Dilaton Theory Research Articles

Exploring non-perturbative corrections in thermodynamics of static dirty black holes

This research delves into an extensive exploration of the thermodynamic characteristics exhibited by a contaminated black hole subject to a uniform electric field, within the theoretical framework of the Einstein-Nonlinear Electrodynamics (ENE)-dilaton theory. The investigation encompasses a thorough analysis of diverse thermodynamic facets, encompassing heat capacity, Helmholtz free energy, and internal energy. Through this comprehensive examination, valuable insights are provided into the distinctive behavior of the black hole when subjected to the influence of the electric field. Moreover, our study embarks on an exploration of the nuanced interplay between quantum effects and the thermodynamic profile, with a particular focus on scrutinizing the quantum-corrected entropy. This approach allows for a deeper understanding of the intricate relationship between quantum mechanics and the thermodynamic attributes exhibited by the system. By doing so, we aim to illuminate the non-perturbative corrections inherent in this intricate system, thereby contributing to a holistic comprehension of the altered thermodynamics characterizing dirty black holes within the confines of the specified theoretical framework. In essence, this research endeavors to uncover the subtleties of the modified thermodynamic landscape governing black holes tainted by external factors, specifically within the context of the ENE-dilaton theory. The outcomes of this study promise to extend our understanding of the intricate interactions within such complex systems, offering valuable insights into the non-perturbative corrections that manifest in their thermodynamic behavior.

Search for environment-dependent dilatons

The environment-dependent dilaton field is a well-motivated candidate for dark energy and naturally arises in the strong coupling limit of string theory. In this article, we present the very first experimental constraints on the parameters of this model. For this, we employ data obtained from the qBounce collaboration and the Lunar Laser Ranging (LLR) experiment. Furthermore, we forecast expected constraints for the Casimir And Non Newtonian force EXperiment (Cannex) soon to be realized in an improved setup. Finally, we provide a detailed analysis of the screening mechanism and additional symmetries of the dilaton field theory.

Islands in Generalized Dilaton Theories

This work systematically studies the island formula in the general asymptotically flat eternal black holes in generalized dilaton gravity theories or higher-dimensional spherical black holes. Under some reasonable and mild assumptions, we prove that (the boundary of) the island always appears barely outside the horizon in the late time of Hawking radiation, so the information paradox is resolved. In particular, we find a proper island in the Liouville black hole that solves the previous the puzzle.

Thermodynamics of Brans–Dicke–BTZ black holes coupled to conformal-invariant electrodynamics

Abstract The field equations of Brans–Dicke conformal-invariant theory in (2+1)-dimensions are highly nonlinear and difficult to solve directly. They are related to those of Einstein–dilaton theory, where the solutions can be obtained easily, by use of a mathematical tool known as the conformal transformation. The exact solutions of three-dimensional Brans–Dicke theory, which are obtained from their Einstein-dilaton counterparts, give two novel classes of conformal-invariant black holes. When the scalar potential is absent (or is considered constant) in the action, it has been shown that the exact solution of this theory is just the conformal-invariant BTZ black hole with a trivial constant scalar field. This issue corresponds to the four-dimensional Brans–Dicke–Maxwell theory discussed in Ref. [R.-G. Cai, Y. S. Myung, Phys. Rev. D 56, 3466 (1997)]. The Brans–Dicke conformal-invariant black holes’ thermodynamic quantities have been calculated by use of the appropriator methods, and it has been shown that they satisfy the first law of black hole thermodynamics in its standard form. The thermal stability of Brans–Dicke black holes has been studied by use of the canonical ensemble method and noting the signature of the black holes’ heat capacity.

Near-horizon quantum dynamics of 4D Einstein gravity from 2D Jackiw-Teitelboim gravity

We study quantum fluctuations in the light-cone metric of the 4D Einstein-Hilbert action via dimensional reduction to Jackiw-Teitelboim (JT) gravity. In particular, we show that, in Einstein gravity, the causal development of a region in flat Minkowski spacetime, near a horizon defined by light sheets, can be described by an effective two-dimensional dilaton theory. This enables us to make use of known solutions of the JT action, where the spacetime position of a horizon has quantum uncertainty due to metric fluctuations. This quantum uncertainty can be then directly related to the original 4D light-cone coordinates, allowing us to compute the uncertainty in the time of a photon to travel from tip-to-tip of a causal diamond in flat 4D Minkowski space. We find that both Planck and infrared scales (with the latter set by the size of the causal diamond) enter the uncertainty in photon travel time, such that the quantum fluctuation in the arrival time may be observably large.

