Related papers: Temporal variation of coupling constants and nucle…
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…
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…
We compute primordial light-element abundances for cases with fine structure constant alpha different from the present value, including many sources of alpha dependence neglected in previous calculations. Specifically, we consider…
We report a robust constrain on the possible variation of fine-structure constant, alpha = e^2/(hbar*c), obtained using O III 4959,5007, nebular emission lines from QSOs. We find Delta-alpha/alpha=-(2.1 +/- 1.6) x 10^(-5) based on a well…
Testing possible variations in fundamental constants of nature is a crucial endeavor in observational cosmology. This paper investigates potential cosmological variations in the fine structure constant ($\alpha$) through a non-parametric…
In this thesis, we focus on the study of the variation of the electron mass $m_e$, and the fine structure constant $\alpha$, at different cosmic times. We analyze the details of the recombination physics, including helium recombination, in…
We discuss experiments and observations aimed at testing the possible space-time variability of fundamental physical constants, predicted by the modern theory. Specifically, we consider two of the dimensionless physical parameters which are…
This thesis describes a detailed investigation of the effects of matter inhomogeneities on the cosmological evolution of the fine structure constant using the Bekenstein-Sandvik-Barrow-Magueijo (BSBM) theory. We briefly review the…
A general model for the cosmological evolution of the fine structure constant \alpha driven by a typical Quintessence scenario is presented. We consider a coupling between the Quintessence scalar \phi and the electromagnetic kinetic term…
There is a growing interest in astrophysical tests of the stability of dimensionless fundamental couplings, such as the fine-structure constant $\alpha$, as an optimal probe of new physics. The imminent arrival of the ESPRESSO spectrograph…
We consider several transitions between narrow lines that have an enhanced sensitivity to a possible variation of the fine structure constant, alpha. This enhancement may allow a search to be performed with an effective suppression of the…
We studied the role of fundamental constants in an updated recombination scenario, focusing on the time variation of the fine structure constant \alpha and the electron mass m_e in the early Universe. Using CMB data including WMAP 5-yr…
The formation of the cosmic microwave background radiation (CMBR) provides a very powerful probe of the early universe at the epoch of recombination. Specifically, it is possible to constrain the variation of fundamental physical constants…
By integration of generalized BSBM and Brans-Dicke cosmological models, in this article, we investigate the theoretical framework of fine structure constant variation and current cosmic acceleration. We first develop a mathematical…
A new method for examining the possible space-time variation of the fine structure constant ($\alpha$) is proposed. The technique uses a relatively simple measurement with an optical resonator to compare atom-stabilized optical frequency…
We review astrophysical, cosmological and terrestrial evidence for and against the constancy of fundamental parameters of particle physics, and discuss theoretical issues of unification and scalar-mediated forces, finding that the current…
Within the framework of a model universe with time variable space dimension (TVSD) model, known as decrumpling or TVSD model, we study the time variation of the gravitational coupling constant. Using observational bounds on the present time…
We argue that the accuracy by which the isochron parameters of the decay $^{187}{\rm Re}\to ^{187}{\rm Os}$ are determined by dating iron meteorites may not directly constrain the possible time-dependence of the decay rate and hence of the…
The success of primordial nucleosynthesis as a cornerstone of the hot Big Bang model has been limited by the long-standing lithium problem. Recent work presented a self-consistent perturbative analysis of the effects of variations in…
The possible variation of the fine structure constant may be due to the non-minimal coupling of the electromagnetic field to a light scalar field which can be the candidate of dark energy. Its dynamical nature renders the fine structure…