- Aasmund Folkestad (Massachusetts Institute of Technology)
- "Far-from-equilibrium bounds in uniform critical systems"
[Abstract]
Abstract
We prove novel far-from-equilibrum bounds on conformal field theories, upper bounding the growth rate of entanglement entropy, equal-time correlations, and Wilson loops in spatially uniform states. Example applications include lower bounds on thermalization times or the time it takes for a Wilson loops to transition from perimeter to area laws. Our bounds are proven for holographic conformal field theories at strong coupling and large$-N$, but for several of our bounds we provide evidence that they are valid independent of these assumptions. In two dimensions, our results prove a conjectured bound on entanglement growth by Liu and Suh for a large class of states. We also derive bounds on spatial derivatives of correlation measures. From a gravitational perspective, our results constitute new lower bounds on the mass of asymptotically AdS spacetimes with planar symmetry, strengthening the positive mass theorem for these spacetimes. We also derive novel relations in AdS/CFT relating various geometric features directly to entropy derivatives.
- Kanato Goto (Yukawa Institute for Theoretical Physics, Kyoto University, Princeton University)
- "Factorization in Quantum Gravity"
[Abstract] [pdf]
Abstract
Recent studies revealed that wormhole geometries play a central role in understanding quantum gravity. After disorder-averaging over random couplings, Sachdev-Ye-Kitaev (SYK) model has a collective field description of wormhole saddles. A recent paper by Saad, Shenker, Stanford, and Yao studied the SYK model with fixed couplings and found that the wormhole saddles persist, but that new saddles called “half-wormholes” also appear in the path-integral.
In this talk, we introduce a “partially disorder-averaged SYK model” and study how these half-wormholes emerge as we gradually fix the coupling constants. This model has a real parameter that smoothly interpolates between the ordinary totally disorder-averaged SYK model and the totally fixed-coupling model. For the large N effective description, in addition to the usual bi-local collective fields, we also introduce a new additional set of local collective fields. These local fields can be understood as the “half” of the bi-local collective fields, and they represent the half-wormholes in the totally fixed-coupling limit. We found that the large N saddles of these local fields vanish in the total-disorder-averaged limit, while they develop non-trivial profiles as we gradually fix the coupling constants. This illuminates how the half-wormhole saddles emerge in the SYK model with fixed couplings.
- Sergio Hernandez-Cuenca (Center for Theoretical Physics, Massachusetts Institute of Technology)
- "Quenching the near-extremal black hole spectrum_ The replica trick for general matrix integrals"
[Abstract] [pdf]
Abstract
A generic pathology one encounters when computing the thermal entropy of a black hole is that it becomes negatively divergent as the temperature goes to zero, and only those whose extremal limit preserve some supersymmetry yield a sensible low-temperature entropy. The physics relevant to these phenomena are all captured by Jackiw-Teitelboim theories of gravity, which have been rather explicitly shown to be dual to various matrix ensembles. The issues and features mentioned above can all be precisely understood from this perspective:
traditional gravitational calculations are always computing annealed quantities, which give inherently wrong approximations near extremality. We use the matrix integral formulation to show how quenched quantities do in fact behave sensibly and yield non-negative entropies at all temperatures. By using a suitable replica trick, this is done for a completely general matrix ensemble, thus settling the question for any black hole whose near-extremal spectrum is captured by such ensembles. Crucially, this result only requires working perturbatively to leading order in the size of the matrices, which hints at the possibility of an analogous semiclassical gravitational computation where one just needs to account for wormhole contributions appropriately (and not for doubly non-perturbative effects in 1/G).
- Alexander Jahn (Free University Berlin)
- "De Sitter tensor networks with overlapping qubits"
[Abstract] [pdf]
Abstract
The time evolution of de Sitter space has been previously suggested to be isometric, described by a continuously growing Hilbert space. In our work, we study the consequences of restricting this growth by constraining the fundamental Hilbert space, allowing for "overlapping" qubits with small non-orthogonality. We find that constructions based on non-isometric maps can spoof a much larger effective Hilbert space, with deviations consistent with features of quantum gravity. Using a MERA-based tensor network model, we construct examples of such non-isometric maps and show how they approximately preserve local physics for a long period of de Sitter evolution. Our work relates de Sitter quantum gravity to questions of Hilbert space dimension verification, degree-of-freedom counting in black holes, and von Neumann algebra descriptions of holographic systems.
