arXiv subjects

Andrea Fontanella

Publications and source records attributed to Andrea Fontanella.

At least 19 recordsLinked to original sources

arXiv2026

An Introduction to String Newton-Cartan Holography and Integrability

String Newton-Cartan holography is a new example of gauge/gravity duality relating non-relativistic string theory and gauge theories. We review how to construct a family of string and $p$-brane Newton-Cartan holographic dualities by consistently taking the non-relativistic limit of the AdS/CFT correspondence. We also review classical string solutions, quantisation, string coset action and integrability of the non-relativistic string theory appearing in the String Newton-Cartan limit of the AdS$_5$/CFT$_4$ correspondence.

hep-th↗

arXiv2025

A Carroll Limit of AdS/CFT: A Triality with Flat Space Holography?

We construct a novel holographic duality by taking a Carrollian limit of the AdS/CFT correspondence, relating string theory in a Carroll bulk geometry to a Carroll $\mathcal{N}=4$ Super Yang-Mills theory. We further propose the existence of an underlying triality connecting Carroll string theory, relativistic string theory in flat spacetime, and Carroll gauge theory. Finally, we analyse the symmetries of the Carroll gauge theory, showing that they are non-linearly realised and do not close under ordinary Lie brackets.

hep-th↗

arXiv2025

An integrable deformed Landau-Lifshitz model with particle production?

We discuss the continuum limit of a non-Hermitian deformation of the Heisenberg XXX spin chain. This model appeared in the classification of $4\times4$ solutions of the Yang--Baxter equation and it has the particular feature that the transfer matrix is non-diagonalisable. We show that the model is given by a Drinfeld twist of the XXX spin chain and its continuum limit is a non-unitary deformation of the Landau-Lifshitz model. We compute the tower of conserved charges for this deformed Landau-Lifshitz model and show that they are generated by a boost operator. We furthermore show that it gives a non-vanishing $1\to 2$ S-matrix, where one of the outgoing particles has vanishing energy and momentum, and thus it does not fulfil the usual "no particle production" condition of integrability. We argue that this result is natural when looked from the point of view of the non-diagonalisability of the spin chain.

hep-th↗

arXiv2024

Revisiting the Symmetries of Galilean Electrodynamics

We determine the symmetries of four different theories: I) Galilean Electrodynamics (GED), II) GED coupled to 5 free static scalar fields, III) Galilean Yang-Mills (GYM), and IV) GYM coupled to 5 interacting scalar fields. We correct some old results in the literature, by finding that the symmetries of GED in a spacetime of generic dimension $d+1$ is always infinite dimensional, and in $3+1$ they correspond to the conformal Milne algebra extended by a spatial dilatation generator, which we call $D_x$. Finally, we comment on how these results fit into the framework of the non-relativistic AdS$_5$/CFT$_4$ correspondence.

hep-th↗

arXiv2024

Non-Relativistic Holography from AdS$_5$/CFT$_4$

We show that a novel holographic correspondence appears after taking a suitable stringy non-relativistic limit of the AdS$_5$/CFT$_4$ duality. This correspondence relates string theory in String Newton-Cartan AdS$_5\times$S$^5$ with Galilean Yang-Mills with five interacting adjoint scalars defined on the Penrose conformal boundary. As a first test, we match the Killing vectors on the string theory side with the symmetries of the dual field theory.

hep-th↗

arXiv2024

Carroll Fermions

Using carefully chosen projections, we consider different Carroll limits of relativistic Dirac fermions in any spacetime dimensions. These limits define Carroll fermions of two types: electric and magnetic. The latter type transforms as a reducible but indecomposable representation of the Carroll group. We also build action principles for all Carroll fermions we introduce; in particular, in even dimensions we provide an action principle for a minimal magnetic Carroll fermion, having the same number of components as a Dirac spinor. We then explore the coupling of these fermions to magnetic Carroll gravity in both its first-order and second-order formulations.

