In this paper, we consider the correspondence between the tachyon dark energy model and the Tsallis holographic dark energy scenario in an FRW universe.We demonstrate the Tsallis holographic description of tachyon dark energy in an FRW universe and reconstruct the potential and basic results of the dynamics of the scalar field which describe the tachyon cosmology. In a flat universe, in the tachyon model of Tsallis holographic dark energy, independent of the existence of interaction between dark energy and matter or not, \dot{T}^2 must always be zero. Therefore, the equation of state ω_D is always -1 in such a flat universe. For a non-flat universe, \dot{T}^2 cannot be zero so that ω_D=-1 which cannot be used to explain the origin of the cosmological constant. \dot{T}^2 monotonically decreases with the increase in \cos(R_h/a) and \cosh(R_h/a) for different δ's. In particular, for an open universe, \dot{T}^2 is always larger than zero, while for a closed universe, \dot{T}^2 is always smaller than zerowhich is physically invalid. In addition, we conclude that with the increase in \cos(R_h/a) and \cosh(R_h/a), \dot{T}^2 always decreases monotonically irrespective of the value of b^2.
In this paper we consider a correspondence between the holographic dark energy density and tachyon energy density in FRW universe. Then we reconstruct the potential and the dynamics of the tachyon field which describe tachyon cosmology.
After a brief introduction to the AdS/CFT holography a tachyon inflation will be discussed in the framework of holographic cosmology. The model is based on a holographic braneworld scenario with an effective tachyon field on a D3-brane located at the holographic bound of an asymptotic ADS$_5$ bulk.
We investigate some phenomenological aspects of the holographic models based on the tachyon Dirac-Born-Infeld action in the AdS space-time. These holographic theories model strongly interacting fermions and feature dynamical mass generation and symmetry breaking. We show that they can be viewed as models of holographic walking technicolor and compute the Peskin-Takeuchi S-parameter and masses of lightest technimesons for a variety of the tachyon potentials. We also investigate the phase structure at finite temperature and charge density. Finally, we comment on the holographic Wilsonian RG in t…
Employing the modified entropy-area relation suggested by Tsallis and Cirto \cite{non3}, and the holographic hypothesis, a new holographic dark energy (HDE) model is proposed. Considering a flat Friedmann-Robertson-Walker (FRW) universe in which there is no interaction between the cosmos sectors, the cosmic implications of the proposed HDE are investigated. Interestingly enough, we find that the identification of IR-cutoff with the Hubble radius, can lead to the late time accelerated Universe even in the absence of interaction between two dark sectors of the Universe. This is in contrast to th…
D-branes with a U-shaped geometry, like the D8 flavor branes in the Sakai-Sugimoto model of QCD, are encountered frequently in holographic backgrounds. We argue that the commonly used DBI action is inadequate as an effective field theory description of these branes, because it misses a crucial component of the low-energy dynamics: a light complex scalar mode. Following an idea of Erkal, Kutasov and Lunin we elaborate on an effective description based on the abelian tachyon-DBI action which incorporates naturally the non-local physics of the complex scalar mode. We demonstrate its power in a co…
We propose in this Letter a holographic model of tachyon dark energy. A connection between the tachyon scalar-field and the holographic dark energy is established, and accordingly, the potential of the holographic tachyon field is constructed. We show that the holographic evolution of the universe with $c\geqslant 1$ can be described completely by the resulting tachyon model in a certain way.
We propose a holographic tachyon model of dark energy with interaction between the components of the dark sector. The correspondence between the tachyon field and the holographic dark energy densities allows the reconstruction of the potential and the dynamics of the tachyon scalar field in a flat Friedmann-Robertson-Walker universe. We show that this model can describe the observed accelerated expansion of our universe with a parameter space given by the most recent observational results.
