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A 4D duality web
[article]

2021
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arXiv
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pre-print

We construct a web of non-supersymmetric dualities in four spacetime dimensions for theories with theta and Maxwell terms. Our construction mirrors the recipe used in (2+1)-dimensions to demonstrate a similar duality for theories with Chern-Simons terms. As in the 3-dimensional case, the web consists of boson-boson, fermion-fermion and boson-fermion dualities, any one of which can be taken as a seed for the remaining two. To be concrete, we begin by constructing the basic bosonization duality

arXiv:2103.12667v1
fatcat:ggqebmrmivhb7fgzmi2edt2owm
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... ich we then use to generate the web, using an analog of the 3-dimensional massive construction given in . The resulting 4-dimensional duality web is best understood as an extension of the, by now well-known, 3-dimensional case due to its somewhat singular nature. We conjecture that this is the final thread in a multi-dimensional duality web that connects low energy theories in 4-, 3- and 2-spacetime dimensions and speculate on its application to 3-dimensional topological insulators.##
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Operator Delocalization in Quantum Networks
[article]

2021
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arXiv
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pre-print

*Murugan*, and M. ...

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Emergent Spacetime
[article]

2009
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arXiv
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pre-print

We give an introductory account of the AdS/CFT correspondence in the 1/2-BPS sector of N=4 super Yang-Mills theory.Six of the dimensions of the string theory are emergent in the Yang-Mills theory. In this article we suggest how these dimensions and local physics in these dimensions emerge. The discussion is aimed at non-experts.

arXiv:0911.4817v2
fatcat:f3oau2b6ynffxgdnbqciyowp6a
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Chaos and Scrambling in Quantum Small Worlds
[article]

2019
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arXiv
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pre-print

Quantum small-worlds are quantum many-body systems that interpolate between completely ordered (nearest-neighbour, next-to-nearest-neighbour etc.) and completely random interactions. As such, they furnish a novel new laboratory to study quantum systems transitioning between regular and chaotic behaviour. In this article, we introduce the idea of a quantum small-world network by starting from a well understood integrable system, a spin-1 Heisenberg chain. We then inject a small number of

arXiv:1901.04561v1
fatcat:lz76jmfx2be6dpjiwjzat2gfpi
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... ge interactions into the spin chain and study its ability to scramble quantum information using two primary devices: the out-of-time-order correlator (OTOC) and the spectral form factor (SFF). We find that the system shows increasingly rapid scrambling as its interactions become progressively more random, with no evidence of quantum chaos.##
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Amplitudes, Gravity and Classical Discontinuities
[article]

2019
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arXiv
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pre-print

On-shell methods have revitalized interest in scattering amplitudes which have, in turn, shed some much needed light on the structure of quantum field theories. These developments have been warmly embraced by the particle physics community. Less so in the astrophyical and cosmological contexts. As part of an effort to address this imbalance, we illustrate these methods by revisiting two classic problems in gravity: gravitational light-bending and the vDVZ discontinuity of massive gravity.

arXiv:1905.05128v1
fatcat:bumbtwsyvfh7bggfw4j4dnadle
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On-Shell Electric-Magnetic Duality and the Dual Graviton
[article]

2020
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arXiv
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pre-print

Using on-shell amplitude methods, we explore 4-dimensional Electric-Magnetic duality and its double copy. We show explicitly that the on-shell scattering amplitudes know about 'dual' photons (and dual gravitons), that the off-shell photon propagator double copies to the graviton propagator and that the magnetic part of the propagator is essential for the double copy to hold. We also show that there is an equivalent gravito-magnetic part of the graviton propagator which is essential in giving

arXiv:2002.11085v1
fatcat:rnamf2wi5jbvdgq4dtvcigyjoi
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... e to solutions with either angular momentum or NUT charge. Furthermore, we comment on the so-called Weinberg paradox, which states that scattering amplitudes involving the mixing of electric and magnetic monopoles cannot be Lorentz invariant, and would seem to preclude the existence of the 't Hooft-Polyakov (topological) monopole. We trace this paradox to the magnetic part of the propagator, showing that it can be eliminated if one restricts to proper orthochronous Lorentz transformations. Finally, we compute the fully relativistic cross-section for arbitrary spin dyons using the recently formulated on-shell duality transformation and show that this is always fully Lorentz invariant.##
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Amplitudes for Astrophysicists I: Known Knowns
[article]

2017
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arXiv
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pre-print

The use of quantum field theory to understand astrophysical phenomena is not new. However, for the most part, the methods used are those that have been developed decades ago. The intervening years have seen some remarkable developments in computational quantum field theoretic tools. In particle physics, this technology has facilitated calculations that, even ten years ago would have seemed laughably difficult. It is remarkable, then, that most of these new techniques have remained firmly within

arXiv:1704.05067v1
fatcat:qogoxgdjzjc43ewdmytdt6mwdm
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... the domain of high energy physics. We would like to change this. As alluded to in the title, this is the first in a series of papers aimed at showcasing the use of modern on-shell methods in the context of astrophysics and cosmology. In this first article, we use the old problem of the bending of light by a compact object as an anchor to pedagogically develop these new computational tools. Once developed, we then illustrate their power and utility with an application to the scattering of gravitational waves.##
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Notes on the Squashed Sphere Lowest Landau Level
[article]

2019
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arXiv
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pre-print

