  The top quark has been discovered in 1995 by the CDF and D0 experiments
located at the two beam-crossing points at the Tevatron ppbar collider. The top
quark is the most massive of the known elementary particles. At hadron-hadron
colliders, top quarks are mostly produced in pairs through strong interactions.
The measurement of the cross section for top quark pair production is a test of
our understanding of QCD prediction at next-to-leading order (NLO). This
measurement requires a deep understanding of the backgrounds to top quark
production, thus setting the ground for the measurements of top quark intrinsic
properties. Finally, measuring sigma(ttbar) allows to set limits on new physics
models that predict new particles coupling to the most recently discovered
quark. The top quark discovery needed only few tens of p-1 . The Tevatron
integrated luminosity is now about 9 fb-1 , more than two orders of magnitude
larger. In this document I will present some of the latest measurements of
total and differential cross sections for top quark pair production performed
by the CDF and D0 collaborations, that analyze up to about 6 fb-1 to provide a
refined understanding of this extremely interesting particle. The
identification of hadronic jets with sub- structure is thought to be a crucial
tool towards the search for new phenomena at the Large Hadron Collider (LHC)
proton-proton collisions at >= 7 TeV using the CMS and ATLAS detectors. The
first search for highly boosted top quarks has been performed by CDF and is
presented here.
