We study the presence of chaotic behavior in phase space in the
pre-inflationary stage of hybrid inflation models. This is closely related to
the problem of initial conditions associated to these inflationary type of
models. We then show how an expected dissipative dynamics of fields just before
the onset of inflation can solve or ease considerably the problem of initial
conditions, driving naturally the system towards inflation. The chaotic
behavior of the corresponding dynamical system is studied by the computation of
the fractal dimension of the boundary, in phase space, separating inflationary
from non-inflationary trajectories. The fractal dimension for this boundary is
determined as a function of the dissipation coefficients appearing in the
effective equations of motion for the fields.Comment: 10 pages, 4 eps figures (uses epsf), Revtex. Replaced with version to
match one in press Physical Review
