DSpace Repository :: Browsing by Author "Kaminski, Matthias"

Browsing by Author "Kaminski, Matthias"

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3rd Karl Schwarzschild Meeting – Gravity and the Gauge/Gravity Correspondence, 24-28 July 2017, Frankfurt am Main, Germany
(2017) Nicolini, Piero; Kaminski, Matthias; Mureika, Jonas; Bleicher, Marcus; University of Alabama Tuscaloosa
AdS/CFT far from equilibrium in a Vaidya setup
(2017) Wondrak, Michael F.; Kaminski, Matthias; Nicolini, Piero; Bleicher, Marcus; University of Alabama Tuscaloosa
In this paper we apply the AdS/CFT correspondence to study a strongly coupled plasma far from equilibrium with a strong emphasis on the shear behavior. The plasma serves as a model for an electrically charged quark-gluon plasma. On the gravitational side, we use an ingoing Vaidya black brane spacetime. The highest rate of mass infall is confined to a short time interval.
Anomalous hydrodynamics kicks neutron stars
(2016) Kaminski, Matthias; Uhlemann, Christoph F.; Bleicher, Marcus; Schaffner-Bielich, Jürgen; University of Alabama Tuscaloosa
Chiral hydrodynamics in strong external magnetic fields
(2021) Ammon, Martin; Grieninger, Sebastian; Hernandez, Juan; Kaminski, Matthias; Koirala, Roshan; Leiber, Julian; Wu, Jackson; University of Alabama Tuscaloosa
We construct the general hydrodynamic description of (3+1)-dimensional chiral charged (quantum) fluids subject to a strong external magnetic field with effective field theory methods. We determine the constitutive equations for the energy-momentum tensor and the axial charge current, in part from a generating functional. Furthermore, we derive the Kubo formulas which relate two-point functions of the energy-momentum tensor and charge current to 27 transport coefficients: 8 independent thermodynamic, 4 independent non-dissipative hydrodynamic, and 10 independent dissipative hydrodynamic transport coefficients. Five Onsager relations render 5 more transport coefficients dependent. We uncover four novel transport effects, which are encoded in what we call the shear-induced conductivity, the two expansion-induced longitudinal conductivities and the shear-induced Hall conductivity. Remarkably, the shear-induced Hall conductivity constitutes a novel non-dissipative transport effect. As a demonstration, we compute all transport coefficients explicitly in a strongly coupled quantum fluid via holography.
Constraints on quasinormal modes and bounds for critical points from pole-skipping
(2021) Abbasi, Navid; Kaminski, Matthias; University of Alabama Tuscaloosa
We consider a holographic thermal state and perturb it by a scalar operator whose associated real-time Green’s function has only gapped poles. These gapped poles correspond to the non-hydrodynamic quasinormal modes of a massive scalar perturbation around a Schwarzschild black brane. Relations between pole-skipping points, critical points and quasinormal modes in general emerge when the mass of the scalar and hence the dual operator dimension is varied. First, this novel analysis reveals a relation between the location of a mode in the infinite tower of quasinormal modes and the number of pole-skipping points constraining its dispersion relation at imaginary momenta. Second, for the first time, we consider the radii of convergence of the derivative expansions about the gapped quasinormal modes. These convergence radii turn out to be bounded from above by the set of all pole-skipping points. Furthermore, a transition between two distinct classes of critical points occurs at a particular value for the conformal dimension, implying close relations between critical points and pole-skipping points in one of those two classes. We show numerically that all of our results are also true for gapped modes of vector and tensor operators.
