62 results found
Cheamsawat K, Fischetti S, Wallis L, et al., 2021, A surprising similarity between holographic CFTs and a free fermion in (2+1) dimensions, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Catterall S, Giedt J, Jha RG, et al., 2020, Three-dimensional super-Yang-Mills theory on the lattice and dual black branes, PHYSICAL REVIEW D, Vol: 102, ISSN: 2470-0010
Fischetti S, Wallis L, Wiseman T, 2020, Does the round sphere maximize the free energy of (2+1)-dimensional QFTs?, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
In this paper, which is of programmatic rather than quantitative nature, we aim to further delineate and sharpen the future potential of the LISA mission in the area of fundamental physics. Given the very broad range of topics that might be relevant to LISA,we present here a sample of what we view as particularly promising fundamental physics directions. We organize these directions through a “science-first” approach that allows us to classify how LISA data can inform theoretical physics in a variety of areas. For each of these theoretical physics classes, we identify the sources that are currently expected to provide the principal contribution to our knowledge, and the areas that need further development. The classification presented here should not be thought of as cast in stone, but rather as a fluid framework that is amenable to change with the flow of new insights in theoretical physics.
Cheamsawat K, Wallis L, Wiseman T, 2019, Free energy dependence on spatial geometry for (2+1)-dimensional QFTs, Classical and Quantum Gravity, Vol: 36, ISSN: 0264-9381
We consider (2+1)-QFT at finite temperature on a product of time with astatic spatial geometry. The suitably defined difference of thermal vacuum freeenergy for the QFT on a deformation of flat space from its value on flat spaceis a UV finite quantity, and for reasonable fall-off conditions on thedeformation is IR finite too. For perturbations of flat space we show this freeenergy difference goes quadratically with perturbation amplitude and may becomputed from the linear response of the stress tensor. As an illustration wecompute it for a holographic CFT finding that at any temperature, and for anyperturbation, the free energy decreases. Similar behaviour was previously foundfor free scalars and fermions, and for unitary CFTs at zero temperature,suggesting (2+1)-QFT may generally energetically favour a crumpled spatialgeometry. We also treat the deformation in a hydrostatic small curvatureexpansion relative to the thermal scale. Then the free energy variation isdetermined by a curvature correction to the stress tensor and for thesetheories is negative for small curvature deformations of flat space.
Fischetti S, Wallis L, Wiseman T, 2019, What spatial geometry does the (2+1)-dimensional QFT vacuum prefer?, Physical Review Letters, Vol: 120, ISSN: 0031-9007
We consider relativistic (2+1)-dimensional quantum field theories (QFTs) on a product of time with a two-space and study the vacuum free energy as a functional of the temperature and spatial geometry. We focus on free scalar and Dirac fields on arbitrary perturbations of flat space, finding that the free energy difference from flat space is finite and always negative to leading order in the perturbation. Thus, free (2+1)-dimensional QFTs appear to always energetically favor a crumpled space on all scales; this is true both as a purely quantum effect at zero temperature and as a purely thermal effect at high temperature. Importantly, we show that this quantum effect is non-negligible for the relativistic Dirac degrees of freedom on monolayer graphene even at room temperature, so we argue that this vacuum energy effect should be included for a proper analysis of the equilibrium configuration of graphene or similar materials.
Cheamsawat K, Gibbons G, Wiseman T, 2019, A new energy upper bound for AdS black holes inspired by free field theory, Publisher: arXiv
We consider the toroidally compactified planar AdS-Schwarzschild solution to4-dimensional gravity with negative cosmological constant. This has a flattorus conformal boundary metric. We show that if the spatial part of theboundary metric is deformed, keeping it static and the temperature and areafixed, then assuming a static bulk solution exists, its energy is less thanthat of the AdS-Schwarzschild solution. The proof is non-perturbative in themetric deformation. While we expect the same holds for the free energy forblack hole solutions we are so far are not able to prove it. In the context ofAdS-CFT this implies a 3-dimensional holographic CFT on a flat spatial toruswhose bulk dual is AdS-Schwarzschild has a greater energy than if the spatialgeometry is deformed in any way that preserves temperature and area. This workwas inspired by previous results in free field theory, where scalars andfermions in 3-dimensions have been shown to energetically disfavour flat space.
