Physics / Fizik

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

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  • Article
    Citation - WoS: 4
    Citation - Scopus: 4
    Higher Curvature Quantum Gravity and Large Extra Dimensions
    (Elsevier Ltd., 2006) Demir, Durmuş Ali; Tanyıldızı, Şükrü Hanif
    We discuss effective interactions among brane matter induced by modifications of higher dimensional Einstein gravity via the replacement of Einstein-Hilbert term with a generic function f(R) of the curvature scalar R. After deriving the graviton propagator, we analyze impact of virtual graviton exchanges on particle interactions, and conclude that f(R) gravity effects are best probed by high-energy processes involving massive gauge bosons, heavy fermions or the Higgs boson. We perform a comparative analysis of the predictions of f(R) gravity and of Arkani-Hamed-Dvali-Dimopoulos (ADD) scenario, and find that the former competes with the latter when f″(0) is positive and comparable to the fundamental scale of gravity in higher dimensions. In addition, we briefly discuss graviton emission from the brane as well as its decays into brane-localized matter, and find that they hardly compete with the ADD expectations. Possible existence of higher-curvature gravitational interactions in large extra spatial dimensions opens up various signatures to be confronted with existing and future collider experiments.
  • Article
    Citation - WoS: 6
    Citation - Scopus: 6
    Generalized Modified Gravity in Large Extra Dimensions
    (Elsevier Ltd., 2006) Aslan, Önder; Demir, Durmuş Ali
    We discuss effective interactions among brane matter induced by modifications of higher-dimensional Einstein gravity through the replacement of Einstein-Hilbert term with a generic function f ( R, RA B RA B, RA B C D RA B C D ) of the curvature tensors. We determine gravi-particle spectrum of the theory, and perform a comparative analysis of its predictions with those of the Einstein gravity within Arkani-Hamed-Dvali-Dimopoulos (ADD) setup. We find that this general higher-curvature quantum gravity theory contributes to scatterings among both massive and massless brane matter (in contrast to much simpler generalization of the Einstein gravity, f ( R ), which influences only the massive matter), and therefore, can be probed via various scattering processes at present and future colliders and directly confronted with the ADD expectations. In addition to collision processes which proceed with tree-level gravi-particle exchange, effective interactions among brane matter are found to exhibit a strong sensitivity to higher-curvature gravity via the gravi-particle loops. Furthermore, particle collisions with missing energy in their final states are found to be sensitive to additional gravi-particles not found in Einstein gravity. In general, road to a correct description of quantum gravity above Fermi energies depends crucially on if collider and other search methods end up with a negative or positive answer for the presence of higher-curvature gravitational interactions.