Charged kaon and pion production at midrapidity in proton-nucleus and sulphur-nucleus collisions

Citation
H. Boggild et al., Charged kaon and pion production at midrapidity in proton-nucleus and sulphur-nucleus collisions, PHYS REV C, 59(1), 1999, pp. 328-335
Citations number
30
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
PHYSICAL REVIEW C-NUCLEAR PHYSICS
ISSN journal
0556-2813 → ACNP
Volume
59
Issue
1
Year of publication
1999
Pages
328 - 335
Database
ISI
SICI code
0556-2813(199901)59:1<328:CKAPPA>2.0.ZU;2-J
Abstract
The NA44 Collaboration has measured charged kaon and pion distributions at midrapidity in sulphur and proton collisions with nuclear targets at 200 an d 450 GeV/c per nucleon, respectively. The inverse slopes of kaons, are lar ger than those of pions. The difference in the inverse slopes of pions, kao ns, and protons, all measured in our spectrometer, increases with system si ze and is consistent with the buildup of collective flow for larger systems . The target dependence of both the yields and inverse slopes is stronger f or the sulphur beam, suggesting the increased importance of secondary resca ttering for SA reactions. The rapidity density dN/dy of both K+ and K- incr eases more rapidly with system size than for pi(+) in a similar rapidity re gion. This trend continues with increasing centrality, and according to RQM D, it is caused by secondary reactions between mesons and baryons. The K-/K + ratio falls with increasing system size but more slowly than the (p) over bar/p ratio. The pi(-)/pi(+) ratio is close to unity for all systems. From pBe to SPb the K+/p ratio decreases while K-/(p) over bar increases and ro ot((K+.K-)/(p.(p) over bar)) stays constant. These data suggest that as lar ger nuclei collide, the resulting system has a larger transverse expansion and baryon density and an increasing fraction of strange quarks. [S0556-281 3(99)02201-3].