The inverse cascade in two-dimensional hydrodynamic turbulence exhibits a mysterious phenomenon. Numerical simulations have shown that the nodal isolines of certain scalars actively transported in the flow (eg, the vorticity in Navier-Stokes theory) obey Schramm-Loewner evolution (SLE), which indicates the presence of conformal invariance. Therefore, these turbulent isolines are somehow in the same class as cluster boundaries in equilibrium statistical mechanical models at criticality, such as critical percolation. In this paper, we propose that the inverse cascade is characterized by a local energy (or in some cases, enstrophy) flux field that spontaneously breaks time reversal invariance. The turbulent state consists of random constant flux domains, with the nodal isolines acting as domain walls where the local flux vanishes. The generalized circulation of the domains is proportional to a topological winding number. We argue that these turbulent states are gapped states, in analogy with quantum Hall systems. The turbulent flow consists of many strongly coupled vortices that are analogous to quasi-particles. The nodal isolines are associated with the gapless topological degrees of freedom in the flow, where scale invariance is enhanced to conformal invariance. We introduce a concrete model of this behavior using a two-dimensional effective theory involving the canonical Clebsch scalars. This theory has patch solutions that exhibit power law scaling. The fractional winding number associated with the patches can be related to the Kolmogorov-Kraichnan scaling dimension of the corresponding fluid theory. We argue that the fully developed inverse cascade is a scale invariant gas of these patches. This theory has a conformally invariant sector described by a Liouville conformal field theory whose central charge is fixed by the fractional winding number.

We explore a general mechanism that allows (1+1)d CFTs to have interesting interface conformal manifolds even in the absence of any continuous internal symmetry or supersymmetry. This is made possible by the breaking of an enhanced continuous symmetry, which is generically non-invertible, arising in the folded theory. We provide several examples and showcase the power of the symmetry-based approach by computing the evolution of the reflection coefficient along the defect conformal manifold. We also discuss higher-dimensional generalizations and we comment on no-go theorems.

We demonstrate some very special features of the Dirac-Born-Infeld--like (DBI) gravitational counter-term in AdS$_4$ spacetime, in the context of holography with a sharp radial cut-off. We show that the three-sphere partition function is not only independent of a constant radial cut-off, but also remains unchanged under deformations of the cut-off surface. We also consider the renormalized holographic entanglement entropy for an equatorial Ryu-Takayanagi surface with a cut-off with an arbitrary shape and show that it can also be independent of the cut-off under a special condition. We also numerically study the behavior of the renormalized entropy with different counter-terms and relate the results to monotonicity properties under holographic renormalization group flow. The DBI counter-term is always seen to be associated with integrating out fewer degrees of freedom compared to other counter-terms.

Cosmic censorship posits spacetime singularities remain concealed behind event horizons, preserving the determinism of General Relativity. While quantum gravity is expected to resolve singularities, we argue that cosmic censorship remains necessary whenever spacetime has a reliable semi-classical description. Using holography to construct exact solutions to semi-classical gravity, we show backreaction of quantum matter generates horizons -- quantum censors -- to thwart potential violations of censorship. Along with a quantum Penrose inequality, this provides compelling evidence cosmic censorship is robust, even nonperturbatively, in semi-classical gravity.

In holography, the isometry group of the bulk spacetime corresponds to the symmetries of the boundary theory. We thus approach the question of whether (and when) scale invariance in combination with Poincar\'e invariance implies full conformal invariance in quantum field theory from a holographic bulk perspective. To do so, we study bulk spacetimes that include a warped extra dimension and in which the isometry group corresponds to scale without conformal invariance. Firstly, we show that the bulk Weyl tensor plays a pivotal role in distinguishing those metrics exhibiting conformal invariance (Weyl=0) from those merely exhibiting scale invariance (Weyl$\neq$0). Based on this, we then prove the following theorem: For putative boundary theories with $n\geq2$ dimensions, the bulk metric can not exhibit scale without conformal invariance if its warped extra dimension is compact and the null energy condition is required to hold. For $n=1$, we discuss that a more general ansatz for the bulk metric must be made, a detailed analysis of which is left for future research.

