We analyse the effect of velocity and acceleration on the temperature felt by particles and strings in backgrounds relevant in holographic models. First, we compare accelerated strings and strings at finite temperature. We find that for fixed Unruh temperature felt by the string endpoints, the screening length is smaller for the accelerated Wilson loop than for the static one in a thermal background of the same temperature; hence acceleration provides a "more efficient" mechanism for melting of mesons. Secondly, we show that the velocity-dependence of the screening length of the colour force, previously obtained from a moving Wilson loop in a finite temperature background, is not specific for the string, but is a consequence of the generic fact that an observer which moves with constant velocity in a black hole background measures a velocity-dependent temperature. Finally, we analyse accelerated particles and strings in the AdS black hole background, and show that these feel a temperature which increases as a function of time. As a byproduct of our analysis we find a global Minkowski embedding for the planar AdS black hole.
In this Letter we study the radiation measured by an accelerated detector, coupled to a scalar field, in the presence of a fundamental minimal length. The latter is implemented by means of a modified momentum space Green's function. After calibrating the detector, we find that the net flux of field quanta is negligible, and that there is no Planckian spectrum. We discuss possible interpretations of this result, and we comment on experimental implications in heavy ion collisions and atomic systems.
It is shown that the Unruh effect, i.e. the increase in temperature indicated by a uniformly accelerated thermometer in an inertial vacuum state of a quantum field, cannot be interpreted as the result of an exchange of heat with a surrounding gas. Since the vacuum is spatially homogeneous in the accelerated system its temperature must be zero everywhere as a consequence of Tolman's law. In fact, the increase of temperature of accelerated thermometers is due to systematic quantum effects induced by the local coupling between the thermometer and the vacuum. This coupling inevitably creates excit…
A uniformly acclerated observer in anti-deSitter space-time is known to detect thermal radiation when the acceleration exceeds a critical value. We investigate the holographic interpretation of this phenomenon. For uniformly accelerated trajectories transverse to the boundary of the AdS space, the hologram is a blob which expands along the boundary. Observers on the boundary co-moving with the hologram become observers in cosmological space-times. For supercritical accelerations one gets a Milne universe when the holographic screen is the boundary in Poincare coordinates, while for the boundar…
In this Letter we make a critique of, and comparison between, the anomaly method and WKB/tunneling method for obtaining radiation from non-trivial spacetime backgrounds. We focus on Rindler spacetime (the spacetime of an accelerating observer) and the associated Unruh radiation since this is the prototype of the phenomena of radiation from a spacetime, and it is the simplest model for making clear subtle points in the tunneling and anomaly methods. Our analysis leads to the following conclusions: (i) neither the consistent and covariant anomaly methods gives the correct Unruh temperature for R…
Descent extensions of the soft-wall model are used to accommodate two variants of Regge trajectories of vector meson excitations. At non-zero temperatures, various options for either sequential or instantaneous disappearance of vector mesons as normalisable modes are found, thus emulating deconfinement at a certain temperature in the order of the (pseudo-) critical temperature of QCD. The crucial role of the blackness function, which steers the thermodynamic properties of the considered system, is highlighted.
We make a detailed comparison between entanglement harvesting for uniformly accelerated detectors in vacuum and static ones in a thermal bath at the Unruh temperature and find that, for a small energy gap relative to the Heisenberg energy of the detectors, static detectors in the thermal bath can harvest more entanglement and possess a comparatively larger harvesting-achievable range than the uniformly accelerated ones; however, as the energy gap grows sufficiently large, the uniformly accelerated detectors are instead likely to harvest more entanglement and possess a relatively larger harvest…
We consider a model of a holographic braneworld universe in which a cosmological fluid occupies a 3+1 dimensional brane located at the boundary of the asymptotic AdS$_5$ bulk. We combine the AdS/CFT correspondence and the second Randall-Sundrum (RSII) model to establish a relationship between the RSII braneworld cosmology and the boundary metric induced by the time dependent bulk geometry. In the framework of the Friedmann Robertson Walker cosmology we discuss some physically interesting scenarios involving the RSII and holographic braneworlds.
