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We have recently constructed a manifestly local formulation of a nonlocal approach to the cosmological constant problem which can treat with quantum effects from both matter and gravitational fields. In this formulation, it has been…

High Energy Physics - Theory · Physics 2018-05-09 Ichiro Oda

I propose an observationally and theoretically consistent resolution of the cosmological constant problem: $\Lambda$ is a counterterm -- with a running coupling -- that balances the monopole celestial sky average of the kinetic energy of…

General Relativity and Quantum Cosmology · Physics 2024-04-03 David L. Wiltshire

In construction of an inflationary model, one usually assumes that the matter sector of the gravitational action is minimally coupled to the background. It means that the matter (inflaton) part of the action is coupled with the same metric…

General Relativity and Quantum Cosmology · Physics 2021-05-25 Yousef Bisabr

We argue that, when a theory of gravity and matter is endowed with (classical) conformal symmetry, the fine tuning required to obtain the cosmological constant at its observed value can be significantly reduced. Once tuned, the cosmological…

General Relativity and Quantum Cosmology · Physics 2018-10-23 Stefano Lucat , Tomislav Prokopec , Bogumila Swiezewska

With attempts to quench the cosmological constant $\Lambda$ having so far failed, we instead investigate what could be done if $\Lambda$ is not quenched and actually gets to be as big as elementary particle physics suggests. Since the…

Astrophysics · Physics 2007-05-23 Philip D. Mannheim

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…

High Energy Physics - Theory · Physics 2022-12-07 Nemanja Kaloper , Alexander Westphal

After recalling why dynamical adjustment mechanisms represent a particularly attractive possibility for solving the cosmological constant problem, we briefly discuss their intrinsic difficulties as summarized in Weinberg's no-go theorem. We…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. Hebecker

We examine an extension of General Relativity with an explicit non-minimal coupling between matter and curvature. The purpose of this work is to present an overview of the implications of the latter to various contexts, ranging from…

General Relativity and Quantum Cosmology · Physics 2014-01-20 Orfeu Bertolami , Jorge Páramos

After a brief outlook of the dynamic quantization method and application of the method to gravity the idea of natural solution of cosmological constant problem in inflating Universe is presented.

High Energy Physics - Theory · Physics 2016-09-06 S. N. Vergeles

We show that the cosmological constant appears as a Lagrange multiplier if nature is described by a canonical noncommutative spacetime. It is thus an arbitrary parameter unrelated to the action and thus to vacuum fluctuations. The…

High Energy Physics - Theory · Physics 2008-11-26 Xavier Calmet

In this paper we present a cosmological model arising from a non-conservative gravitational theory proposed in [PRD 95, 101501(R) (2017)]. The novel feature where comparing with previous implementations of dissipative effects in gravity is…

General Relativity and Quantum Cosmology · Physics 2018-05-28 Júlio C. Fabris , Hermano Velten , Thiago R. P. Caramês , Matheus J. Lazo , Gastão S. F. Frederico

The presence of a cosmological constant, Lambda, in an action with higher powers of the curvature can produce rapidly oscillating metrics. We develop a perturbative approach for generating periodic solutions to the non-linear field…

High Energy Physics - Theory · Physics 2009-11-07 Hael Collins , Bob Holdom

We demonstrate that there exists a large class of action functionals of the scalar curvature and of the Gauss-Bonnet invariant which are able to relax dynamically a large cosmological constant (CC), whatever it be its starting value in the…

High Energy Physics - Theory · Physics 2011-05-19 Florian Bauer , Joan Sola , Hrvoje Stefancic

The problem of the cosmological constant appears in a new light in Unimodular Gravity. In particular, the zero momentum piece of the potential (that is, the constant piece independent of the matter fields) does not automatically produce a…

High Energy Physics - Theory · Physics 2018-02-15 Enrique Álvarez , Sergio González-Martín , Mario Herrero-Valea , Carmelo P. Martín

We consider phase transitions and their contributions to vacuum energy in the manifestly local theory of vacuum energy sequestering. We demonstrate that the absence of instabilities imposes constraints on the couplings of gravitating and…

High Energy Physics - Theory · Physics 2016-07-20 Nemanja Kaloper , Antonio Padilla , David Stefanyszyn

We consider a two-dimensional model of gravity with the cosmological constant as a dynamical variable. The effective cosmological constant is derived when the universe has no initial boundary. It turns out to be extremely small if the…

High Energy Physics - Theory · Physics 2017-02-01 Izawa K. -I

We perform a combined perturbation and observational investigation of the scenario of non-minimal derivative coupling between a scalar field and curvature. First we extract the necessary condition that ensures the absence of instabilities,…

Cosmology and Nongalactic Astrophysics · Physics 2013-12-02 James B. Dent , Sourish Dutta , Emmanuel N. Saridakis , Jun-Qing Xia

We show that a theory with conformal invariance, which is explicitly broken by small terms, provides a solution to the fine tuning problem of the cosmological constant. In the absence of the symmetry breaking terms, the cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-19 Pankaj Jain , Gopal Kashyap

The Cosmological Constant Problem emerges when Quantum Field Theory is applied to the gravitational theory, due to the enormous magnitude of the induced energy of the vacuum. The unique known solution of this problem involves an extremely…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Ilya L. Shapiro , Joan Sola

We propose an alternative scenario for the dark matter generation from an evolving cosmological constant which interacts with the dominant background in certain intermediate phase of the universe, and relaxes to the observed small value at…

Cosmology and Nongalactic Astrophysics · Physics 2013-01-01 Murli Manohar Verma