Multistrange Hyperon Production in Pb+Pb collisions at 30, 40, 80 and 158 A ⋅ GeV
Abstract
A non-monotonic energy dependence of the
K
+
/
π
+
ratio with a sharp maximum close to 30 A
⋅
GeV is observed in central Pb+Pb collisions. Within a statistical model of the early stage, this is interpreted as a sign of the phase transition to a QGP, which causes a sharp change in the energy dependence of the strangeness to entropy ratio. This observation naturally motivates us to study the production of multistrange hyperons (
Ξ
,
Ω
) as a function of the beam energy. Furthermore it was suggested that the kinematic freeze-out of
Ω
takes place directly at QGP hadronization. If this is indeed the case, the transverse momentum spectra of the
Ω
directly reflect the transverse expansion velocity of a hadronizing QGP. In this report we show preliminary NA49 results on
Ω
−
and
Ω
¯
+
production in central Pb+Pb collisions at 40 and 158 A
⋅
GeV and compare them to measurements of
Ξ
−
and
Ξ
¯
+
production in central Pb+Pb collisions at 30, 40, 80 and 158 A
⋅
GeV.