We study the Unruh effect on the dynamics of quarks and mesons in the context of AdS$_5$/CFT$_4$ correspondence. We adopt an AdS$_5$ metric with the boundary Rindler horizon extending into a bulk Rindler-like horizon, which yields the thermodynamics with Unruh temperature verified by computing the boundary stress tensor. We then embed in it a probe fundamental string and a $D7$ brane in such a way that they become the dual of an accelerated quark and a meson in Minkowski space, respectively. Using the standard procedure of holographic renormalization, we calculate the chiral condensate, and al…
Motivated by recent studies of deep inelastic scattering (DIS) off the $\mathcal{N}=4$ super-Yang-Mills (SYM) plasma, holographically dual to $AdS_5\times S^5$ black hole, we in this note use the spacelike flavor current to probe the internal structure of one holographic quark-gluon plasma, which is described by the Sakai-Sugimoto model at high temperature phase (i.e., the chiral symmetric phase). The plasma structure function is extracted from the retarded flavor current-current correlator. Our main aim here is to explore the effect of non-conformality on these physical quantities. As usual, …
We study the relationship between charge density (ρ) and chemical potential (μ) for an array of Lorentz invariant 3 + 1 dimensional holographic field theories with the minimal structure of a conserved charge. The systems considered include Dp-Dq probe brane constructions and probe and backreacted 'bottom-up' models with gauge and scalar fields. In all cases, at large density, the relationship is well modelled by a power law behaviour of the form ρ $\propto$ μ^α. A variety of powers α are found in the brane systems while in most of the bottom-up models α is determined by the underlying conforma…
Given a local quantum field theory net A on the de Sitter spacetime dS^d, where geodesic observers are thermalized at Gibbons-Hawking temperature, we look for observers that feel to be in a ground state, i.e. particle evolutions with positive generator, providing a sort of converse to the Hawking-Unruh effect. Such positive energy evolutions always exist as noncommutative flows, but have only a partial geometric meaning, yet they map localized observables into localized observables. We characterize the local conformal nets on dS^d. Only in this case our positive energy evolutions have a comple…
Over the last few years a certain class of dark-energy models decaying inversely proportional to the square of the horizon distance emerged on the basis either of Heisenberg uncertainty relations or of the uncertainty relation between the four-volume and the cosmological constant. The very nature of these dark energies is understood to be the same, namely it is the energy of background space/metric fluctuations. Putting together these uncertainty relations one finds that the model of random fluctuations of the background metric is favored over the holographic one.
Considering the classical two-point correlators built from (axial)-vector, scalar \bar qq and gluonium currents, we confront results obtained using the SVZ + 1/q^2 expansion to the ones from some QCD holographic models in the Euclidian region and with negative dilaton Φ_i(z)=- |c_i^2| z^2. We conclude that the presence of the 1/q^2-term in the SVZ-expansion due to a tachyonic gluon mass appears naturally in the Minimum Soft Wall (MSW) and the Gauge/String Dual (GSD) models which can also reproduce semi-quantitatively some of the higher dimension condensate contributions appearing in the OPE. T…
We discuss the description of baryon as the dyonic instanton in holographic QCD. The solution generalizes the Skyrmion taking into account the infinite tower of vector and axial mesons as well as the chiral condensate. We construct the solution with unit baryon charge and study the dependence of its mass on the chiral condensate. The elegant explanation of the Ioffe's formula has been found and we speculate on the relation between physical scales of the chiral and conformal symmetry breaking.
