arXiv subjects

Ali Fatemiabhari

Publications and source records attributed to Ali Fatemiabhari.

17 recordsLinked to original sources

arXiv2026

Krylov Complexity, Confinement and Universality

We perform a systematic holographic study of Krylov complexity for a wide class of confining quantum field theories. Using the geometric prescription that identifies the time derivative of the complexity with the proper momentum of a massive probe, we analyse radial geodesics in several top-down gravity duals exhibiting confinement and a mass gap. In all geometries with a smooth infrared end-of-space we uncover a robust and universal qualitative feature: Krylov complexity exhibits oscillatory behaviour. The oscillation frequency is controlled by the confinement scale, while the amplitude depends on both the ultraviolet cutoff and the infrared scale. Additional conserved charges modify these patterns without altering their qualitative structure. We further compare our results with the Krylov complexity of the longitudinally perturbed Ising model. The qualitative agreement suggests that oscillatory behaviour of Krylov complexity constitutes a universal signature of confinement and provides a sensitive probe of infrared reorganisation in strongly coupled quantum field theories.

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arXiv2026

Bound states and deconfinement from Romans supergravity with magnetic flux

We apply the dictionary of gauge-gravity dualities to study the spectrum of bound states in a special one-parameter family of strongly coupled, confining field theories in four dimensions. The top-down, holographic gravity dual description of this class of theories has been identified recently. It consists of non-supersymmetric regular background solutions of Romans half-maximal supergravity theory in six dimensions, in the presence of a non-trivial Abelian magnetic flux along a compactified direction of the geometry. A zero-temperature, deconfinement, first-order phase transition appears at one end of this branch of solutions. It is triggered by the strength of the flux, setting an upper bound on the magnitude of the magnetic flux that can be supported by the geometry. We compute the spectrum of fluctuations of the background fields in the gravity description, that correspond to field-theory bound states. Two scalar particles are the lightest in the spectrum, their masses being suppressed and almost degenerate across the whole parameter space. Away from the transition, the heaviest between these two particles is identified as a dilaton, the pseudo-Nambu-Goldstone boson associated with scale invariance. It couples to the trace of the stress-energy tensor of the dual field theory, while the lightest scalar does not. In the range of parameter space closest to the extremum of the one-parameter family, near the first-order phase transition, a region with large curvature appears at the end of space of the geometry of the solutions. In this range, the two scalars mix non-trivially, and their masses are parametrically suppressed, in respect to the other bound states.

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arXiv2026

Complexity and Operator Growth in Holographic 6d SCFTs

We study Krylov (spread) complexity in strongly coupled six-dimensional ${\cal N}=(1,0)$ superconformal field theories with holographic duals in massive type IIA supergravity. Extending recent holographic proposals relating Krylov complexity growth to the proper momentum of an infalling particle, we analyse the dynamics of massive geodesic probes in these geometries. In our setup, the bulk particle is allowed to move along three directions: the radial AdS coordinate, the internal $S^2$ associated with the $SU(2)_R$ symmetry, and the coordinate parametrising the quiver. In the dual field theory these motions encode, respectively, operator growth, the presence of R-symmetry charges, and spreading across different nodes of the quiver. We analyse the geodesic motion both analytically and numerically for representative quiver configurations. The motion along the quiver direction is typically damped and localised at early times, while the late-time behaviour is dominated by the radial AdS motion. As a consequence, the generalised proper momentum grows linearly at late times, consistent with expectations for Krylov complexity in conformal theories. The inclusion of angular momentum ($SU(2)_R$ charge) introduces additional constraints on the allowed motion and modifies the early-time dynamics while leaving the asymptotic behaviour unchanged. These results provide a first exploration of Krylov complexity in higher-dimensional holographic conformal theories and reveal how operator growth can probe both internal symmetries and quiver structure in strongly coupled conformal field theories.

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arXiv2025

Holographic Krylov complexity in ${\cal N}=4$ SYM

We propose and calculate a holographic Krylov complexity in ${\cal N}=4$ SYM via the proper momentum for motion in $AdS_5$ sliced by $AdS_3$. The motion in an $AdS_3$ subgroup corresponds to the Krylov complexity of the $Sl(2)$ subsector. The general motion corresponds to the Krylov complexity of the ${\cal N}=4$ SYM.

