Anisotropic homogeneous string cosmology with two-loop corrections

Naderi, Fouad; Rezaei-Aghdam, A.

doi:10.1016/j.nuclphysb.2017.08.005

Cited by 8 publications

(14 citation statements)

References 57 publications

(182 reference statements)

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“…In some hairy black hole solutions, the regularity condition of φ and φ ′ has been employed to relate the dilaton charge to the mass of black hole implying that the scalar hair is of secondary type [51]. In our case, it just fixed the integrating constant n by (34). Considering the mass expression (92) along with aforementioned λ = 0 condition, the dilaton charge (117) coincides with the first term in mass (92) and we have…”

Section: Thermodynamic Properties Of the Topological Black Hole Solutmentioning

confidence: 97%

“…The Bianchi types are defined based on the simply-transitive three-dimensional Lie groups classification. Since the isometries of the Riemannian manifold form a Lie group, the Bianchi classification is widely used for studying the spatially homogeneous spacetimes in relativity and cosmology [31,32,33,34,35]. The spacetimes in these models are assumed to possess a symmetry, namely the spatial homogeneity [36].…”

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confidence: 99%

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New five-dimensional Bianchi type magnetically charged hairy topological black hole solutions in string theory

Naderi

Rezaei-Aghdam

2019

Eur. Phys. J. C

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We construct black hole solutions to the leading order of string effective action in five dimensions with the source given by dilaton and magnetically charged antisymmetric gauge B-field. Presence of the considered B-field leads to the unusual asymptotic behavior of the solutions which are neither asymptotically flat nor asymptotically (A)dS. We consider the three-dimensional space part to correspond to the Bianchi classes and so the horizons of these topological black hole solutions are modeled by seven homogeneous Thurstons geometries of E 3 , S 3 , H 3 , H 2 × E 1 , SL2R, nilgeometry, and solvegeometry. Calculating the quasi-local mass, temperature, entropy, dilaton charge, and magnetic potential, we show that the first law of black hole thermodynamics is satisfied by these quantities and the dilaton charge is not independent of mass and magnetic charge. Furthermore, for Bianchi type V , the T -dual black hole solution is obtained which carries no charge associated with B-field and the entropy turns to be invariant under the presented in [25,26], whose horizons are not compactificable and their described spacetimes are rotating black branes [27].Usually, the horizon geometries of topological black hole solutions are considered to be spherical, hyperbolic or flat. For the five-dimensional black hole solutions the situation can be more extensive. The geometries of three-dimensional homogeneous manifolds has been classified by Thurston into eight types [28], where in addition to three isotropic constant curvature cases of spherical S 3 , Hyperbolic H 3 , and Euclidean E 3 , there are five anisotropic alternative three-dimensional geometries of S 2 × R, H 2 × R, SL 2 R, solvegeometry, and nilgeometry. Admitting homogeneous metrics, these model geometries have close correspondence with the homogeneous geometries of Bianchi types and Kantowski-Sachs [29,30]. The Bianchi types are defined based on the simply-transitive three-dimensional Lie groups classification. Since the isometries of the Riemannian manifold form a Lie group, the Bianchi classification is widely used for studying the spatially homogeneous spacetimes in relativity and cosmology [31,32,33,34,35]. The spacetimes in these models are assumed to possess a symmetry, namely the spatial homogeneity [36]. Families of five-dimensional black hole solutions of gravity theories where the horizons are modeled by some of the Thurston 3-geometries have been presented in [37,38,39,40,41]. Also, extremal black branes whose geometries are classified by nine Bianchi types have been studied in [42].Recently, the black hole solutions in string theory have attracted an increasing interest [43,44,45,46,47,48,49]. Nevertheless, the effect of the magnetically charged B-field has not been discussed so much in previous works [7,6,8,9,10,11]. In this work, we are interested in five-dimensional black hole solutions in string theory including a dilaton field and a 3-form field strength tensor of B-field associated with a magnetic charge. The inclusion of B-field in this class wil...

