A bstract We revisit the calculation of thermal free energy for string theory in three-dimensional anti-de Sitter spacetime with Neveu-Schwarz-Neveu-Schwarz flux. The path integral is exploited to confirm off-shell Hilbert space and we find that Casimir discrete representations isometry group takes values a half-open interval. extend case superstrings, calculate boundary toroidal twisted partit...

We describe a class of impulsive gravitational waves which propagate either in a de Sitter or an anti-de Sitter background. They are conformal to impulsive waves of Kundt’s class. In a background with positive cosmological constant they are spherical (but non-expanding) waves generated by pairs of particles with arbitrary multipole structure propagating in opposite directions. When the cosmolog...