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arXiv2025

Holographic Krylov Complexity for Conformal Quiver Gauge Theories

We investigate holographic Krylov complexity in fully top-down AdS$_3$ and AdS$_2$ supergravity backgrounds dual to two-dimensional linear-quiver SCFTs and one-dimensional conformal quantum mechanics. In these geometries, the warp factors, dilaton and other fields depend non-trivially on the 'quiver coordinate' (denoted by $η$ in this paper). This $η$-coordinate encodes the color and flavor data of the dual theories. As a consequence, a massive probe following a holographic geodesic necessarily moves simultaneously in the radial AdS direction and along the 'quiver direction'. This produces new contributions to the proper momentum and hence to the rate of Krylov complexity growth, which is absent in bottom-up AdS models. We show that the $η$-motion is generically damped, with a time-scale governed by the UV cutoff of the geodesic problem, and modifies the early-time evolution of complexity in a quiver-dependent way. At late times, the $η$-dynamics freezes and the growth becomes universal, matching pure Poincare AdS predictions. Studying Abelian and non-Abelian T-dual backgrounds of AdS$_3\times S^3\times T^4$, quivers with localized flavor groups, and quivers with smeared flavor groups, we quantify how quiver parameters shape the operator-spreading dynamics. Our results provide a systematic characterization of Krylov complexity in top-down AdS$_3$/AdS$_2$ duals and reveal a holographic mechanism through which complexity probes both ultraviolet quiver structure and emergent infrared universality.

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arXiv2025

Holographic Krylov complexity in confining gauge theories

We study holographic Krylov complexity in the Anabalon-Ross solitonic background, a top-down Type IIB solution describing a twisted-circle compactification of ${\cal N}=4$ SYM that flows to a confining, gapped three-dimensional theory. Following the proposal that the time derivative of Krylov complexity is dual to the proper radial momentum of a falling bulk particle, we analyze probe geodesics in this geometry. We obtain exact analytic solutions for the radial trajectory in terms of elliptic functions, confirming and extending UV and IR asymptotic expansions. The proper momentum and resulting complexity exhibit oscillatory behaviour, which we interpret as a holographic signature of the finite Hilbert-space truncation induced by the UV cutoff together with the IR end-of-space. Our results provide a controlled top-down test of the spread-momentum correspondence and highlight qualitative differences between conformal and confining holographic dynamics.

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arXiv2025

Holographic Entanglement Entropy in Quiver Theories

This work presents a study of the entanglement entropy (EE) in a class of four-dimensional ${\cal N}=1$ linear quiver SCFTs deformed by the presence of a VEV. We review the holographic backgrounds dual to these theories, and calculate the EE for different Ryu-Takayanagi embeddings. We allow the embeddings to explore, in addition to the usual spatial direction, the internal coordinate $z$, associated with the quiver degrees of freedom. Via the numerical optimization of splines on triangulations, we find the minimal configuration and the value of the EE for the different embeddings and quiver parameters. Our results agree with previous studies showcasing phase transitions in the EE. We also provide novel results illuminating the dependence of the EE on the fundamental and gauge degrees of freedom, signaling partial deconfinement, which are worthy of further study.

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arXiv2025

On the stability of holographic confinement with magnetic fluxes

We analyze the stability properties of a simple holographic model for a confining field theory. The gravity dual consists of an Abelian gauge field, with non-trivial magnetic flux, coupled to six-dimensional gravity with a negative cosmological constant. We construct a one-parameter family of regular solitonic solutions, where the gauge field carries flux along a compact circle that smoothly shrinks. The free energy of these solitonic backgrounds is compared to that of domain-wall solutions. This reveals a zero-temperature first-order phase transition in the dual field theory, separating confining and conformal phases. We compute the spectrum of bound states by analysing field fluctuations in the gravity background, after dimensional reduction on the circle. A tachyonic instability emerges near a turning point in the free energy. The phase transition prevents the realisation of this instability. Near the phase transition and beyond, in metastable and unstable regions, we find evidence that the lightest scalar may be interpreted as an approximate dilaton.

