We report 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 at $\sqrt{s_{NN}}$=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 $\sqrt{s_{NN}}$=200 GeV. However, the volume and the lifetime of the produced medium may be insufficient for observing strangeness-enhancement and jet-quenching effects. The 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 $\sqrt{s_{NN}}$=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.
There is strong evidence for the formation of small droplets of quark-gluon plasma in p/d/He3+Au collisions at the Relativistic Heavy Ion Collider (RHIC) and in p+p/Pb collisions at the Large Hadron ...Collider. In particular, the analysis of data at RHIC for different geometries obtained by varying the projectile size and shape has proved insightful. In the present analysis, we find excellent agreement with the previously published PHENIX at RHIC results on elliptical and triangular flow with an independent analysis via the two-particle correlation method, which has quite different systematic uncertainties and an independent code base. In addition, the results are extended to other detector combinations with different kinematic (pseudorapidity) coverage. These results provide additional constraints on contributions from nonflow and longitudinal decorrelations.
There is strong evidence for the formation of small droplets of quark-gluon plasma in p/d/He3+Au collisions at the Relativistic Heavy Ion Collider (RHIC) and in p+p/Pb collisions at the Large Hadron ...Collider. In particular, the analysis of data at RHIC for different geometries obtained by varying the projectile size and shape has proved insightful. In the present analysis, we find excellent agreement with the previously published PHENIX at RHIC results on elliptical and triangular flow with an independent analysis via the two-particle correlation method, which has quite different systematic uncertainties and an independent code base. In addition, the results are extended to other detector combinations with different kinematic (pseudorapidity) coverage. These results provide additional constraints on contributions from nonflow and longitudinal decorrelations.
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