Correlations far from equilibrium in charged strongly coupled fluids subjected to a strong magnetic field
(2019) Cartwright, Casey; Kaminski, Matthias; University of Alabama Tuscaloosa
Within a holographic model, we calculate the time evolution of 2-point and 1-point correlation functions (of selected operators) within a charged strongly coupled system of many particles. That system is thermalizing from an anisotropic initial charged state far from equilibrium towards equilibrium while subjected to a constant external magnetic field. One main result is that thermalization times for 2-point functions are significantly (approximately three times) larger than those of 1-point functions. Magnetic field and charge amplify this difference, generally increasing thermalization times. However, there is also a competition of scales between charge density, magnetic field, and initial anisotropy, which leads to an array of qualitative changes on the 2- and 1-point functions. There appears to be a strong effect of the medium on 2-point functions at early times, but approximately none at later times. At strong magnetic fields, an apparently universal thermalization time emerges, at which all 2-point functions appear to thermalize regardless of any other scale in the system. Hence, this time scale is referred to as saturation time scale. As extremality is approached in the purely charged case, 2- and 1-point functions appear to equilibrate at infinitely late time. We also compute 2-point functions of charged operators. Our results can be taken to model thermalization in heavy ion collisions, or thermalization in selected condensed matter systems.
Deep Learning in Theoretical and Experimental Physics and with Applications in Holography, Feynman Diagram and Calculations and Delay Line Detectors
(University of Alabama Libraries, 2023) Knipfer, Marco; Kaminski, Matthias; Gleyzer, Sergei
This dissertation combines three topics from different corners of physics glued together by my interests and Machine Learning (ML). First, the most important ML concepts needed for this thesis are introduced. Then, we investigate hydrodynamic attractors and the speed of sound in Holography. In this correspondence, a strongly coupled Quantum Field Theory (QFT) is mapped to a gravitational system. Out-of-equilibrium dynamics of heavy ion collisions are simulated in the setting of Bjorken flow. As in the literature, time-evolution quantities approach a hydrodynamic attractor, where differences in initial conditions quickly die off,resulting in a single curve. For the entropy density, dimensionless normalization gives a clear attractor behavior contrary to claims in previous literature. A holographic method forcalculating the speed of sound is suggested, as well as a setup for ML of the time evolutionof a N = 4 SYM plasma from holographic data and using domain adaptation to adapt to Quantum Chromodynamics (QCD) data. The hydrodynamic behavior learned through the former is expected to be useful for the latter. We explore Natural Language Processing(NLP)-based Feynman diagram calculations. While tree-level calculations can be fast up toaround five or six external particles, current non-ML methods quickly become unfeasible with more particles or loops. Using data from Quantum Electrodynamics (QED), an analysis ofthe possible data representation methods for use with Neural Networks (NNs) is given. Thise stablishes a foundation for further development of time-consuming or otherwise impossible diagram calculations. We develop a NN-based method to evaluate Delay Line Detector datausing a classifier network to determine the number of particles and a separate network to locate particles in challenging double-hit events. Our approach outperforms classical methods, as confirmed separately by simulation and experimental data with a grid projected onto the detector.
Dispersion relations in non-relativistic two-dimensional materials from quasinormal modes in Hǒrava Gravity
(2019) Garbiso, Markus; Kaminski, Matthias; University of Alabama Tuscaloosa
We compute dispersion relations of non-hydrodynamic and hydrodynamic modes in a non-relativistic strongly coupled two-dimensional quantum field theory. This is achieved by numerically computing quasinormal modes (QNMs) of a particular analytically known black brane solution to 3+1-dimensional Hǒrava Gravity. Hǒrava Gravity is distinguished from Einstein Gravity by the presence of a scalar field, termed the khronon, defining a preferred time-foliation. Surprisingly, for this black brane solution, the khronon fluctuation numerically decouples from all others, having its own set of purely imaginary eigenfrequencies, for which we provide an analytic expression. All other Hǒrava Gravity QNMs are expressed analytically in terms of QNMs of Einstein Gravity, in units involving the khronon coupling constants and various horizons. Our numerical computation reproduces the analytically known momentum diffusion mode, and extends the analytic expression for the sound modes to a wide range of khronon coupling values. In the eikonal limit (large momentum limit), the analytically known dispersion of QNM frequencies with the momentum is reproduced by our numerics. We provide a parametrization of all QNM frequencies to fourth order in the momentum. We demonstrate perturbative stability in a wide range of coupling constants and momenta.