Tsallis holographic dark energy with power law ansatz approach
International Centre for Space and Cosmology, School of Arts and Sciences, Ahmedabad University（艾哈迈达巴德大学艺术与科学学院太空与宇宙学国际中心）；Research Institute of Physics, Southern Federal University（南联邦大学物理研究所）；Virtual Institute of Astroparticle Physics（高能粒子物理学虚拟研究所）；Center for Cosmoparticle Physics Cosmion, National Research Nuclear University “MEPHI”（国立研究核子大学“MEPHI”宇宙粒子物理中心Cosmion）；Lab. for Theor. Cosmology, International Centre of Gravity and Cosmos, Tomsk State University of Control Systems and Radio Electronics (TUSUR)（托木斯克国立控制系统与无线电电子大学国际重力与宇宙中心理论宇宙学实验室）
本文研究了Tsallis holographic dark energy模型，通过幂律假设方法探讨了粘性、非粘性及Chaplygin气体三种宇宙学场景，分析了模型的稳定性及 phantom divide 交叉特性。
We consider the intersecting D4-brane and anti-D4-brane model of holographic QCD, motivated by the model that has recently been suggested by Van Raamsdonk and Whyte. We analyze such D4-branes by the use of the action with a bi-fundamental ``tachyon'' field, so that we find the classical solutions describing the intersecting D4-branes and the U-shaped D4-branes. We show that the ``tachyon'' field in the bulk theory provides a current quark mass and a quark condensate to the dual gauge theory and that the lowest modes of mesons obtain mass via tachyon condensation. Then evaluating the properties…
In this paper, we use a Tsallis holographic dark energy model in two forms, interacting and non-interacting cases, to acquire some parameters as the equation of state for the energy density of the Tsallis model in the FRW universe concerning the complex form of quintessence model. We will study the cosmology of complex quintessence by revamping the potential and investigating the scalar field dynamics. Then we analyze ($ω-ω'$) and stability in two cases, i.e., non-interacting and interacting. We will explore whether these cases describe a real universe by calculating fractional energy density …
A model of tachyon inflation is proposed in the framework of holographic cosmology. The model is based on a holographic braneworld scenario with a D3-brane located at the holographic boundary of an asymptotic ADS$_5$ bulk. The tachyon field that drives inflation is represented by a DBI action on the brane. We solve the evolution equations analytically in the slow-roll regime and solve the exact equations numerically. We calculate the inflation parameters and compare the results with Planck 2018 data.
In this paper, we investigate the dark energy phenomenon by studying the Tsallis holographic dark energy within the framework of Brans-Dicke (BD) scalar-tensor theory of gravity [Phys. Rev. \textbf{124}, 925 (1961)]. In this context, we choose the BD scalar field $ϕ$ as a logarithmic function of the average scale factor $a(t)$ and Hubble horizon as the IR cutoff ($L=H^{-1}$). We reconstruct two cases of non-interacting and interacting fluid (dark sectors of cosmos) scenario. The physical behavior of the models are discussed with the help of graphical representation to explore the accelerated e…
In order to apply holography and entropy relations to the whole universe, which is a gravitational and thus nonextensive system, for consistency one should use the generalized definition for the universe horizon entropy, namely Tsallis nonextensive entropy. We formulate Tsallis holographic dark energy, which is a generalization of standard holographic dark energy quantified by a new dimensionless parameter $δ$, possessing the latter as a particular sub-case. We provide a simple differential equation for the dark energy density parameter, as well as an analytical expression for its equation-of-…
Hints Beyond $Λ$CDM from Barrow and Tsallis Holographic Dark Energy with GO cutoff
Universidad de Lleida（莱里达大学）；Durban University of Technology（德班理工大学）；National Institute for Theoretical and Computational Sciences (NITheCS)（南非理论与计算科学国家研究所）；Universidad Catòlica del Norte（北天主教学会大学）；Shiraz University（设拉子大学）
We use holography to study Conformal Phase Transitions, which are believed to be realized in four dimensional QCD and play an important role in walking technicolor models of electroweak symmetry breaking. At strong coupling they can be modeled by the non-linear dynamics of a tachyonic scalar field with mass close to the Breitenlohner-Freedman bound in anti de Sitter spacetime. Taking the action for this field to have a Tachyon-Dirac-Born-Infeld form gives rise to models that resemble hard and soft wall AdS/QCD, with a dynamically generated wall. For hard wall models, the highly excited spectru…
We apply the holographic principle to a flat dark energy dominated Friedmann-Robertson-Walker spacetime filled with a tachyon scalar field with constant equation of state $w=p/ρ$, both for $w>-1$ and $w<-1$. By using a geometrical covariant procedure, which allows the construction of holographic hypersurfaces, we have obtained for each case the position of the preferred screen and have then compared these with those obtained by using the holographic dark energy model with the future event horizon as the infrared cutoff. In the phantom scenario, one of the two obtained holographic screens is pl…
We investigate the difference between holographic dark energy, Chaplygin gas, and tachyon model with constant potential. For this purpose, we examine their squared speeds of sound which are evaluated to zeroth order in perturbation theory and hence depends only on time. We find that the squared speed for holographic dark energy is always negative when choosing the future event horizon as the IR cutoff, while those for Chaplygin gas and tachyon are non-negative. This means that the perfect fluid for holographic dark energy is classically unstable. Hence the holographic interpretation for Chaply…
