arXiv subjects

Alfredo Pérez

Publications and source records attributed to Alfredo Pérez.

At least 19 recordsLinked to original sources

arXiv2026

Superfluid memory effect

We identify a memory effect produced by phonon scattering in a superfluid: a localized scattering event generates a far-field pressure pulse with vanishing time integral but a nonzero first temporal moment, corresponding to a permanent shift in a prepotential for the far-field velocity. The effect is controlled by the soft factor for phonon emission, including corrections from nonlinear dispersion. In superfluid $^4$He, scattering macroscopic phonon wave packets produces a signal whose estimated magnitude may lie within experimental reach, thereby providing a laboratory analogue of electromagnetic and gravitational memory.

hep-th↗

arXiv2026

Scalar subleading soft theorems from an infinite tower of charges

We investigate conservation laws in the absence of gauge invariance by analyzing interacting scalar theories with a massless scalar field. We construct an infinite tower of charges that arise from the subleading equations of motion at null infinity and are built from specific combinations of asymptotic field coefficients. Interestingly, these expressions are finite from the outset, requiring no holographic renormalization. By carefully analyzing the dynamics at spatial infinity, we show that this tower of surface integrals commutes with the S-matrix of the interacting model at tree level. As an application, we demonstrate that the conservation of these charges leads to an infinite set of subleading soft relations, valid at tree level in a cubic interaction with massive scalar fields.

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arXiv2026

Kerroll black holes

We construct rotating black holes in Carroll gravity using two distinct approaches. In one of them, we exploit the freedom in the Carroll compatible connection to encode rotation. In particular, we construct rotating solutions in magnetic Carroll gravity by dressing the Carroll-Schwarzschild black hole with a rotational charge. This solution is intrinsically Carrollian and has no Lorentzian analog. In the other approach, we construct an extension of magnetic Carroll gravity from general relativity in an odd-power expansion in the speed of light. This theory contains magnetic Carroll gravity as a subsector but has in general more physical degrees of freedom. We show that this theory admits a Carroll analog of the Kerr black hole as a solution, which we refer to as the "Kerroll black hole". Its rotation appears as an intrinsically odd-power effect in the Carroll data. We compute the corresponding conserved charges for both theories.

hep-th↗

arXiv2026

Carroll black holes

Despite the absence of a lightcone structure, some solutions of Carroll gravity show black hole-like behaviour. We define Carroll black holes as solutions of Carroll gravity that exhibit Carroll thermal properties and have a Carroll extremal surface, notions introduced in our work. The latter is a Carroll analogue of a Lorentzian extremal surface. As examples, we discuss the Carroll versions of Schwarzschild, Reissner-Nordstroem, and BTZ black holes and black hole solutions of generic 1+1 dimensional Carroll dilaton gravity, including Carroll JT and Carroll Witten black holes.

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arXiv2025

Matching conditions at null infinity in the presence of logarithms: the role of advanced and retarded radiation

We provide a new perspective on the general matching conditions between the future of past null infinity and the past of future null infinity, emphasizing the impact of dominant logarithmic terms in the asymptotic expansion of the fields near null infinity. We explicitly consider the cases of a massless scalar field and of electromagnetism. Key in our derivation is the identification of the physical origin of these logarithms, which are associated with advanced and retarded radiation saturating the finite energy flux condition at null infinity (in a space of functions which is made precise). The matching conditions arise then from the requirement of Coulombic (i.e., $1/r$) behaviour at spatial infinity.

hep-th↗

arXiv2025

Planons and their Carroll-Galilei symmetries

We study the dynamics of planons, particles whose mobility is restricted to a plane, through the classification of coadjoint orbits and unitary irreducible representations of the centrally extended planon group. Planons are closely related to Galilei/Bargmann symmetries and, remarkably, the often-ignored massless coadjoint orbits of the Galilei group play a central rôle in their description. We thereby provide a nontrivial physical interpretation of these orbits. We further construct classical and quantum dipoles as bound states of monopoles, where the restricted planar motion arises from a novel mixed Carroll-Galilei symmetry. We also argue that the simplest and already experimentally realised systems with Carroll symmetry are in crystals.

