arXiv subjects

Suat Dengiz

Publications and source records attributed to Suat Dengiz.

At least 19 recordsLinked to original sources

arXiv2025

Domain Wall Skyrmions in Holographic Quantum Chromodynamics: Topological Phases and Phase Transitions

We investigate the domain wall skyrmions phase in the framework of holographic quantum chromodynamics (QCD) using the Sakai-Sugimoto model. Building on previous work regarding chiral soliton lattices (CSLs) in strong magnetic fields, we study the emergence of localized skyrmions a top domain walls formed by CSLs. These skyrmions, realized as undissolved D4-branes embedded in the D8-branes, carry baryon number two and exhibit complex topological and energetic features. We explore the interplay between magnetic field strength, pion mass, and baryon chemical potential in stabilizing these configurations and demonstrate the existence of a mixed CSL-skyrmions phase. Through systematic energy analysis, we establish that the domain wall skyrmions become energetically favorable when $\mu_B |B| \gtrsim \Lambda \cdot m_\pi f_\pi^2$, with the transition occurring around $\mu_B |B| \sim 4.5$ in our holographic framework. Our phase diagram reveals three distinct regions: the CSL phase at low chemical potential and magnetic field, the domain wall skyrmions phase at intermediate scales, and a conjectured skyrmions crystal phase at the highest densities. The instanton density profiles $\text{Tr}(F \wedge F)$ show sharp localization in the domain wall skyrmions phase, contrasting with the smooth, extended distribution characteristic of the pure CSL configuration. These findings provide non-perturbative insights into baryonic matter in the dense QCD and offer a geometrical picture of topological phase transitions via string theory duality, with potential applications to neutron star physics and the broader QCD phase diagram under extreme conditions.

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arXiv2025

Thermal and Optical Signatures of Einstein-Dyonic ModMax Black Holes with GUP and Plasma Modifications

We explore the thermodynamic and optical properties of Einstein-Dyonic-ModMax (EDM) black holes (BHs), incorporating quantum gravity corrections and plasma effects. The ModMax theory promotes the classical Maxwell theory to a non-linear electrodynamics with a larger symmetry structure (electromagnetic duality plus conformal invariance), and provides dyonic BH solutions characterized by both electric and magnetic charges modulated by the nonlinearity parameter $\gamma$. Using the Hamilton-Jacobi tunneling formalism, we derive the Hawking radiation spectrum and demonstrate how the Generalized Uncertainty Principle (GUP) modifies the thermal emission, potentially leading to stable remnants. Our analysis of gravitational lensing employs the Gauss-Bonnet theorem to compute light deflection angles in both vacuum and plasma environments, revealing strong dependencies on the ModMax parameter and plasma density. We extend this to axion-plasmon environments, uncovering frequency-dependent modifications that could serve as dark matter signatures. The photon motion analysis in plasma media shows how the exponential damping term $e^{-\gamma}$ affects electromagnetic backreaction on spacetime geometry. We compute quantum-corrected thermodynamic quantities, including internal energy, Helmholtz free energy, pressure, and heat capacity, using exponentially modified entropy models. The heat capacity exhibits second-order phase transitions with critical points shifting as functions of $\gamma$, indicating rich thermodynamic phase structures. The energy condition analysis shows that classical ModMax electrodynamics satisfies the null and weak energy conditions, while the observed near-horizon violations arise only after incorporating quantum-corrected entropy effects.

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arXiv2025

Quantum-Corrected Thermodynamics of Conformal Weyl Gravity Black Holes: GUP Effects and Phase Transitions

We investigate the thermodynamic properties of black holes in Conformal Weyl Gravity (CWG) using the Mannheim-Kazanas solution, with particular emphasis on quantum corrections that become significant near the Planck scale. Our analysis employs the Hamilton-Jacobi tunneling formalism to derive the Hawking temperature, revealing explicit contributions from the conformal parameters $\beta$, $\gamma$, and $k$ that lead to substantial deviations from the behavior of a Schwarzschild black hole. We incorporate quantum gravitational effects through the Generalized Uncertainty Principle, demonstrating systematic suppression of thermal radiation in the near-Planckian regime. Using an exponentially corrected entropy model, we compute the complete spectrum of QC thermodynamic potentials, including internal energy, pressure, heat capacity, and free energies. Our heat capacity analysis shows divergence behavior that separates stable and unstable regions, indicating possible thermodynamic transitions controlled by the scale-dependent parameter $\gamma$. The Joule-Thomson expansion analysis shows distinct cooling and heating regimes with inversion points that shift systematically with CWG parameters, capturing QC phase transitions absent in general relativity. We also examine gravitational redshift in CWG geometry, finding complex radial dependence that highlights modifications compared to the Schwarzschild case, although redshift alone cannot observationally distinguish CWG from Einstein's theory. Our results demonstrate that CWG offers a consistent framework for studying black hole thermodynamics beyond general relativity, with quantum corrections modifying phase structures in the near-Planckian regime, though these effects are not expected to yield direct observational consequences.

