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Learning low-dimensional numerical representations from symbolic data, e.g., embedding the nodes of a graph into a geometric space, is an important concept in machine learning. While embedding into Euclidean space is common, recent…

Machine Learning · Computer Science 2024-10-10 Thomas Bläsius , Jean-Pierre von der Heydt , Maximilian Katzmann , Nikolai Maas

We generalize the vacuum-Unruh effect to arbitrary excited states in the Fock space and find that the Unruh mode at the horizon induces coherent excitation on the canonical background ensemble measured by an accelerated observer. When there…

General Relativity and Quantum Cosmology · Physics 2023-03-29 Angela Chen

Heterogeneous graphs (HGs) also known as heterogeneous information networks have become ubiquitous in real-world scenarios; therefore, HG embedding, which aims to learn representations in a lower-dimension space while preserving the…

Social and Information Networks · Computer Science 2020-12-02 Xiao Wang , Deyu Bo , Chuan Shi , Shaohua Fan , Yanfang Ye , Philip S. Yu

It is often easier to study pseudo-Riemannian manifolds by presenting them as surfaces in some ambient space. We propose an algorithm for construction of explicit isometric embeddings of pseudo-Riemannian manifolds with symmetries into an…

General Relativity and Quantum Cosmology · Physics 2023-07-04 A. A. Sheykin , M. V. Markov , S. A. Paston

We obtain universal models for several types of locally conformal symplectic manifolds via pullback or reduction. The relation with recent embedding results for locally conformal K\"ahler manifolds is discussed.

Differential Geometry · Mathematics 2011-02-24 Juan C. Marrero , David Martínez Torres , Edith Padron

In this paper, we study a free scalar field in a specific (1+1)-dimensional curved spacetime. By introducing an algebraic state that is locally Hadamard, we derive the renormalized Wightman function and explicitly calculate the covariantly…

High Energy Physics - Theory · Physics 2025-12-18 Jeongwon Ho , O-Kab Kwon , Sang-Heon Yi

We investigate a class of semi-Riemannian manifolds characterized by smooth metric signature changes with a transverse radical. This class includes spacetimes relevant to cosmological models such as the Hartle-Hawking "no boundary"…

Differential Geometry · Mathematics 2025-09-04 N. E. Rieger

This paper introduces a novel boundary integral approach of shape uncertainty quantification for the Helmholtz scattering problem in the framework of the so-called parametric method. The key idea is to construct an integration grid whose…

Computational Engineering, Finance, and Science · Computer Science 2018-11-29 Yuval Harness

In the context of the natural splitting, the standard relative dynamics can be expressed in terms of gravito-electromagnetic fields, which allow to formally introduce a gravito-magnetic Aharonov-Bohm effect. We showed elsewhere that this…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Matteo Luca Ruggiero

Temporal knowledge graphs represent temporal facts $(s,p,o,\tau)$ relating a subject $s$ and an object $o$ via a relation label $p$ at time $\tau$, where $\tau$ could be a time point or time interval. Temporal knowledge graphs may exhibit…

Artificial Intelligence · Computer Science 2023-12-27 Jiaxin Pan , Mojtaba Nayyeri , Yinan Li , Steffen Staab

We give analytic expressions for image properties of objects seen around point mass lenses embedded in a flat $\Lambda$CDM universe. An embedded lens in an otherwise homogeneous universe offers a more realistic representation of the lens's…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Ronald Kantowski , Bin Chen , Xinyu Dai

We give a pedagogical introduction to the Generalized Hydrodynamic approach to inhomogeneous quenches in integrable many-body quantum systems. We review recent applications of the theory, focusing in particular on two classes of problems:…

Statistical Mechanics · Physics 2021-11-24 Vincenzo Alba , Bruno Bertini , Maurizio Fagotti , Lorenzo Piroli , Paola Ruggiero

Complicated time-dependent curved spacetime and electric field are involved in many astrophysical situations, including the early universe, Hawking radiation, the Schwinger effect, and gravitational pair production. In this Letter, a…

General Relativity and Quantum Cosmology · Physics 2025-02-18 Orkash Amat , Nurimangul Nurmamat , Yong-Feng Huang , Cheng-Ming Li , Jin-Jun Geng , Chen-RanHu , Ze-Cheng Zou , Xiao-Fei Dong , Chen Deng , Fan Xu , Xiao-li Zhang , Chen Du

The curvature of a spacetime, either in a topological sense, or averaged over super-horizon-sized patches, is often equated with the global curvature term that appears in Friedmann's equation. In general, however, the Universe is…

Cosmology and Nongalactic Astrophysics · Physics 2021-04-21 Chi Tian , Stefano Anselmi , Matthew F. Carney , John T. Giblin , James Mertens , Glenn Starkman

We introduce a method to compute particle detector transition probability in spacetime regions of general curved spacetimes provided that the curvature is not above a maximum threshold. In particular we use this method to compare the…

Quantum Physics · Physics 2017-02-23 Aida Ahmadzadegan , Eduardo Martin-Martinez , Robert B. Mann

The search for a relation among GR, QFT and TFT is the toughest challenge of theoretical physics since Hawking's discovery. The emergence of a temperature in spacetimes with an event horizon has unveiled the existence of a fertile…

High Energy Physics - Theory · Physics 2019-11-15 Giuseppe Gaetano Luciano

Majority of the current dimensionality reduction or retrieval techniques rely on embedding the learned feature representations onto a computable metric space. Once the learned features are mapped, a distance metric aids the bridging of gaps…

Computer Vision and Pattern Recognition · Computer Science 2018-10-17 Muhammad Kamran Janjua , Shah Nawaz , Alessandro Calefati , Ignazio Gallo

We propose a fully covariant model for smeared particle detectors in quantum field theory in curved spacetimes. We show how effects related to accelerated motion of the detector and the curvature of spacetime influence the way different…

Quantum Physics · Physics 2020-06-26 Eduardo Martín-Martínez , T. Rick Perche , Bruno de S. L. Torres

We consider a microscopic model of spacetime, where spacetime is assumed to be a specific graph with Planck size quantum black holes on its vertices. As a thermodynamical system under consideration we take a certain uniformly accelerating,…

General Relativity and Quantum Cosmology · Physics 2008-10-28 Jarmo Makela

The Unruh effect has been investigated from the point of view of the quantum statistical Zubarev density operator in space with the Minkowski metric. Quantum corrections of the fourth order in acceleration to the energy-momentum tensor of…

High Energy Physics - Theory · Physics 2020-04-22 Georgy Y. Prokhorov , Oleg V. Teryaev , Valentin I. Zakharov