In this paper, we explore the Chamber dissection of the loop-geometry of Correlehedron, which encodes the loop integrand of four-point stress-energy correlators in planar $\mathcal{N}=4$ super Yang-Mills. We demonstrate that at four loops, continuing the pattern of lower loops, the integrand of four-point correlation function can be written as a sum over products of chamber-forms and local loop integrands. The chambers and their associated forms are identical to those of three-loops, indicating that the dissection may be complete to all loop orders. Furthermore, this suggests that the leading singularities to all loops are simply linear combinations of these chamber forms. This is especially intriguing at four loops since it contains elliptic functions. Interestingly, each elliptic function appears in a subset of chambers. Our geometric approach allows us to ``diagonalize" the representation, where the local integrals only possess a single leading singularity or elliptic cut. In such a representation, all integrals must evaluate to pure functions, including a single pure elliptic integral. Inspired by this picture, we also present a simplified form of the three-loop correlator in terms of two independent pure functions (weight-$6$ single-valued multiple polylogarithms), which are directly computed from local integrals with unit leading singularities, multiplied by the leading singularities from chamber forms.

We analyze the matching of high and low temperature expansions of the effective action of massive scalar fields confined between two infinite walls with different boundary conditions. One remarkable low temperature effect is the exponential decay of the vacuum energy with the separation of the walls and the fact that the rate of decay is half for the boundary conditions which involve a connection between the boundary conditions of the two walls. In particular, the rate for Dirichlet boundary conditions is double than that of periodic boundary conditions.

In this essay, we argue that an observer outside the horizon can reconstruct the geometry of a black hole's interior through external measurements. This procedure builds on recent studies of the holographic duality of timelike entanglement entropy and its connection to spacelike entanglement entropy. Furthermore, we propose that this phenomenon reveals a fundamental correlation between the degrees of freedom inside and outside the black hole at the level of classical spacetime.

The Batalin-Vilkovisky formulation of a general local gauge theory can be encoded in the structure of a so-called presymplectic gauge PDE -- an almost-$Q$ bundle over the spacetime exterior algebra, equipped with a compatible presymplectic structure. In the case of a trivial bundle and an invertible presymplectic structure, this reduces to the well-known AKSZ sigma model construction. We develop an extension of the presympletic BV-AKSZ approach to describe local gauge theories with background fields. It turns out that such theories correspond to presymplectic gauge PDEs whose base spaces are again gauge PDEs describing background fields. As such, the geometric structure is that of a bundle over a bundle over a given spacetime. Gauge PDEs over backgrounds arise naturally when studying linearisation, coupling (gauge) fields to background geometry, gauging global symmetries, etc. Less obvious examples involve parameterised systems, Fedosov equations, and the so-called homogeneous (presymplectic) gauge PDEs. The latter are the gauge-invariant generalisations of the familiar homogeneous PDEs and they provide a very concise description of gauge fields on homogeneous spaces such as higher spin gauge fields on Minkowski, (A)dS, and conformal spaces. Finally, we briefly discuss how the higher-form symmetries and their gauging fit into the framework using the simplest example of the Maxwell field.

We numerically evaluate, for slab entangling geometries, the mutual information and the holographic entanglement entropy between strongly interacting fields in different spatial regions for two different conformal holographic models at finite temperature and R-charge density. The 1 R-Charge Black Hole (1RCBH) model describes a strongly interacting fluid with a critical point in its phase diagram, while the 2 R-Charge Black Hole (2RCBH) model has no critical point. In both cases, we find that the mutual information in the thermodynamically stable branch of black hole solutions is reduced by increasing the value of the dimensionless ratio of R-charge chemical potential over temperature, $\mu/T$, indicating that the R-charge chemical potential acts as a suppressor of total correlations between fields in two disjoint spatial regions of a hot and dense strongly interacting medium. Moreover, the mutual information between the fields in the two disjoint regions is observed to be enhanced by increasing the size of these regions, with such an enhancement asymptotically saturating. The finite part of the entanglement entropy may change sign depending on the values of $\mu/T$ and the variable size $\ell$ of the entangling slab geometry, and it correctly detects the critical point of the 1RCBH model, a feature that is also adequately detected by the mutual information.

