Hadron-string cascade versus hydrodynamics in Cu+Cu collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV

Single particle spectra as well as elliptic flow in Cu+Cu collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV are investigated within a hadronic cascade model and an ideal hydrodynamic model. Pseudorapidity distribution and transverse momentum spectra for charged hadrons are surprisingly comparable between these two models. However, a large deviation is predicted for the elliptic flow. The forthcoming experimental data will clarify the transport and thermalization aspects of matter produced in Cu+Cu collisions.

Figure 1

(Color online) Pseudorapidity distributions for charged hadrons in Cu+Cu collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV for impact parameters $b=$ 1, 2, and 5 fm. Circles correspond to the result of JAM. Lines denote the results of hydrodynamics for $T^{\mathrm{th}}=100$ MeV.

Figure 2

(Color online) Comparison of the transverse momentum distributions for charged hadrons between JAM (circles) and hydrodynamics for $T^{\mathrm{th}}=100$ MeV (lines) at $\left|\eta \right|<0.33$ in Cu+Cu collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV. The results for b = 2 fm (5 fm) are scaled by 10${}^{-2}$ (10${}^{-4}$).

Figure 3

(Color online) Elliptic flow $v_2$ for charged hadrons at midrapidity as a function of impact parameter in Cu+Cu collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV. Circles connected by line show the results of JAM. Triangles and squares with lines show the results of hydrodynamics with $T^{\mathrm{th}}=$100 MeV and 160 MeV, respectively.

Figure 4

(Color online) Elliptic flow $v_2$ for charged hadrons as a function of pseudorapidity η in Cu+Cu collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV at impact parameter b = 5 fm. Circles connected by line show the results of JAM. Triangles and squares with lines show the results of hydrodynamics with $T^{\mathrm{th}}=100$ MeV and 160 MeV, respectively.

Figure 5

(Color online) The calculated elliptic flow $v_2$ of charged hadrons as a function of transverse momentum $p_T$ for Cu+Cu at $\sqrt{s_{\mathit{NN}}}=200$ GeV for different impact parameters, $b=$ 1 fm (top), 2 fm (middle), and 5 fm (bottom). Circles connected by line show the results of JAM. Triangles and squares with lines show the results of hydrodynamics with $T^{\mathrm{th}}=100$ MeV and 160 MeV, respectively.