29 citations · 158 across the 18 of their papers we have counts for
4 papers · 1 filter
Regular non-twisting S-branes
Octavio Obregon, Hernando Quevedo, Michael P. Ryan
We construct a family of time and angular dependent, regular S-brane solutions which corresponds to a simple analytical continuation of the Zipoy-Voorhees 4-dimensional vacuum spac…
The conformally invariant Laplace-Beltrami operator and factor ordering
Michael P. Ryan, Alexander V. Turbiner
In quantum mechanics the kinetic energy term for a single particle is usually written in the form of the Laplace-Beltrami operator. This operator is a factor ordering of the classi…
Time and "angular" dependent backgrounds from stationary axisymmetric solutions
Octavio Obregon, Hernando Quevedo, Michael P. Ryan
Backgrounds depending on time and on "angular" variable, namely polarized and unpolarized Gowdy models, are generated as the sector inside the horizons of the mani…
Duality Symmetry in Kaluza-Klein Dimensional Cosmological Model
J. A. Nieto, M. P. Ryan, O. Velarde +1
It is shown that, with the only exception of , the Einstein-Hilbert action in dimensions, with times, is invariant under the duality transformation $a\to \frac{1}{…