(full paper at arXiv:2304.02673)
- Yiyang Jia (Weizmann Institute of Science)
- " Parisi’s hypercube, double-scaled SYK, Fock-space fluxes and NAdS_2/NCFT_1
duality"
[Abstract] [pdf]
Abstract
We consider a model of Parisi where a single particle hops on an infinite-dimensional hypercube, under the influence of a uniform but disordered magnetic flux. We reinterpret the hypercube as the Fock-space graph of a many-body Hamiltonian, and the flux as a frustration of the return amplitudes in Fock space. We will show that this model has the same correlation functions as the double-scaled Sachdev-Ye-Kitaev model, and hence is an equally good quantum model for near-AdS$_2$/near-CFT$_{1}$ holography. Unlike the SYK model, the hypercube Hamiltonian is not $p$-local. Instead, the SYK model can be understood as a Fock-space model with similar frustrations. Hence we propose this type of Fock-space frustration as the broader characterization for NAdS$_2$/NCFT$_1$ microscopics, and speculate the possible origin of such frustrations.
- Yoshinori Matsuo (Department of Physics, Kindai University)
- "Islands and quantum focusing conjecture"
[Abstract] [pdf]
Abstract
In this presentation, we discuss how islands affect the quantum focusing conjecture. The classical focusing theorem states that the expansion along null lines is non-increasing if the null energy condition is satisfied. However, the null energy condition is violated by quantum effects such as the Hawking radiation. The quantum focusing conjecture was proposed as a generalization of the classical focusing conjecture to the semi-classical regime. It can be interpreted as a condition for the entanglement entropy including gravitational effects. We consider the quantum focusing conjecture in an evaporating black hole geometry and study effects of islands.
- Akihiro Miyata (the Kavli Institute for Theoretical Sciences, the University of Chinese Academy of Sciences)
- "Recovery maps/protocols in Quantum black holes and their SYK realizations"
[Abstract] [pdf]
Abstract
In this presentation, we will discuss the recovery maps/protocol to decode black hole interior information from Hawking radiation under the Hayden-Preskill protocol. Usually, such recovery maps are the Petz map, Petz lite, and the Kitaev-Yoshida protocol. Beni Yoshida suggests the relation between the Petz map and the Kitaev-Yoshida protocol. We will revisit those relations in terms of replica wormhole-like objects. After the discussion, we will also discuss SYK realizations of such recovery maps/protocol and their consequences. This presentation is based on work with Yasuaki Nakayama and Tomonori Ugajin.
- Giuseppe Policastro (Ecole Normale Superieure, Paris)
- "Quantum Complexity and Entanglement"
[Abstract]
Abstract
I will discuss the relation of quantum complexity, especially in the geometric Nielsen's formulation, to entanglement. In particular I will show that there is a class of complexity measures, defined by a certain choice of penalty factors, which is closely related to entanglement and Renyi entropies, and anser the questions: what is the minimal complexity needed to produce a certain amount of entanglement?
- Martin Sasieta (Brandeis University)
- "Cosmology from entanglement"
[Abstract]
Abstract
I will construct entangled microstates of a pair of holographic CFTs which describe big-bang/big-crunch AdS cosmologies in spaces without boundaries. The cosmology is supported by heavy matter and it partially purifies the bulk entanglement of two auxiliary AdS spaces. In this setup, the island formula for the fine grained entropy of one of the CFTs follows from a standard replica trick calculation. The cosmology always lies in the entanglement island of one of the two CFTs. I will then study the encoding of the cosmology on the CFT, as a function of the amount of bulk entanglement, with tensor network toy models as a guide.
- Hiroyasu Tajima (The university of Electro-Communications)
- "Universal trade-off structure between symmetry, irreversibility, and quantum coherence in quantum processes"
[Abstract]
Abstract
Symmetry, irreversibility, and quantum coherence are foundational concepts in physics. Here, we present a universal trade-off relation that builds a bridge between these three concepts. This particularly reveals that (1) under a global symmetry, any attempt to induce local dynamics that changes the conserved quantity will cause inevitable irreversibility, and (2) such irreversibility can be mitigated by quantum coherence. Our fundamental relation also admits broad applications in physics and quantum information processing. For black hole physics, our theorem also provides fundamental limitations on quantum and classical information recovery. For example, it predicts how many bits of classical information thrown into a black hole become unreadable under the Hayden-Preskill model with the energy conservation law. This particularly shows that when the black hole is large enough, under suitable encoding, at least about $m/4$ bits of the thrown $m$ bits will be irrecoverable until 99 percent of the black hole evaporates. For quantum information theory, our trade-off also unifies and extends various restrictions on quantum information processing imposed by symmetry. It recovers and extends the Eastin-Knill theorems for error-correcting codes, the Wigner-Araki-Yanase (WAY) theorems for quantum measurements, and the unitary Wigner-Araki-Yanase theorems for unitary gates as corollaries. This particularly answers an open problem in this field: quantitative WAY theorems for arbitrary errors and disturbances. In the context of thermodynamics, our theorem gives a universal trade-off between the coherence cost of an arbitrary quantum process and the entropy production in a standard quantum thermodynamic setting.
