  We give an explicit expression for the contact loci of hyperplane
arrangements and show that their cohomology rings are combinatorial invariants.
We also give an expression for the restricted contact loci in terms of Milnor
fibers of associated hyperplane arrangements. We prove the degeneracy of a
spectral sequence related to the restricted contact loci of a hyperplane
arrangement and which conjecturally computes algebraically the Floer cohomology
of iterates of the Milnor monodromy. We give formulas for the Betti numbers of
contact loci and restricted contact loci in generic cases.
