We study the energy dependence of the transverse momentum $(p_T)$ spectra for charged pions, protons and anti-protons for Au+Au collisions at $\sqrt{S_{NN}$=62.4 and 200 GeV. Data are presented at ...mid-rapidity (|y|<0.5) for $0.2\le p_T\le12 $ GeV/c . In the intermediate $p_T$ region $(0.2\le p_T\le 6 GeV/c$ ), the nuclear modification factor is higher at 62.4 GeV than at 200 GeV, while at higher $p_T (p_T\ge 7 GeV/c)$ the modification is similar for both energies. The p/$\pi+$ and $\bar{p} \pi^-$ ratios for central collisions at $\sqrt{S_{NN}}$ =62.4 GeV/c peak at $p_t \appeq 2 Gev/c$ . In the $p_T$ range where recombination is expected to dominate, the p/$\pi + ratios at 62.4 GeV are larger than at 200 GeV, while the $\bar{p}$/$\pi _-} ratios are smaller. For $p_T$, the $\bar{p} /\pi_-$ ratios at the two beam energies are independent of $p_T$ and centrality indicating that the dependence of the $\bar{p}:\pi_-$ ratio on $p_T$ does not change between 62.4 and 200 GeV. These findings challenge various models incorporating jet quenching and/or constituent quark coalescence
Transverse momentum spectra of pi(+/-), p, and (p) over bar p up to 12 GeV/c at midrapidity in centrality selected Au + Au collisions at root s(NN) = 200 GeV are presented. In central Au + Au ...collisions, both pi(+/-) and p((p) over bar) show significant suppression with respect to binary scaling at p(T) greater than or similar to 4 GeV/c. Protons and antiprotons are less suppressed than pi(+/-), in the range 1.5 less than or similar to p(T) less than or similar to 6 GeV/c. The pi(-)/pi(+) and (p) over bar /p ratios show at most a weak pT dependence and no significant centrality dependence. The p/pi ratios in central Au + Au collisions approach the values in p + p and d + Au collisions at p(T) greater than or similar to 5 GeV/c. The results at high p(T) indicate that the partonic sources of pi(+/-), p, and (p) over bar have similar energy loss when traversing the nuclear medium
The Fourier harmonics, \(v_2\) and \(v_3\) of negative pions are measured at center-of-mass energy per nucleon pair of \(\sqrt{s_{\mathrm{NN}}}\)= 17.3 GeV around midrapidity by the CERES/NA45 ...experiment at the CERN SPS in 0--30% central PbAu collisions with a mean centrality of 5.5%. The analysis is performed in two centrality bins as a function of the transverse momentum \(\mathrm{p_{\mathrm{T}}}\) from 0.05 GeV/\(c\) to more than 2 GeV/\(c\). This is the first measurement of the \(v^{1/3}_{3}/v^{1/2}_{2}\) ratio as a function of transverse momentum at SPS energies. For \(\mathrm{p_{\mathrm{T}}}\) above 0.5 GeV/\(c\), the ratio is nearly flat in accordance with the hydrodynamic prediction and as previously observed by the ATLAS and ALICE experiments at the much higher LHC energies. The results are also compared with the SMASH-vHLLE hybrid model predictions.
We present
π
−
Ξ
correlation analysis in Au-Au collisions at
S
N
N
=
200
G
e
V
and
S
N
N
=
62.4
G
e
V
, performed using the STAR detector at RHIC. A
Ξ
*
(1530) resonance signal is observed for the ...first time in Au-Au collisions. Experimental data are compared with theoretical predictions. The strength of the
Ξ
*
peak is reproduced in the correlation function assuming that
π and Ξ emerge from a system in collective expansion.
We report the measurements of Sigma(1385) and Lambda(1520) production in p+p and Au+Au collisions at root s(NN)=200 GeV from the STAR Collaboration. The yields and the p(T) spectra are presented and ...discussed in terms of chemical and thermal freeze-out conditions and compared to model predictions. Thermal and microscopic models do not adequately describe the yields of all the resonances produced in central Au+Au collisions. Our results indicate that there may be a time span between chemical and thermal freeze-out during which elastic hadronic interactions occur
PDF