A closed clockwork theory: ℤ2 parity and more

We develop a new class of clockwork theories with an augmented structure of the near-neighbour interactions along a one-dimensional closed chain. Such a topology leads to new and attractive features in addition to generating light states with hierarchical couplings via the usual clockwork mechanism. For one, there emerges a ℤ2 symmetry under the exchange of fields resulting in a physical spectrum consisting of states, respectively even and odd under the exchange parity with a two-fold degeneracy at each level. The lightest odd particle, being absolutely stable, could be envisaged as a potential dark matter candidate. The theory can also be obtained as a deconstruction of a five-dimensional theory embedded in a geometry generated by a linear dilaton theory on a S1/ℤ2 orbifold with three equidistant 3-branes. Analogous to the discrete picture, the ℤ2 symmetry in the bulk theory necessitates the existence of a KK spectrum of even and odd states, with doubly degenerate modes at each KK level when subject to certain boundary conditions.

Destroying Kaluza–Klein black holes

We investigate the destroying of charged and rotating black holes in Einstein–Maxwell-(dilaton) theory. We show that a test particle with some appropriate properties in the black hole background can turn the black hole into a naked singularity. In this work, we neglect the self-force, self-energy and radiative effects as considered by some others in literature. As the result, we are able to show that the Kaluza–Klein black holes can be destroyed by the test particle. Furthermore, we consider the overspinning of the black hole by a neutral test scalar field.

Exploring the small mass limit of stationary black holes in theories with Gauss–Bonnet terms

In this work we examine the small mass limit of black holes (BHs), with and without spin, in theories where a scalar field is non-minimally coupled to a Gauss–Bonnet (GB) term. First, we provide an analytical example for a theory where a static closed-form solution with a small mass limit is known, and later use analytical and numerical techniques to explore this limit in standard scalar-GB theories with dilatonic, linear and quadratic-exponential couplings. In most cases studied here, we find an inner singularity that overlaps with the event horizon of the static BH as the small mass limit is reached. Moreover, since solutions in this limit possess a non-vanishing Hawking temperature, a naked singularity is expected to be reached through evaporation, raising questions concerning the consistency of these theories altogether. On the other hand, we provide for the first time in this context an example of a coupling where the small mass limit is never reached, thus preferred from the point of view of cosmic censorship. Finally, we consider BHs with spin and numerically investigate how this changes the picture, using these to place the tightest upper bounds to date on the coupling constant for the dilatonic and linear theories, with km.

Black hole sensitivities in Einstein-scalar-Gauss-Bonnet gravity

The post-Newtonian dynamics of black hole binaries in Einstein-scalar-Gauss-Bonnet theories of gravity depends on the so-called "sensitivities", quantities which characterize a black hole's adiabatic response to the time-dependent scalar field environment sourced by its companion. In this work, we calculate numerically the sensitivities of nonrotating black holes, including spontaneously scalarized ones, in three classes of Einstein-scalar-Gauss-Bonnet gravity: the shift-symmetric, dilatonic and Gaussian theories. When possible, we compare our results against perturbative analytical results, finding excellent agreement. Unlike their general relativistic counterparts, black holes in Einstein-scalar-Gauss-Bonnet gravity only exist in a restricted parameter space controlled by the theory's coupling constant. A preliminary study of the role played by the sensitivities in black hole binaries suggests that, in principle, black holes can be driven outside of their domain of existence during the inspiral, for binary parameters which we determine.

The universality of islands outside the horizon

We systematically calculate the quantum extremal surface (QES) associated with Hawking radiation for general D-dimensional (D ≥ 2) asymptotically flat (or AdS) eternal black holes using the island formula. We collect the Hawking radiation particles by a non-gravitational bath and find that a QES exists in the near-horizon region outside the black hole when c · G(D) is smaller enough where c is the central charge of the conformal matter and G(D) the D-dimensional Newton constant. The locations of the QES in these backgrounds are obtained and the late-time radiation entropy saturates the two times of black hole entropy. Finally, we numerically check that the no island configuration exists once c · G(D) exceeds a certain upper bound in two-dimensional generalized dilaton theories (GDT). When c · G(D) close to the upper bound, the backreaction of the matter field on the background can not be neglected. We also consider the conditions of existence of the island configuration with the backreaction and prove that the upper bound also exist for the Witten black hole and Weyl-related Witten black hole.

