Related papers: Is the $\bar \theta$ parameter of QCD constant?
Newton's constant has observational effects on both the CMB power spectra and the light curves of SNIa. We use Planck data, BAO data and the SNIa measurement to constrain the varying Newton's constant $G$ during the CMB epoch and the…
According to recent astrophysical observations the large scale mean pressure of our present universe is negative suggesting a positive cosmological constant like term. This article addresses the question of whether non-perturbative effects…
We analyse the constraints obtained from new atomic clock data on the possible time variation of the fine structure `constant' and the electron-proton mass ratio and show how they are strengthened when the seasonal variation of Sun's…
The bound on the time variation of the fine structure constant ($\alpha$) driven by the dynamics of quintessence scalar field which is coupled to electromagnetism is discussed using phenomenological quintessential models constrained by SNIa…
The Hubble crisis is the discrepancy in the values of the Hubble constant inferred from diverse observations in the late and early Universe, being of the order 5$\sigma$. Instead of resolution, the conflict is getting larger with further…
Setting aside anthropic arguments, there is no reason for CP symmetry to be obeyed within the theory of quantum chromodynamics. However, no such violation of CP symmetry has ever been observed in a strongly interacting experiment. This is…
Varying fundamental constants (VFC) [e.g., the fine-structure constant, $\alpha_{\rm EM}$] can arise in numerous extended cosmologies. Through their effect on the decoupling of baryons and photons during last scattering and reionisation,…
Observations indicate that most of the universal matter are invisible and the gravitational constant $G(t)$ maybe depends on the time. A theory of the variational $G$ (VG) is explored in this paper, with naturally producing the useful dark…
A method offering an order of magnitude sensitivity gain is described for using quasar spectra to investigate possible time or space variation in the fine structure constant, alpha. Applying the technique to a sample of 30 absorption…
Several authors have recently explored the idea that physical constants such as c and G might vary over time and have formulated theories describing this variation that can address a range of cosmological problems. Such work typically…
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…
The idea that the cosmological term, Lambda, should be a time dependent quantity in cosmology is a most natural one. It is difficult to conceive an expanding universe with a strictly constant vacuum energy density, namely one that has…
We investigate the perihelion shift of the planetary motion and the bending of starlight in the Schwarzschild field modified by the presence of a $\Lambda$-term plus a conical defect. This analysis generalizes an earlier result obtained by…
Fundamental physical constants need not be constant, neither spatially nor temporally. -- This seeming simple statement has profound implications for a wide range of physical processes and interactions, and can be probed through a number of…
It is argued by Duff that only the time variation of dimensionless constants of nature is a legitimate subject of enquiry, and that dimensional constants such as c, h-bar and G... are merely human constructs whose value has no operational…
Many models of quintessence predict a time variation of the fundamental constants as well as a composition-dependent gravity like long-range force mediated by the cosmon. We present bounds for the cosmon coupling to matter and radiation…
A type of exponential correction to General Relativity gives viable modified gravity model of dark energy. The model behaves as $R-2\Lambda$ at large curvature where an effective cosmological constant appears, but it becomes zero in flat…
We analyse the constraints obtained from new atomic clock data on the possible time variation of the fine structure `constant' and the electron-proton mass ratio and show how they are strengthened when the seasonal variation of Sun's…
Recent cosmological tensions pose difficulties for $\Lambda$CDM. Forthcoming facilities will be able to check whether these tensions result from systematic effects or indeed with the $\Lambda$CDM model itself. However, these new data will…
Astrophysical indications that the fine structure constant has undergone a small time variation during the cosmological evolution are discussed within the framework of the standard model of the electroweak and strong interactions and of…