A computation of the quotient of shear viscosity to entropy density, or KSS number $η/s$ is performed, in the non-relativistic and classical regime, first in Chiral Perturbation Theory, and then in the $SO(g+1)/SO(g)$ Non-Linear Sigma Model in the large $g$ limit. Both are field theories stemming from a renormalizable Sigma Model but in spite of that, we explicitly calculate how one undercomes the KSS bound by increasing the number of degenerate pions sufficiently. However we argue that particle production could still keep the validity of the KSS bound in the weak sense. We also show how a lar…
In this paper, by using the holographic principle, a modified equipartition theorem where we assume that below a critical temperature the energy is not equally divided on all bits, and the Unruh temperature, we derive MOND theory and a modified Friedmann equation compatible with MOND theory. Furthermore, we rederive a modified Newton's law of gravitation by employing an adequate redefinition of the numbers of bits.
A profound quantum-gravitational effect of space-time dimension running with respect to the size of space-time region has been discovered a few years ago through the numerical simulations of lattice quantum gravity in the framework of causal dynamical triangulation [hep-th/0505113] as well as in renormalization group approach to quantum gravity [hep-th/0508202]. Unfortunately, along these approaches the interpretation and the physical meaning of the effective change of dimension at shorter scales is not clear. The aim of this paper is twofold. First, we find that box-counting dimension in face…
The limitations of the approach based on using fields restricted to the lightfront (Lightfront Quantization or p$\to \infty $ Frame Approach) which drive quantum fields towards canonical and ultimately free fields are well known. Here we propose a new concept which does not suffer from this limitation. It is based on a procedure which cannot be directly formulated in terms of pointlike fields but requires ``holographic'' manipulations of the algebras generated by those fields. We illustrate the new concepts in the setting of factorizable d=1+1 models and show that the known fact of absence of …
In a previous work an approximate static metric was found of a test black string that stretches from the boundary to the horizon of the planar Schwarzschild-AdS_5 geometry. This is the gravity dual of the Unruh state for \mathcal{N}=4, SU(N) super Yang-Mills theory on a 4-dimensional Schwarzschild background, at large N and large 'tHooft coupling. We compute the holographic stress tensor of the gravitational solution and it turns out to possess many essential features of the Unruh state for weakly-coupled Hawking radiation, such as the appearance of a negative energy density near the black hol…
We introduce the cavity enclosing a source mass $M$ to define the temperature force. Starting with the Tolman temperature in the stationary spacetime, we find a non-relativistic temperature $T_{non}= T_\infty(1-Φ/c^2)$ with the Newtonian potential $Φ$. This temperature could be also derived from the Tolman-Ehrenfest effect, satisfying a relation of $T=T_{\infty}e^{-Φ/c^2}$ with the local temperature $T$. Finally, we derive the temperature force $\vec{F}_{tem}=mc^2(\vec{\nabla} \ln T )$ which leads to the Newtonian force law without introducing the holographic screen defined by holographic prin…
We investigate the temperature and energy on holographic screens for 4-dimensional black holes with the entropic force idea proposed by Verlinde. We find that the "Unruh-Verlinde temperature" is equal to the Hawking temperature on the horizon and can be considered as a generalized Hawking temperature on the holographic screen outside the horizons. The energy on the holographic screen is not the black hole mass $M$ but the reduced mass $M_0$, which is related to the black hole parameters. With the replacement of the black hole mass $M$ by the reduced mass $M_0$, the entropic force can be writte…
We revisit the problem of dipole-dipole scattering via exchanges of soft Pomerons in the context of holographic QCD. We show that a single closed string exchange contribution to the eikonalized dipole-dipole scattering amplitude yields a Regge behavior of the elastic amplitude; the corresponding slope and intercept are different from previous results obtained by a variational analysis of semi-classical surfaces. We provide a physical interpretation of the semi-classical worldsheets driving the Regge behavior for (-t)>0 in terms of worldsheet instantons. The latter describe the Schwinger mechan…
In this article we probe the proposed holographic duality between $T\bar{T}$ deformed two dimensional conformal field theory and the gravity theory of $\rm AdS_3$ with a Dirichlet cutoff by computing correlators of energy-momentum tensor. We focus on the large central charge sector of the $T\bar{T}$ CFT in a Euclidean plane and in a sphere, and compute the correlators of energy-momentum tensor using an operator identity promoted from the classical trace relation. The result agrees with a computation of classical pure gravity in $\rm AdS_3$ with the corresponding cutoff surface, given a hologra…
We construct the gravitational dual, in the Unruh state, of the "jammed" phase of a CFT at strong coupling and infinite N on a fixed five-dimensional rotating Myers-Perry black hole with equal angular momenta. When the angular momenta are all zero, the solution corresponds to the five-dimensional generalization of the solution first studied by Figueras, Lucietti, and Wiseman. In the extremal limit, when the angular momenta of the Myers-Perry black hole are maximum, the Unruh, Boulware and Hartle-Hawking states degenerate. We give a detailed analysis of the corresponding holographic stress ener…
We study the dimensionality manifested in the AdS/CFT correspondence. We show that the dimensionality as expressed by the high temperature behavior of a system has a holographic nature also at the quantum level. The emergence of the AdS black hole as a master field at high temperature leads to the screening of the extra dimensions in its excluded volume.