hep-th↗

arXiv2024

A perturbative approach to the non-relativistic string spectrum

In this letter we use a perturbative approach to find the spectrum of non-relativistic strings in the String Newton-Cartan (SNC) AdS$_5\times$S$^5$ spacetime. We perturb the bosonic sector of the action around a BMN-like folded string solution in light-cone gauge. We find strong evidence that the theory is described by a combination of massive and massless free fields in an anti-de Sitter background by showing that interaction terms up to six scalars vanish after field redefinitions.

hep-th↗

arXiv2024

Constructing Non-Relativistic AdS$_5$/CFT$_4$ Holography

We construct a new type of holographic correspondence between non-relativistic string theory in String Newton-Cartan AdS$_5\times$S$^5$ and Galilean Yang-Mills supplemented with 5 adjoint interacting scalar fields living on the 3+1 dimensional Penrose conformal boundary. In our derivation, we start with Maldacena's setting of a stack of $N$ coincident D3-branes and we show that the near-horizon/decoupling limit commutes with the non-relativistic limit, giving a unique answer both from the gravity and gauge theory perspectives. As a first evidence, we systematically compute the Killing vectors on the string theory side, and find that they match the symmetries of the dual gauge theory.

hep-th↗

arXiv2023

Light-Cone Gauge in Non-Relativistic AdS$_5\times$S$^5$ String Theory

We discuss the non-relativistic limit of string theory in AdS$_5\times$S$^5$ for different choices of embedding coordinates. We show that, if we consider Cartesian coordinates, the action of fluctuations around the twisted BMN-like string found in arXiv:2109.13240 in uniform light-cone gauge becomes the one of free fields at large string tension and large AdS$_5$ radius.

hep-th↗

arXiv2023

Flowing from relativistic to non-relativistic string vacua in AdS$_5 \times$S$^5$

We find the connection between relativistic and non-relativistic string vacua in AdS$_5 \times$S$^5$ in terms of a free parameter $c$ flow. First, we show that the famous relativistic BMN vacuum flows in the large $c$ parameter to an unphysical solution of the non-relativistic theory. Then, we consider the simplest non-relativistic vacuum, found in arXiv:2109.13240 (called BMN-like), and we identify its relativistic origin, namely a non-compact version of the folded string with zero spin, ignored in the past due to its infinite energy. We show that, once the critical closed B-field required by the non-relativistic limit is included, the total energy of such relativistic solution is finite, and in the large $c$ parameter it precisely matches the one of the BMN-like string. We also analyse the case with spin in the transverse AdS directions.

hep-th↗

arXiv2023

Non-extremal near-horizon geometries

When Gaussian null coordinates are adapted to a Killing horizon, the near-horizon limit is defined by a coordinate rescaling and then by taking the regulator parameter $\varepsilon$ to be small, as a way of zooming into the horizon hypersurface. In this coordinate setting, it is known that the metric of a non-extremal Killing horizon in the near-horizon limit is divergent, and it has been a common practice to impose extremality in order to set the divergent term to zero. Although the metric is divergent, we show for a class of Killing horizons that the vacuum Einstein's equations can be separated into a divergent and a finite part, leading to a well-defined minimal set of Einstein's equations one needs to solve. We extend the result to Einstein gravity minimally coupled to a massless scalar field. We also discuss the case of Einstein gravity coupled to a Maxwell field, in which case the separability holds if the Maxwell potential has non-vanishing components only in the directions of the horizon spatial cross section.

gr-qc↗

arXiv2022

Non-relativistic string monodromies

Spectral curve methods proved to be powerful techniques in the context of relativistic integrable string theories, since they allow to derive the semiclassical spectrum from the minimal knowledge of a Lax pair and a classical string solution. In this paper we initiate the study of the spectral curve for non-relativistic strings in AdS$_5\times S^5$. First we show that for string solutions whose Lax connection is independent of $σ$, the eigenvalues of the monodromy matrix do not have any spectral parameter dependence. We remark that this particular behaviour also appears for relativistic strings in flat space. Second, for some simple non-relativistic string solutions where the path ordered exponential of the Lax connection can be computed, we show that the monodromy matrix is either diagonalisable with quasi-momenta independent of the spectral parameter, or non-diagonalisable. For the latter case, we propose a notion of generalised quasi-momenta, based on maximal abelian subalgebras, which retain a dependence on the spectral parameter.

