The flatness of the inflaton potential and lightness of the Higgs could have the common origin of... more The flatness of the inflaton potential and lightness of the Higgs could have the common origin of the breaking of a global symmetry. This scenario provides a unified framework of Goldstone Inflation and Composite Higgs, where the inflaton and the Higgs both have a pseudo–Goldstone boson nature. The inflaton reheats the Universe via decays to the Higgs and subsequent secondary production of other SM particles via the top and massive vector bosons. We find that inflationary predictions and perturbative reheating conditions are consistent with CMB data for sub–Planckian values of the fields, as well as opening up the possibility of inflation at the TeV scale. We explore this exciting possibility, leading to an interplay between collider data cosmological constraints.
We show that General Relativity coupled to a quantum field theory generically leads to non-local ... more We show that General Relativity coupled to a quantum field theory generically leads to non-local effects in the matter sector. These non-local effects can be described by non-local higher dimensional operators which remarkably have an approximate shift symmetry. When applied to inflationary models, our results imply that small non-Gaussianities are a generic feature of models based on General Relativity coupled to matter fields. However, these effects are too small to be observable in the Cosmic Microwave Background.
Identifying the inflaton with a pseudo-Goldstone boson explains the flatness of its potential. Ad... more Identifying the inflaton with a pseudo-Goldstone boson explains the flatness of its potential. Additionally, successful Goldstone Inflation should be robust against UV corrections, such as from quantum gravity. In this paper we present the scenarios which lead to this successful model by examining the structure of Goldstone potentials arising from Coleman-Weinberg contributions. In particular, we notice that both bosonic and fermionic contributions are required to build a successful inflationary model. In single field inflation, we find that spinorial, and not fundamental, fermion representations can generate the right potential shape. This indicates that the Goldstone inflaton comes from the breaking of a SO(N) global symmetry. We also evaluate the constraints from higher-derivative interactions, finding that axiomatic constraints on Goldstone boson scattering prevail over the current CMB constraints on the speed of sound. We connect inflationary constraints to the UV completions for Goldstone Inflation, finding relations in the spectrum of new resonances. Finally, we present models of hybrid inflation, where both the inflaton and the waterfall fields share a common origin as Goldstones.
Slow-roll inflation requires the inflaton field to have an exceptionally flat potential, which co... more Slow-roll inflation requires the inflaton field to have an exceptionally flat potential, which combined with measurements of the scale of inflation demands some degree of fine-tuning. Alternatively, the flatness of the potential could be due to the inflaton's origin as a pseudo-Goldstone boson, as in Natural Inflation. Alas, consistency with Planck data places the original proposal of Natural Inflation in a tight spot, as it requires a trans-Planckian excursion of the inflaton. Although one can still tune the renormalizable potential to sub-Planckian values, higher order corrections from quantum gravity or sources of breaking of the Goldstone symmetry would ruin the predictivity of the model. In this paper we show how in more realistic models of Natural Inflation one could achieve inflation without a trans-Planckian excursion of the field. We show how a variant of Extra-natural inflation with bulk fermions can achieve the desired goal and discuss its four-dimensional duals. We also present a new type of four dimensional models inspired in Little Higgs and Composite Higgs models which can lead to sub-Planckian values of the inflaton field.
We discuss cosmological inflation in the minimal Wess-Zumino model with a single massive chiral s... more We discuss cosmological inflation in the minimal Wess-Zumino model with a single massive chiral supermultiplet. With suitable parameters and assuming a plausible initial condition at the start of the inflationary epoch, the model can yield scalar perturbations in the Cosmic Microwave Background (CMB) of the correct strength with a spectral index n_s ~ 0.96 and a tensor-to-scalar perturbation ratio r < 0.1, consistent with the Planck CMB data. We also discuss the possibility of topological inflation within the Wess-Zumino model, and the possibility of combining it with a seesaw model for neutrino masses. This would violate R-parity, but at such a low rate that the lightest supersymmetric particle would have a lifetime long enough to constitute the astrophysical cold dark matter.
