Abstracts

Dragoljub Dimitrijevic

Tachyon scalar field in DBI and RSII cosmological context

The role tachyon fields may play in evolution of early universe is discussed.

We consider the evolution of a flat and homogeneous universe governed by a tachyon scalar field with the DBI-type action and calculate the slow-roll parameters of inflation, scalar spectral index and tensor-scalar ratio for several models. We compare the available results obtained by analytical and numerical methods with those obtained by observation.

The possibility that influence of the radion field can extend a range of the acceptable values of the parameters came form the string theory motivated is also considered in the RSII model.

We conclude our consideration with discussion of possibilities for and consequences of "linearization" of DBI tachyon action at archimedean and nonarchimedean spaces.

References:

• N. Bilic, D.D. Dimitrijevic, G.S. Djordjevic and M. Milosevic, Int. Jour. Mod. Phys. A, 32 (2017) 1750039.
• M. Milosevic, D.D. Dimitrijevic, G.S. Djordjevic and M.D. Stojanovic, Serb. Astron. Jour., 192 (2016) 1-8.
• G.S. Djordjevic, D.D. Dimitrijevic and M. Milosevic, Rom. Jour. Phys., 61 (2016) 99-109.