We study three-dimensional conformal field theories with a large-$N$ limit. Leveraging the framework of slightly broken higher-spin symmetry, we bootstrap correlation functions between the single-trace, local operators and straight, conformal line defects with boundaries. These correlation functions, which depend on a single conformal cross-ratio, encapsulate all bulk-defect operator product expansion coefficients. Concentrating on the quasi-fermionic theory, we explicitly compute all correlators involving the spin-zero and spin-one conserved currents, along with an infinite family of correlators involving the higher-spin currents. Furthermore, we demonstrate that the dependence of these correlators on the defect's shape is fully determined by our bootstrap constraints.

We provide a complete classification of the Feynman integral geometries relevant to the scattering of two black holes at fifth order in the post-Minkowskian (PM) expansion, i.e. at four loops. The analysis includes integrals relevant to both the conservative and dissipative dynamics, as well as to all orders in the self-force (SF) expansion, i.e. the 0SF, 1SF and 2SF orders. By relating the geometries of integrals across different loop orders and integral families, we find that out of the 16,596 potentially contributing integral topologies, only 70 need to be analyzed in detail. By further computing their leading singularities using the loop-by-loop Baikov representation, we show that there only appear two different three-dimensional Calabi-Yau geometries and two different K3 surfaces at this loop order, which together characterize the space of functions beyond polylogarithms to which the 5PM integrals evaluate.

Thermal two-point functions in holographic CFTs receive contributions from two parts. One part comes from the identity, the stress tensor and multi-stress tensors and constitutes the stress-tensor sector. The other part consists of contributions from double-trace operators. The sum of these two parts must satisfy the KMS condition -- it has to be periodic in Euclidean time. The stress-tensor sector can be computed by analyzing the bulk equations of motions near the AdS boundary and is not periodic by itself. We show that starting from the expression for the stress-tensor sector one can impose the KMS condition to fix the double-trace part, and hence the whole correlator. We perform explicit calculations in the asymptotic approximation, where the stress-tensor sector can be computed exactly. One can either sum over the thermal images of the stress-tensor sector and subtract the singularities or solve for the KMS condition directly and perform the Borel resummation of the resulting double-trace data -- the results are the same.

We argue that black holes microstates leave an imprint on the gravitational vacuum through their virtual fluctuations. This imprint yields a power law fall off -- rather than an exponential fall off -- for the entanglement of planck scale fluctuations at different points. These entanglements generate an extra energy when space stretches too {\it fast}, since causality prevents a relaxation of these entanglements to their vacuum values. We obtain semiclassical dynamics for slow processes like star formation, but a radical departure from semiclassicality when a black hole horizon forms even though curvatures remain low everywhere. This resolution of the information puzzle also implies an extra energy source at the scale of the cosmological horizon, which may explain the mysteries of dark energy and the Hubble tension.

Cosmological observations of the recent universe suggest that dark energy equation of state parameter $w$ is growing with time, departing from a cosmological constant for which $w=-1$. Standard quintessence models allow for a varying $w\geq-1$, but observations report that a phantom regime, $w<-1$, is quickly reached in the past. Often discarded because of uncertainties or parametrisation, we rather propose here to embrace the reality of this phantom regime. We revisit an elegant mechanism that accounts for it, thanks to a coupling of quintessence field(s) to matter (and possibly radiation). We show that this allows for steep scalar potentials, and illustrate this with string-inspired models, where $V=V_0\, e^{-\lambda\, \varphi}$ and $\lambda \geq \sqrt{2}$. Those provide solutions in very good agreement with observations, including the phantom regime. We then discuss poles that can appear in $w$, making it diverge at recent times ($z\leq 4$), and that could be detected by observations. We finally comment on an Early Dark Energy-like feature, that systematically appears for free from the models considered, and could be of interest for the Hubble tension.