Catterall S, Jha RG, Schaich D, et al., 2018, Testing holography using lattice super-Yang--Mills on a 2-torus, Physical Review D, Vol: 97, ISSN: 2470-0010
We consider maximally supersymmetric SU(N) Yang--Mills theory in Euclideansignature compactified on a flat two-dimensional torus with anti-periodic(`thermal') fermion boundary conditions imposed on one cycle. At large N,holography predicts that this theory describes certain black hole solutions inType IIA and IIB supergravity, and we use lattice gauge theory to test this.Unlike the one-dimensional quantum mechanics case where there is only thedimensionless temperature to vary, here we emphasize there are two moreparameters which determine the shape of the flat torus. While a rectangularEuclidean torus yields a thermal interpretation, allowing for skewed torimodifies the holographic dual black hole predictions and results in anotherdirection to test holography. Our lattice calculations are based on asupersymmetric formulation naturally adapted to a particular skewing. Usingthis we perform simulations up to N=16 with several lattice spacings for bothskewed and rectangular tori. We observe the two expected black hole phases withtheir predicted behavior, with a transition between them that is consistentwith the gravity prediction based on the Gregory--Laflamme transition.
Jha RG, Catterall S, Schaich D, et al., 2018, Testing the holographic principle using lattice simulations, EPJ Web of Conferences, Vol: 175, Pages: 08004-08004
<jats:p>The lattice studies of maximally supersymmetric Yang-Mills (MSYM) theory at strong coupling and large N is important for verifying gauge/gravity duality. Due to the progress made in the last decade, based on ideas from topological twisting and orbifolding, it is now possible to study these theories on the lattice while preserving an exact supersymmetry on the lattice. We present some results from the lattice studies of two-dimensional MSYM which is related to Type II supergravity. Our results agree with the thermodynamics of different black hole phases on the gravity side and the phase transition (Gregory–Laflamme) between them.</jats:p>
Fischetti S, Wiseman T, 2017, On universality of holographic results for (2+1)-dimensional CFTs on curved spacetimes, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Figueras P, Wiseman T, 2017, On the existence of stationary Ricci solitons, Classical and Quantum Gravity, Vol: 34, ISSN: 0264-9381
Previously the DeTurck 'trick' has been used to render the stationary Einstein's equation a well posed elliptic system that may be solved numerically by geometric flow or directly. Whilst in the static case for pure gravity with zero or negative cosmological constant there is a simple proof that solving the modified 'harmonic' Einstein's equation leads to a solution of the original Einstein system—i.e. not a Ricci soliton—in the stationary case this argument no longer works. Here we provide a new argument that extends the static result to the case of stationary spacetimes that possess a 't-phgr reflection symmetry. Defining a 'soliton charge' from the asymptotic behaviour of the solution, we show that this quantity is always non-positive. Provided asymptotic conditions are chosen such that this charge vanishes, then stationary solitons cannot exist.
Fischetti S, Wiseman T, 2017, A bound on holographic entanglement entropy from inverse mean curvature flow, Classical and Quantum Gravity, Vol: 34, ISSN: 0264-9381
Entanglement entropies are notoriously difficult to compute. Large-N strongly-coupled holographic CFTs are an important exception, where the AdS/CFT dictionary gives the entanglement entropy of a CFT region in terms of the area of an extremal bulk surface anchored to the AdS boundary. Using this prescription, we show—for quite general states of (2 + 1)-dimensional such CFTs—that the renormalized entanglement entropy of any region of the CFT is bounded from above by a weighted local energy density. The key ingredient in this construction is the inverse mean curvature (IMC) flow, which we suitably generalize to flows of surfaces anchored to the AdS boundary. Our bound can then be thought of as a 'subregion' Penrose inequality in asymptotically locally AdS spacetimes, similar to the Penrose inequalities obtained from IMC flows in asymptotically flat spacetimes. Combining the result with positivity of relative entropy, we argue that our bound is valid perturbatively in 1/N, and conjecture that a restricted version of it holds in any CFT.
Fischetti S, Hickling A, Wiseman TAJ, 2016, Bounds on the local energy density of holographic CFTs from bulk geometry, Classical and Quantum Gravity, Vol: 33, ISSN: 1361-6382
The stress tensor is a basic local operator in any field theory; in the context of AdS/CFT, it isthe operator which is dual to the bulk geometry itself. Here we exploit this feature by using thebulk geometry to place constraints on the local energy density in static states of holographic (2+ 1)-dimensional CFTs living on a closed (but otherwise generally curved) spatial geometry. We allowfor the presence of a marginal scalar deformation, dual to a massless scalar field in the bulk. Forcertain vacuum states in which the bulk geometry is well-behaved at zero temperature, we find thatthe bulk equations of motion imply that the local energy density integrated over specific boundarydomains is negative. In the absence of scalar deformations, we use the inverse mean curvature flowto show that if the CFT spatial geometry has spherical topology but non-constant curvature, thelocal energy density must be positive somewhere. This result extends to other topologies, but onlyfor certain types of vacuum; in particular, for a generic toroidal boundary, the vacuum’s bulk dualmust be the zero-temperature limit of a toroidal black hole.