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arXiv2024

Cosmological Weyl-Einsteinian-Cubic Gravity as a Gauge Theory of Gravity

We construct a Weyl-Einsteinian-Cubic Gravity (ECG) as a cubic gauge theory of gravity via abelian gauge and properly tuned compensating real scalar fields. The model is free from any dimensionful parameters. The bare ECG emerges as the lower energy limit of the Weyl-ECG in the local {\it non}-conformal-invariant vacua (i.e., broken phase) in the maximally symmetric spacetimes fixing the vacuum expectation value of the scalar field to the Planck mass scale. Here, the natural presence of (anti-) de Sitter backgrounds spontaneously breaks Weyl's local conformal symmetry akin to the Higgs mechanism, while it is radiatively broken at the renormalization scale at the one-loop level in flat vacua through the Coleman-Weinberg mechanism. The model allows anti-de Sitter and flat spaces but does not allow de Sitter to be vacuum spacetime solutions. The properties of the model deserve further exploration, specifically, those of nonperturbative (e.g., instantons and/or anti-instantons) contributions, for example, in the resurgence or tachyon condensation context requires detailed study.

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arXiv2021

New Chiral Generalized Minimal Massive Gravity

We study the generalized minimal massive gravity (GMMG) in Compere, Song and Strominger boundary conditions employing a semi-product of a Virasoro and a $\hat{u}(1)$ Kac-Moody current algebras as the asymptotic symmetry algebra. We calculate the entropy of BTZ black holes via the degeneracy of states belonging to a Warped-CFT. We compute the linearized energy excitations by using the representations of the algebra $\hat{u}(1) \times SL(2,R)_R$ and show that energies of excitations are non-negative at (two) chiral points in the parameter space. At these special points, the charge algebra is described by either Virasoro algebra or Kac-Moody algebra. We also consider some special limits of the GMMG theory which correspond to $2+1$-dimensional massive gravity theories such as new massive and minimal massive gravity theories.

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arXiv2021

Exact gyratons in higher and infinite derivative gravity

We study solutions describing spinning null sources called gyratons in generic theories of gravity with terms that are quadratic in curvature and contain an arbitrary number of covariant derivatives. In particular, we show that the properties of pp-waves of the algebraic type III allow for extreme simplification of the field equations. It turns out that the resulting differential equations are exactly solvable due to partial decoupling and linearity of the equations. This is demonstrated explicitly by finding axially symmetric gyraton solutions in Stelle's fourth derivative gravity and the non-local gravity with an infinite number of derivatives.

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arXiv2020

Lee-Wald Charge and Asymptotic Behaviors of the Weyl-invariant Topologically Massive Gravity

We apply the Lee-Wald covariant phase space method to the Weyl-invariant Topologically Massive Gravity and compute the corresponding on-shell conserved charges. By using appropriate decay conditions for the existing propagating modes in the near-horizon of a stationary black hole, we obtain the charges generating the asymptotic symmetries. We show that the charges are integrable and the (modified) algebras among the asymptotic generators are closed for the certain choice of central extensions.

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arXiv2020

Impulsive waves in ghost free infinite derivative gravity in anti-de Sitter spacetime

We study exact impulsive gravitational waves propagating in anti-de Sitter spacetime in the context of the ghost free infinite derivative gravity. We show that the source-free theory does not admit any AdS wave solutions other than that of Einstein's general relativity. The situation is significantly different in the presence of sources. We construct impulsive-wave solutions of the infinite derivative gravity generated by massless particles and linear sources in four and three dimensions. The singularities corresponding to distributional curvature at the locations of the sources get smeared by the non-localities. The obtained solutions are regular everywhere. They reduce to the corresponding solutions of general relativity in the infrared regime and in the local limit.

