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Cosmology in f (Q) geometry
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- Beltran Jimenez, Jose (författare)
- Univ Salamanca, Dept Fis Fundamental & IUFFyM, E-37008 Salamanca, Spain.
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- Heisenberg, Lavinia (författare)
- Swiss Fed Inst Technol, Inst Theoret Phys, Wolfgang Pauli Str 27, CH-8093 Zurich, Switzerland.
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- Koivisto, Tomi S. (författare)
- Stockholms universitet,KTH,Nordic Institute for Theoretical Physics NORDITA,Stockholm Univ, Roslagstullsbacken 23, SE-10691 Stockholm, Sweden.;Univ Tartu, Inst Phys, Lab Theoret Phys, W Ostwaldi 1, EE-50411 Tartu, Estonia.;NICPB, Ravala Pst 10, EE-10143 Tallinn, Estonia.,Nordiska institutet för teoretisk fysik (Nordita),University of Tartu, Estonia; National Institute of Chemical Physics and Biophysic, Estonia
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- Univ Salamanca, Dept Fis Fundamental & IUFFyM, E-37008 Salamanca, Spain Swiss Fed Inst Technol, Inst Theoret Phys, Wolfgang Pauli Str 27, CH-8093 Zurich, Switzerland. (creator_code:org_t)
- American Physical Society (APS), 2020
- 2020
- Engelska.
- Ingår i: Physical Review D. - : American Physical Society (APS). - 1550-7998 .- 1550-2368. ; 101:10
- Tidskriftsartikel (refereegranskat)
Abstract
Ämnesord
Stäng
- The universal character of the gravitational interaction provided by the equivalence principle motivates a geometrical description of gravity. The standard formulation of general relativity a la Einstein attributes gravity to the spacetime curvature, to which we have grown accustomed. However, this perception has masked the fact that two alternative, though equivalent, formulations of general relativity in flat spacetimes exist, where gravity can be fully ascribed either to torsion or to nonmetricity. The latter allows a simpler geometrical formulation of general relativity that is oblivious to the affine spacetime structure. Generalizations along this line permit us to generate teleparallel and symmetric teleparallel theories of gravity with exceptional properties. In this work we explore modified gravity theories based on nonlinear extensions of the nonmetricity scalar. After presenting some general properties and briefly studying some interesting background cosmologies (including accelerating solutions with relevance for inflation and dark energy), we analyze the behavior of the cosmological perturbations. Tensor perturbations feature a rescaling of the corresponding Newton's constant, while vector perturbations do not contribute in the absence of vector sources. In the scalar sector we find two additional propagating modes, hinting that f(Q) theories introduce, at least, 2 additional degrees of freedom. These scalar modes disappear around maximally symmetric backgrounds because of the appearance of an accidental residual gauge symmetry corresponding to a restricted diffeomorphism. We finally discuss the potential strong coupling problems of these maximally symmetric backgrounds caused by the discontinuity in the number of propagating modes.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
- NATURVETENSKAP -- Fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences (hsv//eng)
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