a T6T6 torus and on T6/Z2T6/Z2 orbifolds. The temperature T and the supersymmetry breaking scale M are generated via the Scherk–Schwarz mechanism on the Euclidean time cycle and on an internal spatial cycle respectively. The Effective field theory corresponds to a no-scale supergravity, where the corresponding no-scale modulus controls the SUSY-breaking scale. The classical flatness of this modulus is lifted by an Effective thermal potential, given by the free energy. The gravitational field equations admit solutions where M, T and the inverse scale factor 1/a1/a of the universe remain proportional. In particular the ratio M/TM/T is fixed during time evolution. The induced cosmology is governed by a Friedmann–Hubble equation involving an Effective radiation term ∼1/a4∼1/a4 and an Effective Curvature term ∼1/a2∼1/a2, whose coefficients are functions of the complex structure ratio M/TM/T.
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Thermal/quantum effects and induced superstring cosmologies
Nuclear Physics B, 2008Co-Authors: Tristan Catelin-jullien, Hervé Partouche, Costas Kounnas, Nicolaos ToumbasAbstract:55 pages, 10 figuresWe consider classical superstring theories on flat four dimensional space-times, and where N=4 or N=2 supersymmetry is spontaneously broken. We obtain the thermal and quantum corrections at the string one-loop level and show that the back-reaction on the space-time metric induces a cosmological evolution. We concentrate on heterotic string models obtained by compactification on a T^6 torus and on T^6/Z_2 orbifolds. The temperature T and the supersymmetry breaking scale M are generated via the Scherk-Schwarz mechanism on the Euclidean time cycle and on an internal spatial cycle respectively. The Effective field theory corresponds to a no-scale supergravity, where the corresponding no-scale modulus controls the Susy-breaking scale. The classical flatness of this modulus is lifted by an Effective thermal potential, given by the free energy. The gravitational field equations admit solutions where M, T and the inverse scale factor 1/a of the universe remain proportional. In particular the ratio M/T is fixed during the time evolution. The induced cosmology is governed by a Friedmann-Hubble equation involving an Effective radiation term ~1/a^4 and an Effective Curvature term ~1/a^2, whose coefficients are functions of the complex structure ratio M/T
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Thermal/quantum effects and induced superstring cosmologies
Nuclear Physics, 2007Co-Authors: Tristan Catelin-jullien, Hervé Partouche, Costas Kounnas, Nicolaos ToumbasAbstract:We consider classical superstring theories on flat four dimensional space-times, and where N=4 or N=2 supersymmetry is spontaneously broken. We obtain the thermal and quantum corrections at the string one-loop level and show that the back-reaction on the space-time metric induces a cosmological evolution. We concentrate on heterotic string models obtained by compactification on a T^6 torus and on T^6/Z_2 orbifolds. The temperature T and the supersymmetry breaking scale M are generated via the Scherk-Schwarz mechanism on the Euclidean time cycle and on an internal spatial cycle respectively. The Effective field theory corresponds to a no-scale supergravity, where the corresponding no-scale modulus controls the Susy-breaking scale. The classical flatness of this modulus is lifted by an Effective thermal potential, given by the free energy. The gravitational field equations admit solutions where M, T and the inverse scale factor 1/a of the universe remain proportional. In particular the ratio M/T is fixed during the time evolution. The induced cosmology is governed by a Friedmann-Hubble equation involving an Effective radiation term ~1/a^4 and an Effective Curvature term ~1/a^2, whose coefficients are functions of the complex structure ratio M/T.
Sunita Singh - One of the best experts on this subject based on the ideXlab platform.
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Quintessence and Effective AdS brane geometries
International Journal of Modern Physics A, 2015Co-Authors: K. Priyabrat Pandey, Abhishek K Singh, Sunita Singh, Supriya KarAbstract:A geometric torsion dynamics leading to an Effective Curvature in a second-order formalism on a D4-brane is revisited with a renewed interest. We obtain two Effective AdS 4 brane geometries on a vacuum created pair of [Formula: see text]-brane. One of them is shown to describe an AdS Schwarzschild spinning black hole and the other is shown to describe a spinning black hole bound state. It is argued that a D-instanton in a vacuum created anti-D3-brane within a pair may describe a quintessence. It may seem to incorporate a varying vacuum energy density in a brane universe. We consider the Effective Curvature scalar on S1 × S1 to analyze torsionless geometries on a vacuum created pair of [Formula: see text]-brane. The emergent AdS 3 brane is shown to describe a Schwarzschild and a Reissner–Nordstrom (RN) geometries in the presence of extra dimension(s).