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arXiv2020

High temperature behavior of non-local observables in boosted strongly coupled plasma: A holographic study

In this work, we perform a holographic analysis to study non local observables associated to a uniformly \textit{boosted} strongly coupled large $N$ thermal plasma in $d$-dimensions. In order to accomplish the holographic analysis, the appropriate dual bulk theory turns out to be $d+1$ dimensional \textit{boosted} AdS-Schwarzschild blackhole background. In particular, we compute entanglement entropy of the boosted plasma at high temperature living inside a strip geometry with entangling width $l$ in the boundary at a particular instant of time. We also study the two-point correlators in the boundary by following geodesic approximation method. For analyzing the effect of boosting on the thermal plasma and correspondingly on both non local observables, we keep the alignment of the width of region of interest both parallel and perpendicular to the direction of the boost. We find our results significantly modified compared to those in un-boosted plasma up to the quadratic order of the boost velocity $v$. More interestingly, the relative orientation of the boost and the entangling width plays a crucial role to quantify the holographic entanglement entropy in the boundary theory. The breaking of rotational symmetry in the boundary theory due to the boosting of the plasma along a specific flat direction causes this interesting feature.

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arXiv2018

Note on soft photons and Faddeev-Jackiw symplectic reduction of quantum electrodynamics in the eikonal limit

In this note, we go over the recent soft photon model and Faddeev-Jackiw quantization of the massless quantum electrodynamics in the eikonal limit to some extent. Throughout our readdressing, we observe that the gauge potentials in both approaches become pure gauges and the associated eikonal Faddeev-Jackiw quantum bracket matches with the soft quantum bracket. These observations and the fact that the gauge fields in two cases localize in two-dimensional plane (even if it is spatial in soft photon case and $1+1$-dimensional Minkowski in the eikonal case) imply that there might be an interesting relation between these two distinct perspectives.

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arXiv2017

A Note on Noncompact and Nonmetricit Quadratic Curvature Gravity Theories

In this note, we evaluate the Weyl-invariant quadratic curvature tensors for the particular Weyl's gauge field constructed in the $3+1$-dimensional noncompact Weyl-Einstein-Yang-Mills model. We subsequently extend the model to its higher curvature version. Here, we also compute Weyl-invariant extension of topological Gauss-Bonnet term for this specific choice of vector field.

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arXiv2017

A Noncompact Weyl-Einstein-Yang-Mills Model: A Semiclassical Quantum Gravity

We construct and study perturbative unitarity (i.e., ghost and tachyon analysis) of a $3+1$-dimensional noncompact Weyl-Einstein-Yang-Mills model. The model describes a local noncompact Weyl's scale plus $SU(N)$ phase invariant Higgs-like field, conformally coupled to a generic Weyl-invariant dynamical background. Here, the Higgs-like sector generates the Weyl's conformal invariance of system. The action does not admit any dimensionful parameter and genuine presence of de Sitter vacuum spontaneously breaks the noncompact gauge symmetry in an analogous manner to the Standard Model Higgs mechanism. As to flat spacetime, the dimensionful parameter is generated within the dimensional transmutation in quantum field theories, and thus the symmetry is radiatively broken through the one-loop Effective Coleman-Weinberg potential. We show that the mere expectation of reducing to Einstein's gravity in the broken phases forbids anti-de Sitter space to be its stable vacua. The model is unitary in de Sitter and flat vacua around which a massless graviton, $N^2-1$ massless scalar bosons, $N$ massless Dirac fermions, $N^2-1$ Proca-type massive Abelian and non-Abelian vector bosons are generically propagated.

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arXiv2016

Faddeev-Jackiw Hamiltonian Reduction for Free and Gauged Rarita-Schwinger Theories

We study the Faddeev-Jackiw symplectic Hamiltonian reduction for 3+1-dimensional free and Abelian gauged Rarita-Schwinger theories that comprise Grassmannian fermionic fields. We obtain the relevant fundamental brackets and find that they are in convenient forms for quantization. The brackets are independent of whether the theories contain mass or gauge fields, and the structure of constraints and symplectic potentials largely determine characteristic behaviors of the theories. We also note that, in contrast to the free massive theory, the Dirac field equations for free massless Rarita-Schwinger theory cannot be obtained in a covariant way.