In a recent article, we were motivated by the question of whether any of the remarkable condensed matter phenomena, such as the quantum Hall effect (QHE), the Integer quantum Hall effect (IQHE) etc., could potentially be observed in the extreme astrophysical environments of neutron stars. As a prequel to that work, and with the aim of understanding better the role of the geometry of the conducting surface on the structure of Landau levels, in this article we study the quantum dynamics of a

arXiv:1909.08042v1
fatcat:gmfz7ymrqbf4xb5slzlaqu6v5a
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... um particle on a squashed sphere. More specifically, we study the dynamics of a single particle on an oblate squashed Haldane sphere i.e. a 2-sphere enclosing a single magnetic monopole at its center. While several features of the conventional Haldane sphere persist, by numerically solving the Schrodinger equation in this background, we find that the particle becomes increasingly localised in a band between the equator and the poles, with a corresponding increase of the eccentricity of the spheroid.##
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Remarks on Fermions in a Dipole Magnetic Field
[article]

2021
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arXiv
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pre-print

This work is a continuation of our recent study of non-relativistic charged particles, confined to a sphere enclosing a magnetic dipole at its center. In this sequel, we extend our computations in two significant ways. The first is to a relativistic spin-1/2 fermion and the second concerns the interpretation of the physics. Whereas in a previous paper, we speculated on the possibility of observing such condensed matter systems in the astrophysics of extreme magnetic sources such as neutron

arXiv:2107.10076v1
fatcat:v6yumcwy3bdwjo6y7mvsr5d3aa
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... , the physical systems in this study are more down-to-earth objects such as a 𝖢_60 fullerine enclosing a current loop. We unpack some of the details of our previous analysis for the spinless fermion on the dipole sphere and adapt it to solve the eigenvalue problem for the single-particle Dirac Hamiltonian. In the strong-field/small-radius limit, the spectrum of the spin-12 Hamiltonian, like the spinless case, exhibits a Landau level structure in the |m|≪ Q regime. It features a new, additional (approximately) zero-energy lowest Landau level which persists into the |m|<Q regime. As in the spinless system, the spectrum exhibits level-crossing as the strength of the magnetic field increases, with the wavefunctions localising at the poles in the strong-field/small-radius limit.##
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Probability Density Functions from the Fisher Information Metric
[article]

2015
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arXiv
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pre-print

We show a general relation between the spatially disjoint product of probability density functions and the sum of their Fisher information metric tensors. We then utilise this result to give a method for constructing the probability density functions for an arbitrary Riemannian Fisher information metric tensor. We note further that this construction is extremely unconstrained, depending only on certain continuity properties of the probability density functions and a select symmetry of their domains.

arXiv:1504.03184v1
fatcat:6zximcrbnfe4zpzzrkp3cpbh24
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The KLT relations in unimodular gravity
[article]

2015
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arXiv
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pre-print

With this article, we initiate a systematic study of some of the symmetry properties of unimodular gravity, building on much of the known structure of general relativity, and utilising the powerful technology developed in that context. In particular, we show, up to four-points and tree-level, that the KLT relations of perturbative gravity hold for tracefree or unimodular gravity.

arXiv:1511.08517v1
fatcat:brydj2lrzjfy5komnkhxugveuy
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One-dimensional bosonization and the SYK model
[article]

2018
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arXiv
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pre-print

We explore the possibility of extending the familiar bosonization of two dimensions to (0+1)- dimensional systems with a large number of degrees of freedom. As an application of this technique, we consider a class of SYK-type models, and argue that the corresponding action on the gravity dual of the SYK model is given by an STS sequence of dualities.

arXiv:1812.11929v1
fatcat:ju5gsrf3ubgrxndnfgopryzuwa
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On-Shell Perspectives on the Massless Limit of Massive Supergravity
[article]

2020
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arXiv
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pre-print

Massive gravity exhibits a famous discontinuity in its 2-point linearized amplitude for t-channel scattering of gravitational sources, in the m → 0 limit. In essence, the source of this vDVZ discontinuity is in the failure of the zero-helicity mode to decouple in this limit. In [1], we showed how this result could be understood in the context of modern on-shell methods and, in particular, the BCFW construction. In this article, we provide a similar on-shell perspective to the equally

arXiv:2005.14077v1
fatcat:7hsss7qfhfanzlnqyn2xjhc5ae
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... but lesser known discontinuity first discovered by Deser, Kay and Stelle in massive supergravity.##
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An Introduction to Topological Data Analysis for Physicists: From LGM to FRBs
[article]

2019
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arXiv
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pre-print

Topological Data Analysis (TDA) is a novel, and relatively new approach to analysing high-dimensional data sets. It does this by focussing on global properties like the shape and connectivity of the data giving it a significant advantage over more conventional tools based on cluster analysis, a localised property of the data. However, some of its mathematical foundations, like algebraic topology and discrete Morse theory, are perceived as an intimidatingly steep upramp into the subject.

arXiv:1904.11044v1
fatcat:indgfphbibfppckxq52avwlwx4
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... ntly, it has enjoyed much less popularity as a data-analysis tool than less abstract methods. This article aims to change this. By focusing on a small set of simple examples, chosen primarily for their pedagogical value, we introduce and explain TDA's two principle branches; persistent homology and the Mapper algorithm. We then illustrate the universality of the method by discussing its application to the intriguing data set of fast radio burst (FRB) observations. We close the article with a discussion of the resilience of topological data analysis to noise and some statistical and computational challenges faced by the method.##
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The Catenary Revisited: From Newtonian Strings to Superstrings
[article]

2011
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arXiv
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pre-print

The dynamics of extended objects, such as strings and membranes, has attracted more attention in the past decades since the fundamental objects introduced in high-energy physics are no longer pointlike. Their motion is generally quite intricate to describe and usually requires the sophisticated tools of Conformal Field Theory, Quantum Field Theory and General Relativity. This article argues that the Newtonian analogy of a catenary with free ends offers a good description of some processes such as gravitational radiation by an accelerated brane.

arXiv:1103.0788v1
fatcat:ciqpy5nb7bb4nfvg6ng6empfrq
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