157 citations · 245 across the 4 of their papers we have counts for
4 papers
Unitarity in the Presence of Closed Timelike Curves
Lorenzo Cornalba, Miguel S. Costa
We conjecture that, in certain cases, quantum dynamics is consistent in the presence of closed timelike curves. We consider time dependent orbifolds of three dimensional Minkowski…
Time-dependent Orbifolds and String Cosmology
Lorenzo Cornalba, Miguel S. Costa
In these lectures, we review the physics of time-dependent orbifolds of string theory, with particular attention to orbifolds of three-dimensional Minkowski space. We discuss the p…
On the Classical Stability of Orientifold Cosmologies
L. Cornalba, M. S. Costa
We analyze the classical stability of string cosmologies driven by the dynamics of orientifold planes. These models are related to time-dependent orbifolds, and resolve the orbifol…
Superstring dualities and p-brane bound states
M. S. Costa, G. Papadopoulos
We show that the M-theory/IIA and IIA/IIB superstring dualities together with the diffeomorphism invariance of the underlying theories require the presence of certain p-brane bound…