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arXiv2024

Fractons on curved spacetime in $2+1$ dimensions

We study dipole Chern-Simons theory with and without a cosmological constant in $2+1$ dimensions. We write the theory in a second order formulation and show that this leads to a fracton gauge theory coupled to Aristotelian geometry which can also be coupled to matter. This coupling exhibits the remarkable property of generalizing dipole gauge invariance to curved spacetimes, without placing any limitations on the possible geometries. We also use the second order formulation to construct a higher dimensional generalization of the action. Finally, for the $(2+1)$-dimensional Chern-Simons theory we find solutions and interpret these as electric monopoles, analyze their charges and argue that the asymptotic symmetries are infinite-dimensional.

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arXiv2024

Cartan-like formulation of electric Carrollian gravity

We present a Cartan-like first-order action principle for electric Carrollian gravity. The action is invariant under the local homogeneous Carroll group, albeit in a different representation than the one obtained by gauging the Carroll algebra. Additionally, we show that this first-order action can be derived from a smooth Carrollian limit of the Einstein-Cartan action. The connection with the Hamiltonian and metric forms of the action for electric Carrollian gravity, as well as with previous works in the literature, is also discussed.

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arXiv2024

Galilei particles revisited

We revisit the classifications of classical and quantum galilean particles: that is, we fully classify homogeneous symplectic manifolds and unitary irreducible projective representations of the Galilei group. Equivalently, these are coadjoint orbits and unitary irreducible representations of the Bargmann group, the universal central extension of the Galilei group. We provide an action principle in each case, discuss the nonrelativistic limit, as well as exhibit, whenever possible, the unitary irreducible representations in terms of fields on Galilei spacetime. Motivated by a forthcoming study of planons we pay close attention to the mobility of the less familiar massless Galilei particles.

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arXiv2023

Fracton infrared triangle

In theories with conserved dipole moment, isolated charged particles (fractons) are immobile, but dipoles can move. We couple these dipoles to the fracton gauge theory and analyze the universal infrared structure. This uncovers an observable double kick memory effect which we relate to a novel dipole soft theorem. Together with their asymptotic symmetries this constitutes the first realization of an infrared triangle beyond Lorentz symmetry. This demonstrates the robustness of these IR structures and paves the way for their investigation in condensed matter systems and beyond.

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arXiv2023

Gravitational radiation with $Λ>0$

We study gravitational radiation for a positive value of the cosmological constant $Λ$. We rely on two battle-tested procedures: (i) We start from the same null coordinate system used by Bondi and Sachs for $Λ= 0$, but, introduce boundary conditions adapted to allow radiation when $Λ>0$. (ii) We determine the asymptotic symmetries by studying, à la Regge-Teitelboim, the surface integrals generated in the action by these boundary conditions. A crucial difference with the $Λ=0$ case is that the wave field does not vanish at large distances, but is of the same order as de Sitter space. This novel property causes no difficulty; on the contrary, it makes quantities finite at every step, without any regularization. A direct consequence is that the asymptotic symmetry algebra consists only of time translations and space rotations. Thus, it is not only finite-dimensional, but smaller than de Sitter algebra. We exhibit formulas for the energy and angular momentum and their fluxes. In the limit of $Λ$ tending to zero, these formulas go over continuously into those of Bondi, but the symmetry jumps to that of Bondi, Metzner and Sachs. The expressions are applied to exact solutions, with and without radiation present, and also to the linearized theory.

gr-qc↗

arXiv2023

Quantum Carroll/fracton particles

We classify and relate unitary irreducible representations (UIRs) of the Carroll and dipole groups, i.e., we define elementary quantum Carroll and fracton particles and establish a correspondence between them. Whenever possible, we express the UIRs in terms of fields on Carroll/aristotelian spacetime subject to their free field equations. We emphasise that free massive (or "electric") Carroll and fracton quantum field theories are ultralocal field theories and highlight their peculiar and puzzling thermodynamic features. We also comment on subtle differences between massless and "magnetic" Carroll field theories and discuss the importance of Carroll and fractons symmetries for flat space holography.

hep-th↗

arXiv2023

Carroll/fracton particles and their correspondence

We exploit the close relationship between the Carroll and fracton/dipole algebras, together with the method of coadjoint orbits, to define and classify classical Carroll and fracton particles. This approach establishes a Carroll/fracton correspondence and provides an answer to the question "What is a fracton?". Under this correspondence, carrollian energy and center-of-mass correspond to the fracton electric charge and dipole moment, respectively. Then immobile massive Carroll particles correspond to the fracton monopoles, whereas certain mobile Carroll particles ("centrons") correspond to fracton elementary dipoles. We uncover various new massless carrollian/neutral fractonic particles, provide an action in each case and relate them via a $GL(2,\mathbb{R})$ symmetry. We also comment on the limit from Poincaré particles, the relation to (electric and magnetic) Carroll field theories, contrast Carroll boosts with dipole transformations and highlight a generalisation to curved space ((A)dS Carroll).

