Search results for "kosminen inflaatio"
showing 4 items of 4 documents
Despicable dark relics: generated by gravity with unconstrained masses
2019
We demonstrate the existence of a generic, efficient and purely gravitational channel producing a significant abundance of dark relics during reheating after the end of inflation. The mechanism is present for any inert scalar with the non-minimal curvature coupling $\xi R\chi^2$ and the relic production is efficient for natural values $\xi = {\cal O}(1)$. The observed dark matter abundance can be reached for a broad range of relic masses extending from $m \sim 1 {\rm k eV}$ to $m \sim 10^{8} {\rm GeV}$, depending on the scale of inflation and the dark sector couplings. Frustratingly, such relics escape direct, indirect and collider searches since no non-gravitational couplings to visible ma…
Higgs-Inflaton Mixing and Vacuum Stability
2019
The quartic and trilinear Higgs field couplings to an additional real scalar are renormalizable, gauge and Lorentz invariant. Thus, on general grounds, one expects such couplings between the Higgs and an inflaton in quantum field theory. In particular, the (often omitted) trilinear coupling is motivated by the need for reheating the Universe after inflation, whereby the inflaton decays into the Standard Model (SM) particles. Such a coupling necessarily leads to the Higgs-inflaton mixing, which could stabilize the electroweak vacuum by increasing the Higgs self-coupling. We find that the inflationary constraints on the trilinear coupling are weak such that the Higgs-inflaton mixing up to ord…
Higgs-like spectator field as the origin of structure
2021
We show that the observed primordial perturbations can be entirely sourced by a light spectator scalar field with a quartic potential, akin to the Higgs boson, provided that the field is sufficiently displaced from vacuum during inflation. The framework relies on the indirect modulation of reheating, which is implemented without any direct coupling between the spectator field and the inflaton and does not require non-renormalisable interactions. The scenario gives rise to local non-Gaussianity with $f_{\rm NL}\simeq 5$ as the typical signal. As an example model where the indirect modulation mechanism is realised for the Higgs boson, we study the Standard Model extended with right-handed neu…
Inflaatio ja rakenteiden synty
2016
Kosmologian standardimallina tunnettu LCDM-malli on vakiinnuttanut asemansa parhaana mahdollisena selityksenä viimeaikaisille kosmologisille havainnoille. Ilman ns. inflaatiovaihetta malli törmää kuitenkin varhaista maailmankaikkeutta koskeviin vakaviin ongelmiin. Se ei kykene antamaan selitystä avaruuden laakeudelle, taustasäteilyn tasaisuudelle, raskaiden reliikkihiukkasten puuttumiselle ja taustasäteilyn anisotropioille. Edellä mainittujen ongelmien ratkaisuksi on esitetty kosmologista inflaatiota, jonka mukaan hyvin varhainen maailmankaikkeus on käynyt läpi kehitysvaiheen, jossa sen koko kasvoi lähes eksponentiaalisesti. Tässä pro gradu -tutkielmassa perehdytään lähdeaineiston avulla in…