3 research outputs found
Supersymmetric Intersecting Branes on the Waves
We construct a general family of supersymmetric solutions in time- and
space-dependent wave backgrounds in general supergravity theories describing
single and intersecting p-branes embedded into time-dependent dilaton-gravity
plane waves of an arbitrary (isotropic) profile, with the brane world-volume
aligned parallel to the propagation direction of the wave. We discuss how many
degrees of freedom we have in the solutions. We also propose that these
solutions can be used to describe higher-dimensional time-dependent "black
holes", and discuss their property briefly.Comment: 12 pages, LaTe
Accelerating Universes in String Theory via Field Redefinition
We study cosmological solutions in the effective heterotic string theory with
-correction terms in string frame. It is pointed out that the
effective theory has an ambiguity via field redefinition and we analyze
generalized effective theories due to this ambiguity. We restrict our analysis
to the effective theories which give equations of motion of second order in the
derivatives, just as "Galileon" field theory. This class of effective actions
contains two free coupling constants. We find de Sitter solutions as well as
the power-law expanding universes in our four-dimensional Einstein frame. The
accelerated expanding universes are always the attractors in the present
dynamical system.Comment: 22 pages, 3 figures, some additional formulae adde