External Fields in Holography Near and Far from Equilibrium
(University of Alabama Libraries, 2022) Cartwright, Casey Cameron; Kaminski, Matthias; University of Alabama Tuscaloosa
This dissertation is devoted to addressing the still ill understood behavior of electromagnetic fields on thermalizing matter in heavy ion collisions. This topic is considered in the context of charged strongly coupled supersymmetric conformal field theory subjected to strong external fields evaluated in thermal states. I begin by presenting studies of three, distinct, time-dependent solutions to the non-linear Einstein-Maxwell-Chern-Simons equations of motion of increasing complexity and phenomenological relevance. The results of these analyses display universal thermalization times for thermalizing matter in strong magnetic fields, linear growth of entropy and entanglement entropy during the production of axial charges and evidence that chiral magnetic signals in heavy ion collisions are more favorable at higher beam energies. Looking more closely at possible final states of these time-dependent systems I study a measure of information via holographic c-functions and demonstrate these functions obey an inverted c-theorem. Finally, I conclude this work by providing evidence that topological gauge field configurations modify the usual notions of confinement/deconfinement transitions in holography.
Fermionic Operator Mixing in Holographic P-Wave Superfluids
(2010-05-14) Ammon, Martin; Erdmenger, Johanna; Kaminski, Matthias; O'Bannon, Andy; University of Alabama Tuscaloosa
We use gauge-gravity duality to compute spectral functions of fermionic operators in a strongly-coupled defect field theory in p-wave superfluid states. The field theory is (3+1)-dimensional N = 4 supersymmetric SU(Nc) Yang-Mills theory, in the 't Hooft limit and with large coupling, coupled to two massless flavors of (2+1)-dimensional N = 4 supersymmetric matter. We show that a sufficiently large chemical potential for a U(1) subgroup of the global SU(2) isospin symmetry triggers a phase transition to a p-wave superfluid state, and in that state we compute spectral functions for the fermionic superpartners of mesons valued in the adjoint of SU(2) isospin. In the spectral functions we see the breaking of rotational symmetry and the emergence of a Fermi surface comprised of isolated points as we cool the system through the superfluid phase transition. The dual gravitational description is two coincident probe D5-branes in AdS5 × S5 with non-trivial worldvolume SU(2) gauge fields. We extract spectral functions from solutions of the linearized equations of motion for the D5-branes' worldvolume fermions, which couple to one another through the worldvolume gauge field. We develop an efficient method to compute retarded Green's functions from a system of coupled bulk fermions. We also perform the holographic renormalization of free bulk fermions in any asymptotically Euclidean AdS space.
Finite baryon and isospin chemical potential in AdS/CFT with flavor
(Springer, 2008-11-11) Erdmenger, Johanna; Kaminski, Matthias; Kerner, Patrick; Rust, Felix; Max Planck Society; University of Alabama Tuscaloosa
We investigate the thermodynamics of a thermal field theory in presence of both a baryon and an isospin chemical potential. For this we consider a probe of several D7-branes embedded in the AdS-Schwarzschild black hole background. We determine the structure of the phase diagram and calculate the relevant thermodynamical quantities both in the canonical and in the grand canonical ensemble. We discuss how accidental symmetries present reflect themselves in the phase diagram: In the case of two flavors, for small densities, there is a rotational symmetry in the plane spanned by the baryon and isospin density which breaks down at large densities, leaving a Z(4) symmetry. Finally, we calculate vector mode spectral functions and determine their dependence on either the baryon or the isospin density. For large densities, a new excitation forms with energy below the known supersymmetric spectrum. Increasing the density further, this excitation becomes unstable. We speculate that this instability indicates a new phase of condensed mesons.