The minimal theory in which baryon number is spontaneously broken at the low scale predicts new fermions, one of which is a dark matter candidate, from gauge anomaly cancellation. We discuss the production mechanisms and decays of these new fermions, which include channels with multi-leptons, and channels with long-lived charged fermions that can give rise to exotic signatures with 'kinked' tracks at the Large Hadron Collider. We evaluate the contraints on the theory from current LHC searches and measurements, and briefly comment on the excess in top pair production at threshold recently reported by CMS. We also discuss predictions for the $h \to \gamma Z_B$ decay, where $h$ is the SM-like Higgs and $Z_B$ is the new gauge boson associated with baryon number.

We investigate the structure and uniqueness of squeezed vacuum states defined by annihilation conditions of the form $(a - \alpha a^\dagger)|\psi\rangle = 0$ and their multimode generalizations. For $N=1$ and $N=2$, we rigorously show that these conditions uniquely define the standard single- and two-mode squeezed states in the Fock basis. We then analyze a cyclically coupled $N$-mode system governed by $(a_i - \alpha_i a_{i+1}^\dagger)|\psi\rangle = 0$ with $a_{N+1} \equiv a_1$. Although the recurrence structure restricts solutions to equal-photon-number states, we prove that for $N>2$ no such state satisfies the full set of conditions. This establishes a sharp no-go result for multipartite squeezed states under cyclic annihilation constraints, underscoring a fundamental structural limitation beyond pairwise squeezing.

It has been recently shown that regular black holes arise as the unique spherically symmetric solutions of broad families of generalizations of Einstein gravity involving infinite towers of higher-curvature corrections in $D\geq 5$ spacetime dimensions. In this paper we argue that such regular black holes arise as the byproduct of the gravitational collapse of pressureless dust stars. We show that, just like for Einstein gravity, the modified junction conditions for these models impose that the dust particles on the star surface follow geodesic trajectories on the corresponding black hole background. Generically, in these models the star collapses until it reaches a minimum size (and a maximum density) inside the inner horizon of the black hole it creates. Then, it bounces back and reappears through a white hole in a different universe, where it eventually reaches its original size and restarts the process. Along the way, we study FLRW cosmologies in the same theories that regularize black hole singularities. We find that the cosmological evolution is completely smooth, with the big bang and big crunch singularities predicted by Einstein gravity replaced by cosmological bounces.

Complex quantum systems -- composed of many, interacting particles -- are intrinsically difficult to model. When a quantum many-body system is subject to disorder, it can undergo transitions to regimes with varying non-ergodic and localized behavior, which can significantly reduce the number of relevant basis states. It remains an open question whether such transitions are also directly related to an abrupt change in the system's complexity. In this work, we study the transition from chaotic to integrable phases in several paradigmatic models, the power-law random banded matrix model, the Rosenzweig--Porter model, and a hybrid SYK+Ising model, comparing three complementary complexity markers -- fractal dimension, von Neumann entanglement entropy, and stabilizer R\'enyi entropy. For all three markers, finite-size scaling reveals sharp transitions between high- and low-complexity regimes, which, however, can occur at different critical points. As a consequence, while in the ergodic and localized regimes the markers align, they diverge significantly in the presence of an intermediate fractal phase. Additionally, our analysis reveals that the stabilizer R\'enyi entropy is more sensitive to underlying many-body symmetries, such as fermion parity and time reversal, than the other markers. As our results show, different markers capture complementary facets of complexity, making it necessary to combine them to obtain a comprehensive diagnosis of phase transitions. The divergence between different complexity markers also has significant consequences for the classical simulability of chaotic many-body systems.

In this note we present a brief overview of connections between Chern-Simons theory and topological strings. A prominent role in this link has been played by large N dualities and holography. We demystify this by explaining why the Kahler form should be viewed as dual to the field strength associated with a 3-form gauge potential, sourced by Lagrangian D-branes. We explain how this leads to the computation of topological string amplitudes in terms of topological vertex for toric Calabi-Yau threefolds. Furthermore, applications of topological strings to a conceptual derivation of Skein relations for link invariants as well as some of its physical applications to black hole physics are also reviewed.

