67,923 research outputs found
Non-Canonical Inflation in Supergravity
We investigate the effect of non-canonical kinetic terms on inflation in
supergravity. We find that the biggest impact of such higher-derivative kinetic
terms is due to the corrections to the potential that they induce via their
effect on the auxiliary fields, which now have a cubic equation of motion. This
is in contrast to the usual (non-supersymmetric) effective field theory
expansion which assumes that mass-suppressed higher-derivative terms do not
affect the lower-derivative terms already present. We demonstrate with several
examples that such changes in the potential can significantly modify the
inflationary dynamics. Our results have immediate implications for effective
descriptions of inflation derived from string theory, where higher-derivative
kinetic terms are generally present. In addition we elucidate the structure of
the theory in the parameter range where there are three real solutions to the
auxiliary field's equation of motion, studying the resulting three branches of
the theory, and finding that one of them suffers from a singularity in the
speed of propagation of fluctuations.Comment: 22 pages + Appendix, 16 figure
Canonical and non-canonical equilibrium distribution
We address the problem of the dynamical foundation of non-canonical
equilibrium. We consider, as a source of divergence from ordinary statistical
mechanics, the breakdown of the condition of time scale separation between
microscopic and macroscopic dynamics. We show that this breakdown has the
effect of producing a significant deviation from the canonical prescription. We
also show that, while the canonical equilibrium can be reached with no apparent
dependence on dynamics, the specific form of non-canonical equilibrium is, in
fact, determined by dynamics. We consider the special case where the thermal
reservoir driving the system of interest to equilibrium is a generator of
intermittent fluctuations. We assess the form of the non-canonical equilibrium
reached by the system in this case. Using both theoretical and numerical
arguments we demonstrate that Levy statistics are the best description of the
dynamics and that the Levy distribution is the correct basin of attraction. We
also show that the correct path to non-canonical equilibrium by means of
strictly thermodynamic arguments has not yet been found, and that further
research has to be done to establish a connection between dynamics and
thermodynamics.Comment: 13 pages, 6 figure
Initial Conditions for Non-Canonical Inflation
We investigate the dynamics of homogeneous phase space for single-field
models of inflation. Inflationary trajectories are formally attractors in phase
space, but since in practice not all initial conditions lead to them, some
degree of fine tuning is required for successful inflation. We explore how the
dynamics of non-canonical inflation, which has additional kinetic terms that
are powers of the kinetic energy, can play a role in ameliorating the initial
conditions fine tuning problem. We present a qualitative analysis of
inflationary phase space based on the dynamical behavior of the scalar field.
This allows us to construct the flow of trajectories, finding that trajectories
generically decay towards the inflationary solution at a steeper angle for
non-canonical kinetic terms, in comparison to canonical kinetic terms, so that
a larger fraction of the initial-conditions space leads to inflation. Thus,
non-canonical kinetic terms can be important for removing the initial
conditions fine-tuning problem of some small-field inflation models.Comment: 15 pages, 9 figure
Syntactic annotation of non-canonical linguistic structures
This paper deals with the syntactic annotation of corpora that contain both ‘canonical’ and ‘non-canonical’ sentences
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