engleski

Study of ϕ-meson production in p+Al, p+Au, d+Au, and 3He+Au collisions at sqrt(s_NN)=200 GeV

Small nuclear collisions are mainly sensitive to cold-nuclear-matter effects ; however, the collective behavior observed in these collisions shows a hint of hot-nuclear-matter effects. The identified-particle spectra, especially the ϕ mesons which contain strange and antistrange quarks and have a relatively small hadronic- interaction cross section, are a good tool to study these effects. The PHENIX experiment has measured ϕ mesons in a specific set of small collision systems p+Al, p+Au, and 3He+Au, as well as d+Au [Phys. Rev. C {;\bf 83};, 024909 (2011)], at sNN−−−√=200 GeV. The transverse-momentum spectra and nuclear-modification factors are presented and compared to theoretical-model predictions. The comparisons with different calculations suggest that quark-gluon plasma may be formed in these small collision systems at sNN−−−√=200 GeV. However, the volume and the lifetime of the produced medium may be insufficient for observing strangeness-enhancement and jet-quenching effects. Comparison with calculations suggests that the main production mechanisms of ϕ mesons at midrapidity may be different in p+Al versus p/d/3He+Au collisions at sNN−−−√=200 GeV. While thermal quark recombination seems to dominate in p/d/3He+Au collisions, fragmentation seems to be the main production mechanism in p+Al collisions.

phi meson, 200 GeV, PHENIX, RHIC

nije evidentirano