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BICEP2, the curvature perturbation and supersymmetry
David H. Lyth
The tensor fraction found by BICEP2 corresponds to a Hubble parameter $H\simeq 1.0\times 10^{14}\GeV$ during inflation. This has two implications for the (single-fie…
Preheating and the non-gaussianity of the curvature perturbation
Kazunori Kohri, David H. Lyth, Cesar A. Valenzuela-Toledo
The perturbation of a light field might affect preheating and hence generate a contribution to the spectrum and non-gaussianity of the curvature perturbation ζ. The field might app…
Flaxino dark matter and stau decay
Eung Jin Chun, Hang Bae Kim, Kazunori Kohri +1
If the spontaneous breaking of Peccei-Quinn symmetry comes from soft supersymmetry breaking, the fermionic partners of the symmetry-breaking fields have mass of order the gravitino…
Black hole formation and slow-roll inflation
Kazunori Kohri, David H. Lyth, Alessandro Melchiorri
Black hole formation may occur if the spectrum of the curvature perturbation ζincreases strongly as the scale decreases. As no such increase is observed on cosmological scales, bla…
More hilltop inflation models
Kazunori Kohri, Chia-Min Lin, David H. Lyth
Using analytic expressions, we explore the parameter space for hilltop inflation models with a potential of the form . With the positive sign and p>2 this conv…
A-term inflation and the MSSM
J. C. Bueno Sanchez, K. Dimopoulos, David H. Lyth
The parameter space for A-term inflation is explored with . With p=6 and λ_p~1, the observed spectrum and spectral tilt can be obtained with soft mass of o…
MSSM inflation
David H. Lyth
Variants of the -term model of hep-ph/0605035 are considered. They are equally successful, indicating that the model is quite robust once the relation between and the soft m…
Hilltop Inflation
Lotfi Boubekeur, David. H. Lyth
We study `hilltop' inflation, in which inflation takes place near a maximum of the potential. Viewed as a model of inflation after the observable Universe leaves the horizon (obser…
Low scale inflation and the curvaton mechanism
Konstantinos Dimopoulos, David H. Lyth, Yeinzon Rodriguez
The primordial curvature perturbation may be due to a `curvaton' field, which dominates (or almost dominates) the energy density before it decays. In the simplest version of the cu…
Note about leptogenesis from gravity waves in models of inflation
David H. Lyth, Yeinzon Rodriguez, Carlos Quimbay
We show how the mechanism recently proposed by Alexander, Peskin, and Sheikh-Jabbari, in which the observed cosmic matter-antimatter asymmetry comes from the contribution of the co…
The masses of weakly-coupled scalar fields in the early Universe
David H. Lyth, Takeo Moroi
We consider the effective mass-squared in the early Universe, of a scalar field which has only Planck-suppressed couplings with light fields and whose true mass is less than the Hu…
Curvaton and QCD Axion in Supersymmetric Theories
Eung Jin Chun, Konstantinos Dimopoulos, David Lyth
A pseudo Nambu-Goldstone boson as curvaton avoids the eta-problem of inflation which plagues most curvaton candidates. We point out that a concrete realization of the curvaton mech…
Curvaton Dynamics
Konstantinos Dimopoulos, George Lazarides, David Lyth +1
In contrast to the inflaton's case, the curvature perturbations due to the curvaton field depend strongly on the evolution of the curvaton before its decay. We study in detail the…
The Curvaton as a Pseudo-Nambu-Goldstone Boson
K. Dimopoulos, D. H. Lyth, A. Notari +1
The field responsible for the cosmological curvature perturbations generated during a stage of primordial inflation might be the ``curvaton'', a field different from the inflaton f…
The Peccei-Quinn Field as Curvaton
Konstantinos Dimopoulos, George Lazarides, David Lyth +1
A simple extension of the minimal supersymmetric standard model which naturally and simultaneously solves the strong CP and mu problems via a Peccei-Quinn and a continuous R symmet…
New Constraints on the running-mass inflation model
Laura Covi, David H. Lyth, Alessandro Melchiorri
We evaluate new observational constraints on the two-parameter scale-dependent spectral index predicted by the running-mass inflation model by combining the latest Cosmic Microwave…
Models of inflation liberated by the curvaton hypothesis
Konstantinos Dimopoulos, David H. Lyth
It is usually supposed that inflation is of the slow-roll variety, and that the inflaton generates the primordial curvature perturbation. According to the curvaton hypothesis, infl…
Generating the primordial curvature perturbation from inflation
David H. Lyth
The scale--independence of the primordial curvature perturbation suggests that it comes from the vacuum fluctuation during inflation of a light scalar field. This field may be the…
The failure of cosmological perturbation theory in the new ekpyrotic and cyclic ekpyrotic scenarios
D H Lyth
Cosmological perturbation theory fails in the new ekpyrotic and cyclic ekpyrotic scenarios, before the scale factor of the Universe reaches zero. As a result, a recently-proposed r…
Generating the curvature perturbation without an inflaton
David H. Lyth, David Wands
We present a mechanism for the origin of the large-scale curvature perturbation in our Universe by the late decay of a massive scalar field, the curvaton. The curvaton is light dur…
The primordial curvature perturbation in the ekpyrotic Universe
David H. Lyth
In the ekpyrotic scenario the Universe is initially collapsing, the energy density coming from a scalar field with a negative exponential potential. On the basis of a calculation i…
Hybrid Inflation and Baryogenesis at the TeV Scale
Edmund J. Copeland, David Lyth, Arttu Rajantie +1
We consider the construction of inverted hybrid inflation models in which the vacuum energy during inflation is at the TeV scale, and the inflaton couples to the Higgs field. Such…
Observational constraints on models of inflation from the density perturbation and gravitino production
David H. Lyth
Present data require a spectral index $n\gsim 0.95$ at something like 1- level. If this lower bound survives it will constrain `new' and `modular' inflation models, while raisin…
Gravitino creation by an oscillating scalar field
David H. Lyth, Hang Bae Kim
This paper has been withdrawn because the analytic estimates are not confirmed by the numerical calculation of Nilles, Peloso and Sorbo (hep-ph/0102264 and hep-th/0103202).