In supersymmetric models where the mu problem is solved via discrete R-symmetries, then both the global U(1)_{PQ} (Peccei-Quinn, needed to solve the strong CP problem) and R-parity conservation (RPC, needed for proton stability) are expected to arise as accidental, approximate symmetries. Then in some cases, SUSY dark matter is expected to be all axions since the relic lightest SUSY particles (LSPs) can decay away via small R-parity violating (RPV) couplings. We examine several aspects of this {\it all axion} SUSY dark matter scenario. 1. We catalogue the operator suppression which is gained from discrete R-symmetry breaking via four two-extra-field base models. 2. We present exact tree-level LSP decay rates including mixing and phase space effects and compare to results from simple, approximate formulae. 3. Natural SUSY models are characterized by light higgsinos with mass ~100-350 GeV so that the dominant sparticle production cross sections at LHC14 are expected to be higgsino pair production which occurs at the 10^2-10^4 fb level. Assuming nature is natural, the lack of an RPV signal from higgsino pair production in LHC data translates into rather strong upper bounds on nearly all trilinear RPV couplings in order to render the SUSY signal (nearly) invisible. Thus, in natural SUSY models with light higgsinos, the RPV-couplings must be small enough that the LSP has a rather high quality of RPC.

In this paper, we investigate quasinormal modes in holographic QCD models from the perspective of the WKB approximation. We derive the generalized Bohr Sommerfeld quantization rules for quasi-stationary states in holographic QCD models. As a simple application of these formulas, we compute the quasinormal modes of scalar and vector fields in the soft wall model, where an analytic expression for the real part of the frequency can be found in the low temperature regime. Additionally, this study provides useful insights into the dissociation process in holographic QCD models.

The Sachdev--Ye--Kitaev (SYK) model may provide us with a good starting point for the experimental study of quantum chaos and holography in the laboratory. Still, the four-local interaction of fermions makes quantum simulation challenging, and it would be good to search for simpler models that keep the essence. In this paper, we argue that the four-local interaction may not be important by introducing a few models that have two-local interactions. The first model is a generalization of the spin-SYK model, which is obtained by replacing the spin variables with SU($d$) generators. Simulations of this class of models might be straightforward on qudit-based quantum devices. We study the case of $d=3, 4, 5, 6$ numerically and observe quantum chaos already for two-local interactions in a wide energy range. We also introduce modifications of spin-SYK and SYK models that have similar structures to the SU($d$) model (e.g., $H=\sum_{p,q}J_{pq}\chi_p\chi_{p+1}\chi_q\chi_{q+1}$ instead of the original SYK Hamiltonian $H=\sum_{p,q,r,s}J_{pqrs}\chi_p\chi_q\chi_r\chi_{s}$), which shows strongly chaotic features although the interaction is essentially two-local. These models may be a good starting point for the quantum simulation of the original SYK model.

We describe a family of 1+1 classical integrable space-discrete models of the Landau-Lifshitz type through the usage of ansatz for $U$-$V$ (Lax) pair with spectral parameter satisfying the semi-discrete Zakharov-Shabat equation. The ansatz for $U$-$V$ pair is based on $R$-matrices satisfying the associative Yang-Baxter equation and certain additional properties. Equations of motion are obtained using a set of $R$-matrix identities. In the continuous limit we reproduce the previously known family of the higher rank Landau-Lifshitz equations.