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arXiv2024

SCFT deformations via uplifted solitons

A holographic method for implementing a particular supersymmetry-preserving deformation to 4d SCFTs is presented. At the heart of the procedure is a soliton solution of minimal $d=5$ gauged supergravity. Embedding this solution into ten- and eleven-dimensional string theory backgrounds of the form AdS$_5 \times M$, we systematically construct a range of new solutions. Each holographically realizes a twisted compactification of the SCFT$_4$ dual to the original background. In the IR, the resulting SQFTs flow to gapped three-dimensional systems. Using a variety of holographic observables, we give evidence for this interpretation and for confinement in the deformed SQFTs. Our method applies to any holographic solutions admitting a consistent truncation to minimal $d=5$ gauged supergravity, and can likely be generalized to solutions with other AdS$_d$ factors.

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arXiv2024

On Holographic Vacuum Misalignment

We develop a bottom-up holographic model that provides the dual description of a strongly coupled field theory, in which the spontaneous breaking of an approximate global symmetry yields the SO(5)/SO(4) coset relevant to minimal composite-Higgs models. The gravity background is completely regular and smooth, and has an end of space that mimics confinement on the field theory side. We add to the gravity description a set of localised boundary terms, that introduce additional symmetry-breaking effects, capturing those that would result from coupling the dual strongly coupled field theory to an external, weakly coupled sector. Such terms encapsulate the gauging of a subgroup of the global $SO(5)$ symmetry of the dual field theory, as well as additional explicit symmetry-breaking effects. We show how to combine spurions and gauge fixing and how to take the appropriate limits, so as to respect gauge principles and avoid violations of unitarity. The interplay of bulk and boundary-localised couplings leads to the breaking of the SO(5) symmetry to either its SO(4) or SO(3) subgroup, via vacuum misalignment. In field theory terms, the model describes the spontaneous breaking of a SO(4) gauge symmetry to its SO(3) subgroup. We expose the implications of the higgsing phenomenon by computing the spectrum of fluctuations of the model, which we interpret in four-dimensional field-theory terms, for a few interesting choices of parameters. We conclude by commenting on the additional steps needed to build a realistic composite Higgs model.

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arXiv2024

Progress on Holographic Vacuum Misalignment

We summarise highlights from an ongoing research programme that aims, in the long run, at the ambitious goal of building a realistic, complete holographic composite-Higgs model. This contribution focuses on vacuum misalignment, by showing how to unify its description, as a phenomenon arising from weak coupling considerations, in the holographic description of a strongly coupled field theory in terms of a dual gravity theory. This is achieved by a non-trivial treatment of boundary-localised terms in the gravity action. The gravity backgrounds considered are completely regular and smooth. We provide numerical examples showing that the mass spectrum of particles in the four-dimensional theory is free of pathologies, and that a small hierarchy arises naturally, between the light states that, in this simplified set up, are analogous to the standard-model particles, and all the other, new composite states emerging in the strongly coupled theory.

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arXiv2024

Confinement and screening via holographic Wilson loops

We present the holographic dual to a family of ${\cal N}=1$ SCFTs in four dimensions, deformed by a VEV leading to a gapped system. We calculate Wilson loops in this system containing adjoint, bifundamental and fundamental matter. We calculate the quark-antiquark energy $E$ in terms of their separation $L$, finding an approximate analytic expression for $E(L)$. This expression shows the transition between conformal, confining and screened behaviours. Interesting phenomenology is discussed in a variety of examples. The tool used is the minimization of the F1 string action, for which the code used is made publicly available.

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arXiv2024

Conformal to confining SQFTs from holography

In this paper we present three new families of smooth Type II string theory backgrounds. These are dual to supersymmetry-preserving deformations of 4d SCFTs. The deformations include a VEV for a global current and a `twisted compactification' on a circle. We study various holographic aspects of the dual QFTs, focusing on Wilson loops and Entanglement Entropy. Additionally, we present a monotonic quantity calculating the density of degrees of freedom in terms of the energy, which interpolates between the IR 3d gapped theory and the 4d SCFT result. Other probes related to global aspects of the QFTs are briefly discussed.