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arXiv2022

Asymptotic symmetries in Carrollian theories of gravity with a negative cosmological constant

Asymptotic symmetries of electric and magnetic Carrollian gravitational theories with a negative cosmological constant $Λ$ are analyzed in 3+1 space-time dimensions. In the magnetic theory, the asymptotic symmetry algebra is given by the conformal Carroll algebra in three dimensions, which is infinite-dimensional and isomorphic to the BMS$_{4}$ algebra. These results are in full agreement with holographic expectations, providing a new framework for the study of "Carrollian holography." On the contrary, in the case of the electric theory, the presence of a negative $Λ$ turns out to be incompatible with a consistent set of asymptotic conditions, that can be traced back to the absence of a sensible ground state configuration. This can be improved if the Carrollian theory obtained from an electric contraction of Euclidean General Relativity is considered. In this case, asymptotic conditions can be constructed with an asymptotic symmetry algebra given by $so\left(1,4\right)$. However, it is shown that the space of spherically symmetric solutions of this theory is degenerate.

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arXiv2022

Asymptotic symmetries and soft charges of fractons

The asymptotic structure of gauge theories describing fracton interactions is analyzed. Two sets of asymptotic conditions are proposed. Both encompass all known solutions, lead to finite charges and resolve the problem of the divergent energy coming from the monopole contribution. While the first set leads to the expected fracton symmetry algebra, including a dipole charge, the second set provides a soft infinite-dimensional extension of it. These soft charges provide evidence of a rich infrared structure for fracton-like theories and provide one corner of a possible fracton infrared triangle.

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arXiv2022

Magnetic Carrollian gravity from the Carroll algebra

We explicitly establish the equivalence between the magnetic Carrollian limit of Einstein gravity defined through the Hamiltonian formalism and the Carrollian theory of gravity defined through a gauging of the Carroll algebra along the lines of standard Poincaré (or (A)dS) gaugings.

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arXiv2021

Asymptotic symmetries in Carrollian theories of gravity

Asymptotic symmetries in Carrollian gravitational theories in 3+1 space and time dimensions obtained from "magnetic" and "electric" ultrarelativistic contractions of General Relativity are analyzed. In both cases, parity conditions are needed to guarantee a finite symplectic term, in analogy with Einstein gravity. For the magnetic contraction, when Regge-Teitelboim parity conditions are imposed, the asymptotic symmetries are described by the Carroll group. With Henneaux-Troessaert parity conditions, the asymptotic symmetry algebra corresponds to a BMS-like extension of the Carroll algebra. For the electric contraction, because the lapse function does not appear in the boundary term needed to ensure a well-defined action principle, the asymptotic symmetry algebra is truncated, for Regge-Teitelboim parity conditions, to the semidirect sum of spatial rotations and spatial translations. Similarly, with Henneaux-Troessaert parity conditions, the asymptotic symmetries are given by the semidirect sum of spatial rotations and an infinite number of parity odd supertranslations. Thus, from the point of view of the asymptotic symmetries, the magnetic contraction can be seen as a smooth limit of General Relativity, in contrast to its electric counterpart.

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arXiv2020

Integrable systems and the boundary dynamics of higher spin gravity on AdS$_3$

We introduce a new set of boundary conditions for three-dimensional higher spin gravity with gauge group $SL(3,\mathbb{R})\times SL(3,\mathbb{R})$, where its dynamics at the boundary is described by the members of the modified Boussinesq integrable hierarchy. In the asymptotic region the gauge fields are written in the diagonal gauge, where the excitations go along the generators of the Cartan subalgebra of $sl(3,\mathbb{R})\oplus sl(3,\mathbb{R})$. We show that the entire integrable structure of the modified Boussinesq hierarchy, i.e., the phase space, the Poisson brackets and the infinite number of commuting conserved charges, are obtained from the asymptotic structure of the higher spin theory. Furthermore, its known relation with the Boussinesq hierarchy is inherited from our analysis once the asymptotic conditions are re-expressed in the highest weight gauge. Hence, the Miura map is recovered from a purely geometric construction in the bulk. Black holes that fit within our boundary conditions, the Hamiltonian reduction at the boundary, and the generalization to higher spin gravity with gauge group $SL(N,\mathbb{R})\times SL(N,\mathbb{R})$ are also discussed.

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