  We analyse strangeness production in proton-proton (pp) collisions at SPS and
RHIC energies, using the recently advanced NeXus approach. After having
verified that the model reproduces well the existing data, we interpret the
results: strangeness is suppressed in proton-proton collisions at SPS energy as
compared to electron-positron (e+e-) annihilation due to the limited masses of
the strings produced in the reaction, whereas high energy pp and e+e-
collisions agree quantitatively . Thus strangeness suppression at SPS energies
is a consequence of the limited phase-space available in string fragmentation.