We introduce Scale Factorized-Quantum Field Theory (SF-QFT), a framework that performs path-integral factorization of ultraviolet (UV) and infrared (IR) momentum modes at a physical scale $Q^*$ before perturbative expansion. This approach yields a UV-finite effective action whose Wilson coefficients $C_i(Q)$ and coupling $a_{\mathrm{eff}}(Q)$ are fixed by matching to experiment. Because the two-loop $\beta$-function is universal in massless QCD, $a_{\mathrm{eff}}(Q)$ evolves with a scheme-independent equation, with higher-order $\beta$-coefficients absorbed into the $C_i$. Applying SF-QFT to the inclusive ratio $R_{e^{+}e^{-}}$ gives $R^{\mathrm{SF-QFT}}(31.6\,\mathrm{GeV}) = 1.04911 \pm 0.00084$, in excellent agreement with experiment ($R^{\mathrm{exp}}(31.6\,\mathrm{GeV})= 1.0527 \pm 0.005$) while requiring orders of magnitude fewer calculations than a conventional four-loop $\overline{\mathrm{MS}}$ approach. We find universal algebraic recursion relations that generate all higher-order contributions without additional Feynman diagrams, yielding scheme-invariant predictions with remarkable convergence. SF-QFT provides a rigorous proof for the existence of a positive mass gap in Yang-Mills theory, resolving one of the Millennium Prize Problems by demonstrating how non-perturbative effects emerge naturally from the path-integral factorization. For QED, the same formalism integrates out high-energy modes above $Q^*$, producing scheme-independent predictions for the electron anomalous magnetic moment with unprecedented precision ($a_e^{\text{theory}} = 0.001~159~652~183~56(76)$). SF-QFT heralds a paradigm shift in quantum field theory, replacing the pursuit of ever-higher loop orders with a unified framework that handles both perturbative and non-perturbative physics while maintaining manifest gauge invariance and eliminating renormalization ambiguities.

We present a family of charged, traversable wormhole solutions in the presence of a cosmological constant. In de Sitter spacetime, two types of wormhole throats can exist--referred to as typical and cosmological throat--located at small and large radial values, respectively. In anti-de Sitter spacetime, the throat geometry allows for positive, zero, or negative curvature, enabling the possibility of an infinite throat area. We analyze the flare-out condition, a key requirement for the existence of traversable wormholes, which imposes constraints on the equation of state parameters governing the supporting matter. These solutions are shown to be of Petrov type D. Furthermore, we examine radial geodesics of null and timelike particles. In the de Sitter case, particles traverse the wormhole, passing from one throat to the other. In contrast, in the anti-de Sitter case, particles exhibit recurrent oscillatory motion between two asymptotic regions, cyclically disappearing and reappearing across the throats.

We develop a thorough theoretical framework based on the nonperturvative renormalization group (RG) a la Wetterich to tackle the interplay of coupled fermionic and order-parameter fluctuations at metallic quantum critical points with ordering wavevectors $\vec{Q}=\vec{0}$. We consistently treat the dynamical emergence of the Landau damping of the bosonic mode and non-Fermi liquid scaling of fermions upon lowering the cutoff scale. The loop integrals of the present theory involve only contributions from fluctuations above the cutoff scale, which drive the system to a non-Fermi liquid RG fixed point of different scaling properties from those obtained within the random phase approximation (RPA) or expansions around it. In particular the scaling exponent for the Fermi self-energy acquires the value $\alpha\approx 0.50$ rather than the anticipated $\alpha\approx 0.66$, while the bosonic dynamical exponent $z\approx 2$. We demonstrate how results characteristic for the RPA-type fixed-point scaling are recovered in our framework by a questionable procedure of removing the fermionic cutoff much faster than the bosonic one.

Double Field Theory (DFT) has emerged as a comprehensive framework for gravity, presenting a testable and robust alternative to General Relativity (GR), rooted in the $\mathbf{O}(D,D)$ symmetry principle of string theory. These lecture notes aim to provide an accessible introduction to DFT, structured in a manner similar to traditional GR courses. Key topics include doubled-yet-gauged coordinates, Riemannian versus non-Riemannian parametrisations of fundamental fields, covariant derivatives, curvatures, and the $\mathbf{O}(D,D)$-symmetric augmentation of the Einstein field equation, identified as the unified field equation for the closed string massless sector. By offering a novel perspective, DFT addresses unresolved questions in GR and enables the exploration of diverse physical phenomena, paving the way for significant future research.

