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Concept

Problème de la constante cosmologique

Publications associées (31)

Simple metastable de Sitter vacua in N=2 gauged supergravity

Claudio Scrucca, Paul Smyth

We construct a simple class of N=2 gauged supergravity theories that admit metastable de Sitter vacua, generalizing the recent work done in the context of rigid supersymmetry. The setup involves one hypermultiplet and one vector multiplet spanning suitably ...

Springer Nature2013

Cosmological constraints on Lorentz violating dark energy

Julien Lesgourgues, Sergey Sibiryakov, Diego Blas Temino, Benjamin Audren

The role of Lorentz invariance as a fundamental symmetry of nature has been lately reconsidered in different approaches to quantum gravity. It is thus natural to study whether other puzzles of physics may be solved within these proposals. This may be the c ...

Iop Publishing Ltd2013

Higgs-Dilaton cosmology: Are there extra relativistic species?

Mikhail Chapochnikov, Javier Rubio

Recent analyses of cosmological data suggest the presence of an extra relativistic component beyond the Standard Model content. The Higgs-Dilaton cosmological model predicts the existence of a massless particle - the dilaton - associated with the spontaneo ...

Elsevier Science Bv2012

Scale-invariant alternatives to general relativity

Mikhail Chapochnikov, Diego Blas Temino, Daniel Zenhäusern

We study the general class of gravitational field theories constructed on the basis of scale invariance (and therefore absence of any mass parameters) and invariance under transverse diffeomorphisms, which are the 4-volume conserving coordinate transformat ...

American Physical Society2011

Technically natural dark energy from Lorentz breaking

Sergey Sibiryakov, Diego Blas Temino

We construct a model of dark energy with a technically natural small contribution to cosmic acceleration, i.e. this contribution does not receive corrections from other scales in the theory. The proposed acceleration mechanism appears generically in the lo ...

2011

Scale-Invariant Models of Gravity and Particle Physics and their Cosmological Implications

Daniel Zenhäusern

Currently, the best theoretical description of fundamental matter and its gravitational interaction is given by the Standard Model (SM) of particle physics and Einstein's theory of General Relativity (GR). These theories contain a number of seemingly unrel ...

EPFL2011

Mildly sequestered supergravity models and their realization in string theory

Claudio Scrucca, Christopher John Andrey

We elaborate on the idea that five-dimensional models where sequestering is spoiled due to contact interactions induced by vector multiplets may still be mildly sequestered if a global version of the gauge symmetry associated to the latter survives in the ...

2010

Quantum scale invariance, cosmological constant and hierarchy problem

Mikhail Chapochnikov, Daniel Zenhäusern

We construct a class of theories which are scale-invariant on quantum level in all orders of perturbation theory. In a subclass of these models scale invariance is spontaneously broken, leading to the existence of a massless dilaton. The applications of th ...

2009

No metastable de Sitter vacua in N=2 supergravity with only hypermultiplets

Claudio Scrucca

We study the stability of vacua with spontaneously broken supersymmetry in N = 2 supergravity theories with only hypermultiplets. Focusing on the projection of the scalar mass matrix along the sGoldstino directions, we are able to derive a universal upper ...

Springer Nature2009

Scale invariance, unimodular gravity and dark energy

Mikhail Chapochnikov, Daniel Zenhäusern

We demonstrate that the combination of the ideas of unimodular gravity, scale invariance, and the existence of an exactly massless dilaton leads to the evolution of the universe supported by present observations: inflation in the past, followed by the radi ...

2009

Phenomenology of 10(32) dark sectors

We postulate an exact permutation symmetry acting on 10(32) standard model copies as the largest possible symmetry extension of the standard model. This setup automatically lowers the fundamental gravity cutoff down to TeV, and thus, accounts for the quant ...

American Physical Society2009