Our theorem further applies to other targets, including Petz map recovery and OTOC. Our main relation is based on quantum uncertainty relation, showcasing intimate relations between fundamental physical principles and ultimate operational capability.
- Christopher Waddell (Perimeter Institute)
- "Accelerating Cosmology from Lambda<0 Gravitational Effective Field Theory"
[Abstract]
Abstract
A large class of Lambda<0 cosmologies have big-bang / big crunch spacetimes with time-symmetric backgrounds and asymptotically AdS Euclidean continuations suggesting a possible holographic realization. We argue that these models generically have time-dependent scalar fields, and these can lead to realistic cosmologies at the level of the homogeneous background geometry, with an accelerating phase prior to the turnaround and crunch. We first demonstrate via explicit effective field theory examples that models with an asymptotically AdS Euclidean continuation can also exhibit a period of accelerated expansion without fine tuning. We then show that certain significantly more tuned examples can give predictions arbitrarily close to a LambdaCDM model. Finally, we demonstrate via an explicit construction that the potentials of interest can arise from a superpotential, thus suggesting that these solutions may be compatible with an underlying supersymmetric theory.
- Zhencheng Wang (University of California, Santa Barbara/University of Illinois, Urbana-Champaign)
- "Algebras of boundary observables from the gravitational path integral"
[Abstract]
Abstract
In this talk, I will show that for each asymptotically anti-de Sitter boundary B, the quantum gravity path integral defines a Type I von Neumann algebra of observables acting at B, as long as the path integral satisfies a set of axioms. Such an algebra admits an entropy, and in the semiclassical limit, this entropy is given by the (quantum-corrected) Ryu-Takayanagi formula. Our construction does not rely on the holographic dual field theory, therefore, the (quantum-corrected) Ryu-Takayanagi formula can be understood as computing an entropy in the bulk Hilbert space. The reason that this algebra is of Type I is strongly related to the fact that the gravitational path integral satisfies a "trace inequality": tr(ab) ≤ tr(a)tr(b) for positive operators a and b.
- Daisuke Yoshida (Nagoya University)
- "Entropy Bound and a Geometrically Nonsingular Universe"
[Abstract]
Abstract
Bousso's entropy bound is a conjecture that the entropy through a null hypersurface emanating from a two-dimensional surface with a nonpositive expansion is bounded by the area of that two-dimensional surface. We investigate the validity of Bousso's entropy bound in the spatially flat, homogeneous, and isotropic universe with an adiabatic entropy current. We find that the bound is satisfied in the entire spacetime in which a cutoff time is introduced based on the entropy density and the energy density. Compared to the previously used prescription which puts a cutoff near the curvature singularity, our criterion for introducing the cutoff is applicable even to a nonsingular universe. Our analysis provides an interpretation of the incompleteness implied by the recently proposed singularity theorem based on the entropy bounds.
- Baasanchimed Avirmed (Toyohashi University of Technology)
- "A parallel, branch and bound algorithm for a combinatorial instance of quantum hypothesis testing"
[Abstract]
Abstract
We consider a particular instance of the quantum hypothesis testing problem, known as quantum guesswork, in which the guessing party receives an unknown state from a quantum ensemble and is allowed to query one state at a time. It has recently been shown that such an operational setup is equivalent to a particular instance of a combinatorial problem known as quadratic assignment problem, which is known to be NP-hard in general. Here, we exploit such a combinatorial reformulation of the quantum guesswork to devise and implement in the C programming language a parallel, branch and bound algorithm for the exact computation of the guesswork of any given qubit ensemble. While problem sizes above twenty are typically considered challenging for general quadratic assignment instances, our algorithm solves instances of size thirty in hours. In particular, we report on the exact expression of the guesswork for a broad class of symmetric ensembles.
