Abstract:We study F -functions in the context of field theories on S 3 using gaugegravity duality, with the radius of S 3 playing the role of RG scale. We show that the on-shell action, evaluated over a set of holographic RG flow solutions, can be used to define good F -functions, which decrease monotonically along the RG flow from the UV to the IR for a wide range of examples. If the operator perturbing the UV CFT has dimension ∆ > 3/2 these F -functions correspond to an appropriately renormalized free energy. If inst… Show more
“…The divergent piece of the entanglement entropy satisfies an area law, which prohibits a direct extraction of the IR part of the entropy (see also [46]). It is hence difficult to have a direct interpretation of the entropy of de Sitter itself (see however [62], where a thermodynamic interpretation with a suitable regulated free energy is proposed), but we note that in a theory with dynamical gravity it is conjectured that this entropy is limited by a Bekenstein-Hawking term of A/4G 4 . This entropy, or part thereof, can then potentially be identified with the entanglement entropy whereby 1/G 4 plays the role of the UV cut-off [63].…”
We use holography to study the dynamics of a strongly-coupled gauge theory in four-dimensional de Sitter space with Hubble rate H. The gauge theory is non-conformal with a characteristic mass scale M. We solve Einstein’s equations numerically and determine the time evolution of homogeneous gauge theory states. If their initial energy density is high compared with H4 then the early-time evolution is well described by viscous hydrodynamics with a non-zero bulk viscosity. At late times the dynamics is always far from equilibrium. The asymptotic late-time state preserves the full de Sitter symmetry group and its dual geometry is a domain-wall in AdS5. The approach to this state is characterised by an emergent relation of the form $$ \mathcal{P} $$
P
= w ℰ that is different from the equilibrium equation of state in flat space. The constant w does not depend on the initial conditions but only on H/M and is negative if the ratio H/M is close to unity. The event and the apparent horizons of the late-time solution do not coincide with one another, reflecting its non-equilibrium nature. In between them lies an “entanglement horizon” that cannot be penetrated by extremal surfaces anchored at the boundary, which we use to compute the entanglement entropy of boundary regions. If the entangling region equals the observable universe then the extremal surface coincides with a bulk cosmological horizon that just touches the event horizon, while for larger regions the extremal surface probes behind the event horizon.
“…The divergent piece of the entanglement entropy satisfies an area law, which prohibits a direct extraction of the IR part of the entropy (see also [46]). It is hence difficult to have a direct interpretation of the entropy of de Sitter itself (see however [62], where a thermodynamic interpretation with a suitable regulated free energy is proposed), but we note that in a theory with dynamical gravity it is conjectured that this entropy is limited by a Bekenstein-Hawking term of A/4G 4 . This entropy, or part thereof, can then potentially be identified with the entanglement entropy whereby 1/G 4 plays the role of the UV cut-off [63].…”
We use holography to study the dynamics of a strongly-coupled gauge theory in four-dimensional de Sitter space with Hubble rate H. The gauge theory is non-conformal with a characteristic mass scale M. We solve Einstein’s equations numerically and determine the time evolution of homogeneous gauge theory states. If their initial energy density is high compared with H4 then the early-time evolution is well described by viscous hydrodynamics with a non-zero bulk viscosity. At late times the dynamics is always far from equilibrium. The asymptotic late-time state preserves the full de Sitter symmetry group and its dual geometry is a domain-wall in AdS5. The approach to this state is characterised by an emergent relation of the form $$ \mathcal{P} $$
P
= w ℰ that is different from the equilibrium equation of state in flat space. The constant w does not depend on the initial conditions but only on H/M and is negative if the ratio H/M is close to unity. The event and the apparent horizons of the late-time solution do not coincide with one another, reflecting its non-equilibrium nature. In between them lies an “entanglement horizon” that cannot be penetrated by extremal surfaces anchored at the boundary, which we use to compute the entanglement entropy of boundary regions. If the entangling region equals the observable universe then the extremal surface coincides with a bulk cosmological horizon that just touches the event horizon, while for larger regions the extremal surface probes behind the event horizon.
“…Moreover, thanks to the last property in the list above, a DGP‐like mechanism of gravity quasi‐localisation [ 12 ] allows the four‐dimensional observers on the brane to experience ordinary four‐dimensional gravity in a range of scales. In [18] it was shown that the self‐tuning mechanism is robust, in the sense that stabilized solutions with curved branes require a modification of the boundary conditions at the AdS boundary, and therefore belong to a different superselection sector than flat solutions. A dynamical study of this model in the cosmological setting was initiated in [19].…”
Section: Introduction and Resultsmentioning
confidence: 99%
“…The expansions for for small φ can be found using similar techniques as in [46,47]. The leading terms in this expansion are universal.…”
Section: The Bulk Theory and Its Dual Qftmentioning
We propose a brane‐world setup based on gauge/gravity duality that permits the simultaneous realisation of self‐tuning of the cosmological constant and a stabilisation of the electroweak hierarchy. The Standard Model dynamics including the Higgs sector is confined to a flat 4‐dimensional brane, embedded in a 5‐dimensional bulk whose dynamics is governed by Einstein‐dilaton‐axion gravity. The inclusion of a dynamical bulk axion is new compared to previous implementations of the self‐tuning mechanism. Because of the presence of the axion, the model generically exhibits a multitude of static solutions, with different values for the equilibrium position for the brane. Under mild assumptions regarding the dependence of brane parameters on bulk fields, a number of these solutions exhibit electroweak symmetry breaking with a small Higgs mass as compared to the cutoff‐scale of the brane theory. The realisation of self‐tuning of the cosmological constant is generic and as efficient as in previous constructions without a bulk axion. Vacua with a small Higgs mass can sometimes be found, regardless of whether the brane theory depends explicitly on the bulk axion. Because it is expected on general principles that the brane action will depend on the axion, the generation of solutions with a hierarchy is a robust feature.
“…It would be useful to develop more such examples. Finally, it would be interesting to put the Chern-Simons field theory studied in this paper on a 3-sphere and test the recent proposal for the c-function [38].…”
We use holographic methods to characterize the RG flow of quantum information in a Chern-Simons theory coupled to massive fermions. First, we use entanglement entropy and mutual information between strips to derive the dimension of the RG-driving operator and a monotonic c-function. We then display a scaling regime where, unlike in a CFT, the mutual information between strips changes non-monotonically with strip width, vanishing in both IR and UV but rising to a maximum at intermediate scales. The associated information transitions also contribute to non-monotonicity in the conditional mutual information which characterizes the independence of neighboring strips after conditioning on a third. Finally, we construct a measure of extensivity which tests to what extent information that region A shares with regions B and C is additive. In general, mutual information is super-extensive in holographic theories, and we might expect super-extensivity to be maximized in CFTs since they are scale-free. Surprisingly, our massive theory is more superextensive than a CFT in a range of scales near the UV limit, although it is less super-extensive than a CFT at all lower scales. Our analysis requires the full ten-dimensional dual gravity background, and the extremal surfaces computing entanglement entropy explore all of these dimensions.
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