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Journal articleEtkin A, Magueijo J, Rassouli F-S, 2024,
Vortices, topology and time
, Physics Letters B: Nuclear Physics and Particle Physics, Vol: 855, ISSN: 0370-2693We relate physical time with the topology of magnetic field vortices. We base ourselves on a formulation of unimodular gravity where the cosmological constant Λ appears as the canonical dual to a variable which on-shell becomes four-volume time. If the theory is restricted to a topological axionic form (viz. a parity-odd product of an electric and a magnetic field), such a time variable becomes the spatial integral of the Chern-Simons density. The latter equates to helicity, so that unimodular time is transmuted into the linking number of the vortices of the topological magnetic field, times their flux. With the added postulate that this flux is a universal constant, the flow of time can thus be interpreted as the progressive weaving of further links between magnetic field vortices, each link providing a quantum of time with value related to the fixed flux. Non-abelian extensions, and targetting parameters other than Λ are briefly examined, exposing different types of vortices and a possible role for inter-linking leading to new phenomenology.
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Journal articleJiang H, Tseytlin AA, 2024,
On co-dimension 2 defect anomalies in <i>N</i>=4 SYM and (2,0) theory via brane probes in AdS/CFT
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleGkountoumis G, Hull C, Vandoren S, 2024,
Exact moduli spaces for N=2, <i>D</i>=5 freely acting orbifolds
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleHull C, Hutt ML, Lindstrom U, 2024,
Charges and topology in linearised gravity
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleChester SM, Dempsey R, Pufu SS, 2024,
Level repulsion in N=4 super-Yang-Mills via integrability, holography, and the bootstrap
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleChen S, Dechant P-P, He Y-H, et al., 2024,
Machine Learning Clifford Invariants of ADE Coxeter Elements
, Advances in Applied Clifford Algebras, Vol: 34, ISSN: 0188-7009<jats:title>Abstract</jats:title><jats:p>There has been recent interest in novel Clifford geometric invariants of linear transformations. This motivates the investigation of such invariants for a certain type of geometric transformation of interest in the context of root systems, reflection groups, Lie groups and Lie algebras: the Coxeter transformations. We perform exhaustive calculations of all Coxeter transformations for<jats:inline-formula><jats:alternatives><jats:tex-math>$$A_8$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>A</mml:mi><mml:mn>8</mml:mn></mml:msub></mml:math></jats:alternatives></jats:inline-formula>,<jats:inline-formula><jats:alternatives><jats:tex-math>$$D_8$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>D</mml:mi><mml:mn>8</mml:mn></mml:msub></mml:math></jats:alternatives></jats:inline-formula>and<jats:inline-formula><jats:alternatives><jats:tex-math>$$E_8$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>E</mml:mi><mml:mn>8</mml:mn></mml:msub></mml:math></jats:alternatives></jats:inline-formula>for a choice of basis of simple roots and compute their invariants, using high-performance computing. This computational algebra paradigm generates a dataset that can then be mined using techniques from data science such as supervised and unsupervised machine learning. In this paper we focus on neural network classification and principal component analysis. Since the output—the invariants—is fully determined by the choice of simple roots and the permutation order of the corresponding reflections in the Coxeter elemen
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Journal articleGonzalez MC, de Rham C, Jaitly S, et al., 2024,
Positivity-causality competition: a road to ultimate EFT consistency constraints
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleMagueijo J, 2024,
Dark matter and spacetime symmetry restoration
, Physical Review D: Particles, Fields, Gravitation and Cosmology, Vol: 109, ISSN: 1550-2368We examine local physics in the presence of global variables: variables associated with the whole of the spacelike surfaces of a foliation. These could be the (pseudo)constants of nature and their conjugate times, but our statements are more general. Interactions between the local and the global (for example, dependence of the local action on global times dual to constants) degrades full space-time diffeomorphism invariance down to spatial diffeomorphism invariance, and so an extra degree of freedom appears. When these presumably primordial global interactions switch off, the local action recovers full invariance and so the usual two gravitons, but a legacy matter component is left over, bearing the extra degree of freedom. Under the assumption that the preferred foliation is geodesic, this component behaves like dark matter, except that 3 of its 4 local degrees of freedom are frozen, forcing its rest frame to coincide with the preferred foliation. The nonfrozen degree of freedom (the number density of the effective fluid) is the survivor of the extra “graviton” present in the initial theory and keeps memory of all the past global interactions that took place in a given location in the preferred foliation. Such “painted-on” dark matter is best distinguished from the conventional one in situations where the preferred frame would be preposterous if all 4 degrees of freedom of dark matter were available. We provide one example: an outflowing halo of legacy matter with exact escape speed at each point and a very specific profile, surrounding a condensed structure made of normal matter.
