Cosmological evolution ofαandμand the dynamics of dark energy

Abstract

We study the cosmological evolution of the fine structure constant, α, and the proton-to-electron mass ratio, µ = mp/me, in the context of a generic class of models where the gauge kinetic function is a linear function of a quintessence-type real scalar field, φ, described by a Lagrangian with a standard kinetic term and a scalar field potential, V (φ). We further assume that the scalar field potential is a monotonic function of φ and that the scalar field is always rolling down the potential. We show that, for this class of models, low-redshift constrains on the evolution of α and µ can provide very stringent limits on the corresponding variations at high-redshift. We also demonstrate that these limits may be relaxed by considering more general models for the dynamics of α and µ. However, in this case, the ability to reconstruct the evolution of the dark energy equation of state using varying couplings could be seriously compromised.

Time variation of fundamental couplings and dynamical dark energy

“…One could use linearity in ln(1 + z) instead of t, but even this improvement may lead to unreliable extrapolations for models with a particular dynamics of the scalar field, such as crossover quintessence. An alternative approach to relating present-day variation to cosmological history in previous epochs, under certain assumptions on the scalar evolution, is given in [41].…”

SENSITIVITY OF THE H3O+INVERSION-ROTATIONAL SPECTRUM TO CHANGES IN THE ELECTRON-TO-PROTON MASS RATIO

“…Examples of dark energy in a form of a scalar field with a self-interaction potential can be found in reviews by Peebles & Ratra (2003), Copeland et al (2006), and by Uzan (2010). Since that time many sophisticated models have been suggested to explain the nature of dark energy and among them the scalar fields which are ultra-light in cosmic vacuum but possess a large mass locally when they are coupled to ordinary matter by the so-called chameleon mechanism Brax et al 2004;Avelino 2008;Brax et al 2010a,b). A subclass of these models considered by Olive & Pospelov (2008) predicts that fundamental physical quantities such as elementary particle masses and lowenergy coupling constants may also depend on the local matter density.…”

Observational constraints on f(T) gravity from varying fundamental constants

“…In general, in a given theory the fine-structure constant is obtained using the coefficient of the electromagnetic Lagrangian. In the case of modified gravities, this coefficient generally depends on the new degrees of freedom of the theory [56][57][58][59][60][61][62][63]78]. Even if one starts from the Jordan-frame formulation of a theory, with an uncoupled electromagnetic Lagrangian, and although the electromagnetic Lagrangian is conformally invariant, and it is not affected by conformal transformations between the Jordan and Einstein frames, thus it will acquire a dependence on the extra degree(s) of freedom due to quantum effects [79,80].…”

“…Later on, Brans and Dicke proposed the time variation of the Newton constant, driven by a dynamical scalar field coupled to curvature [48,49], while Gamow triggered subsequent speculations on the possible variation of the fine-structure constant [50]. Similarly, in recent modified gravities, which involve extra degrees of freedom compared with general relativity, one may obtain such a variation of the fundamental constants [51][52][53][54][55][56][57][58][59][60][61][62][63]. However, since experiments and observations give strict bounds on these variations [64][65][66][67][68][69][70][71][72][73][74][75][76], one can use them in order to constrain the theories at hand.…”