English
Related papers

Related papers: Spatial and temporal variations of fundamental con…

200 papers

We investigate constraints on scalar dark matter (DM) by analyzing the Lyman-alpha forest, which probes structure formation at medium and small scales, and also by studying its cosmological consequences at high and low redshift. For scalar…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-18 Takeshi Kobayashi , Riccardo Murgia , Andrea De Simone , Vid Iršič , Matteo Viel

We present updated observational constraints on the spatially flat $\phi$CDM model, where dark energy is described by a minimally coupled scalar field $\phi$ with an inverse power-law potential $V=V_0 \phi^{-\alpha}$. Using Planck 2018 CMB…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-01 Chan-Gyung Park , Bharat Ratra

In this work we analyze the spatial and time variation of the fine structure constant (\alpha) upon the theoretical framework developed by Bekenstein [1]. We have computed the field \psi related to \alpha at first order of the weak field…

High Energy Physics - Theory · Physics 2018-02-26 Lucila Kraiselburd , Florencia L. Castillo , Mercedes E. Mosquera , Héctor Vucetich

We demonstrate that massive fields, such as dark matter, can directly produce a cosmological evolution of the fundamental constants of Nature. We show that a scalar or pseudoscalar (axion-like) dark matter field $\phi$, which forms a…

Cosmology and Nongalactic Astrophysics · Physics 2015-11-18 Y. V. Stadnik , V. V. Flambaum

Laboratory and astrophysical tests of ''constant variation'' have so far concentrated on the dimensionless fine-structure constant $\alpha$ and on the electron or quark mass ratios $X_{e,q}=m_{e,q}/\Lambda_{\text{QCD}}$, treating the QCD…

High Energy Physics - Phenomenology · Physics 2025-11-20 V. V. Flambaum , A. J. Mansour

In this paper we study the impact of cosmic variance and observational uncertainties in constraining the mass and occupation fraction, $f_{\rm occ}$, of dark matter halos hosting Ly-$\alpha$ Emitting Galaxies (LAEs) at high redshift. To…

Astrophysics of Galaxies · Physics 2016-08-31 Julian E. Mejia-Restrepo , Jaime E. Forero-Romero

A molecular hydrogen absorber at a lookback time of 12.4 billion years, corresponding to 10$\%$ of the age of the universe today, is analyzed to put a constraint on a varying proton--electron mass ratio, $\mu$. A high resolution spectrum of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-23 J. Bagdonaite , W. Ubachs , M. T. Murphy , J. B. Whitmore

We generalize the Bekenstein-Sandvik-Barrow-Magueijo (BSBM) model for the variation of the fine structure 'constant', $\alpha ,$ to include an exponential or inverse power-law self-potential for the scalar field $% \phi $ which drives the…

General Relativity and Quantum Cosmology · Physics 2012-07-04 John D. Barrow , Baojiu Li

Absorption line systems detected in quasar spectra can be used to compare the value of the fine-structure constant, {\alpha}, measured today on Earth with its value in distant galaxies. In recent years, some evidence has emerged of small…

Dilatons (and moduli) couple to the masses and coupling constants of ordinary matter, and these quantities are fixed by the local value of the dilaton field. If, in addition, the dilaton with mass $m_\phi$ contributes to the cosmic dark…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-20 Louis Hamaide , Hendrik Müller , David J. E. Marsh

We review some of the history and properties of theories for the variation of the gravitation and fine structure 'constants'. We highlight some general features of the cosmological models that exist in these theories with reference to…

General Relativity and Quantum Cosmology · Physics 2014-11-17 John D. Barrow

We constrain two non-flat time-evolving dark energy cosmological models by using Hubble parameter data, Type Ia supernova apparent magnitude measurements, and baryonic acoustic oscillation peak length scale observations. The inclusion of…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-22 Omer Farooq , Data Mania , Bharat Ratra

A new method based on large-scale structure observations is proposed to probe a possible time variation of the fine-structure constant ($\alpha$). Our analyses are based on time-delay of Strong Gravitational Lensing and Type Ia Supernovae…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-09 L. R. Colaço , J. E. Gonzalez , R. F. L. Holanda

Molecular transitions recently discovered at redshift z_abs=2.059 toward the bright background quasar J2123-0050 are analysed to limit cosmological variation in the proton-to-electron mass ratio, mu=m_p/m_e. Observed with the Keck…

We investigate a link between the running of the fine structure constant $\alpha$ and a time evolving scalar dark energy field. Employing a versatile parameterization for the equation of state, we exhaustively cover the space of dark energy…

Astrophysics · Physics 2009-11-10 Michael Doran

Theories unifying gravity and other interactions suggest the possibility of spatial and temporal variation of physical ``constants'' in the Universe. Detection of high redshift absorption systems intersecting the sight lines towards distant…

Astrophysics · Physics 2009-08-18 V. A. Dzuba , V. V. Flambaum , M. T. Murphy , J. K. Webb

The gravitational field produced by a domain wall acts as a medium with spacetime-dependent permittivity \epsilon. Therefore, the fine structure constant \alpha = e^2/4 \pi \epsilon will be a time-dependent function at fixed position. The…

Astrophysics · Physics 2008-11-26 L. Campanelli , P. Cea , L. Tedesco

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

Spectra of molecular hydrogen (H$_2$) are employed to search for a possible proton-to-electron mass ratio ($\mu$) dependence on gravity. The Lyman transitions of H$_2$, observed with the Hubble Space Telescope towards white dwarf stars that…

General Relativity and Quantum Cosmology · Physics 2014-10-02 Julija Bagdonaite , Edcel J. Salumbides , Simon P. Preval , Martin A. Barstow , John D. Barrow , Michael T. Murphy , Wim Ubachs

The anomalous magnetic moment of the muon is one of the most precisely measured quantities in physics. Its experimental value exhibits a $4.2 \, \sigma$ discrepancy $\delta a_\mu=(251 \pm 59) \times 10^{-11}$ with its theoretical value…

General Physics · Physics 2021-04-20 Laurent Nottale
‹ Prev 1 8 9 10 Next ›