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Abstract:
Scale invariance is considered in the context of gravitational theories where the action, in the first order formalism, is of the form S=L1Φd4xS = \int L_{1} \Phi d^4x + L2gd4x\int L_{2}\sqrt{-g}d^4x where the volume element Φd4x\Phi d^4x is independent of the metric. For global scale invariance, a "dilaton" ϕ\phi has to be introduced, with non-trivial potentials V(ϕ)V(\phi) = f1eαϕf_{1}e^{\alpha\phi} in L1L_1 and U(ϕ)U(\phi) = f2e2αϕf_{2}e^{2\alpha\phi} in L2L_2. This leads to non-trivial mass generation and a potential for ϕ\phi which is interesting for inflation. Interpolating models for natural transition from inflation to a slowly accelerated universe at late times appear naturally. This is also achieved for "Quintessential models", which are scale invariant but formulated with the use of volume element Φd4x\Phi d^4x alone. For closed strings and branes (including the supersymmetric cases), the modified measure formulation is possible and does not require the introduction of a particular scale (the string or brane tension) from the begining but rather these appear as integration constants.
  • talk: Ramat Gan 2000/06/26
  • gravitation: action
  • gravitation: induced
  • field theory: scalar
  • field equations
  • inflation
  • invariance: conformal
  • string model
  • membrane model
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