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Register a new userA Extended Cosmological Cardy-Verlinde Formula
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Added by
Thiago Gilberto do Prado
Publication date
2010
fields
Physics
and research's language is
English
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E. Verlinde obtained a generalized formula for the entropy of a conformal field theory. For this we consider a (n+1) dimensional closed radiation dominated FLWR in the context of the holographic principle. In this work we construct a extension of the Cardy-Verlinde formula to positive cosmological constant spaces (dS spaces) with arbitrary topology
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Primordial cosmological perturbations are the seeds that were cultivated by inflation and the succeeding dynamical processes, eventually leading to the current Universe. In this work, we investigate the behavior of the gauge-invariant scalar and tensor perturbations under the general extended disformal transformation, namely, $g_{mu u} rightarrow A(X,Y,Z)g_{mu u} + Phi_muPhi_ u$, where $X equiv -tfrac{1}{2}phi^{;mu}phi_{;mu}, Y equiv phi^{;mu}X_{;mu}, Z equiv X^{;mu}X_{;mu} $ and $Phi_mu equiv Cphi_{;mu} + DX_{;mu}$, with $C$ and $D$ being a general functional of $(phi,X,Y,Z)$. We find that the tensor perturbation is invariant under this transformation. On the other hand, the scalar curvature perturbation receives a correction due the conformal term only; it is independent of the disformal term at least up to linear order. Within the framework of the full Horndeski theory, the correction terms turn out to depend linearly on the gauge-invariant comoving density perturbation and the first time-derivative thereof. In the superhorizon limit, all these correction terms vanish, leaving only the original scalar curvature perturbation. In other words, it is invariant under the general extended disformal transformation in the superhorizon limit, in the context of full Horndeski theory. Our work encompasses a chain of research studies on the transformation or invariance of the primordial cosmological perturbations, generalizing their results under our general extended disformal transformation.
We show that the extended cosmological equation-of-state developed starting from a Chaplygin equation-of-state, recently applied to stellar modeling, is a viable dark energy model consistent with standard scalar potentials. Moreover we find a Lagrangian formulation based on a canonical scalar field with the appropriate self-interaction potential. Finally, we fit the scalar potential obtained numerically with concrete functions well studied in the literature. Our results may be of interest to model builders and particle physicists.
We conjecture a formula for the virtual elliptic genera of moduli spaces of rank 2 sheaves on minimal surfaces $S$ of general type. We express our conjecture in terms of the Igusa cusp form $chi_{10}$ and Borcherds type lifts of three quasi-Jacobi forms which are all related to the Weierstrass elliptic function. We also conjecture that the generating function of virtual cobordism classes of these moduli spaces depends only on $chi(mathcal{O}_S)$ and $K_S^2$ via two universal functions, one of which is determined by the cobordism classes of Hilbert schemes of points on $K3$. We present generalizations of these conjectures, e.g. to arbitrary surfaces with $p_g>0$ and $b_1=0$. We use a result of J. Shen to express the virtual cobordism class in terms of descendent Donaldson invariants. In a prequel we used T. Mochizukis formula, universality, and toric calculations to compute such Donaldson invariants in the setting of virtual $chi_y$-genera. Similar techniques allow us to verify our new conjectures in many cases.
The cosmological constant $Lambda$ is usually interpreted as Dark Energy (DE) or modified gravity (MG). Here we propose instead that $Lambda$ corresponds to a boundary term in the action of classical General Relativity. The action is zero for a perfect fluid solution and this fixes $Lambda$ to the average density $rho$ and pressure $p$ inside a primordial causal boundary: $Lambda = 4pi G <rho+3p>$. This explains both why the observed value of $Lambda$ is related to the matter density today and also why other contributions to $Lambda$, such as DE or MG, do not produce cosmic expansion. Cosmic acceleration results from the repulsive boundary force that occurs when the expansion reaches the causal horizon. This universe is similar to the $Lambda$CDM universe, except on the largest observable scales, where we expect departures from homogeneity/isotropy, such as CMB anomalies and variations in cosmological parameters indicated by recent observations.
The aim of this paper is to confirm in new concrete examples that the semiclassical entropy of a three-dimensional Lifshitz black hole can be recovered through an anisotropic generalization of the Cardy formula derived from the growth of the number of states of a boundary non-relativistic field theory. The role of the ground state in the bulk is played by the corresponding Lifshitz soliton obtained by a double Wick rotation. In order to achieve this task, we consider a scalar field nonminimally coupled to new massive gravity for which we study different classes of Lifshitz black holes as well as their respective solitons, including new solutions for a dynamical exponent z=3. The masses of the black holes and solitons are computed using the quasilocal formulation of conserved charges recently proposed by Gim, Kim, Kulkarni and Yi and based on the off-shell extension of the ADT formalism. We confirm the anisotropic Cardy formula for each of these examples, providing a stronger base for its general validity. Consistently, the first law of thermodynamics together with a Smarr formula are also verified.
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