## Abstract

Scale invariance is considered in the context of gravitational theories where the action, in the first order formalism, is of the form S = ∫ L_{1} Φ d^{4}x + ∫ L_{2} √ - g d^{4}x where the volume element Φ d^{4}x is independent of the metric. For global scale invariance, a "dilaton" φ has to be introduced, with non-trivial potentials V(φ) = f_{1} e^{αφ} L_{1} and U(φ) = f_{2} e^{2αφ} in L_{2}. This leads to non-trivial mass generation and a potential for φ 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 Φ d^{4}x alone. For closed strings and brunes (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.

Original language | English |
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Pages (from-to) | 1019-1037 |

Number of pages | 19 |

Journal | Foundations of Physics |

Volume | 31 |

Issue number | 7 |

DOIs | |

State | Published - 1 Jan 2001 |

## ASJC Scopus subject areas

- Physics and Astronomy (all)