Prof. Aharon Davidson
Born: 1947, Israel
Academic Qualifications:
    M.Sc. 1974, Technion
    Ph.D. 1977, Technion
    Professor 1990, BGU.
Academic Positions:
Department of Physics - Professor
Research Interests:
Brane Gravity, Classical Quantum Cosmology, Kaluza-Klein/Dilaton Gravity, Grand Unifying Theories, Electro/Nuclear Interactions.
Research Projects:
Black Hole Horizon Phase Transition in Spontaneously Induced Gravity, Zero Cosmological Constant from Normalized General Relativity, Dirac Relaxation of the Israel Junction Conditions in Unified Brane Gravity, Dirac Quantization of the Pais-Uhlenbeck Fourth Order Oscillator.
Abstracts of Current Research:
  • Brane Gravitational Extension of Dirac''s "Extensible Model of the Electron": A gravitational extension of Dirac''s "Extensible model of the electron" is presented. The Dirac bubble, treated as a 3-dimensional electrically charged brane, is dynamically embedded within a 4-dimensinal Z2-symmetric Reissner-Nordstrom bulk. Crucial to our analysis is the gravitational extension of Dirac''s brane variation prescription; its major effect is to induce a novel geometrically originated contribution to the energy-momentum tensor on the brane. In turn, the effective potential which governs the evolution of the bubble exhibits a global minimum, such that the size of the bubble stays finite (Planck scale) even at the limit where the mass approaches zero. This way, without fine-tuning, one avoids the problem so-called ''classical radius of the electron''
  • Zero Cosmological Constant from Normalized General Relativity: Normalizing the Einstein-Hilbert action by the volume functional makes the theory invariant under constant shifts in the Lagrangian. The associated field equations then resemble unimodular gravity whose otherwise arbitrary cosmological constant is now determined as a Machian universal average. We prove that an empty space-time is necessarily Ricci tensor flat, and demonstrate the vanishing of the cosmological constant within the scalar field paradigm. The cosmological analysis, carried out at the mini-superspace level, reveals a vanishing cosmological constant for a Universe which cannot be closed as long as gravity is attractive. Finally, we give an example of a normalized theory of gravity which does give rise to a non-zero cosmological constant.n and the shift vector, the corresponding quadratic Hamiltonian is constructed and a bifurcated Wheeler-Dewitt-like equation is derived. The inclusion of matter resembles minimal coupling.Einstein gravity, associated with the novel Lagrange multiplier being a certain 4-fold degenerate eigenvalue of the density matrix, is simly characterized by a vanishing center-of-mass momentum.
  • Unified Brane Gravity: Artifact Dark Matter from a Scale Dependent Newton Constant: We analyze, within the framework of unified brane gravity, the weak field perturbations caused by the presence of matter on a 3-brane. Although deviating from the Randall-Sundrum approach, the masslessness of the graviton is still preserved. In particular, the 4-dimensional Newton force law is recovered, but serendipitously, the corresponding Newton constant is shown to be necessarily lower than the one which governs FRW cosmology. This has the potential to puzzle out cosmological dark matter. A subsequent conjecture concerning galactic dark matter follows.
Publications:
  • I. Gurwich, S. Rubin, A. Davidson. On the Problem of Vacuum Energy in Brane Theories Physics Letters B 679: 515 (2009)
  • I. Gurwich, A. Davidson. Unified brane gravity: Artifact dark matter from a scale dependent Newton constant} Physical Review D 80: (2009)
  • A. Davidson, D.P. George, A. Kobakhidze, R.R. Volkas, K.C. Wali. SU(5) Grand Uniļ¬cation on a Domain-Wall Brane from E(6) Invariant Action Physical Review D 77: 085031 (2008)
  • A. Davidson, I. Gurwich. Radiation Driven Inflation Journal of Cosmology and Astroparticle Physics 6: 1 (2008)
  • Davidson, A., Gurwich, I.. Dirac Relaxation of the Israel Junction Conditions: Unified Randall-Sundrum Brane Theory Physical Review D 74: 044023 (2006)
  • Davidson, A., Mannheim. P.. Dirac Quantization of the Pais-Uhlenbeck Fourth Order Oscillator Physical Review A 71: 042110 (2005)
  • Davidson, A.. Rippled Cosmological Dark Matter from Damped Oscillating Newton Constant Classical and Quantum Gravity 22: 1119 (2005)
  • Dando, G., Davidson, A., George, D.P., Volkas, R.R., Wali, K.C.. The Clash of Symmetries in a Randall-Sundrum-like Spacetime Physical Review D 72: 045016 (2005)
  • Davidson, A., Gurwich, I.. Spontaneously Induced Gravity: From Rippled Dark Matter to Einstein Corpuscles Proccedings of Science (HEP2005) 010: 1 (2005)
  • Davidson, A., Karasik, D., Lederer, Y.. Geodetic Evolution and Nucleation of de-Sitter Brane Physical Review D 72: 064011 (2005)
  • Davidson, A., Karasik, D.. Brane Variation Dirac Style Classical and Quantum Gravity 21: 1295 (2004)
  • Davidson, A., Karasik, D.. Geodetic Brane Gravity Physical Review D 67: 064012 (2003)
  • Davidson, A., Toner, B.F., Volkas, R.R., Wali, K.C.. Clash of Symmetries on the Brane Physical Review D 65: 125013 (2002)
  • Davidson, A.. Cosmology of a Brane-like universe Class. Quan. Grav 16: 653 (1999)
  • Davidson, A., Shwartz, T. & Wali, K.C.. Light-Heavy symmetry: Geometric Mass Hierarchy for ThreeLight-Heavy symmetry: Geometric Mass Hierarchy for Three Families Jour. Phys. G 24: 55 (1998)
Keywords:Cosmological Constant, Quantum Gravity, Dark Matter, Black Hole, Cosmic Strings/Branes, Quarks/Leptons, Unification.
Phones:
  1. Phone: 08-6461649
  2. Fax: 08-6472904
  3. Home: 08-6518104
Email:davidson@bgu.ac.il