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Inflation in DBI models with constant γ

Michał Spaliński

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Dirac–Born–Infeld scalar field theories which appear in the context of inflation in string theory in general have a field-dependent speed of sound. It is, however, possible to write down DBI models which possess exact solutions characterized by a constant speed of sound different from unity. This requires that the potential and the effective D-brane tension appearing in a DBI action have to be related in a specific way. This paper describes such models in general and presents some examples with a constant speed of sound cs<1 for which the spectrum of scalar perturbations can be found analytically without resorting to the slow-roll approximation.


Keywords

inflation

string theory and cosmology

 

E-print Number: 0711.4326

Cited: by |

Refers: to

PACS

98.80.Cq Particle-theory and field-theory models of the early Universe (including cosmic pancakes, cosmic strings, chaotic phenomena, inflationary universe, etc.)

11.25.Sq Nonperturbative techniques; string field theory

11.25.Uv D branes

Subjects

Gravitation and cosmology

Particle physics and field theory

Astrophysics and astroparticles

Dates

Issue 04 (April 2008)

Received 2 January 2008, accepted for publication 7 March 2008

Published 2 April 2008



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