Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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  • Article
    Citation - WoS: 154
    Citation - Scopus: 154
    Higgs-Palatini Inflation and Unitarity
    (Elsevier Ltd., 2011) Bauer, Florian; Demir, Durmuş Ali; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    In the Higgs inflation scenario the Higgs field is strongly coupled to the Ricci scalar in order to drive primordial inflation. However, in its original form in pure metric formulation of gravity, the ultraviolet (UV) cutoff of the Higgs interactions and the Hubble rate are of the same magnitude, and this makes the whole inflationary evolution dependent of the unknown UV completion of the Higgs sector. This problem, the unitarity violation, plagues the Higgs inflation scenario. In this Letter we show that, in the Palatini formulation of gravitation, Higgs inflation does not suffer from unitarity violation since the UV cutoff lies parametrically much higher than the Hubble rate so that unknown UV physics does not disrupt the inflationary dynamics. Higgs-Palatini inflation, as we call it, is, therefore, UV-safe, minimal and endowed with predictive power.
  • Article
    Citation - WoS: 232
    Citation - Scopus: 233
    Inflation With Non-Minimal Coupling: Metric Vs. Palatini Formulations
    (Elsevier Ltd., 2008) Bauer, Florian; Demir, Durmuş Ali; Demir, Durmuş Ali; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    We analyze non-minimally coupled scalar field theories in metric (second-order) and Palatini (first-order) formalisms in a comparative fashion. After contrasting them in a general setup, we specialize to inflation and find that the two formalisms differ in their predictions for various cosmological parameters. The main reason is that dependencies on the non-minimal coupling parameter are different in the two formalisms. For successful inflation, the Palatini approach prefers a much larger value for the non-minimal coupling parameter than the Metric approach. Unlike the Metric formalism, in Palatini, the inflaton stays well below the Planck scale whereby providing a natural inflationary epoch. © 2008 Elsevier B.V. All rights reserved.