Related papers: Constraining spatial variations of the fine-struct…
We critically assess recent claims suggesting that upper limits on the time variation of the fine-structure constant tightly constrain the coupling of a dark energy scalar field to the electromagnetic sector, and, indirectly, the violation…
Recent astrophysical observations of quasar absorption systems indicate that the fine structure constant $\alpha$ and the proton-electron mass ratio $\mu$ may have evolved through the history of the universe. Motivated by these…
We present observational constraints on a scalar-tensor gravity theory by $\chi^2$ test for CMB anisotropy spectrum. We compare the WMAP temperature power spectrum with the harmonic attractor model, in which the scalar field has its…
We use astrophysical data to shed light on fundamental physics by constraining parametrized theoretical cosmological and gravitational models. Gravitational parameters are those constants that parametrize possible departures from Einstein's…
We review the observational information on the constancy of the fine structure constant alpha. We find that small improvements on the measurement of ^{187}Re lifetime can provide significant progress in exploring the range of variability…
Inspired by recent claims for a varying fine structure constant, alpha, we investigate the effect of ``promoting coupling constants to variables'' upon various parameters of the standard model. We first consider a toy model: Proca's theory…
We study the cosmological constraints of the time variation of the electron mass $m_e$ and the fine-structure constant $\alpha$, using data of cosmic microwave background, supernovae light curve and baryon acoustic oscillation (BAO) data…
A stability analysis of a spherically symmetric star in scalar-tensor theories of gravity is given in terms of the frequencies of quasi-normal modes. The scalar-tensor theories have a scalar field which is related to gravitation. There is…
Verification of theoretical predictions of an oscillating behavior of the fine-structure constant, alpha, with cosmic time requires high precision measurements at individual redshifts, while in earlier studies the mean Delta alpha/alpha…
Noncommutative spectral geometry offers a purely geometric explanation for the standard model of strong and electroweak interactions, including a geometric explanation for the origin of the Higgs field. Within this framework, the…
We present a summary of recent constraints on the value of the fine-structure constant at the epoch of decoupling from the recent observations made by the Wilkinson Microwave Anisotropy Probe (WMAP) satellite. Within the set of models…
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…
We discuss the effects of finite sky coverage and the uncertainty in extracting information about the power spectrum from experiments on small angular scales. In general the cosmic variance is enhanced by a factor of $4\pi/A$, where $A$ is…
In this work we investigate the utility of using SNe Ia observations in constraining the cosmological parameters in BSBM theory where a scalar field is responsible for both fine structure constant variation and late time universe…
We investigate the stability and fluctuations of a soft wall model that has an asymptotically AdS metric and a scalar field that has an asymptotically power-law dependence in the conformal coordinate. By imposing UV boundary conditions, the…
Empirical diagnosis of stability has received considerable attention, mostly focused on variance metrics for early warning signals of abrupt system change. Despite this, the theoretical foundation and application has been limited to…
We consider the application of the Multiple Point Criticality Principle to the Standard Model and its extension to the anti-grand gauge group $SMG^3 \otimes U(1)_f$ at the Planck scale. In particular we discuss the predictions for the fine…
We study the predictions of anomalous inflationary models on the abundance of structures in large scale structure observations. The anomalous features encoded in primordial curvature perturbation power spectrum are (a): localized feature in…
Within the context of mass-varying neutrinos, we construct a cosmological model that has a phase transition in the electromagnetic fine structure constant \alpha at a redshift of 0.5. The model accommodates hints of a time variable \alpha…
Motivated by reported claims of the measurements of a variation of the fine structure constant $\alpha$ we consider a theory where the electric charge, and consequently $\alpha$, is not a constant but depends on the Ricci scalar $R$. %We…