This series consists of talks in the areas of Cosmology, Gravitation and Particle Physics.
The non-Gaussian statistics of
the primordial density perturbation have become a key test of the inflationary
scenario of the very early universe. Currently many techniques are used to
calculate the non-Gaussian signatures of a given model of inflation. In
particular, simple super-horizon techniques such as the deltaN formalism are
often used for models with more than one field, while more technical field
theory techniques, referred to as the In-In formalism, are typically used for
I will present recent work,
done in collaboration with Daniel Roberts, on the global memory of initial
conditions that is sometimes, but not always, retained by fluctuating fields on
de Sitter space, Euclidean anti de Sitter space, and regular infinite trees. I
will discuss applications to the structure of configuration space in de Sitter
space and eternal inflation.
from Planck, a third-generation satellite mission to measure the cosmic
microwave background, have just been announced. These results improve
constraints on essentially all cosmological parameters, and have implications
for several preexisting sources of tension with the standard cosmological
model, while also raising new puzzles. I will discuss these results and
their significance, as well as the next steps forward.
Already the last decade has
witnessed unprecedented progress in the collection of cosmological data.
Presently proposed and designed future cosmological probes and surveys permit
us to anticipate the upcoming avalanche of cosmological information during the
The increase of valuable observations needs to be accompanied with the development
of efficient and accurate information processing technology in order to analyse
and interpret this data. In particular, cosmography projects, aiming at studying
The endgame of massive star evolution is the gravitational-induced collapse of the central inert iron core. The collapse of the core continues until the matter reaches nuclear densities where the strong force between nucleons becomes dominant and provides sufficient pressure to stabilize the newly formed protoneutron star. What ensues is a complex multi-physics problem involving strong gravity, multidimensional hydrodynamic instabilities, magnetic fields, multispecies neutrino radiation, and supranuclear density physics to name a few.
An analytical understanding of large-scale matter
inhomogeneities is an important cornerstone of our cosmological model and helps
us interpreting current and future data. The standard approach, namely Eulerian
perturbation theory, is unsatisfactory for at least three reasons: there is no
clear expansion parameter since the density contrast is not small everywhere;
it does not consistently account for deviations at large scales from a perfect
pressureless fluid induced by short-scale non-linearities; for generic initial
We apply the effective field theory approach to
quasi-single field inflation, which contains an additional scalar field with
Hubble scale mass other than inflaton.
Based on the time-dependent spatial diffeomorphism, which is not broken
by the time-dependent background evolution, the most generic action of
quasi-single field inflation is constructed up to third order
fluctuations. Using the obtained action,
the effects of the additional massive scalar field on the primordial curvature
perturbations are discussed. In
Newton’s inferences from phenomena realize an ideal of
empirical success that’s richer than prediction. To realize Newton’s richer
conception of empirical success a theory needs to do more than to accurately
predict the phenomena it purports to explain: in addition it needs to have the
phenomena accurately measure parameters of the theory. Newton’s method aims to
turn theoretical questions into ones which can be empirically answered by
measurements from phenomena.
The presence of additional light fields during inflation
can source isocurvature fluctuations, which can cause the curvature
perturbation $\zeta$, and its statistics to evolve on superhorizon scales. I
will demonstrate that if these fluctuations have not completely decayed before
the onset of perturbative reheating, then primordial observables such as the
level of non--Gaussianity can develop substantial reheating dependant
corrections. I will argue that for inflationary models where an adiabatic