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We study entanglement entropy (EE) for a Maxwell field in (2+1) dimensions. We do numerical calculations in two-dimensional lattices. This gives a concrete example of the general results of our recent work [1] on entropy for lattice gauge fields using an algebraic approach. To evaluate the entropies we extend the standard calculation methods for the entropy of Gaussian states in canonical commutation algebras to the more general case of algebras with center and arbitrary numerical commutators. We find that while the entropy depends on the details of the algebra choice, mutual information has a well defined continuum limit as predicted in [1]. We study several universal terms for the entropy of the Maxwell field and compare with the case of a massless scalar field. We find some interesting new phenomena: an "evanescent" logarithmically divergent term in the entropy with topological coefficient which does not have any correspondence with ultraviolet entanglement in the universal quantities, and a nonstandard way in which strong subadditivity is realized. Based on the results of our calculations we propose a generalization of strong subadditivity for the entropy on some algebras that are not in tensor product. [ABSTRACT FROM AUTHOR]

We embed spherical Rindler space--a geometry with a spherical hole in its center--in asymptotically anti- de Sitter (AdS) spacetime and show that it carries a gravitational entropy proportional to the area of the hole. Spherical AdS-Rindler space is holographically dual to an ultraviolet sector of the boundary field theory given by restriction to a strip of finite duration in time. Because measurements have finite durations, local observers in the field theory can only access information about bounded spatial regions. We propose a notion of differential entropy that captures uncertainty about the state of a system left by the collection of local, finite-time observables. For two-dimensional conformai field theories we use holography and the strong subadditivity of entanglement to propose a formula for differential entropy and show that it precisely reproduces the areas of circular holes in AdS3. Extending the notion to field theories on strips with variable durations in time, we show more generally that differential entropy computes the areas of all closed, inhomogeneous curves on a spatial slice of AdS3. We discuss the extension to higher-dimensional field theories, the relation of differential entropy to entanglement between scales, and some implications for the emergence of space from the renormalization group flow of entangled field theories. [ABSTRACT FROM AUTHOR]

The nucleon and its negative-parity excited states are examined in a maximum entropy method analysis of QCD sum rules. First, we rederive the parity projected sum rules for baryons using "old-fashioned" correlation functions. Doing this, the method is generalized so that higher order operator product expansion terms can be calculated unambiguously. We then apply this approach to the nucleon channel taking into account all known first order as corrections to the Wilson coefficients of the operator product expansion. As these corrections have turned out to be large, we suppress them by using a phase-rotated Gaussian kernel. Simultaneously, this phase rotation strongly suppresses the continuum contribution and improves the convergence of the operator product expansion. The resulting sum rule has the interesting feature that it is dominated by the term containing the chiral condensate of dimension 3. Analyzing this sum rule by the maximum entropy method, we are able to extract information of both the positive- and negative-parity states. [ABSTRACT FROM AUTHOR]

The mass spectra of isovector Υ, ψ, ϕ, and ω meson resonances are investigated, in the AdS/QCD and information entropy setups. The differential configurational entropy is employed to obtain the mass spectra of radial S-wave resonances, with higher excitation levels, in each one of these meson families, whose respective first undisclosed states are discussed and matched up to candidates in the Particle Data Group. [ABSTRACT FROM AUTHOR]

The basic equations of the thermodynamic system give the relationship between the internal energy, entropy and volume of two neighboring equilibrium states. By using the functional relationship between the state parameters in the basic equation, we give the differential equation satisfied by the entropy of spacetime. We can obtain the entropy by solving the differential equation. This entropy is the sum of entropy corresponding to the two event horizons and the interaction term. The interaction term is the ratio between the location of the black hole horizon and the cosmological horizon. The entropic force, which is strikingly similar to the Lennard-Jones force between particles, varies with the ratio of the two event horizons. The discovery of this phenomenon makes us realize that the entropic force between the two horizons may be one of the candidates to promote the expansion of the universe. [ABSTRACT FROM AUTHOR]

In recent years, many examples appeared in the literature where the configuration entropy (CE), introduced by Gleiser and Stamatopoulos, plays the role of an indicator of stability of physical systems. It was observed that, comparing states of the same system, the lower is the value of the CE, the more stable is the state. In this work, we investigate the behavior of the differential configuration entropy (DCE), that is appropriate for systems with continuous degrees of freedom, in a new context. We consider quasistates of quarkonium (a vector meson made of a heavy quark antiquark pair) inside a plasma at finite density. It is known that the density increases the dissociation effect for quasiparticles inside a plasma. So, increasing the density of a thermal medium corresponds to reducing the stability of the quasiparticles. In order to investigate how this situation is translated in the configuration entropy context, we use a recently developed holographic anti-de Sitter/QCD model for heavy vector mesons. The quasinormal modes describing the quasistates are obtained and the corresponding DCE is calculated. We find, for bottomonium and charmonium 1S quasi-states, that the DCE increases with the quark density, or quark chemical potential, of the medium. This result shows that the DCE works again as an indicator of stability, represented in this case by the dissociation effect associated with the density. [ABSTRACT FROM AUTHOR]

We compute entanglement entropy and differential entropy in inhomogeneous holographic quenches in AdS3/CFT2. The quenches are arbitrarily inhomogeneous and modeled by an infalling shell of massless nonrotating matter where the final state is not dual to a static black hole but rather to a black hole with time-dependent stress-energy tensor modes. We study the entanglement entropy of an interval and differential entropy of a family of intervals analytically when the inhomogeneities have a perturbative amplitude and numerically for nonperturbative inhomogeneities. While we are in principle able to study these quantities for any inhomogeneities, we discuss two concrete examples: an oscillatory quench and a bilocal quench. Both cases display saturation towards a steady state but do not fully thermalize. Depending on the location and size of the interval, the entanglement entropy displays a variety of interesting phenomena such as plateau phases, bumps, and discontinuities in its first derivative with respect to time. [ABSTRACT FROM AUTHOR]