Related papers: Tuning the Cosmological Constant, Broken Scale Inv…
We consider classically scale-invariant theories with non-minimally coupled scalar fields, where the Planck mass and the hierarchy of physical scales are dynamically generated. The classical theories possess a fixed point, where scale…
We study the degrees of freedom in New General Relativity -- flat and metric compatible family of theories -- around the Minkowski background in a gauge invariant manner. First, we confirm the decoupling case, in which the theory reduces to…
We review (and extend) the analysis of general theories of all interactions (gravity included) where the mass scales are due to dimensional transmutation. Quantum consistency requires the presence of terms in the action with four…
In addressing the cosmological constant problem, we propose that the discrepancy between the theoretical and observed values can be ascribed to the inherent uncertainty in the spacetime metric. Mach's principle, which posits that mass…
We exhibit a mechanism which dynamically adjusts cosmological constant toward $0^+$. The adjustment is quantum-mechanical, discharging cosmological constant in random discrete steps. It renders de Sitter space unstable, and triggers its…
The standard model of elementary particle physics and the theory of general relativity can be extended by the introduction of a vacuum variable which is responsible for the near vanishing of the present cosmological constant (vacuum energy…
We study a Newtonian cosmological model in the context of a noncommutative space. It is shown that the trajectories of a test particle undergo modifications such that it no longer satisfies the cosmological principle. For the case of a…
Zero point fluctuations of quantum fields should generate a large cosmological constant energy density in any spacetime. How then can we have anything other than de Sitter space without fine tuning? Well tempering -- dynamical cancellation…
We introduce a dynamical model to reduce a large cosmological constant to a sufficiently small value. The basic ingredient in this model is a distinction which has been made between the two unit systems used in cosmology and particle…
At the level of the Planck scale, the spacetime metric has to be considered a quantum variable. Conformal quantum fluctuations of the metric tensor are studied here. They lead to an extra term in the Einstein equations which can be…
This paper proposes a systematic study of cosmological signatures of modifications of gravity via the presence of a scalar field with a multiplicative coupling to the electromagnetic Lagrangian. We show that, in this framework, variations…
We modify the action of Mannheim's conformally invariant model by changing the sign of two coefficients. This breaks conformal symmetry, but results in a cosmology that has a positive effective G and at the same time retains one of the main…
We reanalyze the problem of the cosmological constant associated with the phase transition in a self-interacting scalar theory. It is pointed out that the generally accepted ``triviality'' of $(\lambda\Phi^4)_4$ implies a first-order phase…
We evaluated the scattering amplitude of neutral scalar particles at one-loop order in the context of effective field theory of quantum gravity in the presence of a cosmological constant. Our study suggests that quantum gravitational…
We consider that the cosmological constant is associated with the vacuum energy density of a particle physics model. In the path integral formalism of euclidean quantum gravity and in the background of the Robertson Walker metric we…
We study a model of quantum cosmology originating from a classical model of gravitation where a self interacting scalar field is coupled to gravity with the metric undergoing a signature transition. We show that there are dual classical…
When physics is expressed in a way that is independent of local choices of unit systems, Riemannian geometry is replaced by conformal geometry. Moreover masses become geometric, appearing as Weyl weights of tractors (conformal multiplets of…
Cosmology in extended theories of gravity is considered assuming the Palatini variational principle, for which the metric and connection are independent variables. The field equations are derived to linear order in perturbations about the…
In this work, a novel mechanism for spontaneous symmetry breaking is presented. This mechanism avoids quadratic divergencies and is thus capable of addressing the hierarchy problem in gauge theories. Using the scale-dependent effective…
The full set of solutions of $f(T)$ gravity with the Minkowski metric is considered in this note. At the 4-th order in perturbations around the trivial tetrad solution, a new mode is found explicitly. Its presence signals a strong coupling…