arXiv subjects

Adam Tropper

Publications and source records attributed to Adam Tropper.

9 recordsLinked to original sources

arXiv2026

Challenges to Understanding Celestial Holography from the Bottom Up

In the bottom-up approach to celestial holography, it is tempting to define celestial amplitudes by transforming momentum-space amplitudes order by order in perturbation theory. We test this prescription in the exactly solvable two-dimensional Sinh-Gordon model. Because the full non-perturbative S-matrix is known, we can compare two operations directly: first transform and then expand, or first expand and then transform. They do not agree, already at leading nontrivial order in the coupling. More broadly, this suggests that naive term-by-term celestial transforms should not be assumed valid in generic quantum field theories with asymptotic weak-coupling expansions. This has an immediate consequence for proposed CCFT duals: if one tries to test them by taking celestial transforms of perturbative bulk amplitudes term-by-term, a mismatch need not falsify the proposal. This makes bottom-up tests of celestial dualities far more subtle than one might have expected.

hep-th↗

arXiv2025

Soft Algebras in AdS$_4$ from Light Ray Operators in CFT$_3$

Flat Minkowski space (M$^4$) and AdS$_4$ can both be conformally mapped to the Einstein cylinder. The maps may be judiciously chosen so that some null generators of the $\mathcal{I}^+$ boundary of M$^4$ coincide with antipodally-terminating null geodesic segments on the boundary of AdS$_4$. Conformally invariant nonabelian gauge theories in M$^4$ have an asymptotic $S$-algebra generated by a tower of soft gluons given by weighted null line integrals on $\mathcal{I}^+$. We show that, under the conformal map to AdS$_4$, the leading soft gluons are dual to light transforms of the conserved global symmetry currents in the boundary CFT$_3$. The tower of light ray operators obtained from the $SO(3,2)$ descendants of this light transform realize a full set of generators of the $S$-algebra in the boundary CFT$_3$. This provides a direct connection between holographic symmetry algebras in M$^4$ and AdS$_4$.

hep-th↗

arXiv2024

Symmetries of the Celestial Supersphere

We study the celestial CFT dual to theories with bulk supersymmetry. The boundary theory realizes supersymmetry in the spirit of the Green-Schwarz superstring: there is manifest 4d super-Poincar\'e symmetry, but no 2d superconformal symmetry. Nevertheless, we can extend the celestial sphere itself to a supermanifold -- the celestial supersphere. This provides a unified framework for describing key features of celestial holography, including conformally soft theorems, OPEs, and chiral soft algebras. Using these tools, we demonstrate that the $\frak{bms}_{4}$ algebra extends to a novel $\frak{sbms}_{4|\mathcal{N}}$ algebra. We also relate the supersymmetric $L(w_{1+\infty}^\wedge)$ algebra to Hamiltonian vector fields on $\mathbb{C}^{2|\mathcal{N}}$, consistent with the expectation from twistor theory, and deduce the deformation of this algebra by a cosmological constant, $\Lambda$. These results are all universal and independent of the specific details of the underlying theory.

hep-th↗

arXiv2024

Chiral Soft Algebras for $\mathcal{N} = 2$ Gauge Theory

Some time ago, Seiberg and Witten solved for moduli spaces of vacua parameterized by scalar vacuum expectation values in $\mathcal{N}=2$ gauge theories. More recently, new vacua associated to soft theorems and asymptotic symmetries have been found. This paper takes some first steps towards a complete picture of the infrared geometry of $\mathcal{N}=2$ gauge theory incorporating both of these infrared structures.