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Journal articleGerhardinger M, Giblin Jr JT, Tolley AJ, et al., 2024,
Simulating a numerical UV completion of quartic Galileons
, PHYSICAL REVIEW D, Vol: 109, ISSN: 2470-0010 -
Journal articleLiu X, Santos JE, Wiseman T, 2024,
New Well-Posed boundary conditions for semi-classical Euclidean gravity
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleChester SM, Pufu SS, Wang Y, et al., 2024,
Bootstrapping M-theory orbifolds
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleBasile T, Joung E, Mkrtchyan K, et al., 2024,
Spinor-helicity representations of particles of any mass in dS 4 and AdS 4 spacetimes
, PHYSICAL REVIEW D, Vol: 109, ISSN: 2470-0010 -
Journal articleMentasti G, Contaldi CR, Peloso M, 2024,
Probing the galactic and extragalactic gravitational wave backgrounds with space-based interferometers
, Journal of Cosmology and Astroparticle Physics, Vol: 2024, ISSN: 1475-7516We employ the formalism developed in [1] and [2] to study the prospect of detecting an anisotropic Stochastic Gravitational Wave Background (SGWB) with the Laser Interferometer Space Antenna (LISA) alone, and combined with the proposed space-based interferometer Taiji. Previous analyses have been performed in the frequency domain only. Here, we study the detectability of the individual coefficients of the expansion of the SGWB in spherical harmonics, by taking into account the specific motion of the satellites. This requires the use of time-dependent response functions, which we include in our analysis to obtain an optimal estimate of the anisotropic signal. We focus on two applications. Firstly, the reconstruction of the anisotropic galactic signal without assuming any prior knowledge of its spatial distribution. We find that both LISA and LISA with Taiji cannot put tight constraints on the harmonic coefficients for realistic models of the galactic SGWB. We then focus on the discrimination between a galactic signal of known morphology but unknown overall amplitude and an isotropic extragalactic SGWB component of astrophysical origin. In this case, we find that the two surveys can confirm, at a confidence level ≳ 3σ, the existence of both the galactic and extragalactic background if both have amplitudes as predicted in standard models. We also find that, in the LISA-only case, the analysis in the frequency domain (under the assumption of a time average of data taken homogeneously across the year) provides a nearly identical determination of the two amplitudes as compared to the optimal analysis.
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Journal articleAbend S, Allard B, Alonso I, et al., 2024,
Terrestrial very-long-baseline atom interferometry: workshop summary
, AVS Quantum Science, Vol: 6, ISSN: 2639-0213This document presents a summary of the 2023 Terrestrial Very-Long-Baseline Atom Interferometry Workshop hosted by CERN. The workshop brought together experts from around the world to discuss the exciting developments in large-scale atom interferometer (AI) prototypes and their potential for detecting ultralight dark matter and gravitational waves. The primary objective of the workshop was to lay the groundwork for an international TVLBAI proto-collaboration. This collaboration aims to unite researchers from different institutions to strategize and secure funding for terrestrial large-scale AI projects. The ultimate goal is to create a roadmap detailing the design and technology choices for one or more kilometer--scale detectors, which will be operational in the mid-2030s. The key sections of this report present the physics case and technical challenges, together with a comprehensive overview of the discussions at the workshop together with the main conclusions.
