44,664 research outputs found

    B\"acklund transformations in 2D dilaton gravity

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    We give a B\"acklund transformation connecting a generic 2D dilaton gravity theory to a generally covariant free field theory. This transformation provides an explicit canonical transformation relating both theories.Comment: LaTeX file, 7 page

    Virasoro Orbits, AdS_3 Quantum Gravity and Entropy

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    We analyse the canonical structure of AdS_3 gravity in terms of the coadjoint orbits of the Virasoro group. There is one subset of orbits, associated to BTZ black hole solutions, that can be described by a pair of chiral free fields with a background charge. There is also a second subset of orbits, associated to point-particle solutions, that are described by two pairs of chiral free fields obeying a constraint. All these orbits admit K\"ahler quantization and generate a Hilbert space which, despite of having Δ0(Δˉ0)=0\Delta_0(\bar{\Delta}_0)=0, does not provide the right degeneracy to account for the Bekenstein-Hawking entropy due to the breakdown of modular invariance. Therefore, additional degrees of freedom, reestablishing modular invariance, are necessarily required to properly account for the black hole entropy.Comment: LaTex file, 12 pages. New references adde

    Minimal mass-size of a stable 3He cluster

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    The minimal number of 3He atoms required to form a bound cluster has been estimated by means of a Diffusion Monte Carlo procedure within the fixed-node approximation. Several importance sampling wave functions have been employed in order to consider different shell-model configurations. The resulting upper bound for the minimal number is 32 atoms.Comment: 2 pages, no figure
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