Flavor superconductivity from gauge/gravity duality
(Springer, 2009-10-26) Ammon, Martin; Erdmenger, Johanna; Kerner, Patrick; Kaminski, Matthias; Max Planck Society; Autonomous University of Madrid; Consejo Superior de Investigaciones Cientificas (CSIC); CSIC - UAM - Institut de Fisica Teorica (IFT); University of Alabama Tuscaloosa
We give a detailed account and extensions of a holographic flavor superconductivity model which we have proposed recently. The model has an explicit field theory realization as strongly coupled N = 2 Super Yang-Mills theory with fundamental matter at finite temperature and finite isospin chemical potential. Using gauge/gravity duality, i.e. a probe of two flavor D7-branes in the AdS black hole background, we show that the system undergoes a second order phase transition with critical exponent 1/2. The new ground state may be interpreted as rho meson superfluid. It shows signatures known from superconductivity, such as an infinite dc conductivity and a gap in the frequency-dependent conductivity. We present a stringy picture of the condensation mechanism in terms of a recombination of strings. We give a detailed account of the evaluation of the non-Abelian Dirac-Born-Infeld action involved using two different methods. Finally we also consider the case of massive flavors and discuss the holographic Meissner-Ochsenfeld effect in our scenario.
Fluid Dynamics of R-charged Black Holes
(2009-01-20) Erdmenger, Johanna; Haack, Michael; Kaminski, Matthias; Yarom, Amos; University of Alabama Tuscaloosa
We construct electrically charged AdS5 black hole solutions whose charge, mass and boost-parameters vary slowly with the space-time coordinates. From the perspective of the dual theory, these are equivalent to hydrodynamic configurations with varying chemical potential, temperature and velocity fields. We compute the boundary theory transport coefficients associated with a derivative expansion of the energy momentum tensor and R-charge current up to second order. In particular, for the current we find a first order transport coefficient associated with the vorticity of the fluid.
From Maxwell-Chern-Simons Theory in AdS₃ Towards Hydrodynamics in 1 + 1 Dimensions
(2014-10-21) Chang, Han-Chih; Fujita, Mitsutoshi; Kaminski, Matthias; University of Alabama Tuscaloosa
We study Abelian Maxwell-Chern-Simons theory in three-dimensional AdS black hole backgrounds for both integer and non-integer Chern-Simons coupling. Such theories can be derived from various string theory constructions, which we review in the present work. In particular we find exact solutions in the low frequency, low momentum limit, ω, k ≪ T (hydrodynamic limit). Using the holographic principle, we translate our results into correlation functions of vector and scalar operators in the dual strongly coupled 1+1-dimensional quantum field theory with a chiral anomaly at non-zero temperature T. Starting from the conformal case we show applicability of the hydrodynamic limit and discuss extensions to the non-conformal case. Correlation functions in the conformal case are compared to an exact field theoretic computation.
Holographic Operator Mixing and Quasinormal Modes on the Brane
(2010-02-04) Kaminski, Matthias; Landsteiner, Karl; Mas, Javier; Shock, Jonathan P.; Tarrío, Javier; University of Alabama Tuscaloosa
We provide a framework for calculating holographic Green’s functions from general bilinear actions and fields obeying coupled differential equations in the bulk. The matrix-valued spectral function is shown to be independent of the radial bulk coordinate, and hence, free from renormalization ambiguities. Applying this framework we improve the analysis of fluctuations in the D3/D7 system at finite baryon density, where the longitudinal perturbations of the world-volume gauge field couple to the scalar fluctuations of the brane embedding. We compute the spectral function and show how its properties are related to those of the quasinormal mode spectrum. We study the crossover from the hydrodynamic diffusive to the reactive regime and the movement of quasinormal modes as functions of temperature and density. We also compute their dispersion relations and find that they asymptote to the lightcone for large momenta.
Holographic Techniques Applied to Rotating Fluids and Non-Relativistic Fluids
(University of Alabama Libraries, 2021) Amano, Markus Antonio; Kaminski, Matthias; University of Alabama Tuscaloosa
With the advent of the influential AdS/CFT correspondence, as a concrete realization of the holographic principle, theoreticians can construct models of strongly coupled quantum systems. In practice the holographic community often constructs toy models qualitatively similar to the Quark Gluon Plasmas (QGP). This dissertation presents three applications of AdS/CFT to model strongly coupled fluids where two symmetries are broken via theory or change of state. As the first application, a model of a 2D non-relativistic strongly coupled fluid is presented. The non-relativistic gravitational dual is is Horava Gravity (HG). A numerical study is conducted to calculate the transport coefficients and Quasinormal Modes (QNM). Second, a model of a strongly coupled rotating plasma is constructed and analyzed. The study is conducted to calculate the transport coefficients. Third, the aforementioned analysis is extended to determine the convergence radius of the hydrodynamic expansion in the rotational case. The convergence radius is determined by the calculation of critical points. This dissertation also covers an international collaboration that studied a 4+1D resonating gravitational soliton. This study focuses on the thermodynamic stability of the spacetime and its dual "glueball phase". The dissertation will close with an exposition of current projects and future prospects.
