A. Ashoorioon, U. Danielsson, M. M. Sheikh-Jabbari
We observe that the dominant one loop contribution to the graviton propagator
in the theory of N (N>>1) light scalar fields \phi_a (with masses smaller than
M_{pl}/\sqrt{N}) minimally coupled to Einstein gravity is proportional to N
while that of graviton-scalar-scalar interaction vertex is N independent. We
use this to argue that the coefficient of the R\phi_a^2 term appearing at one
loop level is 1/N suppressed. This observation provides a resolution to the
\eta-problem, that the slow-roll parameter \eta receives order one quantum loop
corrections for inflationary models built within the framework of scalar fields
minimally coupled to Einstein gravity, for models involving large number of
fields. As particular examples, we employ this to argue in favor of the absence
of \eta-problem in M-flation and N-flation scenarios.
View original:
http://arxiv.org/abs/1112.2272
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