hep-th↗

arXiv2024

Supersymmetric Soft Theorems

We show that in supersymmetric theories, knowing the soft theorem for a single particle in a supermultiplet allows one to immediately determine soft theorems for the remainder of the supermultiplet. While soft theorems in supersymmetric theories have a rich history, they have only been chronicled for specific examples due to the fact that they are usually derived with technical Feynman diagrammatics or amplitudes methods. By contrast, we show that one can compute soft theorems non-perturbatively for entire supermultiplets in one line of algebra. This formalism is directly applicable to the most general supersymmetric theory: one with an arbitrary matter content, number of supercharges, and spacetime dimension. We give many explicit examples illustrating the scope and dexterity of this framework.

hep-th↗

arXiv2023

Lorentz Symmetry and IR Structure of The BFSS Matrix Model

The BFSS matrix model relates flat space M-theory to a large N limit of matrix quantum mechanics describing N D0-branes. M-theory, being a theory of gravity in flat space, has a rich infrared structure that includes various soft theorems and an infinite set of conserved charges associated to asymptotic symmetries. In this work, we ask: to what extent is this infrared structure present in BFSS? We find that all the salient features concerning the infrared structure of M-theory carry over naturally to the quantum mechanics dual. Moreover, we demonstrate that the dual statement of the soft graviton theorem in the matrix model implies that D0-brane scattering amplitudes in BFSS enjoy the full 11d Lorentz symmetry of M-theory, a claim which has been long anticipated. We also offer several first-principle consistency checks for our findings, including a computation of the soft theorem which does not presuppose the BFSS duality and a non-trivial match between several known symmetries of M-theory and BFSS that appear naturally in this formalism. These calculations give non-perturbative evidence in support of the BFSS duality as a model of flat space holography.

hep-th↗

arXiv2022

Integrable Field Theories and Their CCFT Duals

We compute the Mellin transforms of various two-dimensional integrable $S$-matrices, providing the first explicit, non-perturbative realizations of celestial CFT. In two dimensions, the Mellin transform is simply the Fourier transform in rapidity space, and the "celestial correlator" has no position dependence. The simplified setting allows us to study the analytic properties of CCFT correlators exactly as a function of the conformal dimensions. We find that the correlators exist as real distributions of the conformal weights, with asymptotics controlled by the mass spectrum and three-point couplings of the model. Coupling these models to a flat space limit of JT gravity preserves integrability and dresses the amplitudes by a rapidly varying gravitational phase. We find that the coupling to gravity smooths out certain singular aspects of the Mellin-transformed correlators.

hep-th↗

arXiv2022

Soft Gravitons in the BFSS Matrix Model

BFSS proposed that asymptotically flat M-theory is dual to a large $N$ limit of the matrix quantum mechanics describing $N$ nonrelativistic D0-branes. Recent insights on the soft symmetries of any quantum theory of gravity in asymptotically flat space are applied to the BFSS matrix model. It is shown that soft gravitons are realized by submatrices whose rank is held fixed in the large $N$ M-theory limit, rather than the usual linear scaling with $N$ for hard gravitons. The soft expansion is identified with the large $N$ expansion and the soft theorem becomes a universal formula for the quantum mechanical scattering of such submatrix excitations. This formula is shown to be the Ward identity of large type IIA $U(1)_{RR}$ asymptotic gauge symmetry in the matrix model, whose asymptotic boundaries are at future and past timelike infinity.

hep-th↗

arXiv2020

Randomness-Assisted Exponential Hierarchies

Inspired by the localization phenomenon in condensed matter systems, we explore constructions in the theory space of multiple scalar fields, in which exponentially suppressed couplings could originate from random parameters. In particular, we find a new class of non-local theory space models, in which scalar fields at non-adjacent sites interact with each other but with strengths decaying exponentially with the site separation. Such a model could have very different localization properties, compared to the local theory space scenarios with only nearest-site interactions, based on the original Anderson localization model. More specifically, we find that a particular non-local interaction pattern leads to bi-localization of the two lightest eigenstates. Exponential localization (and thus exponentially suppressed couplings) then emerges only and immediately when randomness is introduced, no matter how tiny it is. We discuss variants of the model and possible UV completions as well.

hep-ph↗