Initial conditions in hybrid inflation: exploration by MCMC technique
  In hybrid inflation, initial field values leading to sufficiently long
inflation were thought be fine-tuned in a narrow band along the inflationary
valley. A re-analysis of this problem has shown that there exists a non
negligible proportion of successful initial conditions exterior to the valley,
organized in a complex structure with fractal boundaries, and whose origin has
been explained. Their existence in a large part of the parameter space has been
demonstrated using a bayesian Monte-Carlo-Markov-Chain (MCMC) method, and
natural bounds on potential parameters have been established. Moreover, these
results are shown to be valid not only for the original hybrid model, but also
for other hybrid realizations in various frameworks.