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arXiv2015

More on Cotton Flow

Cotton flow tends to evolve a given initial metric on a three manifold to a conformally flat one. Here we expound upon the earlier work on Cotton flow and study the linearized version of it around a generic initial metric by employing a modified form of the DeTurck trick. We show that the flow around the flat space, as a critical point, reduces to an anisotropic generalization of linearized KdV equation with complex dispersion relations one of which is an unstable mode, rendering the flat space unstable under small perturbations. We also show that Einstein spaces and some conformally flat non-Einstein spaces are linearly unstable. We refine the gradient flow formalism and compute the second variation of the entropy and show that generic critical points are extended Cotton solitons. We study some properties of these solutions and find a Topologically Massive soliton that is built from Cotton and Ricci solitons. In the Lorentzian signature, we also show that the pp-wave metrics are both Cotton and Ricci solitons.

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arXiv2014

Weyl-invariant Higher Curvature Gravity Theories in n Dimensions and Mass Generation by Symmetry Breaking

Weyl-invariant extensions of three-dimensional New Massive Gravity, generic n-dimensional Quadratic Curvature Gravity theories and three-dimensional Born-Infeld gravity theory are analyzed in details. As required by Weyl-invariance, the actions of these gauge theories do not contain any dimensionful parameter; therefore the local symmetry is spontaneously broken in (Anti) de Sitter vacua in analogy with the Standard Model Higgs mechanism. About the flat vacuum, symmetry breaking mechanism is more complicated: The conformal symmetry is radiatively broken (at two loop level in 3-dimensions and at one-loop level in 4-dimensions) a la Coleman-Weinberg mechanism and hence the dimensionful parameters come from dimensional transmutation in the quantum field theory. In the broken phases, save for New Massive Gravity, the theories generically propagate with a unitary (tachyon and ghost-free) massless tensor, massive (or massless) vector and massless scalar particles for the particular intervals of the dimensionless parameters. For New Massive Gravity, there is a massive Fierz-Pauli-type graviton. Finally, it is shown that n-dimensional Weyl-invariant Einstein-Gauss-Bonnet theory is the only unitary higher dimensional Weyl-invariant Quadratic Curvature Gravity theory.

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arXiv2013

Scattering in Topologically Massive Gravity, Chiral Gravity and the corresponding Anyon-Anyon Potential Energy

We compute the tree-level scattering amplitude between two covariantly conserved sources in generic Cosmological Topologically Massive Gravity augmented with a Fierz-Pauli term that has three massive degrees of freedom. We consider the Chiral Gravity limit in the anti-de Sitter space as well as the limit of Flat-Space Chiral Gravity. We show that Chiral Gravity cannot be unitarily deformed with a Fierz-Pauli mass. We calculate the non-relativistic potential energy between two point-like spinning sources. In addition to the expected mass-mass and spin-spin interactions, there are mass-spin interactions due to the presence of the gravitational Chern-Simons term which induces spin for any massive object and turns it to an anyon. We also show that the tree-level scattering is trivial for the Flat-Space Chiral Gravity.

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arXiv2012

Weyl-gauging of Topologically Massive Gravity

We construct a Weyl-invariant extension of topologically massive gravity which, remarkably, turns out to include topologically massive electrodynamics, with a Proca mass term, conformally coupled to a scalar field. The action has no dimensionful parameters, therefore, the masses are generated via symmetry breaking either radiatively in flat backgrounds or spontaneously in constant curvature backgrounds. The broken phase of the theory, generically, has a single massive spin-2 and a massive spin-1 excitation. Chiral gravity in asymptotically anti-de Sitter spacetimes does not arise as a low energy theory, while chiral gravity in de Sitter spacetime is not ruled out.

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arXiv2012

Weyl-Invariant Higher Curvature Gravity Theories in n Dimensions

We study the particle spectrum and the unitarity of the generic n-dimensional Weyl-invariant quadratic curvature gravity theories around their (anti-)de Sitter [(A)dS] and flat vacua. Weyl symmetry is spontaneously broken in (A)dS and radiatively broken at the loop level in flat space. Save the three dimensional theory (which is the Weyl-invariant extension of the new massive gravity), the graviton remains massless and the unitarity requires that the only viable Weyl-invariant quadratic theory is the Weyl-invariant extension of the Einstein-Gauss-Bonnet theory. The Weyl gauge field on the other hand becomes massive. Symmetry breaking scale fixes all the dimensionful parameters in the theory.

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