We investigate observational constraints on inflationary parameters in the context of an holographic cosmology with an induced gravity correction. We consider two situations where a universe is firstly filled with a scalar field and secondly with a tachyon field. Both cases are investigated in a slow-roll regime. We adopt a quadratic potential and an exponential potential for the scalar and the tachyon inflation respectively. In this regard, the standard background and perturbative parameters characterizing the inflationary era are modified by correction terms. We show a good agreement between…
It is an old idea to realize Einstein's equations as a thermodynamical equation of state. Since then, there has been new conjectures to understand gravity from another point of view. In this way we can accept that the gravitational field is not an underlying one like an emergent force from other approaches based on the knowledge of relativity, quantum and black holes thermodynamics, and different statistical formalisms. One important question concerning this gravity/thermostatistics correspondence is whether the holographic screen could be well defined for a nonrelativistic case of a source ma…
Recently, the Rényi and Tsallis generalized entropies have extensively been used in order to study various cosmological and gravitational setups. Here, using a special type of generalized entropy, a generalization of both the Rényi and Tsallis entropy, together with holographic principle, we build a new model for holographic dark energy. Thereinafter, considering a flat FRW universe, filled by a pressureless component and the new obtained dark energy model, the evolution of cosmos has been investigated showing satisfactory results and behavior. In our model, the Hubble horizon plays the role o…
A simple holographic model is presented and analyzed that describes chiral symmetry breaking and the physics of the meson sector in QCD. This is a bottom-up model that incorporates string theory ingredients like tachyon condensation which is expected to be the main manifestation of chiral symmetry breaking in the holographic context. As a model for glue the Kuperstein-Sonnenschein background is used. The structure of the flavor vacuum is analyzed in the quenched approximation. Chiral symmetry breaking is shown at zero temperature. Above the deconfinement transition chiral symmetry is restored.…
In this paper, we study the cosmological analysis of the modified holographic Ricci dark energy model and reconstruct different scalar field models in the context of Chern-Simon modified gravity. We investigate the deceleration parameter, which shows that the universe is in the accelerating expansion phase. The equation of state parameter in this case also favors the fact that dark energy is the dominant component of universe which is responsible for the accelerated expansion. A number of scalar fields, such as: quintessence, tachyon, K-essence and dilaton models are reconstructed using modifi…
We propose a new entropy construct that generalizes the Tsallis, Rényi, Sharma-Mittal, Barrow, Kaniadakis, and Loop Quantum Gravity entropies and reduces to the Bekenstein-Hawking entropy in a certain limit. This proposal is applied to the Schwarzschild black hole and to spatially homogeneous and isotropic cosmology, where it is shown that it can potentially describe inflation and/or holographic dark energy.
We use D-instantons to probe the geometry of Misner universe, and calculate the world volume field theory action, which is of the 1+0 dimensional form and highly non-local. Turning on closed string tachyons, we see from the deformed moduli space of the D-instantons that the spacelike singularity is removed and the region near the singularity becomes a fuzzy cone, where space and time do not commute. When realized cosmologically there can be controllable trans-planckian effects. And the infinite past is now causally connected with the infinite future, thus also providing a model for big crunch/…
Here we consider the entropy-corrected version of the holographic dark energy model in the non-flat universe. We obtain the equation of state parameter in the presence of interaction between dark energy and dark matter. Moreover, we reconstruct the potential and the dynamics of the quintessence, tachyon, K-essence and dilaton scalar field models according to the evolutionary behavior of the interacting entropy-corrected holographic dark energy model.
In this paper we employ a recent proposal of C. Tsallis and formulate the first law of thermodynamics for gravitating systems in terms of the extensive but non-additive entropy. We pay a particular attention to an integrating factor for the heat one-form and show that in contrast to conventional thermodynamics it factorizes into thermal and entropic part. Ensuing first law of thermodynamics implies Tsallis cosmology, which is then subsequently used to address the observed discrepancy between current bound on the Dark Matter relic abundance and present IceCube data on high-energy neutrinos. To …
We study the decay of the unstable D-particle in three-dimensional anti-de Sitter space-time using worldsheet boundary conformal field theory methods. We test the open string completeness conjecture in a background for which the phase space available is only field-theoretic. This could present a serious challenge to the claim. We compute the emission of closed strings in the AdS(3) x S^3 x T^4 background from the knowledge of the exact corresponding boundary state we construct. We show that the energy stored in the brane is mainly converted into very excited long strings. The energy stored in …
We propose a finite-temperature holographic model with a soft-wall geometry that incorporates two scalar fields, dual to the gluon and chiral operators. A series solution is presented as the dynamical, black-hole solution to Einstein's equations. We use the solution to calculate the thermal properties of the corresponding 4D gauge theory. Gluon and chiral thermal condensates contribute leading-order terms that affect the speed of sound through and entropy of the 4D thermal medium. At a temperature $T_c\sim 900$ MeV, we find a phase transition, which is much higher than lattice QCD calculations…