Complexity growth in Gubser–Rocha models with momentum relaxation

The Einstein–Maxwell–Axion–Dilaton (EMAD) theories, based on the Gubser–Rocha (GR) model, are very interesting in holographic calculations of strongly correlated systems in condensed matter physics. Due to the presence of spatially dependent massless axionic scalar fields, the momentum is relaxed, and we have no translational invariance at finite charge density. It would be of interest to study some aspects of quantum information theory for such systems in the context of AdS/CFT where EMAD theory is a holographic dual theory. For instance, in this paper we investigate the complexity and its time dependence for charged AdS black holes of EMAD theories in diverse dimensions via the complexity equals action (CA) conjecture. We will show that the growth rate of the holographic complexity violates Lloyd’s bound at finite times. However, as shown at late times, it depends on the strength of the momentum relaxation and saturates the bound for these black holes.

Constraining massless dilaton theory at Solar system scales with the planetary ephemeris INPOP

We expose the phenomenology of the massless dilaton theory in the Solar system for a non universal quadratic coupling between the scalar field which represents the dilaton, and the matter. Modified post-Newtonian equations of motion of an $N$-body system and the light time travel are derived from the action of the theory. We use the physical properties of the main planets of the Solar system to reduce the number of parameters to be tested to 3 in the linear coupling case. In the linear case, we have an universal coupling constant $\alpha_0$ and two coupling constants $\alpha_T$ and $\alpha_G$ related respectively to the telluric bodies and to the gaseous bodies. We then use the planetary ephemeris, INPOP19a, in order to constrain these constants. We succeeded to constrain the linear coupling scenario and the constraints read $\alpha_0=(1.01\pm23.7)\times 10^{-5}$, $\alpha_T=(0.00\pm24.5)\times 10^{-6}$, $\alpha_G=(-1.46\pm12.0)\times 10^{-5}$, at the 99.5 \% C.L.

A perturbative CFT dual for pure NS–NS AdS3 strings

We construct a conformal field theory dual to string theory on AdS3 with pure NS–NS flux. It is given by a symmetric orbifold of a linear dilaton theory deformed by a marginal operator from the twist-2 sector. We compute two- and three-point functions on the CFT side to 4th order in conformal perturbation theory at large N. They agree with the string computation at genus 0, thus providing ample evidence for a duality. We also show that the full spectra of both short and long strings on the CFT and the string side match. The duality should be understood as perturbative in N −1.

Dilaton chiral perturbation theory and applications

We review dilaton chiral perturbation theory (dChPT), the effective low-energy theory for the light sector of near-conformal, confining theories. dChPT provides a systematic expansion in both the fermion mass and the distance to the conformal window. It accounts for the pions and the light scalar, the approximate Nambu–Goldstone bosons for chiral and scale symmetry, respectively. A unique feature of dChPT is the existence of a large-mass regime in which the theory exhibits approximate hyperscaling, while the expansion nevertheless remains systematic. We discuss applications to lattice data, presenting successes as well as directions for future work.

Slowly rotating black holes in the novel Einstein\u2013Maxwell-scalar theory

We investigate a slowly rotating black hole solution in a novel Einstein–Maxwell-scalar theory, which is prompted by the classification of general Einstein–Maxwell-scalar theory. The gyromagnetic ratio of this black hole is calculated, and it increases as the second free parameter beta increases, but decreases with the increasing parameter gamma equiv frac{2 alpha ^{2}}{1+alpha ^2}. In the Einstein–Maxwell-dilaton (EMD) theory, the parameter beta vanishes but the free parameter alpha governing the strength of the coupling between the dilaton and the Maxwell field remains. The gyromagnetic ratio is always less than 2, the well-known value for a Kerr–Newman (KN) black hole as well as for a Dirac electron. Scalar hairs reduce the magnetic dipole moment in dilaton theory, resulting in a drop in the gyromagnetic ratio. However, we find that the gyromagnetic ratio of two can be realized in this Einstein–Maxwell-scalar theory by increasing beta and the charge-to-mass ratio Q/M simultaneously (recall that the gyromagnetic ratio of KN black holes is independent of Q/M). The same situation also applies to the angular velocity of a locally non-rotating observer. Moreover, we analyze the period correction for circular orbits in terms of charge-to-mass ratio, as well as the correction of the radius of the innermost stable circular orbits. It is found the correction increases with beta but decreases with Q/M. Finally, the total radiative efficiency is investigated, and it can vanish once the effect of rotation is considered.

