Physics / Fizik

Permanent URI for this collectionhttps://hdl.handle.net/11147/6

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COAR Access Rights: search.filters.coarAccessRights.open accessSubject: search.filters.subject.Induced gravity

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  • Article
    Citation - WoS: 22
    Citation - Scopus: 24
    Are There Really Conformal Frames? Uniqueness of Affine Inflation
    (World Scientific Publishing Co. Pte Ltd, 2018) Azri, Hemza
    Here, we concisely review the nonminimal coupling dynamics of a single scalar field in the context of purely affine gravity and extend the study to multifield dynamics. The coupling is performed via an affine connection and its associated curvature without referring to any metric tensor. The latter arises a posteriori and it may gain an emergent character like the scale of gravity. What is remarkable in affine gravity is the transition from nonminimal to minimal couplings which is realized by only field redefinition of the scalar fields. Consequently, the inflationary models gain a unique description in this context where the observed parameters, like the scalar tilt and the tensor-to-scalar ratio, are invariant under field reparametrization. Overall, gravity in its affine approach is expected to reveal interesting and rich phenomenology in cosmology and astroparticle physics.
  • Article
    Citation - WoS: 26
    Citation - Scopus: 26
    Induced Affine Inflation
    (American Physical Society, 2018) Azri, Hemza; Demir, Durmuş Ali
    Induced gravity, metrical gravity in which gravitational constant arises from vacuum expectation value of a heavy scalar, is known to suffer from Jordan frame vs Einstein frame ambiguity, especially in inflationary dynamics. Induced gravity in affine geometry, as we show here, leads to an emergent metric and gravity scale, with no Einstein-Jordan ambiguity. While gravity is induced by the vacuum expectation value of the scalar field, nonzero vacuum energy facilitates generation of the metric. Our analysis shows that induced gravity results in a relatively large tensor-to-scalar ratio in both metrical and affine gravity setups. However, the fact remains that the induced affine gravity provides an ambiguity-free framework.