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We study several approaches for constructing a minimal model of Universe evolution by matching different stages of scale factor laws. We discuss the continuity in the transitions among the stages and the time variables involved. We develop…

General Relativity and Quantum Cosmology · Physics 2007-05-23 M. P. Infante , N. Sanchez

We propose a new approximation-technique to deal with the exact macroscopic integro-differential evolution equations of statistical systems which self-consistently accounts for dissipative effects. Concentrating on one and two point…

High Energy Physics - Phenomenology · Physics 2007-05-23 Herbert Nachbagauer

General positivity constraints linking various powers of observables in energy eigenstates can be used to sharply locate acceptable regions for the energy eigenvalues, provided that efficient recursive methods are available to calculate the…

High Energy Physics - Theory · Physics 2023-12-22 Zane Ozzello , Yannick Meurice

Monte Carlo simulation of gauge theories with a $\theta$ term is known to be extremely difficult due to the sign problem. Recently there has been major progress in solving this problem based on the idea of complexifying dynamical variables.…

High Energy Physics - Lattice · Physics 2020-05-08 Mitsuaki Hirasawa , Akira Matsumoto , Jun Nishimura , Atis Yosprakob

We introduce an approach for approximate real-time evolution of quantum systems using Tensor Renormalization Group (TRG) methods originally developed for imaginary time. We use Higher- Order TRG (HOTRG) to generate a coarse-grained time…

Quantum Physics · Physics 2024-11-11 Michael Hite , Yannick Meurice

Recently it has been questioned, notably in the context of the scalar singlet dark matter model with $m_\varphi^{ }\simeq 60$ GeV, how efficiently kinetic equilibrium is maintained if freeze-out dynamics is pushed down to low temperatures…

High Energy Physics - Phenomenology · Physics 2023-05-08 Seyong Kim , M. Laine

We show how to construct the optimum superstatistical dynamical model for a given experimentally measured time series. For this purpose we generalise the superstatistics concept and study a Langevin equation with a memory kernel whose…

Statistical Mechanics · Physics 2011-01-10 Erik Van der Straeten , Christian Beck

A computational framework that leverages data from self-consistent field theory simulations with deep learning to accelerate the exploration of parameter space for block copolymers is presented. This is a substantial two-dimensional…

Materials Science · Physics 2023-07-04 Yao Xuan , Kris T. Delaney , Hector D. Ceniceros , Glenn H. Fredrickson

We explore numerically the evolution of a collapsing spherical shell of charged, massless scalar field. We obtain an external \RN space-time, and an inner space-time that is bounded by a singularity on the Cauchy Horizon. We compare these…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Yonatan Oren , Tsvi Piran

We study the time evolution of quantum one-dimensional gapless systems evolving from initial states with a domain-wall. We generalize the path-integral imaginary time approach that together with boundary conformal field theory allows to…

Statistical Mechanics · Physics 2009-11-13 Pasquale Calabrese , Christian Hagendorf , Pierre Le Doussal

The problem of sampling a target probability distribution on a constrained domain arises in many applications including machine learning. For constrained sampling, various Langevin algorithms such as projected Langevin Monte Carlo (PLMC),…

Machine Learning · Statistics 2026-04-07 Yingli Wang , Changwei Tu , Xiaoyu Wang , Lingjiong Zhu

We discuss how the kernel convolution approach can be used to accurately approximate the spatial covariance model on a sphere using spherical distances between points. A detailed derivation of the required formulas is provided. The proposed…

Computation · Statistics 2017-01-13 Alexander Gribov , Konstantin Krivoruchko

A novel algorithm is proposed to solve the sample-based optimal transport problem. An adversarial formulation of the push-forward condition uses a test function built as a convolution between an adaptive kernel and an evolving probability…

Machine Learning · Statistics 2020-06-11 Daeyoung Kim , Esteban G. Tabak

We show by using the method of matched asymptotic expansions that a sufficient condition can be derived which determines when a local experiment will detect the cosmological variation of a scalar field which is driving the spacetime…

General Relativity and Quantum Cosmology · Physics 2008-11-26 John D. Barrow , Douglas J. Shaw

Models like support vector machines or Gaussian process regression often require positive semi-definite kernels. These kernels may be based on distance functions. While definiteness is proven for common distances and kernels, a proof for a…

Machine Learning · Computer Science 2018-07-11 Martin Zaefferer , Thomas Bartz-Beielstein , Günter Rudolph

The field-theoretic one-loop effective action in a static scalar background depending nontrivially on a single spatial coordinate is related, in the proper-time formalism, to the trace of the evolution kernel (or heat kernel) for an…

High Energy Physics - Theory · Physics 2009-11-07 Chanju Kim , O-Kab Kwon , Choonkyu Lee

Kernel approximation via nonlinear random feature maps is widely used in speeding up kernel machines. There are two main challenges for the conventional kernel approximation methods. First, before performing kernel approximation, a good…

Machine Learning · Statistics 2015-03-16 Felix X. Yu , Sanjiv Kumar , Henry Rowley , Shih-Fu Chang

We study the evolution of a quantum scalar field in a toy universe which has three stages of evolution, viz., (i) an early (inflationary) de Sitter phase (ii) radiation dominated phase and (iii) late-time (cosmological constant dominated)…

General Relativity and Quantum Cosmology · Physics 2013-12-12 Suprit Singh , Sujoy Kumar Modak , T. Padmanabhan

We study the evolution of the two scalar fields entangled via a mutual interaction in an expanding spacetime. We compute the logarithmic negativity to leading order in perturbation theory and show that for lowest order in the coupling…

Quantum Physics · Physics 2017-06-21 Helder Alexander , I. G. da Paz , Marcos Sampaio

We consider the classical time evolution of a real scalar field in 2 dimensional Minkowski space with a $\lambda \phi^4$ interaction. We compute the spatial and temporal two-point correlation functions and extract the renormalized mass of…

High Energy Physics - Lattice · Physics 2009-11-11 T. Hirayama , B. Holdom , R. Koniuk , T. Yavin