Dynamics in Interacting Scalar-Torsion Cosmology

In a spatially flat Friedmann–Lemaître–Robertson–Walker background space, we consider a scalar-torsion gravitational model which has similar properties to the dilaton theory. This teleparallel model is invariant under a discrete transformation similar to the Gasperini–Veneziano duality transformation. Moreover, in the gravitational action integral, we introduce the Lagrangian function of a pressureless fluid source which is coupled to the teleparallel dilaton field. This specific gravitational theory with interaction in the dark sector of the universe was investigated by using methods of the dynamical system analysis. We calculate that the theory provides various areas of special interest for the evolution of the cosmological history. Inflationary scaling solutions and the de Sitter universe are recovered. Furthermore, we calculate that there exist an attractor which provides a stable solution where the two fluid components, the scalar field and the pressureless matter, contribute in the cosmological fluid. This solution is of special interest because it can describe the present epoch. Finally, the qualitative evolution of the cosmographic parameters is discussed.

Charged black hole and radiating solutions in entangled relativity

In this manuscript, we show that the external Schwarzschild metric can be a good approximation of exact black hole solutions of entangled relativity. Since entangled relativity cannot be defined from vacuum, the demonstrations need to rely on the definition of matter fields. The electromagnetic field being the easiest (and perhaps the only) existing matter field with infinite range to consider, we study the case of a charged black hole – for which the solution of entangled relativity and a dilaton theory agree – as well as the case of a pure radiation – for which the solution of entangled relativity and general relativity seem to agree, despite an apparent ambiguity in the field equations. Based on these results, we argue that the external Schwarzschild metric is an appropriate mathematical idealization of a spherical black hole in entangled relativity. The extension to rotating cases is briefly discussed.

$$O\left( d,d\right) $$ symmetry in teleparallel dark energy

An important characteristic of the dilaton cosmological model is the Gasperini–Veneziano duality transformation which follows from the existence of the $$O\left( d,d\right) $$ symmetry. In this study, we consider the equivalent dilaton theory in teleparallel dark energy with the $$O\left( d,d\right) $$ symmetry, while the equivalent teleparallel-duality transformation is presented. The classical solution of the field equations is derived. Finally, the Wheeler–DeWitt equation of quantum cosmology is discussed.

Quasilocal Smarr relation for an asymptotically flat spacetime

We investigate the thermodynamics of Einstein–Maxwell (-dilaton) theory for an asymptotically flat spacetime in a quasilocal frame. We firstly define a quasilocal thermodynamic potential via the Euclidean on-shell action and formulate a quasilocal Smarr relation from Euler’s theorem. Then we calculate the quasilocal energy and surface pressure by employing a Brown–York quasilocal method along with Mann–Marolf counterterm and find entropy from the quasilocal thermodynamic potential. These quasilocal variables are consistent with the Tolman temperature and the entropy in a quasilocal frame turns out to be same as the Bekenstein–Hawking entropy. As a result, we found that a surface pressure term and its conjugate variable, a quasilocal area, do not participate in a quasilocal thermodynamic potential, but should be present in a quasilocal Smarr relation and the quasilocal first law of black hole thermodynamics. For dyonic black hole solutions having dynamic dilaton field, a non-trivial dilaton contribution should occur in the quasilocal first law but not in the quasilocal Smarr relation.

Mass of dyonic black holes and entropy super-additivity

We study extremal static dyonic black holes in four-dimensional Einstein–Maxwell–Dilaton theory, for general values of the constant a in the exponential coupling of the dilaton to the Maxwell kinetic term. Explicit solutions are known only for a = 0, a = 1 and , and for general a when the electric and magnetic charges Q and P are equal. We obtain solutions as power series expansions around Q = P, in terms of a small parameter . Using these, and also solutions constructed numerically, we test a relation between the mass and the charges that had been conjectured long ago by Rasheed. We find that although the conjecture is not exactly correct it is in fact quite accurate for a wide range of the black hole parameters. We investigate some improved conjectures for the mass relation. We also study the circumstances under which entropy super-additivity, which is related to Hawking’s area theorem, is violated. This extends beyond previous examples exhibited in the literature for the particular case of dyonic black holes.