We argue that the relativistic Unruh temperature cannot be associated with the bits on the screen, in the form considered by Verlinde. The acceleration $a$ is a scalar quantity (the modulus of the acceleration four vecor) and not a vector. When the mass $m$ approaches the holographic screen, viewed as a stretched horizon, the shift $Δx$ from Verlinde's Eq. (3.15) becomes $c^{2}/a$ and the entropy variation equals $(1/2) k_{B} ΔN$, in accordance with Gao's calculations. Using the Heisenberg Principle we show that the energy on the causal horizon (viewed as a holographic screen) of an inertial o…
In this paper, we look for signatures of quantum revivals in two-dimensional conformal field theories (2d CFTs) on a spatially compact manifold by using operator entanglement. It is believed that thermalization does not occur on spatially compact manifolds as the quantum state returns to its initial state which is a phenomenon known as quantum revival. We find that in CFTs such as the free fermion CFT, the operator mutual information exhibits quantum revival in accordance with the relativistic propagation of quasiparticles while in holographic CFTs, the operator mutual information does not exh…
We continue our program of describing hadrons as rotating strings with massive endpoints. In this paper we propose models of baryons and confront them with the baryon Regge trajectories. We show that these are best fitted by a model of a single string with a quark at one endpoint and a diquark at the other. This model is preferred over the Y-shaped string model with a quark at each endpoint. We show how the model follows from a stringy model of the holographic baryon which includes a baryonic vertex connected with N_c strings to flavor probe branes. From fitting to baryonic data we find that t…
It is shown that the correspondence principle and the holographic principle are incompatible in the background of an eternal Schwarzschild-anti-de Sitter geometry. The argument is based on the observation that algebraic structures of local quantum field and CFT operators are not equivalent. This implies, in particular, the bulk CFT must be singular near the black-hole horizon. A CFT Hilbert space representation is elaborated which may correspond to the AdS black hole in the dual theory.