- Jan Chojnacki (Faculty of Physics University of Warsaw)
- "Finite Action Principle and the beginning of the universe"
[Abstract]
Abstract
The path integral approach yields a powerful framework in the quantum theory. It emphasizes Lorentz covariance and allows for the description of non-perturbative phenomena. In the path integral, one sums over all possible field configurations weighted by an exponential factor containing classical action of the theory.
In the Minkowski path integral, the classical action approaching infinity causes fast oscillations in the exponential weight and hence the destructive interference of the neighboring field configurations. Such configurations do not contribute to the physical quantities. Furthermore, the Wick rotated path integral is weighted by exponentially decaying factor and the field configurations on which the action is infinite do not contribute at all. This provides a theoretical motivation for the Finite Action Principle, stating that an action of the general gravitational theory should be finite.
This principle has a significant impact on the nature of quantum gravity and the cosmological evolution, once the higher-curvature terms are included. In the framework of Horava-Lifshitz gravity, field configurations with finite classical action describe a flat universe with a homogeneous and isotropic beginning without the ghost particles.
- Saskia Demulder (Ben Gurion University of the Negev)
- "New duality frames and the swampland distance conjecture"
[Abstract]
Abstract
String dualities, and in particular T-duality, challenge our understanding of which backgrounds can harbour propagating strings. These spaces are known as non-geometric backgrounds and allow for local patches to be glued not only using diffeomorphisms but also T-duality transformations. This raises the question if these "exotic" backgrounds can lead to consistent quantum gravities. In this poster, we will show how this question can be addressed by exploring the swampland distance conjecture.
This work is in work in progress with Thomas Raml and Dieter Lüst.
- Xia Gu (Yau Mathematical Sciences Center, Tsinghua University)
- "Liouville conformal blocks and Stokes phenomena"
[Abstract]
Abstract
We derive braid group representations and Stokes matrices for Liouville conformal blocks with one irregular operator. By employing the Coulomb gas formalism,
the corresponding conformal blocks can be interpreted as wavefunctions of a Landau-Ginzburg
model specified by a superpotential W. Alternatively, these can also be viewed as wavefunctions of a 3d TQFT on a 3-ball with boundary a 2-sphere on which the operator insertions
represent Anyons whose fusion rules describe novel topological phases of matter.
- Puttarak Jai-akson (iTHEMS, RIKEN)
- "Membrane paradigm and Carrollian hydrodynamics at stretched horizons"
[Abstract] [pdf]
Abstract
The membrane paradigm profoundly bridges gravitational physics at a stretched horizon, a timelike surface located near a null boundary (e.g., black hole horizons), with hydrodynamics. While the connection has been made semi-classically, it could potentially shed light on our understanding of fundamental degrees of freedom, symmetries, and dynamics of quantum spacetime. In this work, we revisit the membrane viewpoint of a finite-distance null boundary and present a unified geometrical treatment for both the stretched horizon and the null boundary. This then allows us to naturally extend the geometrical Carrollian description of the null boundary and the Carrollian hydrodynamics picture, which have been recently argued to be the associated fluid dynamics of any null boundary, to the stretched horizon. To this end, we draw a dictionary between gravitational degrees of freedom on the stretched horizon and the Carrollian fluid quantities and show that Einstein's equations on the horizon correspond to Carrollian hydrodynamic conservation laws. We also demonstrate that the covariant phase space of gravity at the stretched horizon is precisely the phase space of Carrollian hydrodynamics. Lastly, the Carrollian conservation laws and the corresponding Noether charges are also derived from the symmetries of the stretched horizon.
- Matheus H. Martins Costa (Leibniz Institute for Solid State and Materials Research Dresden)
- "Wilsonian RG as a Quantum Channel and Momentum-Space Entanglement"
[Abstract]
Abstract
We establish the Wilson RG as a specific quantum channel acting on the momentum-space density matrices of a field theory at zero temperature. This allows us to develop a method to calculate the entanglement between fast and slow modes in the ground state of a QFT based on the effective action obtained after integrating out high momenta and to show that fixed point theories (for example, CFTs) must be separable with respect to this momentum-space partition. Our results pave the way for further exploring the relation between renormalization and entanglement, including the role played by the latter in determining the phase structure of the underlying theories.
- Ken Matsuno (Osaka Central Advanced Mathematical Institute, Osaka Metropolitan University)
- "Thermodynamics of regular black holes in effective loop quantum gravity"
[Abstract] [pdf]
Abstract
We consider the thermodynamics of the four-dimensional spherically symmetric black holes with the minimal area gap in the loop quantum gravity inspired by the effective field theory. We derive the modified Hawking temperature and the modified heat capacity of the quantum-corrected black hole based on the scalar particle tunneling mechanism. We see that the quantum gravity effect may slow down the increase of the Hawking temperature due to the radiation and result in the thermodynamic stable remnant, similar to the evaporation of the black holes in the noncommutative model and the asymptotically safe gravity. We also find that the modified sparsity of the Hawking radiation may become infinite when the mass of the loop quantum black hole approaches its remnant mass.