The flatness of the inflaton potential and lightness of the Higgs could have the common origin of... more The flatness of the inflaton potential and lightness of the Higgs could have the common origin of the breaking of a global symmetry. This scenario provides a unified framework of Goldstone Inflation and Composite Higgs, where the inflaton and the Higgs both have a pseudo–Goldstone boson nature. The inflaton reheats the Universe via decays to the Higgs and subsequent secondary production of other SM particles via the top and massive vector bosons. We find that inflationary predictions and perturbative reheating conditions are consistent with CMB data for sub–Planckian values of the fields, as well as opening up the possibility of inflation at the TeV scale. We explore this exciting possibility, leading to an interplay between collider data cosmological constraints.
We show that General Relativity coupled to a quantum field theory generically leads to non-local ... more We show that General Relativity coupled to a quantum field theory generically leads to non-local effects in the matter sector. These non-local effects can be described by non-local higher dimensional operators which remarkably have an approximate shift symmetry. When applied to inflationary models, our results imply that small non-Gaussianities are a generic feature of models based on General Relativity coupled to matter fields. However, these effects are too small to be observable in the Cosmic Microwave Background.
Identifying the inflaton with a pseudo-Goldstone boson explains the flatness of its potential. Ad... more Identifying the inflaton with a pseudo-Goldstone boson explains the flatness of its potential. Additionally, successful Goldstone Inflation should be robust against UV corrections, such as from quantum gravity. In this paper we present the scenarios which lead to this successful model by examining the structure of Goldstone potentials arising from Coleman-Weinberg contributions. In particular, we notice that both bosonic and fermionic contributions are required to build a successful inflationary model. In single field inflation, we find that spinorial, and not fundamental, fermion representations can generate the right potential shape. This indicates that the Goldstone inflaton comes from the breaking of a SO(N) global symmetry. We also evaluate the constraints from higher-derivative interactions, finding that axiomatic constraints on Goldstone boson scattering prevail over the current CMB constraints on the speed of sound. We connect inflationary constraints to the UV completions for Goldstone Inflation, finding relations in the spectrum of new resonances. Finally, we present models of hybrid inflation, where both the inflaton and the waterfall fields share a common origin as Goldstones.
Slow-roll inflation requires the inflaton field to have an exceptionally flat potential, which co... more Slow-roll inflation requires the inflaton field to have an exceptionally flat potential, which combined with measurements of the scale of inflation demands some degree of fine-tuning. Alternatively, the flatness of the potential could be due to the inflaton's origin as a pseudo-Goldstone boson, as in Natural Inflation. Alas, consistency with Planck data places the original proposal of Natural Inflation in a tight spot, as it requires a trans-Planckian excursion of the inflaton. Although one can still tune the renormalizable potential to sub-Planckian values, higher order corrections from quantum gravity or sources of breaking of the Goldstone symmetry would ruin the predictivity of the model. In this paper we show how in more realistic models of Natural Inflation one could achieve inflation without a trans-Planckian excursion of the field. We show how a variant of Extra-natural inflation with bulk fermions can achieve the desired goal and discuss its four-dimensional duals. We also present a new type of four dimensional models inspired in Little Higgs and Composite Higgs models which can lead to sub-Planckian values of the inflaton field.
We discuss cosmological inflation in the minimal Wess-Zumino model with a single massive chiral s... more We discuss cosmological inflation in the minimal Wess-Zumino model with a single massive chiral supermultiplet. With suitable parameters and assuming a plausible initial condition at the start of the inflationary epoch, the model can yield scalar perturbations in the Cosmic Microwave Background (CMB) of the correct strength with a spectral index n_s ~ 0.96 and a tensor-to-scalar perturbation ratio r < 0.1, consistent with the Planck CMB data. We also discuss the possibility of topological inflation within the Wess-Zumino model, and the possibility of combining it with a seesaw model for neutrino masses. This would violate R-parity, but at such a low rate that the lightest supersymmetric particle would have a lifetime long enough to constitute the astrophysical cold dark matter.
Uploads
Papers by Djuna Croon
We explore this exciting possibility, leading to an interplay between collider data cosmological constraints.
We explore this exciting possibility, leading to an interplay between collider data cosmological constraints.