main page: GrassmannCosmoFun2009These are just rough notes - feel free to correct them, add links, etc. from the Grassmann ian Conference in Fundamental Cosmology (Grasscosmofun'09). These are not official proceedings. The speakers might even disagree that they said anything even vaguely related to what are in these online notes! Don't say you weren't warned.
violation of these conditions is undesirable also from the classical point of view
f'(R_*) = 0 instant loss of homogeneity and isotropy
f''(R_*) = 0 weak singularity
existence of the Newtonian regime
for (up to some very large R)
de Sitter regime stable if
equivalent to in scalar-tensor gravity
use for inflation Starobinsky 1980:
internally consistent infolationary model with slow-roll decay, a graceful exit to the subsequent RD (radiation-dominated) FRW stage ... and sufficiently effective reheating
model remains viable, e.g.
oher viable f(R) inflationary models
1. chaotic type - inflation over a large range of R
2. new inflationary type - inflation around R =R_0
cosmology - anomalous growth of non-relativistic matter perturbations in the regime
lab and Solar System tests with R = 8 pi G T_m = 8 \pi G \rho_m; otherwise, \gamma_{(?)} = 1/2 and 'fifth' force appears
both OK if n \ge 2
... "scalaron production" problems
"big boost" singularity with and its elimination
elimination: add R^2/{6M^2} to F(R)
conclusions:
viable models of DE, distinguishable from LambdaCDM, exist, given certain conditions:
with a regular f(R) satisfying:
* ...
unification of primordial DE (i.e. inflation) and present DE is possible for
anomalous growth of scalar perturbations at recent times ( z about 1-3 for L = 8 /h Mpc ) would be the most critical test of the f(R) DE models satisfying these conditions