- Javier Moreno (Haifa University-Technion)
- " Conformal bounds in three dimensions from entanglement entropy"
[Abstract]
Abstract
The entanglement entropy of an arbitrary spacetime region $A$
in a three-dimensional conformal field theory (CFT) contains a constant
universal coefficient, $F(A)$. For general theories, the value of F(A) is
minimized when A is a round disk, $F_0$, and in that case it coincides with
the Euclidean free energy on the sphere. We conjecture that, for general
CFTs, the quantity $F(A)/F_0$ is bounded above by the free scalar field
result and below by the Maxwell field one. We provide strong evidence in
favor of this claim and argue that an analogous conjecture in the
four-dimensional case is equivalent to the Hofman-Maldacena bounds. In
three dimensions, our conjecture gives rise to similar bounds on the
quotients of various constants characterizing the CFT. In particular, it
implies that the quotient of the stress-tensor two-point function
coefficient and the sphere free energy satisfies $C_T/F0 \leq 3/(4\pi 2\log
2 − 6\zeta[3]) ≃ 0.14887$ for general CFTs. We verify the validity of this
bound for free scalars and fermions, general O(N) and Gross-Neveu models,
holographic theories, N = 2 Wess- Zumino models and general ABJM theories.
- Kaito Niinomi (Toyohashi University of Technology)
- "A parallel, branch and bound algorithm for a combinatorial instance of quantum hypothesis testing"
[Abstract]
Abstract
We consider a particular instance of the quantum hypothesis testing problem, known as quantum guesswork, in which the guessing party receives an unknown state from a quantum ensemble and is allowed to query one state at a time. It has recently been shown that such an operational setup is equivalent to a particular instance of a combinatorial problem known as quadratic assignment problem, which is known to be NP-hard in general. Here, we exploit such a combinatorial reformulation of the quantum guesswork to devise and implement in the C programming language a parallel, branch and bound algorithm for the exact computation of the guesswork of any given qubit ensemble. While problem sizes above twenty are typically considered challenging for general quadratic assignment instances, our algorithm solves instances of size thirty in hours. In particular, we report on the exact expression of the guesswork for a broad class of symmetric ensembles.
- Christian Northe (Ben-Gurion University of the Negev)
- "Virasoro Entanglement Resolution"
[Abstract]
Abstract
I will present a formalism with which entanglement can be resolved in conformal field theory (CFT) with respect to conformal families to all orders in the UV cutoff. To leading order, symmetry-resolved entanglement is connected to the quantum dimension of a conformal family, while to all orders it depends on null vectors. Criteria for equipartition between sectors are provided in both cases. This analysis exhausts all unitary conformal families. Furthermore, topological entanglement entropy is shown to symmetry-resolve the Affleck-Ludwig boundary entropy. Configuration and fluctuation entropy are analyzed on grounds of conformal symmetry.
- Himanshu Parihar (National Center for Theoretical Sciences, National Tsing Hua University, Taiwan)
- "Time-like Entanglement Entropy in AdS/BCFT"
[Abstract] [pdf]
Abstract
We study the entanglement entropy for time-like subsystem in two-dimensional boundary conformal field theory (BCFT) both from the field theory and holographic point of view. In field theory, we compute the time-like entanglement entropy of a pure time-like interval at zero and finite temperature using the replica technique and analytical continuation. We find that, similar to the ordinary space-like entanglement entropy in BCFT, the time-like entropy also has a bulk phase and a boundary phase which corresponds respectively to the dominance of the identity block in the bulk and boundary OPE channels. However, we find that in Lorentzian BCFT, the time-like entanglement entropy posses a third Regge phase which arises in the Regge limit of the interval, when one endpoint of the time interval approaches the light cone of the mirror image of the other endpoint. We determine the phase diagram for the time-like entanglement entropy. We find that while the time-like entropy is complex in the bulk phase and has a boundary term in the boundary phase, there is no boundary entropy in the Regge phase. Moreover, it can be real or complex depending on which side the Regge limit is approached from. On the gravity side, we obtain the holographic time-like entanglement entropy from the corresponding bulk dual geometries and find exact agreement with the field theory results.