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Journal articleShi D, Shang F, Chen B, et al., 2024,
Local dominance unveils clusters in networks
, Communications Physics, Vol: 7, ISSN: 2399-3650Clusters or communities can provide a coarse-grained description of complex systems at multiple scales, but their detection remains challenging in practice. Community detection methods often define communities as dense subgraphs, or subgraphs with few connections in-between, via concepts such as the cut, conductance, or modularity. Here we consider another perspective built on the notion of local dominance, where low-degree nodes are assigned to the basin of influence of high-degree nodes, and design an efficient algorithm based on local information. Local dominance gives rises to community centers, and uncovers local hierarchies in the network. Community centers have a larger degree than their neighbors and are sufficiently distant from other centers. The strength of our framework is demonstrated on synthesized and empirical networks with ground-truth community labels. The notion of local dominance and the associated asymmetric relations between nodes are not restricted to community detection, and can be utilised in clustering problems, as we illustrate on networks derived from vector data.
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Journal articleHanany A, Kumaran G, Li C, et al., 2024,
Actions on the quiver: discrete quotients on the Coulomb branch
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleAlday LF, Chester SM, Hansen T, et al., 2024,
The AdS Veneziano amplitude at small curvature
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleHull CM, 2024,
Magnetic charges for the graviton
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Conference paperTseytlin AA, 2024,
AdS/CFT, Wilson loops and M2-branes
We discuss testing AdS/CFT correspondence between U(N)<inf>k</inf> × U(N)<inf>-k</inf> Chern-Simons-matter 3d gauge theory and M-theory in AdS<inf>4</inf> × S<sup>7</sup>/Z<inf>k</inf> background. We show that the quantum M2 brane partition function expanded near the corresponding classical solution matches the localization predictions on the gauge theory side in the case of BPS Wilson loop expectation value and instanton corrections to free energy.
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Journal articleAlbertini E, Dowker F, Nasiri A, et al., 2024,
In-in correlators and scattering amplitudes on a causal set
, Physical Review D: Particles, Fields, Gravitation and Cosmology, Vol: 109, ISSN: 1550-2368Causal set theory is an approach to quantum gravity in which spacetime is fundamentally discrete at the Planck scale and takes the form of an irregular Lorentzian lattice, or “causal set,” from which continuum spacetime emerges in a large-scale (low-energy) approximation. In this work, we present new developments in the framework of interacting quantum field theory on causal sets. We derive a diagrammatic expansion for in-in correlators in local scalar field theories with finite polynomial interactions. We outline how these same correlators can be computed using the double-path integral, which acts as a generating functional for the in-in correlators. We modify the in-in generating functional to obtain a generating functional for in-out correlators. We define a notion of scattering amplitudes on causal sets with noninteracting past and future regions and verify that they are given by 𝑆-matrix elements (matrix elements of the time-evolution operator). We describe how these formal developments can be implemented to compute early Universe observables under the assumption that spacetime is fundamentally discrete.
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Journal articlede Rham C, Giblin JT, Tolley AJ, 2024,
Scalar radiation with a quartic Galileon
, PHYSICAL REVIEW D, Vol: 109, ISSN: 2470-0010 -
Journal articleAlday LF, Chester SM, Dorigoni D, et al., 2024,
Relations between integrated correlators in <i>N</i>=4 supersymmetric Yang-Mills theory
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleColas T, de Rham C, Kaplanek G, 2024,
Decoherence out of fire: purity loss in expanding and contracting universes
, JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, ISSN: 1475-7516 -
Journal articleGenolini PB, Gauntlett JP, Jiao Y, et al., 2024,
Localization and attraction
, The Journal of High Energy Physics, Vol: 2024, ISSN: 1029-8479We use equivariant localization to construct of-shell entropy functions for supersymmetric black holes in N = 2, D = 4 gauged supergravity coupled to matter. This allowsone to compute the black hole entropy without solving the supergravity equations of motionand provides a novel generalization of the attractor mechanism. We consider magneticallycharged black holes in AdS4 which have an AdS2 × M2 near horizon geometry, where M2 isa sphere or a spindle, and we also obtain entropy functions for ungauged supergravity as asimple corollary. We derive analogous results for black strings and rings in D = 5 supergravitywhich have an AdS3 × M2 near horizon geometry, and in this setting we derive an of-shellexpression for the central charge of the dual N = (0, 2), d = 2 SCFT.