We explore the phase structure for defect theories in full generality using the gauge/gravity correspondence. On the gravity side, the systems are constructed by introducing M (probe) D(p+4-2k)-branes in a background generated by N Dp-branes to obtain a codimension-k intersection. The dual gauge theory is a U(N) Supersymmetric Yang-Mills theory on a (1+p-k)-dimensional defect with both adjoint and fundamental degrees of freedom. We focus on the phase structure in the chemical potential versus temperature plane. We observe the existence of two universality classes for holographic gauge theories…
We present a theory of accelerated observers in the formalism of holographic space time, and show how to define the analog of the Unruh effect for a one parameter set of accelerated observers in a causal diamond in Minkowski space. The key fact is that the formalism splits the degrees of freedom in a large causal diamond into particles and excitations on the horizon. The latter form a large heat bath for the particles, and different Hamiltonians, describing a one parameter family of accelerated trajectories, have different couplings to the bath. We argue that for a large but finite causal diam…
We investigate the interaction between a moving detector and a quantum field, especially about how the trajectory of the detector would affect the vacuum fluctuations when the detector is moves in a quantum field (the Unruh effect). We focus on two moving detectors system for future application in quantum teleportation. We find that the rajectory of a uniformly accelerated detector in Rindler space cannot be extended to a trajectory in which a detector moves at constant velocity. Based on our previous work, we redo the calculations and find that a term is missing from the past calculations, an…
In this paper we study a new class of holographic heat engines via charged AdS black hole solutions of Einstein gravity coupled with logarithmic nonlinear $U(1)$ gauge theory. So, Logarithmic $U(1)$ AdS black holes with a horizon of positive, zero and negative constant curvatures are considered as a working substance of a holographic heat engine and the corrections to the usual Maxwell field are controlled by non-linearity parameter $β$. The efficiency of an ideal cycle ($η$), consisting of a sequence of isobaric $\to$ isochoric $\to$ isobaric $\to$ isochoric processes, is computed using the e…
N=2 supersymmetric Yang-Mills theory with flavor hypermultiplets at finite temperature and in the dS${}_4$ are studied for finite quark number density ($n_b$) by a dual supergravity background with non-trivial dilaton and axion. The quarks and its number density $n_b$ are introduced by embedding a probe D7 brane. We find a critical value of the chemical potential at the limit of $n_b=0$, and it coincides with the effective quark mass given in each theory for $n_b=0$. At this point, a transition of the D7 embedding configurations occurs between their two typical ones. The phase diagrams of this…
In this work, we investigate the thermodynamical behavior of charged AdS black holes from $f(R)$ gravity corrections with a constant Ricci scalar curvature in the grand-canonical ensemble. Using the holographic entanglement entropy, we show that the physical observables behave as in the case of the thermal entropy. By performing numerical computations associated with the thermodynamical quantities versus the entanglement entropy, we confirm that the same phase portrait persists in the holographic framework. In the grand-canonical ensemble, the present result supports the former finding which r…
We use gauge/gravity duality to explore strongly coupled superconductors with dynamical exponent $z=2$. In the probe limit we numerically establish background solutions for the matter fields and plot the condensate versus the dimensionless temperature. We then investigate electromagnetic perturbations in order to compute the AC conductivity and also calculate the spectral function. Our results for the condensate and conductivity are qualitatively similar to those of the AdS superconductor. However, we find that (for both s- and p-wave) the condensate does not approach a constant at very low te…
We use AdS/CFT to construct the gravitational dual of a 5D CFT in the background of a non-extremal rotating black hole. Our boundary conditions are such that the vacuum state of the dual CFT corresponds to the Unruh state. We extract the expectation value of the stress tensor of the dual CFT using holographic renormalisation and show that it is stationary and regular on both the future and the past event horizons. The energy density of the CFT is found to be negative everywhere in our domain and we argue that this can be understood as a vacuum polarisation effect. We construct the solutions by…
Verlinde's heuristic argument for the interpretation of the standard Newtonian gravitational force as an entropic force is generalized by the introduction of a minimum temperature (or maximum wave length) for the microscopic degrees of freedom on the holographic screen. With the simplest possible setup, the resulting gravitational acceleration felt by a test mass m from a point mass M at a distance R is found to be of the form of the modified Newtonian dynamics (MOND) as suggested by Milgrom. The corresponding MOND-type acceleration constant is proportional to the minimum temperature, which ca…