- Aaron Poole (Kyung Hee University)
- "Phase Space Renormalization and Finite BMS Charges in Six Dimensions"
[Abstract]
Abstract
I will discuss asymptotic symmetries in six dimensional asymptotically flat spacetimes. Working in the full nonlinear regime, I will show that the vacuum Einstein equations admit a solution space near null infinity with a full "BMS group" of asymptotic symmetries - an infinite extension of the Poincaré group consisting of both supertranslations and superrotations. I will use the covariant phase space formalism to construct the charges corresponding to these symmetries, an undertaking which will require a renormalization of the symplectic potential via addition of local and covariant counterterms. Finally, I will show that the Ward identities for the charges correspond to soft graviton theorems, opening the pathway to an "infrared triangle" for spacetime dimension greater than four. This presentation is based on https://arxiv.org/abs/2304.09330 in collaboration with Federico Capone, Prahar Mitra and Bilyana Tomova.
- Jie Ren (Sun Yat-sen University)
- "Holographic Renyi entropies from hyperbolic black holes with scalar hair"
[Abstract]
Abstract
The Renyi entropies as a generalization of the entanglement entropy imply much more information. We analytically calculate the Renyi entropies (with a spherical entangling surface) by means of a class of neutral hyperbolic black holes with scalar hair as a one-parameter generalization of the MTZ black hole. The zeroth-order and third-order phase transitions of black holes lead to discontinuity of the Renyi entropies and their second derivatives, respectively. From the Renyi entropies that are analytic at n=∞, we can express the entanglement spectrum as an infinite sum in terms of the Bell polynomials. We show that the analytic treatment is in agreement with numerical calculations for the low-lying entanglement spectrum in a wide range of parameters.
- Kengo Shimada (Yukawa Institute for Theoretical Physics, Kyoto University)
- "Bulk modified gravity from boundary CFT with gradient flow approach"
[Abstract]
Abstract
We construct a bulk spacetime from a boundary finite temperature CFT (O(N) free scalar) by a coarse graining technique called gradient flow.
The bulk metric is constructed as an information metric associated with the boundary thermal state.
In the UV region, an asymptotically AdS spacetime is obtained with a leading order perturbation of scalar mode.
Based on the falloff behavior of the perturbations and the O(N) symmetry in the CFT,
we argue that the corresponding bulk theory is a modified gravity with scalar mode such as f(R) gravity rather than general relativity with matter fields.
Moving to Einstein frame, we see that the metric is asymptotically the same as AdS black brane solution.
On the other hand, in the IR region, the spacetime turns out to be conformally equivalent to near horizon limit of AdS extremal black brane although it is no longer a solution of f(R) gravity, and hence more general classes of modified gravity need to be considered.
- Takahiro Tanaka (Yukawa Institute for Theoretical Physics, Kyoto University)
- "non invertible symmetry with gravity"
- Konstantin Thomas Weisenberger (University of Cologne)
- "The Chiral SYK model and holography"
[Abstract]
Abstract
We propose a (1+1)-dimensional chiral extension of the SYK model which in the infrared limit is described by the (1+1)-dimensional generalization of the Schwarzian action, namely the Alekseev-Shatashvilli (AS)-action. This action has recently been proposed to govern boundary gravitons in pure AdS3 gravity [Cotler Jensen], giving our model the interpretation of a holographic boundary theory. From the AS-action, correlation functions of Majorana operators can be calculated by means of Liouville field theory on the hyperbolic plane, where we solve two-point functions and out-of-time-order correlation functions using semi-classical methods. As predicted by general results [Stanford/Roberts], we find the maximal Lyapunov exponent $2\pi/\beta$ and additionally an exponential decay of correlations beyond the scrambling time (have this result hopefully until then). Work done in collaboration with A. Altland, D. Bagrets and N. Callebaut.
- Takahiro Yokokura (Tohoku University)
- "The QCD phase diagram in the space of imaginary chemical potential via 't Hooft anomalies"
[Abstract]
Abstract
The QCD phase diagram in the space of temperature and imaginary baryon chemical potential has been an interesting subject in numerical lattice QCD simulations because of the absence of the sign problem and its deep structure related to confinement/deconfinement. We study constraints on the phase diagram by using an 't Hooft anomaly. The relevant anomaly is an anomaly in the space of imaginary chemical potential. We compute it in the UV, and discuss how it is matched by the pion effective field theory at low temperatures. Then we study implications of the anomaly to the phase diagram. Based on 2305.01217.