Holographic vector mesons from spectral functions at finite baryon or isospin density
(American Physical Society, 2008-02-19) Erdmenger, Johanna; Kaminski, Matthias; Rust, Felix; Max Planck Society; University of Alabama Tuscaloosa
We consider gauge/gravity duality with flavor for the finite-temperature field theory dual of the AdS-Schwarzschild black hole background with embedded D7-brane probes. In particular, we investigate spectral functions at finite baryon density in the black hole phase. We determine the resonance frequencies corresponding to meson-mass peaks as function of the quark mass over temperature ratio. We find that these frequencies have a minimum for a finite value of the quark mass. If the quotient of quark mass and temperature is increased further, the peaks move to larger frequencies. At the same time the peaks narrow, in agreement with the formation of nearly stable vector meson states which exactly reproduce the meson-mass spectrum found at zero temperature. We also calculate the diffusion coefficient, which has finite value for all quark mass to temperature ratios, and exhibits a first-order phase transition. Finally we consider an isospin chemical potential and find that the spectral functions display a resonance peak splitting, similar to the isospin meson-mass splitting observed in effective QCD models.
Hydrodynamics of holographic superconductors
(Springer, 2009-05-06) Amado, Irene; Kaminski, Matthias; Landsteiner, Karl; Autonomous University of Madrid; Consejo Superior de Investigaciones Cientificas (CSIC); CSIC - UAM - Institut de Fisica Teorica (IFT); University of Alabama Tuscaloosa
We study the poles of the retarded Green functions of a holographic superconductor. The model shows a second order phase transition where a charged scalar operator condenses and a U(1) symmetry is spontaneously broken. The poles of the holographic Green functions are the quasinormal modes in an AdS black hole background. We study the spectrum of quasinormal frequencies in the broken phase, where we establish the appearance of a massless or hydrodynamic mode at the critical temperature as expected for a second order phase transition. In the broken phase we find the pole representing second sound. We compute the speed of second sound and its attenuation length as function of the temperature. In addition we find a pseudo diffusion mode, whose frequencies are purely imaginary but with a non-zero gap at zero momentum. This gap goes to zero at the critical temperature. As a technical side result we explain how to calculate holographic Green functions and their quasinormal modes for a set of operators that mix under the RG flow.
Hydrodynamics of simply spinning black holes & hydrodynamics for spinning quantum fluids
(2020) Garbiso, Markus; Kaminski, Matthias; University of Alabama Tuscaloosa
We find hydrodynamic behavior in large simply spinning five-dimensional Anti-de Sitter black holes. These are dual to spinning quantum fluids through the AdS/CFT correspondence constructed from string theory. Due to the spatial anisotropy introduced by the angular momentum, hydrodynamic transport coefficients are split into groups longitudinal or transverse to the angular momentum, and aligned or anti-aligned with it. Analytic expressions are provided for the two shear viscosities, the longitudinal momentum diffusion coefficient, two speeds of sound, and two sound attenuation coefficients. Known relations between these coefficients are generalized to include dependence on angular momentum. The shear viscosity to entropy density ratio varies between zero and 1/(4π) depending on the direction of the shear. These results can be applied to heavy ion collisions, in which the most vortical fluid was reported recently. In passing, we show that large simply spinning five-dimensional Myers-Perry black holes are perturbatively stable for all angular momenta below extremality.
Hyperscaling-violation on Probe D-branes
(2012-11-07) Ammon, Martin; Kaminski, Matthias; Karch, Andreas; University of Alabama Tuscaloosa

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