More on Starobinsky model of cosmic inflation in nLab

Starobinsky model of cosmic inflation in nLab:

Contents

• Idea
• References

Idea

In phenomenology of cosmology, the Starobinsky model of cosmic inflation takes into account – and takes as the very source of the inflaton field – higher curvature corrections to the Einstein-Hilbert action ofgravity, notably the term R2 (square of the Ricci curvature).

The Starobinsky model stands out among models of inflation as predicting a low value of the scalar-to-tensor ratio r, specifically it predicts

r∼12N2

where N is the number of e-foldings during inflation (see e.g. Kehagias-Dizgah-Riotto 13 (2.6)).

Models of this type are favored by experimental results (PlanckCollaboration 13, BICEP2-Keck-Planck 15) which give a low upper bound on r around 0.1 (whereas other models like chaotic inflation are disfavored by these values). See (Ellis 13, Ketov 13 for brief survey and see (Kehagias-Dizgah-Riotto 13) for more details. There it is argued that the other types of models which also fit the data are actually equivalent to the Starobinsky model during inflation.

See (PlanckCollaboration 13, figure 1, also Linde 14, figure 5) showing how the Starobinsky model sits right in the center of the experimentally preferred parameter range.

Being concerned with pure gravity (the inflaton not being an extra matter field but part of the field ofgravity) the Starobinsky model lends itself to embedding into supergravity (originally due to Ceotti 87, see e.g. Farakos-Kehagias-Riotto 13). Such embedding seems to improve the model further (highlighted e.g. inEllis 13), for instance by shrinking the necessary initial homogeneous patch from ∼103 down to just 50Planck lengths, and by naturally subsuming a natural mechanism for supersymmetry breaking (Ferrar-Kehagias 14, DFKRU 14).

References

The model is due to

• Aleksei Starobinsky, Phys. Lett. B 91, 99 (1980);

and the analysis of its predictions is due to

• Viatcheslav Mukhanov and G. V. Chibisov, JETP Lett. 33, 532 (1981) [Pisma Zh. Eksp. Teor. Fiz. 33, 549 (1981)];
• Aleksei Starobinsky, Sov. Astron. Lett. 9, 302 (1983).

The experimental data supporting the model is due to

• Planck 2013 results. XXII. Constraints on inflation (arXiv:1303.5082)
  
  • Andrei Linde, Inflationary Cosmology after Planck 2013 (arXiv:1402.0526)
• A Joint Analysis of BICEP2/Keck Array and Planck Data (arXiv:1502.00612)

Reviews and expositon includes

• Alex Kehagias, Azadeh Moradinezhad Dizgah, Antonio Riotto, Comments on the Starobinsky Model of Inflation and its Descendants, Phys. Rev. D 89, 043527 (2014) (arXiv:1312.1155)
• Sergei Ketov, PLANCK mission, Starobinsky inflation and its realization in old-minimal supergravity, talk at Kavli IPMU Workshop: SUSY Model Building and Phenomenology, 2-4 December 2013 (pdf)
• John Ellis, Planck-Compatible Inflationary Models, talk 2013 (pptx)

Discussion of embedding of Starobinsky inflation in supergravity originates in

• S. Cecotti, Phys. Lett. B 190, 86 (1987).
• S. Cecotti, S. Ferrara, M. Porrati and S. Sabharwal, Nucl. Phys. B 306, 160 (1988).

and is further developed in

• John Ellis, Dimitri Nanopoulos, Keith Olive, No-Scale Supergravity Realization of the Starobinsky Model of Inflation Phys. Rev. Lett. 111, 111301 (2013) (arXiv:1305.1247)
  Starobinsky-like Inflationary Models as Avatars of No-Scale Supergravity JCAP 1310, 009 (2013) (arXiv:1307.3537)
• Renata Kallosh, Andrei Linde, Superconformal generalizations of the Starobinsky model JCAP 1306, 028 (2013) (arXiv:1306.3214)
• F. Farakos, Alex Kehagias, A. Riotto, On the Starobinsky Model of Inflation from Supergravity, Nucl. Phys. B 876, 187 (2013) (arXiv:1307.1137)
• S. Ferrara, Renata Kallosh, Andrei Linde and M. Porrati, Minimal Supergravity Models of Inflation(arXiv:1307.7696)
• Andrei Linde and M. Porrati, Higher Order Corrections in Minimal Supergravity Models of Inflation(arXiv:1309.1085)
• S. Ferrara, Renata Kallosh, Antoine Van Proeyen, On the Supersymmetric Completion of R+R2 Gravity and Cosmology JHEP 1311, 134 (2013) (arXiv:1309.4052)
• S. Ferrara, P. Fre and A. S. Sorin, On the Topology of the Inflaton Field in Minimal Supergravity Models(arXiv:1311.5059)
• S. V. Ketov and A. A. Starobinsky, JCAP 1208, 022 (2012) [arXiv:1203.0805 hep-th]. S. V. Ketov and S. Tsujikawa, Phys. Rev. D 86, 023529 (2012) [arXiv:1205.2918 hep-th]. S. V. Ketov, arXiv:1309.0293 [hep-th].
• Sergei Ketov, On the supersymmetrization of inflation in f(R) gravity, Prog. Theor. Exp. Phys. 2013, 123B04 (pdf)
• Sergio Ferrara, Alex Kehagias, Antonio Riotto, The Imaginary Starobinsky Model and Higher Curvature Corrections (arXiv:1405.2353)
• Sergio Ferrara, Alex Kehagias, Higher Curvature Supergravity, Supersymmetry Breaking and Inflation(arXiv:org)
• I. Dalianis, F. Farakos, Alex Kehagias, A. Riotto, R. von Unge, Supersymmetry Breaking and Inflation from Higher Curvature Supergravity (arXiv:1409.8299)

Revised on February 3, 2015 22:45:44 by Urs Schreiber (195.113.30.252)

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