Abstract
We study the beam-energy and system-size dependence of φ{symbol} meson production (using the hadronic decay mode φ{symbol} → K+ K-) by comparing the new results from Cu + Cu collisions and previously reported Au + Au collisions at sqrt(sNN) = 62.4 and 200 GeV measured in the STAR experiment at RHIC. Data presented in this Letter are from mid-rapidity (| y | < 0.5) for 0.4 < pT < 5 GeV / c. At a given beam energy, the transverse momentum distributions for φ{symbol} mesons are observed to be similar in yield and shape for Cu + Cu and Au + Au colliding systems with similar average numbers of participating nucleons. The φ{symbol} meson yields in nucleus-nucleus collisions, normalized by the average number of participating nucleons, are found to be enhanced relative to those from p + p collisions. The enhancement for φ{symbol} mesons lies between strange hadrons having net strangeness =1 (K- and over(Λ, ̄)) and net strangeness =2 (Ξ). The enhancement for φ{symbol} mesons is observed to be higher at sqrt(sNN) = 200 GeV compared to 62.4 GeV. These observations for the produced φ{symbol} (s over(s, ̄)) mesons clearly suggest that, at these collision energies, the source of enhancement of strange hadrons is related to the formation of a dense partonic medium in high energy nucleus-nucleus collisions and cannot be alone due to canonical suppression of their production in smaller systems.
| Original language | English |
|---|---|
| Pages (from-to) | 183-191 |
| Number of pages | 9 |
| Journal | Physics Letters B |
| Volume | 673 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 23 2009 |
| Externally published | Yes |
Funding
We thank the RHIC Operations Group and RCF at BNL, and the NERSC Center at LBNL and the resources provided by the Open Science Grid consortium for their support. This work was supported in part by the Offices of NP and HEP within the US DOE Office of Science, the US NSF, the Sloan Foundation, the DFG Excellence Cluster EXC153 of Germany, CNRS/IN2P3, RA, RPL, and EMN of France, STFC and EPSRC of the United Kingdom, FAPESP of Brazil, the Russian Ministry of Sci. and Tech., the NNSFC, CAS, MoST, and MoE of China, IRP and GA of the Czech Republic, FOM of the Netherlands, DAE, DST, and CSIR of the Government of India, Swiss NSF, the Polish State Committee for Scientific Research, and the Korea Sci. & Eng. Foundation.
| Funders | Funder number |
|---|---|
| EMN | |
| MOE of China | |
| Polish State Committee for Scientific Research | |
| Russian Ministry of Sci | |
| Swiss NSF | |
| National Science Foundation | |
| Alfred P. Sloan Foundation | |
| Office of Science | |
| Engineering and Physical Sciences Research Council | |
| Science and Technology Facilities Council | PP/F001061/1 |
| Science and Technology Facilities Council | |
| Department of Science and Technology, Ministry of Science and Technology, India | |
| Council of Scientific and Industrial Research, India | |
| Department of Atomic Energy, Government of India | |
| Deutsche Forschungsgemeinschaft | EXC153 |
| Deutsche Forschungsgemeinschaft | |
| International Foundation for Research in Paraplegia | |
| Fundação de Amparo à Pesquisa do Estado de São Paulo | |
| National Natural Science Foundation of China | |
| Chinese Academy of Sciences | |
| Ministry of Science and Technology, Taiwan | |
| Centre National de la Recherche Scientifique | |
| Institut National de Physique Nucléaire et de Physique des Particules |
Keywords
- Canonical suppression
- Particle production
- Quark-gluon plasma
- Resonances
- Strangeness enhancement