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The high resolution spectrograph ESPRESSO on the VLT allows measurements of fundamental constants at unprecedented precision and hence enables tests for spacetime variations predicted by some theories. In a series of recent papers, we…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-08 Chung-Chi Lee , John K. Webb , Robert F. Carswell , Vladimir A. Dzuba , Victor V. Flambaum , Dinko Milaković

We perform a Fisher analysis to estimate the expected constraints on the Epoch of Reionization (EoR) model parameters (i.e., minimum virial temperature, the ionizing efficiency and the mean free path of ionizing photons) taking into account…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-04 Hayato Shimabukuro , Shintaro Yoshiura , Keitaro Takahashi , Shuichiro Yokoyama , Kiyotomo Ichiki

Fourier methods are fundamental tools to analyze random fields. Statistical structures of homogeneous Gaussian random fields are completely characterized by the power spectrum. In non-Gaussian random fields, polyspectra, higher-order…

Astrophysics · Physics 2009-11-11 Takahiko Matsubara

The Multi-frequency Angular Power Spectrum (MAPS) is an alternative to spherically-averaged power spectra, and computes local fluctuations in the angular power spectrum without need for line-of-sight spectral transform. To test different…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-19 Cathryn M. Trott , Rajesh Mondal , Garrelt Mellema , Steven G. Murray , Bradley Greig , Jack L. B. Line , Nichole Barry , Miguel F. Morales

We present here an augmented space recursive technique in the k-representation which include diagonal, off-diagonal and the environmental disorder explicitly : an analytic, translationally invariant, multiple scattering theory for phonons…

Materials Science · Physics 2013-12-25 Aftab Alam , Abhijit Mookerjee

Bayesian hierarchical models can provide efficient algorithms for finding sparse solutions to ill-posed inverse problems. The models typically comprise a conditionally Gaussian prior model for the unknown which is augmented by a generalized…

Numerical Analysis · Mathematics 2025-01-09 Jonathan Lindbloom , Jan Glaubitz , Anne Gelb

We present $\mathcal{O}(N^2)$ estimators for the small-scale power spectrum and bispectrum in cosmological simulations. In combination with traditional methods, these allow spectra to be efficiently computed across a vast range of scales,…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-21 Oliver H. E. Philcox

In continuation of our perusal of the studies on transverse momentum spectra for the main varieties of secondaries from a consistent and comprehensive phenomenological approach, we propose to take up here -- after a successful completion of…

High Energy Physics - Phenomenology · Physics 2009-11-10 Bhaskar De , S. Bhattacharyya

Improved performance in higher-order spectral density estimation is achieved using a general class of infinite-order kernels. These estimates are asymptotically less biased but with the same order of variance as compared to the classical…

Statistics Theory · Mathematics 2007-06-13 Arthur Berg , Dimitris Politis

The Ly$\alpha$ forest, a series of HI absorption lines in the quasar spectra, is a powerful tool for probing the large-scale structure of the intergalactic medium. Its three-dimensional (3D) correlation and cross-correlations with quasars…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-23 Koichiro Nakashima , Atsushi J. Nishizawa , Kentaro Nagamine , Yuri Oku , Ikkoh Shimizu

The turnover at the peak of the Fourier matter power spectrum encodes a fundamental signature of matter-radiation equality in the early Universe. This delivers a potential standard ruler, independent of baryon acoustic oscillations and…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-10 Yolanda Dube , Bikash R. Dinda , Sheean Jolicoeur , Roy Maartens

Foregrounds with polarization states that are not smooth functions of frequency present a challenge to HI Epoch of Reionization (EoR) power spectrum measurements if they are not cleanly separated from the desired Stokes I signal. The…

Instrumentation and Methods for Astrophysics · Physics 2018-12-26 Zachary E. Martinot , James E. Aguirre , Saul A. Kohn , Immanuel Q. Washington

We present a novel approach for the inverse problem in electrical impedance tomography based on regularized quadratic regression. Our contribution introduces a new formulation for the forward model in the form of a nonlinear integral…

Geophysics · Physics 2012-05-29 Nick Polydorides , Alireza Aghasi , Eric L. Miller

We present the method of complementary ensemble empirical mode decomposition (CEEMD) and Hilbert-Huang transform (HHT) for analyzing nonstationary financial time series. This noise-assisted approach decomposes any time series into a number…

Computational Finance · Quantitative Finance 2021-05-25 Tim Leung , Theodore Zhao

Recent developments in machine learning and signal processing have resulted in many new techniques that are able to effectively capture the intrinsic yet complex properties of hyperspectral imagery. Tasks ranging from anomaly detection to…

Computer Vision and Pattern Recognition · Computer Science 2020-11-24 Ilya Kavalerov , Weilin Li , Wojciech Czaja , Rama Chellappa

A deformed dielectric microcavity is used as an experimental platform for the analysis of the statistics of chaotic resonances, in the perspective of testing fractal Weyl laws at optical frequencies. In order to surmount the difficulties…

Chaotic Dynamics · Physics 2017-07-26 Domenico Lippolis , Li Wang , Yun-Feng Xiao

The Fractional Fourier Transform (FrFT) has widespread applications in areas like signal analysis, Fourier optics, diffraction theory, etc. The Holomorphic Fractional Fourier Transform (HFrFT) proposed in the present paper may be used in…

Mathematical Physics · Physics 2019-05-13 William D. Kirwin , José Mourão , João P. Nunes , Thomas Thiemann

We introduce a physically-motivated model of the matter power spectrum, based on the halo model and perturbation theory. This model achieves 1\% accuracy on all $k-$scales between $k=0.02h\,\mathrm{Mpc}^{-1}$ to $k=1h\,\mathrm{Mpc}^{-1}$.…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-01 Oliver H. E. Philcox , David N. Spergel , Francisco Villaescusa-Navarro

Accurate spectral analysis of high-energy astrophysical sources often relies on comparing observed data to incident spectral models convolved with the instrument response. However, for Gamma-Ray Bursts and other high-energy transient events…

With extensive variational simulations, dissipative quantum phase transitions in the sub-Ohmic spin-boson model are numerically studied in a dense limit of environmental modes. By employing a generalized trial wave function composed of…

Statistical Mechanics · Physics 2023-09-06 Yulong Shen , Nengji Zhou