Predictions and observations in theories with varying couplings

Abstract

We consider a toy universe containing conventional matter and an additional real scalar field, and discuss how the requirements of gauge and diffeomorphism invariance essentially single out a particular set of theories which might describe such a world at low energies. In these theories, fermion masses and g-factors, as well as the electromagnetic coupling turn to be scalar field dependent; fermion charges and the gravitational coupling might be assumed to be constant. We then proceed to study the impact of a time variation of the scalar field on measurements of atomic spectra at high redshifts. Light propagation is not affected by a sufficiently slow change of the fine structure constant, but changes of the latter as well as variations of fermion masses and g-factors do affect the observed atomic spectra. Finally, we prove the independence of these predictions on the chosen conformal frame, in a further attempt to address differing views about the subject expressed in the literature. * Electronic address: armen@oddjob.uchicago.edu

Extendedf(R,Lm)gravity with generalized scalar field and kinetic term dependences

“…In the latter context, some authors proposed that the dilaton could be a good candidate for the quintessence [14] or the inflaton [15]. But even from a phenomelogical point of view, it has been argued that specific restrictions such as gauge and diffeomorphism invariances essentially single out a particular set of effective theories which turns out to be Brans-Dicke-like theories with scalar/matter coupling [16]. A good feature of such theories is that under various assumptions -and similarly to Brans-Dicke-like theories without scalar/matter coupling -they seem to be driven toward a weak coupling through cosmological evolution [17].…”

Brans–dicke Theory: Jordan Versus Einstein Frame

“…Some works in cosmology do show that it is indeed the case [12][13][14]. Therefore, the question arises if we can take the deflection of light as a physical observable.…”

Spontaneous symmetry breaking in wormholes spacetimes with matter

“…In particular, we consider an Ellis wormhole in General Relativity [1][2][3][4][5][6][7][8]. Such a wormhole connects two asymptotically flat spacetimes by a throat.…”