Resolving the Antibaryon-Production Puzzle in High-Energy Heavy-Ion Collisions

We argue that the observed antiproton production in heavy-ion collisions at CERN-SPS energies can be understood if (contrary to most sequential scattering approaches) the backward direction in the process pp̄↔n̄π (with n̄0ex0ex=0ex0ex5--6) is consistently accounted for within a thermal framework. Employing the standard picture of subsequent chemical and thermal freezeout, which induces an oversaturation of pion number with associated chemical potentials of μ_π60--80MeV, enhances the backward reaction substantially. The resulting rates turn out to be large enough to maintain an antiproton abundance at thermal freezeout in accordance with the measured p̄/p ratio in Pb(158A0ex0exGeV)+Pb collisions.