The Randall-Sundrum model with the Higgs localized on the IR brane solves the gauge hierarchy problem. However, the associated low cutoff ($\Lambda \sim 10$ TeV) generically leads to unacceptably rapid nucleon decay and excessively large Majorana neutrino masses. Achieving consistency while simultaneously explaining the Yukawa hierarchy requires either a horizontal symmetry or a discrete gauged symmetry. We demonstrate that eliminating all dangerous operators within a horizontal symmetry framework must come with large and unattractive charge assignments, if possible at all. Hence, we consider an exact discrete gauged $\mathbf{Z}_N$ symmetry, with fermion mass hierarchies generated via wavefunction overlap. We employ this to reproduce the current CKM and PMNS structures. Under minimal assumptions, it predicts Dirac neutrinos with a total mass $\sim 66$ meV. Since the $\mathbf{Z}_N$ charges must be generation-blind, flavor observables serve as key probes.

We investigate the impact of curvature corrections to Starobinsky inflation in light of the latest observational results from the Atacama Cosmology Telescope (ACT). While the pure Starobinsky model remains a compelling candidate for cosmic inflation, we explore how the higher-order curvature terms $R^3$, $R^{4}$ and $R^{3/2}$ modify the inflationary predictions. Using the scalar-tensor formulation of $f(R)$ gravity, we derive the effective scalar potentials and compute the resulting scalar tilt $n_{s}$ and tensor-to-scalar ratio $r$. We show that those curvature corrections can shift the predictions to align better with the ACT data, thus providing a possible resolution to a minor discrepancy between the standard Starobinsky model and ACT observations. Our findings suggest that the modified Starobinsky models with the higher-order curvature terms offer a viable pathway to reconciling inflationary predictions with precision cosmological measurements. At the same time, measuring or constraining primordial tensor modes can help to discriminate between these corrections.

The Dicke model, renowned for its superradiant quantum phase transition (QPT), also exhibits a transition from regular to chaotic dynamics. In this work, we provide a systematic, comparative study of static and dynamical indicators of chaos for the closed and open Dicke model. In the closed Dicke model, we find that indicators of chaos sensitive to long-range correlations in the energy spectrum such as the the spectral form factor can deviate from the Poissonian random matrix theory (RMT) predictions and show a dip-ramp-plateau feature even in the normal region of the Dicke model unless very large values of the spin size are chosen. Thus, care is needed in using such indicators of chaos. In the open Dicke model with cavity damping, we find that the dissipative spectral form factor emerges as a robust diagnostic displaying a quadratic dip-ramp-plateau behavior in agreement with the Ginebre Unitary Ensemble (GinUE) RMT in the superradiant regime. Moreover, by examining the spectral properties of the Liouvillian, we provide indirect evidence for the concurrence of the dissipative superradiant quantum phase transition and the change in Liouvillian eigenvalue statistics from 2-D Poissonian to GinUE RMT behavior.

We study the behaviour of \SU{2} Yang-Mills fields on a $T_2\times R^2$ geometry where the two-torus is equipped with twisted boundary conditions. We monitor the evolution of the dynamics of the system as a function of the torus size $l_s$. For small sizes the behaviour of the system is well understood in terms of semiclassical predictions. In our case, the long distance structure is that of a two-dimensional gas of vortex-like fractional instantons with size and density growing with $l_s$. Our lattice Monte Carlo simulations confirm the semiclassical predictions and allow the determination of the relevant scale signalling the transition to the non-dilute situation. At low densities the string tension takes the standard value of a 2D center-vortex gas, growing with the density and approaching the value measured at infinite volume. Our work includes preliminary studies of the extension to \SU{N} and to the region of large sizes in which boundary conditions are irrelevant, and all physical scales are determined by the $\Lambda$ parameter.

We investigate the causality and stability of the relativistic theory of magnetohydrodynamics derived in Phys. Rev. D 109, 096021 (2024) to describe a locally neutral two-component plasma of massless particles. We show that this formalism is linearly causal and stable around global equilibrium, for any value of the magnetic field and discuss its qualitative differences to the traditional Israel-Stewart formalism in the linear regime. Finally, we compare this framework with the magnetohydrodynamic model used in the study of astrophysical plasmas, in which only the longitudinal component of the shear-stress tensor is considered. We discuss the domain of applicability of this type of framework in the context of ultrarelativistic heavy-ion collisions.