Two seemingly distinct notions regarding black holes have captured the imagination of theoretical physicists over the past decade: First, black holes are conjectured to be fast scramblers of information, a notion that is further supported through connections to quantum chaos and decay of mutual information via AdS/CFT holography. Second, black hole information paradox has motivated exotic quantum structure near horizons of black holes (e.g., gravastars, fuzzballs, or firewalls) that may manifest themselves through delayed gravitational wave echoes in the aftermath of black hole formation or me…
We study the temperature of extended objects in string theory. Rotating probe D-branes admit horizons and temperatures a la Unruh effect. We find that the induced metrics on slow rotating probe D1-branes in holographic string solutions including warped Calabi-Yau throats have distinct thermal horizons with characteristic Hawking temperatures even if there is no black hole in the bulk Calabi-Yau. Taking the UV/IR limits of the solution, we show that the world volume black hole nucleation depends on the deformation and the warping of the throat. We find that world volume horizons and temperature…
We study the thermodynamical properties of black holes when described as gases of indistinguishable punctures with a chemical potential. In this picture, which arises from loop quantum gravity, the black hole microstates are defined by finite families of half-integers spins coloring the punctures, and the near-horizon energy measured by quasi-local stationary observers defines the various thermodynamical ensembles. The punctures carry excitations of quantum geometry in the form of quanta of area, and the total horizon area $a_\text{H}$ is given by the sum of these microscopic contributions. We…
Detailed knowledge about equilibration processes is of interest for various fields of physics, including heavy ion collision experiments and quantum quenched condensed matter systems. We study the approach to equilibrium at late times within two types of strongly coupled thermal systems in 3+1 dimensions: systems in the presence of (i) a non-zero charge density, or (ii) a magnetic field at vanishing charge density. Utilizing the gauge/gravity correspondence, we map the aforementioned problem to the computation of quasinormal frequencies around two particular classes of black branes within the …
A new approach to black hole thermodynamics is proposed in Loop Quantum Gravity (LQG), by defining a new black hole partition function, followed by analytic continuations of Barbero-Immirzi parameter to $γ\in i\mathbb{R}$ and Chern-Simons level to $k\in i\mathbb{R}$. The analytic continued partition function has remarkable features: The black hole entropy $S=A/4\ell_P^2$ is reproduced correctly for infinitely many $γ= iη$, at least for $η\in\mathbb{Z}\setminus\{0\}$. The near-horizon Unruh temperature emerges as the pole of partition function. Interestingly, by analytic continuation the partit…
In a previous work [arXiv:2009.03428] we proposed a new model for Quantum GRavity(QGR) and cosmology, dubbed $SU(\infty)$-QGR. One of the axioms of this model is that Hilbert spaces of the Universe and its subsystems represent $SU(\infty)$ symmetry group. In this framework, the classical spacetime is interpreted as being the parameter space characterizing states of the $SU(\infty)$ representing Hilbert spaces. Using quantum uncertainty relations, it is shown that the parameter space - the spacetime - has a 3+1 dimensional Lorentzian geometry. Here after a review of $SU(\infty)$-QGR, including …
In loop quantum gravity the quantum states of a black hole horizon are produced by point-like discrete quantum geometry excitations (or {\em punctures}) labelled by spin $j$. The excitations possibly carry other internal degrees of freedom also, and the associated quantum states are eigenstates of the area $A$ operator. On the other hand, the appropriately scaled area operator $A/(8π\ell)$ is also the physical Hamiltonian associated with the quasilocal stationary observers located at a small distance $\ell$ from the horizon. Thus, the local energy is entirely accounted for by the geometric ope…
In this work, we study gravity duals of conformal field theories with boundaries known as AdS/BCFT correspondence, put forward by Takayanagi [1], within a scalar-tensor theory, as proposed by Horndeski in 4D [2]. We consider the case of 3D gravity dual to 2D BCFT, take a Gibbons-Hawking surface term modified by Horndeski's theory and find the corresponding 3D (BTZ) black hole solutions. We analyze the effects of Horndeski's gravity on the profile of the extra boundary for the black hole by using an approximate analytic solution. Performing a holographic renormalization, we have calculated the …
We employ an analytic solution of a magnetized Einstein-Maxwell-dilaton gravity system whose parameters have been determined so that its holographic dual has the most similarity to a confining QCD-like theory influenced by a background magnetic field. Analyzing the total potential of a quark-antiquark pair in an external electric field, we are able to investigate the effect of the electric field on the different phases of the background which are the thermal AdS and the black hole phases. This is helpful for better understanding the confining character and also the phase transitions of the sys…