Bearing holographic dark energy hypothesis in mind, the ability of vacuum energy in describing the current accelerated universe is studied in the framework of Rastall theory. Here, in addition to the ordinary approach in which it is expected that this energy plays the role of dark energy, we also address a new approach where the sum of this energy and Rastall term is responsible for the current accelerated universe. We also investigate the cosmological outcomes of using Tsallis entropy in quantifying the energy of fields in vacuum for both mentioned approaches. The implications of considering …
The low energy field theory for N type IIA D4-branes at strong 't Hooft coupling, wrapped on a circle with antiperiodic boundary conditions for fermions, is known to have a vacuum energy which depends on the $θ$ angle for the gauge fields, and which is a multivalued function of this angle. This gives a field-theoretic realization of "axion monodromy" for a nondynamical axion. We construct the supergravity solution dual to the field theory in the metastable state which is the adiabatic continuation of the vacuum to large values of $θ$. We compute the energy of this state and show that it initia…
We study the entropy-corrected version of the holographic dark energy (HDE) model in the framework of modified FRW cosmology. We consider a non-flat universe filled with an interacting viscous entropy-corrected HDE (ECHDE) with dark matter. We also include the case of variable gravitational constant G in our model. We obtain the equation of state and the deceleration parameters of the interacting viscous ECHDE. Moreover, we reconstruct the potential and the dynamics of the quintessence, tachyon, K-essence and dilaton scalar field models according to the evolutionary behavior of the interacting…
In this paper the cosmological evolution of a holographic dark energy model with a non-linear interaction between the dark energy and dark matter components in a FRW type flat universe is analysed. In this context, the deceleration parameter $q$ and the equation state $w_Λ$ are obtained. We found that, as the square of the speed of sound remains positive, the model is stable under perturbations since early times; it also shows that the evolution of the matter and dark energy densities are of the same order for a long period of time, avoiding the so--called coincidence problem. We have also mad…
A so called "power-law entropy-corrected holographic dark energy" (PLECHDE) was recently proposed to explain the dark energy dominated universe. This model is based on the power-law corrections to black hole entropy which appear in dealing with the entanglement of quantum fields between inside and outside of the horizon. In this paper, we suggest a correspondence between interacting PLECHDE and tachyon, quintessence, K-essence and dilaton scalar field models of dark energy in a non-flat FRW universe. Then, we reconstruct the potential terms accordingly, and present the dynamical equations whic…
The holographic dual of a finite-temperature gauge theory with a small number of flavours typically contains D-brane probes in a black hole background. We have recently shown that these systems undergo a first order phase transition characterised by a `melting' of the mesons. Here we extend our analysis of the thermodynamics of these systems by computing their free energy, entropy and energy densities, as well as the speed of sound. We also compute the meson spectrum for brane embeddings outside the horizon and find that tachyonic modes appear where this phase is expected to be unstable from t…
We propose a new four-parameter entropy function that generalizes the Tsallis, Rényi, Barrow, Sharma-Mittal, Kaniadakis and Loop Quantum Gravity entropies for suitable limits of the parameters. Consequently, we address the early and late universe cosmology corresponding to the proposed four-parameter entropy function. As a result, it turns out that the entropic cosmology from the generalized entropy function can unify the early inflation to the late dark energy era of the universe. In such a unified scenario, we find that -- (1) the inflation era is described by a quasi de-Sitter evolution of …
Motivated by the holographic principle, it has been suggested that the dark energy density may be inversely proportional to the area $A$ of the event horizon of the universe. However, such a model would have a causality problem. In this work, we consider the entropy-corrected version of the holographic dark energy model in the non-flat FRW universe and we propose to replace the future event horizon area with the inverse of the Ricci scalar curvature. We obtain the equation of state (EoS) parameter $ω_Λ$, the deceleration parameter $q$ and $Ω_D'$ in the presence of interaction between Dark Ener…
We study Lorentzian wormholes in the ghost-free bigravity theory described by two metrics, g and f. Wormholes can exist if only the null energy condition is violated, which happens naturally in the bigravity theory since the graviton energy-momentum tensors do not apriori fulfill any energy conditions. As a result, the field equations admit solutions describing wormholes whose throat size is typically of the order of the inverse graviton mass. Hence, they are as large as the universe, so that in principle we might all live in a giant wormhole. The wormholes can be of two different types that w…
We consider the holographic dark energy (HDE) model in the framework of DGP braneworld with Granda-Oliveros infrared (IR) cutoff, $L=(α\dot{H}+βH^2)^{-1/2}$. With this choice for IR cutoff, we are able to derive evolution of the cosmological parameters such as the equation of state and the deceleration parameters, $w$ and $q$, as the functions of the redshift parameter $z$. As far as we know, most previous models of HDE presented in the literatures, do not gives analytically $ω=ω(z)$ and $q=q(z)$. We plot the evolution of these parameters versus $z$ and discuss that the results are compatible …
