Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

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

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Publisher: search.filters.publisher.IOP Publishing Ltd.Subject: search.filters.subject.Vacuum energy

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  • Article
    Citation - WoS: 12
    Citation - Scopus: 12
    Eddington's Gravity in Immersed Spacetime
    (IOP Publishing Ltd., 2015) Azri, Hemza; Azri, Hemza; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    We formulate Eddington's affine gravity in a spacetime that is immersed in a larger eight-dimensional space endowed with a hypercomplex structure. The dynamical equation of the first immersed Ricci-type tensor leads to gravitational field equations which include matter. We also study the dynamical effects of the second Ricci-type tensor when added to the Lagrangian density. A simple Lagrangian density constructed from a combination of the standard Ricci tensor and a new tensor field that appears due to the immersion, leads to gravitational equations in which the vacuum energy gravitates with a different cosmological strength as in Demir (2014 Phys. Rev. D 90 064017), rather than with Newton's constant. As a result, the tiny observed curvature is reproduced due to large hierarchies rather than fine tuning.
  • Article
    Boundary Shape and Casimir Energy
    (IOP Publishing Ltd., 2009) Ahmedov, Hacı; Duru, İsmail Hakkı; 04.02. Department of Mathematics; 04. Faculty of Science; 01. Izmir Institute of Technology
    Casimir energy changes are investigated for geometries obtained by small but arbitrary deformations of a given geometry for which the vacuum energy is already known for the massless scalar field. As a specific case, deformation of a spherical shell is studied. From the deformation of the sphere we show that the Casimir energy is a decreasing function of the surface-to-volume ratio. The decreasing rate is higher for less smooth deformations.
  • Article
    Citation - WoS: 7
    Citation - Scopus: 8
    A Way To Get Rid of Cosmological Constant and Zero-Point Energy Problems of Quantum Fields Through Metric Reversal Symmetry
    (IOP Publishing Ltd., 2008) Erdem, Recai; Erdem, Recai; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    In this paper, a framework is introduced to remove the huge discrepancy between the empirical value of the cosmological constant and the contribution to the cosmological constant predicted from the vacuum energy of quantum fields. An extra-dimensional space with metric reversal symmetry and R2 gravity (that reduces to the usual R gravity after integration over extra dimensions) is considered to this end. The resulting four-dimensional energy-momentum tensor (obtained after integration over extra dimensions) consists of terms that contain off-diagonally coupled pairs of Kaluza-Klein modes. This, in turn, generically results in the vanishing of the vacuum expectation value of the energy-momentum tensor for quantum fields, and offers a way to solve the problem of huge contribution of quantum fields to the vacuum energy density.