-
Discrete Torsion, (Anti) de Sitter D4-Brane and Tunneling
2014Co-Authors: Abhishek K Singh, Sunita Singh, Pratibha Pandey, Supriya KarAbstract:Abstract We obtain quantum geometries on a vacuum created pair of a ( D D ¯ ) 3 -brane, at a Big Bang singularity, by a local two form on a D 4 -brane. In fact our analysis is provoked by an established phenomenon leading to a pair creation by a gauge field at a black hole horizon by Stephen Hawking in 1975. Importantly, the five dimensional microscopic black holes are described by an Effective non-perturbative Curvature underlying a discrete torsion in a second order formalism. In the case for a non-propagating torsion, the Effective Curvature reduces to Riemannian, which in a low energy limit may describe Einstein vacuum in the formalism. In particular, our analysis suggests that a non-trivial space begin with a hot de Sitter brane-Universe underlying a nucleation of a vacuum pair of ( D D ¯ ) -instanton at a Big Bang. A pair of instanton nucleats a D-particle which in turn combines with an anti D-particle to describe a D-string and so on. The nucleation of a pair of higher dimensional pair of brane/anti-brane from a lower dimensional pair may be viewed via an expansion of the brane-Universe upon time. It is in conformity with the conjecture of a branes within a brane presumably in presence of the non-zero modes of two form. Interestingly, we perform a thermal analysis underlying various emergent quantum de Sitter vacua on a D 4 -brane and argue for the plausible tunneling geometries underlying a thermal equilibrium. It is argued that a de Sitter Schwarzschild undergoes quantum tunneling to an AdS-brane Schwarzschild via Nariai and de Sitter topological black hole.
-
Quintessence and Effective AdS brane geometries
arXiv: High Energy Physics - Theory, 2014Co-Authors: K. Priyabrat Pandey, Abhishek K Singh, Sunita Singh, Supriya KarAbstract:A geometric torsion dynamics leading to an Effective Curvature in a second order formalism on a D4-brane is revisited with a renewed interest. We obtain two Effective $AdS_4$ brane geometries on a vacuum created pair of $(D{\bar D})_3$-brane. One of them is shown to describe an AdS Schwarzschild spinning black hole and the other is shown to describe a spinning black hole bound state. It is argued that a D-instanton in a vacuum created anti D3-brane within a pair may describe a quintessence. It may seen to incorporate a varying vacuum energy density in a brane universe. We consider the Effective Curvature scalar on $S^1\times S^1$ to analyze torsion-less geometries on a vacuum created pair of $(D{\bar D})_2$-brane. The emergent $AdS_3$ brane is shown to describe a Schwarzschild and a Reissner-Nordstrom (RN) geometries in presence of extra dimension(s).
-
Emergent Schwarzschild and Reissner-Nordstrom black holes in four dimensions: An Effective Curvature sourced by a B 2 -field on a D 4 -brane
Physical Review D, 2013Co-Authors: Abhishek K Singh, Sunita Singh, K. Priyabrat Pandey, Supriya KarAbstract:We obtain a Schwarzschild and Reissner-Nordstrom emergent black holes by exploring the torsion dynamics in a generalized Curvature formulation, underlying an Effective ${D}_{4}$-brane on ${S}^{1}$. It is shown that a constant Effective metric, sourced by a background fluctuation in ${B}_{2}$ potential, on a ${D}_{3}$-brane receives a dynamical quantum correction in the presence of an electric charge.
-
Discrete torsion, de Sitter tunneling vacua and AdS brane: U(1) gauge theory on D _4-brane and an Effective Curvature
Journal of High Energy Physics, 2013Co-Authors: Abhishek K Singh, Sunita Singh, K. Priyabrat Pandey, Supriya KarAbstract:The U(1) gauge dynamics on a D _4-brane is revisited, with a two form, to construct an Effective Curvature theory in a second order formalism. We exploit the local degrees in a two form, and modify its dynamics in a gauge invariant way, to incorporate a non-perturbative metric fluctuation in an Effective D _4-brane. Interestingly, the near horizon D _4-brane is shown to describe an asymptotic Anti de Sitter (AdS) in a semi-classical regime. Using Weyl scaling(s), we obtain the emergent rotating geometries leading to primordial de Sitter (dS) and AdS vacua in a quantum regime. Under a discrete transformation, we re-arrange the mixed dS patches to describe a Schwazschild-like dS (SdS) and a topological-like dS (TdS) black holes. We analyze SdS vacuum for Hawking radiations to arrive at Nariai geometry, where a discrete torsion forms a condensate. We perform thermal analysis to identify Nariai vacuum with a TdS. Investigation reveals an AdS patch within a thermal dS brane, which may provide a clue to unfold dS/CFT. In addition, the role of dark energy, sourced by a discrete torsion, in the dS vacua is investigated using Painleve geometries. It is argued that a D-instanton pair is created by a discrete torsion, with a Big Bang/Crunch, at the past horizon in a pure dS. Nucleation, of brane/anti-brane pair(s), is qualitatively analyzed to construct an Effective space-time on a D _4-brane and its anti brane. Analysis re-assures the significant role played by a non-zero mode, of NS-NS two form, to generalize the notion of branes within a brane.