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Section: Thermodynamic Properties Of the Topological Black Hole Solutmentioning

confidence: 97%

mentioning

confidence: 99%

New five-dimensional Bianchi type magnetically charged hairy topological black hole solutions in string theory

Naderi

Rezaei-Aghdam

2019

Eur. Phys. J. C

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“…Demanding only the first order α ′ -corrections in the solutions of metric, dilaton field and H-field, only the zeroth order α ′ terms ofK will be considered. Hence, substituting the (32) and (33) into the rewritten versions of (20) in τ coordinate gives the explicit forms ofK. Now, the solutions of (29) and (30) give the general forms of α ′ -corrections of scale factor and dilaton field as follows…”

Section: A Solutions With Vanishing H-fieldmentioning

confidence: 99%

“…We can, therefore, hope to provide a glimpse of the feature that could be obtained considering all orders in α ′ . Similar to what we have done in [20] for classifying and solving the two-loop β-function on all Bianchi type models with Λ = 0 and H-field in χ(↑) class, a perturbative series expansion in α ′ is implemented on background field and the general forms of equations and solutions are presented. Also, we consider the field equations in Einstein frame by obtaining the contribution of H-field in α ′ order of energy-momentum tensor to investigate the cosmological implications of the α ′ -corrected solutions.…”

Section: Introductionmentioning

confidence: 99%

“…In this section, we are going to solve the two-loop β-functions in the presence of central charge deficit Λ on Bianchi-type I space-time with a similar method by which we have calculated the solutions of two-loop βfunctions on homogeneous space-times in [20]. The solutions give the string frame metric g µν , dilaton field, and B-field, where the corresponding Einstein frame solutions can be obtained using the conformal transformation (7).…”

Section: Introductionmentioning

confidence: 99%

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Noncritical anisotropic Bianchi type I string cosmology with α′ corrections

Naderi¹,

Rezaei-Aghdam²,

Darabi³

2018

Phys. Rev. D

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We present noncritical Bianchi type I string cosmology solutions in the presence of central charge deficit term Λ. The leading-order string frame curvature appears to be in the high curvature limit Rα 0 ≳ 1, which underlines the necessity of including higher-order α 0 corrections. We give new solutions of two-loop (firstorder α 0 ) β-function equations of the σ model with nonzero Λ and the dilaton field in both cases of the absence and presence of a spatially homogeneous H field (H ¼ dB). Also, the evolution of solutions is studied in the Einstein frame, in which the string effective action can transform to Gauss-Bonnet gravity model coupled to a dilaton field with potential. We study explicit examples in first-order α 0 with chosen values of appeared constants in the solutions and discuss the cosmological implications.

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Anisotropic dark energy from string compactifications

Gallego,

Orjuela-Quintana,

Valenzuela-Toledo

2024

J. High Energ. Phys.

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We explore the cosmological dynamics of a minimalistic yet generic string-inspired model for multifield dark energy. Adopting a supergravity four-dimensional viewpoint, we motivate the model’s structure arising from superstring compactifications involving a chiral superfield and a pure U(1) gauge sector. The chiral sector gives rise to a pair of scalar fields, such as the axio-dilaton, which are kinetically coupled. However, the scalar potential depends on only one of them, further entwined with the vector field through the gauge kinetic function. The model has two anisotropic attractor solutions that, despite a steep potential and thanks to multifield dynamics, could explain the current accelerated expansion of the Universe while satisfying observational constraints on the late-times cosmological anisotropy. Nevertheless, justifying the parameter space allowing for slow roll dynamics together with the correct cosmological parameters, would be challenging within the landscape of string theory. Intriguingly, we find that the vector field, particularly at one of the studied fixed points, plays a crucial role in enabling geodesic trajectories in the scalar field space while realizing slow-roll dynamics with a steep potential. This observation opens a new avenue for exploring multifield dark energy models within the superstring landscape.

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Anisotropic homogeneous string cosmology with two-loop corrections

Cited by 8 publications

References 57 publications

New five-dimensional Bianchi type magnetically charged hairy topological black hole solutions in string theory

New five-dimensional Bianchi type magnetically charged hairy topological black hole solutions in string theory

Noncritical anisotropic Bianchi type I string cosmology with α′ corrections

Anisotropic dark energy from string compactifications

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