# The Modern Physics of Compact Stars and Relativistic Gravity 2017

18-22 September 2017
Yerevan, Armenia
Etc/GMT+4 timezone

## $f(R)$ relativistic gravity and inflationary models based on it

19 Sep 2017, 11:20
40m
Yerevan, Armenia

#### Yerevan, Armenia

Department of Physics, Alex Manoogian str. 1, Yerevan, Armenia

### Speaker

Prof. Alexei Starobinsky (Landau Institute of RAS)

### Description

The $f(R)$ gravity represents the simplest purely geometrical generalization of
the Einstein general theory of relativity without undesirable ghosts. The
pioneer $R+R^2$ model of inflation (1980) contains only one adjustable
parameter taken from observations, has a graceful exit from inflation and
a natural mechanism for creation and heating of matter after its end. It
produces a very good fit to existing observational data on the power
spectrum of primordial scalar (adiabatic density) perturbations. Due to
the structure of this model, small quantum-gravitational loop corrections
to it from quantum matter fields and gravity itself are important for its
dynamics both during and after inflation and can lead to observable
effects. I present solution of the inverse problem of reconstruction of
slow-roll inflationary models in f(R) gravity using information on the
power spectrum of scalar perturbations only and show how ambiguity in this
procedure due to the absence of data for small scales can be fixed using
simplifying and aesthetic assumptions on the absence of new physical
scales during and after inflation. Also discussed is the problem on
formation of inflation in f(R) gravity from generic classical curvature
singularity preceding it, and which conditions are needed for this.

Type of contribution Invited talk

### Primary author

Prof. Alexei Starobinsky (Landau Institute of RAS)