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We consider the classical stochastic fluctuations of spacetime geometry induced by quantum fluctuations of massless non-conformal matter fields in the Early Universe. To this end, we supplement the stress-energy tensor of these fields with…

General Relativity and Quantum Cosmology · Physics 2008-11-26 E. Calzetta , A. Campos , E. Verdaguer

We study the peak height distribution of certain non-stationary Gaussian random fields. The explicit peak height distribution of smooth, non-stationary Gaussian processes in 1D with general covariance is derived. The formula is determined…

Methodology · Statistics 2025-02-19 Yu Zhao , Dan Cheng , Samuel Davenport , Armin Schwartzman

Gaussian random field on general ultrametric space is introduced as a solution of pseudodifferential stochastic equation. Covariation of the introduced random field is computed with the help of wavelet analysis on ultrametric spaces. Notion…

Probability · Mathematics 2011-05-10 A. Yu. Khrennikov , S. V. Kozyrev

The statistically independent Karhunen-Loeve modes of refractive indices with isotropic Kolmogorov spectrum of the covariance are calculated in a sphere of given radius, rendered as series of 3D Zernike functions. Many of the symmetry…

Astrophysics · Physics 2009-02-19 Richard J. Mathar

We study the stochastic heat equation driven by an additive infinite dimensional fractional Brownian noise on the unit sphere $\mathbb{S}^{2}$. The existence and uniqueness of its solution in certain Sobolev space is investigated and sample…

Probability · Mathematics 2018-07-17 Xiaohong Lan , Yimin Xiao

This paper addresses the direct and inverse source problems for the stochastic acoustic, biharmonic, electromagnetic, and elastic wave equations in a unified framework. The driven source is assumed to be a centered generalized microlocally…

Analysis of PDEs · Mathematics 2021-12-28 Jianliang Li , Peijun Li , Xu Wang

We present a general method for Bayesian inference of the underlying covariance structure of random fields on a sphere. We employ the Bipolar Spherical Harmonic (BipoSH) representation of general covariance structure on the sphere. We…

Cosmology and Nongalactic Astrophysics · Physics 2015-11-04 Santanu Das , Benjamin D. Wandelt , Tarun Souradeep

We prove Central Limit Theorems and Stein-like bounds for the asymptotic behaviour of nonlinear functionals of spherical Gaussian eigenfunctions. Our investigation combine asymptotic analysis of higher order moments for Legendre polynomials…

Mathematical Physics · Physics 2015-06-11 Domenico Marinucci , Igor Wigman

We are concerned with the fast simulation of random fields on closed surfaces in $\mathbb{R}^3$ which are generated by the (Whittle-) Mat\'ern class of covariance functions. To this end, we solve the underlying fractional stochastic partial…

Numerical Analysis · Mathematics 2026-05-26 Helmut Harbrecht , Florian Sonderegger , Remo von Rickenbach

Using a method of eigenfunction expansion, a stochastic equation is developed for the generalized Schr{\"o}dinger equation with random fluctuations. The wave field $ {\psi} $ is expanded in terms of eigenfunctions: $ {\psi} = \sum_{n} a_{n}…

Statistical Mechanics · Physics 2015-06-08 Satoshi Tsuchida , Hiroshi Kuratsuji

The spatial averaging used for the splitting of the local scale factor on the homogeneous background and small inhomogeneous perturbation leads to a non-local relationship between locally and globally defined comoving curvature…

General Relativity and Quantum Cosmology · Physics 2013-10-25 N. A. Koshelev

We study isotropic Gaussian random fields on the high-dimensional sphere with an added deterministic linear term, also known as mixed p-spin Hamiltonians with external field. We prove that if the external field is sufficiently strong, then…

Probability · Mathematics 2022-01-05 David Belius , Jiří Černý , Shuta Nakajima , Marius Schmidt

All prior applications of Diffusing-Wave Spectroscopy (DWS) to aqueous foams rely upon the assumption that the electric field of the detected light is a Gaussian random variable and that, hence, the Siegert relation applies. Here we test…

Soft Condensed Matter · Physics 2009-11-11 A. S. Gittings , D. J. Durian

Random fields are commonly used for modeling of spatially (or timely) dependent stochastic processes. In this study, we provide a characterization of the intrinsic complexity of a random field in terms of its second order statistics, e.g.,…

Statistics Theory · Mathematics 2018-05-07 Jennifer Bryson , Hongkai Zhao , Yimin Zhong

We show that the anisotropies of the astrophysical stochastic gravitational wave background in the mHz band have a strong dependence on the modelling of galactic and sub-galactic physics. We explore a wide range of self-consistent…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-08 Giulia Cusin , Irina Dvorkin , Cyril Pitrou , Jean-Philippe Uzan

It has been observed that an interesting class of non-Gaussian stationary processes is obtained when in the harmonics of a signal with random amplitudes and phases, frequencies can also vary randomly. In the resulting models, the…

Probability · Mathematics 2019-11-19 Anastassia Baxevani , Krzysztof Podgórski

Semiclassical Einstein-Langevin equations for arbitrary small metric perturbations conformally coupled to a massless quantum scalar field in a spatially flat cosmological background are derived. Use is made of the fact that for this problem…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Antonio Campos , Enric Verdaguer

In the present article the classical problem of electromagnetic scattering by a single homogeneous sphere is revisited. Main focus is the study of the scattering behavior as a function of the material contrast and the size parameters for…

Classical Physics · Physics 2017-06-28 Dimitrios C. Tzarouchis , Pasi Ylä-Oijala , Ari Sihvola

Primordial fluctuations in the cosmic density are usually assumed to take the form of a Gaussian random field that evolves under the action of gravitational instability. In the early stages, while they have low amplitude, the fluctuations…

Astrophysics · Physics 2009-11-07 Peter Watts , Peter Coles

This paper presents a general form of the covariance matrix structure for a vector random field that is axially symmetric and mean square continuous on the sphere and provides a series representation for a longitudinally reversible one. The…

Probability · Mathematics 2016-06-14 Chunsheng Ma
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