English
Related papers

Related papers: A Time-Varying Fine Structure Constant from Natura…

200 papers

Theoretical background of our proposed relation between the accelerating universe and the time-variability of the fine-structure constant is discussed, based on the scalar-tensor theory, with emphases on the intuitive aspects of underlying…

Cosmology and Nongalactic Astrophysics · Physics 2009-10-28 Yasunori Fujii

We study the evolution of perturbations during the domination and decay of a massive particle species whose mass and decay rate are allowed to depend on the expectation value of a light scalar field. We specialize in the case where the…

Astrophysics · Physics 2009-11-10 Filippo Vernizzi

I briefly present some current theoretical motivations for time or space variations of the fundamental constants of nature and review current key observational results. I focus on the fine-structure constant, and particularly on…

Astrophysics · Physics 2007-05-23 C. J. A. P. Martins

Astrophysical observations suggest that the fine structure constant (alpha) may (or may not) be evolving over the cosmological time scale. This raises a much debated question: is alpha variation due to the variation of the speed of light…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. Yu. Ignatiev , B. J. Carson

We propose a cosmological scenario based on the assumption that the Standard Model possesses a large number of copies. It is demonstrated that baryons in the hidden copies of the standard model can naturally account for the dark matter. The…

High Energy Physics - Theory · Physics 2009-08-11 Gia Dvali , Ignacy Sawicki , Alexander Vikman

There has been some evidence that the fine structure "constant" $\alpha$ may vary with time. We point out that this variation can be described by a scalar field in some supergravity theory in our toy model, for instance, the N=8 extended…

High Energy Physics - Phenomenology · Physics 2009-11-10 Qing-Guo Huang , Miao Li

The detection of dark matter is a challenging problem in modern physics. The ultralight scalar and axion dark matter could induce the oscillation of the nuclear charge radii and then oscillate the atomic transition frequency by interacting…

High Energy Physics - Phenomenology · Physics 2024-01-31 Wei Zhao , Hui Liu , Xitong Mei

One of the few firm predictions of string theory is the existence of a massless scalar field coupled to gravity, the dilaton. In its presence, the value of the fundamental constants of the universe, such as the fine-structure constant, will…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-03 Léo Vacher , Nils Schöneberg , J. D. F. Dias , C. J. A. P. Martins , Francisco Pimenta

Astrophysical indications that the fine structure constant is time dependent are discussed in the framework of grand unification models. A variation of the electromagnetic coupling constant could either be generated by a corresponding time…

High Energy Physics - Phenomenology · Physics 2007-05-23 X. Calmet , H. Fritzsch

Recent astrophysical observations indicate that the proton-electron mass ratio and the fine structure constant have gone through nontrivial time evolution. We discuss their time variation in the context of a dilaton runaway scenario with…

High Energy Physics - Phenomenology · Physics 2008-11-26 Takeshi Chiba , Tatsuo Kobayashi , Masahide Yamaguchi , Jun'ichi Yokoyama

We discuss present and future cosmological constraints on variations of the fine structure constant $\alpha$ induced by an early dark energy component having the simplest allowed (linear) coupling to electromagnetism. We find that current…

Cosmology and Nongalactic Astrophysics · Physics 2011-08-08 Erminia Calabrese , Eloisa Menegoni , C. J. A. P. Martins , Alessandro Melchiorri , Graca Rocha

Ultra-light scalar fields may explain the nature of the dark matter in our universe. If such scalars couple quadratically to particles of the Standard Model the scalar acquires an effective mass which depends on the local matter energy…

High Energy Physics - Phenomenology · Physics 2026-03-04 Clare Burrage , Angus Macdonald , Michael P. Ross , Gray Rybka , Elisa Todarello

We discuss the fundamemtal constants in the Standard Model of particle physics, in particular possible changes of these constants on the cosmological time scale. The Grand Unification of the observed strong, electromagnetic and weak…

High Energy Physics - Phenomenology · Physics 2016-10-25 Harald Fritzsch

We use recent astrophysical and local tests of the stability of the fine-structure constant, $\alpha$, to constrain a particular phenomenological but physically motivated class of models in which the dark energy equation of state can…

Cosmology and Nongalactic Astrophysics · Physics 2019-03-12 C. J. A. P. Martins , M. Prat Colomer

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

A dark photon may kinetically mix with the ordinary photon, inducing oscillations with observable imprints on cosmology. Oscillations are resonantly enhanced if the dark photon mass equals the ordinary photon plasma mass, which tracks the…

Cosmology and Nongalactic Astrophysics · Physics 2020-12-11 Andrea Caputo , Hongwan Liu , Siddharth Mishra-Sharma , Joshua T. Ruderman

In the present work, we consider the cosmological constant model $\Lambda\propto\alpha^{-6}$, which is well motivated from three independent approaches. As is well known, the hint of varying fine structure constant $\alpha$ was found in…

General Relativity and Quantum Cosmology · Physics 2017-01-10 Hao Wei , Xiao-Bo Zou , Hong-Yu Li , Dong-Ze Xue

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

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

It is known that a coherently oscillating axion field is a candidate of the dark matter. In the presence of the oscillating axion, the photon can be resonantly produced through the parametric amplification. In the universe, there also exist…

High Energy Physics - Phenomenology · Physics 2020-02-12 Emi Masaki , Arata Aoki , Jiro Soda
‹ Prev 1 4 5 6 7 8 10 Next ›