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A 4D duality web [article]

Jeff Murugan, Horatiu Nastase
2021 arXiv   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
more » ... 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.
arXiv:2103.12667v1 fatcat:ggqebmrmivhb7fgzmi2edt2owm

Operator Delocalization in Quantum Networks [article]

Joonho Kim, Jeff Murugan, Jan Olle, Dario Rosa
2021 arXiv   pre-print
Murugan, and M.  ... 
arXiv:2109.05301v1 fatcat:asbco7ep5jg5dhiobo7mqplwqu

Emergent Spacetime [article]

Robert de Mello Koch, Jeff Murugan
2009 arXiv   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

Chaos and Scrambling in Quantum Small Worlds [article]

Jean-Gabriel Hartmann, Jeff Murugan, Jonathan P. Shock
2019 arXiv   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
more » ... 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.
arXiv:1901.04561v1 fatcat:lz76jmfx2be6dpjiwjzat2gfpi

Amplitudes, Gravity and Classical Discontinuities [article]

Daniel J. Burger, Raul Carballo-Rubio, Nathan Moynihan, Jeff Murugan, Amanda Weltman
2019 arXiv   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

On-Shell Electric-Magnetic Duality and the Dual Graviton [article]

Nathan Moynihan, Jeff Murugan
2020 arXiv   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
more » ... 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.
arXiv:2002.11085v1 fatcat:rnamf2wi5jbvdgq4dtvcigyjoi

Amplitudes for Astrophysicists I: Known Knowns [article]

Daniel J. Burger, Raúl Carballo-Rubio, Nathan Moynihan, Jeff Murugan, Amanda Weltman
2017 arXiv   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
more » ... 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.
arXiv:1704.05067v1 fatcat:qogoxgdjzjc43ewdmytdt6mwdm

Notes on the Squashed Sphere Lowest Landau Level [article]

Jeff Murugan, Jonathan P. Shock, Ruach Pillay Slayen
2019 arXiv   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
more » ... 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.
arXiv:1909.08042v1 fatcat:gmfz7ymrqbf4xb5slzlaqu6v5a

Remarks on Fermions in a Dipole Magnetic Field [article]

Jeff Murugan, Jonathan P. Shock, Ruach Pillay Slayen
2021 arXiv   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
more » ... , 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.
arXiv:2107.10076v1 fatcat:v6yumcwy3bdwjo6y7mvsr5d3aa

Probability Density Functions from the Fisher Information Metric [article]

T. Clingman, Jeff Murugan, Jonathan P. Shock
2015 arXiv   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

The KLT relations in unimodular gravity [article]

Daniel J Burger, George F. R. Ellis, Jeff Murugan, Amanda Weltman
2015 arXiv   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

One-dimensional bosonization and the SYK model [article]

Jeff Murugan, Horatiu Nastase
2018 arXiv   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

On-Shell Perspectives on the Massless Limit of Massive Supergravity [article]

Daniel J Burger, Nathan Moynihan, Jeff Murugan
2020 arXiv   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
more » ... but lesser known discontinuity first discovered by Deser, Kay and Stelle in massive supergravity.
arXiv:2005.14077v1 fatcat:7hsss7qfhfanzlnqyn2xjhc5ae

An Introduction to Topological Data Analysis for Physicists: From LGM to FRBs [article]

Jeff Murugan, Duncan Robertson
2019 arXiv   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.
more » ... 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.
arXiv:1904.11044v1 fatcat:indgfphbibfppckxq52avwlwx4

The Catenary Revisited: From Newtonian Strings to Superstrings [article]

David de Klerk, Jeff Murugan, Jean-Philippe Uzan
2011 arXiv   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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