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Journal articleLehners J-L, Stelle KS, 2024,
Higher-order gravity, finite action, and a safe beginning for the universe
, European Physical Journal Plus, Vol: 139, ISSN: 2190-5444General relativity allows for inhomogeneous and anisotropic universes with finite action. By contrast, in quadratic gravity such solutions obtain infinite action and are thus eliminated. What remains are homogeneous and isotropic solutions undergoing accelerated expansion, thereby automatically inducing an early inflationary phase. In this manner, semi-classical consistency may explain some of the basic, coarse-grained features of the early universe. This includes suitable initial conditions for the second law of thermodynamics, in the spirit of the Weyl curvature hypothesis. We note that quadratic gravity is a renormalisable theory and may admit an asymptotically safe regime at high energies, rendering the theory trustworthy to high energies. We also comment on theories containing curvature terms up to infinite derivative order, and on the contrast with no-boundary initial conditions.
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Journal articleMentasti G, Contaldi CR, 2024,
Observing gravitational waves with solar system astrometry
, Journal of Cosmology and Astroparticle Physics, Vol: 2024, ISSN: 1475-7516The subtle influence of gravitational waves on the apparent positioning of celestial bodies offers novel observational windows [1,2,3,4]. We calculate the expected astrometric signal induced by an isotropic Stochastic Gravitational Wave Background (SGWB) in the short distance limit. Our focus is on the resultant proper motion of Solar System objects, a signal on the same time scales addressed by Pulsar Timing Arrays (PTA). We derive the corresponding astrometric deflection patterns, finding that they manifest as distinctive dipole and quadrupole correlations or, in some cases, may not be present. Our analysis encompasses both Einsteinian and non-Einsteinian polarisations. We estimate the upper limits for the amplitude of SGWBs that could be obtained by tracking the proper motions of large numbers of solar system objects such as asteroids. We find that for SGWBs with negative spectral indices, such as that generated by Super Massive Black Hole Binaries (SMBHB), the constraints from these observations could rival those from PTAs. With the Gaia satellite and the Vera C. Rubin Observatory poised to track an extensive sample of asteroids — ranging from Script O(105) to Script O(106), we highlight the significant future potential for similar surveys to contribute to our understanding of the SGWB.
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Journal articleGhoderao PS, Rajantie A, 2024,
Curvature perturbations from preheating with scale dependence
, JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, ISSN: 1475-7516 -
Journal articleFigueroa DG, Pieroni M, Ricciardone A, et al., 2024,
Cosmological Background Interpretation of Pulsar Timing Array Data
, PHYSICAL REVIEW LETTERS, Vol: 132, ISSN: 0031-9007 -
Journal articleCarrillo González M, 2024,
Bounds on EFT’s in an expanding universe
, Physical Review D: Particles, Fields, Gravitation and Cosmology, Vol: 109, ISSN: 1550-2368We find bounds on the Wilson coefficients of effective field theories (EFTs) living in a universe undergoing expansion by requiring that its modes do not propagate further than a minimally coupled photon by a resolvable amount. To do so, we compute the spatial shift suffered by the EFT modes at a fixed time slice within the WKB approximation and the regime of validity of the EFT. We analyze the bounds arising on shift-symmetric scalars and curved space generalizations of Galileons.
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Journal articleHull CM, 2024,
Covariant action for self-dual <i>p</i>-form gauge fields in general spacetimes
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
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