We report new results on identified (anti)proton and charged pion spectra at large transverse momenta (3<$p_{T}$<10 GeV/c) from Cu+Cu collisions at $\sqrt{s_{NN}}$=200 GeV using the STAR detector at the Relativistic Heavy Ion Collider (RHIC). This study explores the system size dependence of two novel features observed at RHIC with heavy ions: the hadron suppression at high-$p_{T}$ and the anomalous baryon to meson enhancement at intermediate transverse momenta. Both phenomena could be attributed to the creation of a new form of QCD matter. The results presented here bridge the system size gap between the available pp and Au+Au data, and allow the detailed exploration for the on-set of the novel features. Comparative analysis of all available 200 GeV data indicates that the system size is a major factor determining both the magnitude of the hadron spectra suppression at large transverse momenta and the relative baryon to meson enhancement.
Transverse momentum spectra of pions (a) and protons (b) produced in Cu+Cu collisions at $\sqrt{s_{NN}}$=200 GeV. Data are presented for four centrality classes: 0-10%, 10-20%, 20-40% and 40-60%. Closed and open symbols are used for particles and antiparticles, respectively. For clarity, data are separated by powers of four.
Transverse momentum spectra of pions (a) and protons (b) produced in Cu+Cu collisions at $\sqrt{s_{NN}}$=200 GeV. Data are presented for four centrality classes: 0-10%, 10-20%, 20-40% and 40-60%. Closed and open symbols are used for particles and antiparticles, respectively. For clarity, data are separated by powers of four.
Anti-particle to particle ratios, as a function of transverse momentum for pions (a) and protons (b). Data for the four centrality classes show little centrality dependence. Errors are statistical only.
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