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CATEGORIES:Cosmology Lunch
SUMMARY:Preheating on curved field-space manifolds - Evang
elos Sfakianakis (Nikhef)
DTSTART;TZID=Europe/London:20191028T130000
DTEND;TZID=Europe/London:20191028T140000
UID:TALK131536AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/131536
DESCRIPTION:I will discuss preheating in multi-field models of
inflation with a curved field-space manifold. In
the case of two-field generalizations of alpha-att
ractor models with is a highly curved hyperbolic f
ield-space manifold\, analytical progress can be m
ade for preheating using the WKB approximation and
Floquet analysis. I will show the emergence of a
simple scaling behavior of the Floquet exponents f
or large values of the field-space curvature\, tha
t enables a quick estimation of the reheating effi
ciency for any large value of the field-space curv
ature. In this regime one can observe and explain
universal preheating features that arise for diffe
rent values of the potential steepness. In general
preheating is faster for larger negative values o
f the field-space curvature and steeper potentials
. For very highly curved field-space manifolds pre
heating is essentially instantaneous.\nIn case of
multi-field models with non-minimal couplings\, wh
ere the field-space in the Einstein frame is highl
y curved near the origin\, I will describe recent
lattice simulations that have been used to capture
significant nonlinear effects like backreaction a
nd rescattering. I will show how we can we extract
the effective equation of state and typical time-
scales for the onset of thermalization\, quantitie
s that could affect the usual mapping between pred
ictions for primordial perturbation spectra and me
asurements of anisotropies in the cosmic microwave
background radiation. For large values of the non
minimal coupling constants\, efficient particle p
roduction gives rise to nearly instantaneous prehe
ating. Moreover\, the strong single-field attracto
r behavior that was identified for these models in
linearized analyses remains robust in the full th
eory\, and in all cases considered the attractor p
ersists until the end of preheating. Finally\, I w
ill discuss the implications for Higgs inflation.
LOCATION:CMS\, Pav. B\, CTC Common Room (B1.19) [Potter Roo
m]
CONTACT:Sadra Jazayeri
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