11 research outputs found
Large Nongaussianity from Nonlocal Inflation
We study the possibility of obtaining large nongaussian signatures in the
Cosmic Microwave Background in a general class of single-field nonlocal
hill-top inflation models. We estimate the nonlinearity parameter f_{NL} which
characterizes nongaussianity in such models and show that large nongaussianity
is possible. For the recently proposed p-adic inflation model we find that
f_{NL} ~ 120 when the string coupling is order unity. We show that large
nongaussianity is also possible in a toy model with an action similar to those
which arise in string field theory.Comment: 27 pages, no figures. Added references and some clarifying remark
String Theory as a diffusing System
Recent results on the effective non-local dynamics of the tachyon mode of
open string field theory (OSFT) show that approximate solutions can be
constructed which obey the diffusion equation. We argue that this structure is
inherited from the full theory, where it admits a universal formulation. In
fact, all known exact OSFT solutions are superpositions of diffusing surface
states. In particular, the diffusion equation is a spacetime manifestation of
OSFT gauge symmetries.Comment: 1+39 pages, 1 figure; v2: section 4 expanded, main result clarified
but unchanged, references adde