Hickling A, Wiseman T, 2016, Vacuum energy is non-positive for (2+1)-dimensional holographic CFTs, CLASSICAL AND QUANTUM GRAVITY, Vol: 33, ISSN: 0264-9381
Hickling A, Wiseman T, 2016, AdS/CFT and the geometry of an energy gap, CLASSICAL AND QUANTUM GRAVITY, Vol: 33, ISSN: 0264-9381
Morita T, Shiba S, Wiseman T, et al., 2015, Moduli dynamics as a predictive tool for thermal maximally supersymmetric Yang-Mills at large N, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Marolf D, Rangamani M, Wiseman T, 2014, Holographic thermal field theory on curved spacetimes, CLASSICAL AND QUANTUM GRAVITY, Vol: 31, ISSN: 0264-9381
Wiseman T, 2013, On black hole thermodynamics from super Yang-Mills, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Figueras P, Wiseman T, 2013, Stationary Holographic Plasma Quenches and Numerical Methods for Non-Killing Horizons, PHYSICAL REVIEW LETTERS, Vol: 110, ISSN: 0031-9007
Bhaseen MJ, Gauntlett JP, Simons BD, et al., 2013, Holographic Superfluids and the Dynamics of Symmetry Breaking, PHYSICAL REVIEW LETTERS, Vol: 110, ISSN: 0031-9007
Catterall S, Joseph A, Wiseman T, 2013, Gauge theory duals of black hole - black string transitions of gravitational theories on a circle, 6TH INTERNATIONAL SYMPOSIUM ON QUANTUM THEORY AND SYMMETRIES (QTS6), Vol: 462, ISSN: 1742-6588
Adam A, Kitchen S, Wiseman T, 2012, A numerical approach to finding general stationary vacuum black holes, CLASSICAL AND QUANTUM GRAVITY, Vol: 29, ISSN: 0264-9381
Wiseman T, 2012, Black Holes in Higher Dimensions, Black Holes in Higher Dimensions, Editors: Horowitz, Horowitz, Publisher: Cambridge University Press, ISBN: 9781107013452
In higher dimensions, black holes exist with exotic shapes and unusual dynamics. Edited by leading expert Gary Horowitz, this exciting book is the first devoted to this new field.
Wiseman T, Withers B, 2011, Inhomogeneous post-inflationary Lambda CDM cosmology as a moduli space expansion, PHYSICAL REVIEW D, Vol: 84, ISSN: 1550-7998
Figueras P, Lucietti J, Wiseman T, 2011, Ricci solitons, Ricci flow and strongly coupled CFT in the Schwarzschild Unruh or Boulware vacua, CLASSICAL AND QUANTUM GRAVITY, Vol: 28, ISSN: 0264-9381
Figueras P, Wiseman T, 2011, Gravity and Large Black Holes in Randall-Sundrum II Braneworlds, PHYSICAL REVIEW LETTERS, Vol: 107, ISSN: 0031-9007
We show how to construct low energy solutions to the Randall-Sundrum II (RSII) model by using an associated five-dimensional anti-de Sitter space (AdS(5)) and/or four-dimensional conformal field theory (CFT(4)) problem. The RSII solution is given as a perturbation of the AdS(5)-CFT(4) solution, with the perturbation parameter being the radius of curvature of the brane metric compared to the AdS length l. The brane metric is then a specific perturbation of the AdS(5)-CFT(4) boundary metric. For low curvatures the RSII solution reproduces 4D general relativity on the brane. Recently, AdS(5)-CFT(4) solutions with a 4D Schwarzschild boundary metric were numerically constructed. We modify the boundary conditions to numerically construct large RSII static black holes with radius up to similar to 20l. For a large radius, the RSII solutions are indeed close to the associated AdS(5)-CFT(4) solution.
Wiseman T, Withers B, 2011, Late time solutions for inhomogeneous Lambda CDM cosmology, their characterization, and observation, PHYSICAL REVIEW D, Vol: 83, ISSN: 1550-7998
Catterall S, Joseph A, Wiseman T, 2010, Thermal phases of D1-branes on a circle from lattice super Yang-Mills, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
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