Figure. K/Pi ratio at midrapidity as a function of sqrt(s). The curves are a
parameterization of the pp data. The STAR data points are indicated by the
caps and the STAR K^{+}/pi ratio is displaced slightly to clarity.

Systematics of the K/pi ratio
Kaons carry ~90% of the strange quarks produced in a collision hence the
K/pi ratio can be used to study strangeness production and the possibility
of strangeness enhancement. As the pi^{+}yield^{ }~
pi^{} yield it is possible to compare the STAR
K^{+}/pi^{} results to lower energy results on the
K^{+}/pi^{+}. The K^{}/pi ratio can be seen to
rise smoothly with sqrt(s) while that of K^{+}/pi in heavy ion
collisions increases sharply at low energies reaching a maximum at
sqrt(s)~10GeV before slowly dropping. At sqrt(s)=130 GeV the
K^{+}/pi ~K^{}/pi. The peak is determined by the dropping
net baryon value combining with increasing K antiK pair production.
Similar behaviour is observed in the strange baryon ratios. Comparisons to
the pp data at sqrt(s)=130 GeV shows a 50% increase in the STAR
(K^{+}+K^{)}/2*<pi> ratio.
Related STAR papers
Kaon Production and Kaon to Pion Ratio in Au + Au Collisions at sqrt(s_{nn}) = 130 GeV
Phys. Lett. B 595 (2004) 143
ePrint Archives (nuclex/0206008):
Abstract 
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Journal article:
Phys. Lett. B server
