English
Related papers

Related papers: Revisiting VLT/UVES constraints on a varying fine-…

200 papers

A new and automated method is presented for the analysis of high-resolution absorption spectra. Three established numerical methods are unified into one "artificial intelligence" process: a genetic algorithm (GVPFIT); non-linear…

Instrumentation and Methods for Astrophysics · Physics 2017-02-01 Matthew B. Bainbridge , John K. Webb

As is well known, a varying effective gravitational "constant" is one of the common features of most modified gravity theories. Of course, as a modified gravity theory, $f(T)$ theory is not an exception. Noting that the observational…

General Relativity and Quantum Cosmology · Physics 2012-08-31 Hao Wei , Hao-Yu Qi , Xiao-Peng Ma

In the present work the part of the quasar UV-optical bump within the wavelength range 1210-1450\AA\ was studied with the help of composite spectra compiled from the samples of SDSS DR7 spectra with the similar spectral index…

Cosmology and Nongalactic Astrophysics · Physics 2012-11-07 O. Torbaniuk , G. Ivashchenko , O. Sergijenko

The minimum achievable statistical uncertainty in the estimation of physical parameters is determined by the quantum Fisher information. Its computation for noisy systems is still a challenging problem. Using a variational approach, we…

Quantum Physics · Physics 2012-11-21 B. M. Escher , L. Davidovich , N. Zagury , R. L. de Matos Filho

Cosmography is a model-independent phenomenological approach to observational cosmology, relying on Taylor series expansions of physical quantities as a function of the cosmological redshift or other analogous variables. A recent work…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-27 C. J. A. P. Martins

Some attempts of easing the critical Hubble tension present in modern cosmology have resorted to using variations of fundamental constants, such as the fine-structure constant, at the time of recombination. In this article we demonstrate…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-22 Léo Vacher , Nils Schöneberg

Introducing accelerated reconstruction algorithms into clinical settings requires measures of uncertainty quantification that accurately assess the relevant uncertainty introduced by the reconstruction algorithm. Many currently deployed…

Image and Video Processing · Electrical Eng. & Systems 2025-08-12 Luca L. C. Trautmann , Peter A. Wijeratne , Itamar Ronen , Ivor J. A. Simpson

UBVR photometry of a sample of B3-VLA radio quasars, about 80 per cent complete, is used to analyse their spectral energy distribution (SED). The SEDs are generally well fitted with power-laws, with an average slope alpha=-0.39 (S_nu propto…

Astrophysics · Physics 2009-10-31 R. Carballo , J. I. González-Serrano , C. R. Benn , S. F. Sánchez , M. Vigotti

The Euler-$\alpha$ equations model the averaged motion of an ideal incompressible fluid when filtering over spatial scales smaller than $\alpha$. We show that there exists $\beta>1$ such that weak solutions to the two and three dimensional…

Analysis of PDEs · Mathematics 2021-11-10 Rajendra Beekie , Matthew Novack

Astrophysical tests of the stability of Nature's fundamental couplings are a key probe of the standard paradigms in fundamental physics and cosmology. In this report we discuss updated constraints on the stability of the fine-structure…

High Energy Physics - Phenomenology · Physics 2015-08-26 S. M. João , C. J. A. P. Martins , I. S. A. B. Mota , P. M. T. Vianez

QSO absorption spectra provide an extremely useful probe of possible cosmological variation in various physical constants. Comparison of H I 21cm absorption with corresponding molecular (rotational) absorption spectra allows us to constrain…

Astrophysics · Physics 2009-08-18 M. T. Murphy , J. K. Webb , V. V. Flambaum , M. J. Drinkwater , F. Combes , T. Wiklind

Recent detections of high-redshift absorption by both atomic hydrogen and molecular gas in the radio spectra of quasars have provided a powerful tool to measure possible temporal and spatial variations of physical `constants' in the…

Astrophysics · Physics 2009-10-30 M. J. Drinkwater , J. K. Webb , J. D. Barrow , V. V. Flambaum

The differences are discussed between various next-to-leading order prescriptions for the QCD evolution of parton densities and structure functions. Their quantitative impact is understood to an accuracy of 0.02\%. The uncertainties due to…

High Energy Physics - Phenomenology · Physics 2015-06-25 J. Blümlein , S. Riemersma , W. L. van Neerven , A. Vogt

The fine structure constant, alpha, is shown to be proportional to the ratio of the quanta of electric and magnetic flux of force of the electron, and provides a new representation, which is global across all unit systems. Consequently, a…

High Energy Physics - Phenomenology · Physics 2023-03-14 Michael Edmund Tobar

We discuss how existing astrophysical measurements of various combinations of the fine-structure constant $\alpha$, the proton-to-electron mass ratio $\mu$ and the proton gyromagnetic ratio g$_{p}$ towards the radio source PKS1413+135 can…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-01 A. M. R. V. L. Monteiro , M. C. Ferreira , M. D. Julião , C. J. A. P. Martins

This paper presents the constraints on the time variation of the fine structure constant at recombination relative to its present value, Delta_alpha = (alpha_rec-alpha_0) / alpha_0, obtained from the analysis of the WMAP-3yr Cosmic…

Astrophysics · Physics 2008-11-26 Petruta Stefanescu

We introduce the Variational Holder (VH) bound as an alternative to Variational Bayes (VB) for approximate Bayesian inference. Unlike VB which typically involves maximization of a non-convex lower bound with respect to the variational…

Machine Learning · Statistics 2015-06-22 Guillaume Bouchard , Balaji Lakshminarayanan

The nature of the dark matter remains a mystery. The possibility of an unstable dark matter particle decaying to invisible daughter particles has been explored many times in the past few decades. Meanwhile, weak gravitational lensing shear…

Cosmology and Nongalactic Astrophysics · Physics 2010-12-24 Mei-Yu Wang , Andrew R. Zentner

Accurate prediction of molecular vibrational frequencies is important to identify spectroscopic signatures and reaction thermodynamics. In this work, we develop a method to quantify uncertainty associated with density functional theory…

Chemical Physics · Physics 2019-03-13 Holden L. Parks , Alan. J. H. McGaughey , Venkatasubramanian Viswanathan

Based on superfluid behavior of a (boson) dark matter as the light itself, a unified model for dark matter and quintessence is proposed. Inspired by (O'Dell et al. 2000) which in an exciting study showed that particular configurations of…

General Physics · Physics 2007-05-23 Reza Dastvan
‹ Prev 1 8 9 10 Next ›