Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

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

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Scopus Q: search.filters.scopusQuartile.Q2Subject: search.filters.subject.Vacuum energy

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  • Article
    Citation - WoS: 10
    Citation - Scopus: 11
    Separate Einstein-Eddington Spaces and the Cosmological Constant
    (John Wiley and Sons Inc., 2016) Azri, Hemza
    Based on Eddington affine variational principle on a locally product manifold, we derive the separate Einstein space described by its Ricci tensor. The derived field equations split into two field equations of motion that describe two maximally symmetric spaces with two cosmological constants. We argue that the invariance of the bi-field equations under projections on the separate spaces, may render one of the cosmological constants to zero. We also formulate the model in the presence of a scalar field. The resulted separate Einstein-Eddington spaces maybe considered as two states that describe the universe before and after inflation. A possibly interesting affine action for a general perfect fluid is also proposed. It turns out that the condition which leads to zero cosmological constant in the vacuum case, eliminates here the effects of the gravitational mass density of the perfect fluid, and the dynamic of the universe in its final state is governed by only the inertial mass density of the fluid.
  • Article
    Boundary Shape and Casimir Energy
    (IOP Publishing Ltd., 2009) Ahmedov, Hacı; Duru, İsmail Hakkı
    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
    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.