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arXiv2024

From conformal to confining field theories using holography

We construct a new family of Type IIB backgrounds that are dual to five dimensional conformal field theories compactified and deformed by VEVs of certain operators. This generates an RG flow into a smooth background dual to non-SUSY gapped field theories in four dimensions. We study various holographic observables: a monotonic quantity associated with the number of degrees of freedom, Wilson loops that interpolate between conformal and confining behaviour with the possibility of screening, Entanglement Entropy, etc. We also give a prescription to compute the Holographic Complexity in this type of backgrounds and calculate the spectrum of spin-two glueballs of the field theories.

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arXiv2023

Phase transitions and light scalars in bottom-up holography

Within the bottom-up approach to holography, we construct a class of six-dimensional gravity models, and discuss solutions that can be interpreted, asymptotically in the far UV, in terms of dual five-dimensional conformal field theories deformed by a single scalar operator. We treat the scaling dimension of such operator, related to the mass of the one scalar field in the gravity theory, as a free parameter. One dimension in the regular geometry is compactified on a shrinking circle, hence mimicking confinement in the resulting dual four-dimensional theories. We study the mass spectrum of bosonic states. The lightest state in this spectrum is a scalar particle. Along the regular (confining) branch of solutions, we find the presence of a tachyonic instability in part of the parameter space, reached by a smooth deformation of the mass spectrum, as a function of the boundary value of the background scalar field in the gravity theory. In a region of parameter space nearby the tachyonic one, the lightest scalar particle can be interpreted as an approximate dilaton, sourced by the trace of the stress-energy tensor, and its mass is parametrically suppressed. We also compute the free energy, along several branches of gravity solutions. We find that both the dilatonic and tachyonic regions of parameter space, identified along the branch of confining solutions, are hidden behind a first-order phase transition, so that they are not realised as stable solutions, irrespectively of the scaling dimension of the deforming field-theory operator. The (approximate) dilaton, in particular, appears in metastable solutions. Yet, the mass of the lightest state, computed close to the phase transition, is (mildly) suppressed. This feature is amplified when the (free) parameter controlling the scaling dimension of the deformation is 5/2, half the dimension of space-time in the field theory.

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arXiv2023

Toward minimal composite Higgs models from regular geometries in bottom-up holography

We study a bottom-up, holographic description of a field theory yielding the spontaneous breaking of an approximate SO(5) global symmetry to its SO(4) subgroup. The weakly-coupled, six-dimensional gravity dual has regular geometry. One of the dimensions is compactified on a circle that shrinks smoothly to zero size at a finite value of the holographic direction, hence introducing a physical scale in a way that mimics the effect of confinement in the dual four-dimensional field theory. We study the spectrum of small fluctuations of the bulk fields carrying SO(5) quantum numbers, which can be interpreted as spin-0 and spin-1 bound states in the dual field theory. This work supplements an earlier publication, focused only on the SO(5) singlet states. We explore the parameter space of the theory, paying particular attention to composite states that have the right quantum numbers to be identified as pseudo-Nambu-Goldstone Bosons (PNGBs). We find that in this model the PNGBs are generally heavy, with masses of the same order as other bound states, indicating the presence of a sizeable amount of explicit symmetry breaking in the field theory side. But we also find a qualitatively new, unexpected result. When the dimension of the field-theory operator inducing SO(5) breaking is close to half of the space-time dimensionality, there exists a region of parameter space in which the PNGBs and the lightest scalar are both parametrically light in comparison to all other bound states of the field theory. Although this region is known to yield metastable classical backgrounds, this finding might be relevant to model building in the composite Higgs context.

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arXiv2022

Wilson loops for 5d and 3d conformal linear quivers

Within the electrostatic formulation of holographic duals to (balanced) conformal quivers in five and three dimensions, we study Wilson loops in antisymmetric representations. We derive general expressions for various quantities participating in the formalism (VEV of Wilson loops, representation, gauge-node) and apply these to examples, connecting some results present in the bibliography. In the case of three dimensional quivers, we present a relation between Wilson loops in an 'electric' and in the 'magnetic/mirror' descriptions. In a very detailed appendix, we relate the electrostatic and holomorphic description of the holographic duals to these SCFTS.

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