Tristan Catelin-jullien - One of the best experts on this subject based on the ideXlab platform.
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Thermal/quantum effects and induced superstring cosmologies
Nuclear Physics, 2008Co-Authors: Tristan Catelin-jullien, Hervé Partouche, Costas Kounnas, Nicolaos ToumbasAbstract:We consider classical superstring theories on flat four-dimensional space–times, and where N=4N=4 or N=2N=2 supersymmetry is spontaneously broken. We obtain the thermal and quantum corrections at the string one-loop level and show that the back-reaction on the space–time metric induces a cosmological evolution. We concentrate on heterotic string models obtained by compactification on a T6T6 torus and on T6/Z2T6/Z2 orbifolds. The temperature T and the supersymmetry breaking scale M are generated via the Scherk–Schwarz mechanism on the Euclidean time cycle and on an internal spatial cycle respectively. The Effective field theory corresponds to a no-scale supergravity, where the corresponding no-scale modulus controls the SUSY-breaking scale. The classical flatness of this modulus is lifted by an Effective thermal potential, given by the free energy. The gravitational field equations admit solutions where M, T and the inverse scale factor 1/a1/a of the universe remain proportional. In particular the ratio M/TM/T is fixed during time evolution. The induced cosmology is governed by a Friedmann–Hubble equation involving an Effective radiation term ∼1/a4∼1/a4 and an Effective Curvature term ∼1/a2∼1/a2, whose coefficients are functions of the complex structure ratio M/TM/T.
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Thermal/quantum effects and induced superstring cosmologies
Nuclear Physics B, 2008Co-Authors: Tristan Catelin-jullien, Hervé Partouche, Costas Kounnas, Nicolaos ToumbasAbstract:55 pages, 10 figuresWe consider classical superstring theories on flat four dimensional space-times, and where N=4 or N=2 supersymmetry is spontaneously broken. We obtain the thermal and quantum corrections at the string one-loop level and show that the back-reaction on the space-time metric induces a cosmological evolution. We concentrate on heterotic string models obtained by compactification on a T^6 torus and on T^6/Z_2 orbifolds. The temperature T and the supersymmetry breaking scale M are generated via the Scherk-Schwarz mechanism on the Euclidean time cycle and on an internal spatial cycle respectively. The Effective field theory corresponds to a no-scale supergravity, where the corresponding no-scale modulus controls the Susy-breaking scale. The classical flatness of this modulus is lifted by an Effective thermal potential, given by the free energy. The gravitational field equations admit solutions where M, T and the inverse scale factor 1/a of the universe remain proportional. In particular the ratio M/T is fixed during the time evolution. The induced cosmology is governed by a Friedmann-Hubble equation involving an Effective radiation term ~1/a^4 and an Effective Curvature term ~1/a^2, whose coefficients are functions of the complex structure ratio M/T
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Thermal/quantum effects and induced superstring cosmologies
Nuclear Physics, 2007Co-Authors: Tristan Catelin-jullien, Hervé Partouche, Costas Kounnas, Nicolaos ToumbasAbstract:We consider classical superstring theories on flat four dimensional space-times, and where N=4 or N=2 supersymmetry is spontaneously broken. We obtain the thermal and quantum corrections at the string one-loop level and show that the back-reaction on the space-time metric induces a cosmological evolution. We concentrate on heterotic string models obtained by compactification on a T^6 torus and on T^6/Z_2 orbifolds. The temperature T and the supersymmetry breaking scale M are generated via the Scherk-Schwarz mechanism on the Euclidean time cycle and on an internal spatial cycle respectively. The Effective field theory corresponds to a no-scale supergravity, where the corresponding no-scale modulus controls the Susy-breaking scale. The classical flatness of this modulus is lifted by an Effective thermal potential, given by the free energy. The gravitational field equations admit solutions where M, T and the inverse scale factor 1/a of the universe remain proportional. In particular the ratio M/T is fixed during the time evolution. The induced cosmology is governed by a Friedmann-Hubble equation involving an Effective radiation term ~1/a^4 and an Effective Curvature term ~1/a^2, whose coefficients are functions of the complex structure ratio M/T.