hep-th↗

arXiv2022

Extending the non-relativistic string AdS coset

Inspired by Lie algebra expansion, we consider an extension of the algebra introduced in arXiv:2203.07386 for the non-relativistic string coset action in AdS$_5\times$S$^5$. We show that the extended algebra admits a non-degenerate inner product which is adjoint invariant under the full extended algebra. Furthermore, we provide a finite-dimensional representation of the extended algebra.

hep-th↗

arXiv2022

Coset space actions for nonrelativistic strings

We formulate the stringy nonrelativistic limits of the flat space and AdS$_5\times$S$^5$ string as coset models, based on the string Bargmann and extended string Newton-Hooke algebras respectively. Our construction mimics the typical relativistic one, but differs in several interesting ways. Using our coset formulation we give a Lax representation of the equations of motion of both models.

hep-th↗

arXiv2022

Classical string solutions in Non-Relativistic AdS$_5\times$S$^5$: Closed and Twisted sectors

We find classical closed string solutions to the non-relativistic AdS$_5\times$S$^5$ string theory which are the analogue of the BMN and GKP solutions for the relativistic theory. We show that non-relativistic AdS$_5\times$S$^5$ string theory admits a $\mathbb{Z}_2$ orbifold symmetry which allows us to impose twisted boundary conditions. Among the solutions in the twisted sector, we find the one around which the semiclassical expansion in arXiv:2102.00008 takes place.

hep-th↗

arXiv2021

On the supersymmetric solutions of the Heterotic Superstring effective action

We consider the effective action of the Heterotic Superstring to first order in alpha prime and derive the necessary and sufficient conditions that a field configuration has to satisfy in order to admit at least one Killing spinor using the spinor bilinear method and making minimal coordinate and frame choices. As a previous step in this derivation, we compute the complete spinor bilinear algebra using the Fierz identities, obtaining as a by-product the algebra satisfied by the Spin(7) structure contained in the bilinears in an arbitrary basis. We find the relations existing between the left-hand-sides of the bosonic equations of motion evaluated on supersymmetric field configurations using the Killing Spinor Identities instead of the (far more complicated) integrability conditions of the Killing Spinor Equations as it is common in the literature. We show how to include the Kalb-Ramond's Bianchi identity in the Killing Spinor Identities.

hep-th↗

arXiv2020

Lie Algebra Expansion and Integrability in Superstring Sigma-Models

Lie algebra expansion is a technique to generate new Lie algebras from a given one. In this paper, we apply the method of Lie algebra expansion to superstring $σ$-models with a $\mathbb{Z}_4$ coset target space. By applying the Lie algebra expansion to the isometry algebra, we obtain different $σ$-models, where the number of dynamical fields can change. We reproduce and extend in a systematic way actions of some known string regimes (flat space, BMN and non-relativistic in AdS$_5 \times$S$^5$). We define a criterion for the algebra truncation such that the equations of motion of the expanded action of the new $σ$-model are equivalent to the vanishing curvature condition of the Lax connection obtained by expanding the Lax connection of the initial model.

hep-th↗

arXiv2019

The Effectiveness of Relativistic Invariance in AdS${}_3$

We use relativistic invariance to investigate two aspects of integrable AdS${}_3$ string theory. Firstly, we write down the all-loop TBA equations for the massless sector of the theory with R-R flux, using the recently discovered hidden relativistic symmetry. Secondly, for the low-energy relativistic limit of the theory with NS-NS flux we write down the S matrix, dressing factors and TBA. We find that the integrable system coincides with a restriction to AdS${}_3$ of the relativistic q-deformed AdS${}_5$ theory. We also comment on the relativistic limit of the the small-$k$ NS-NS theory.

hep-th↗