13 Elliptic Flow in Relativistic Heavy-Ion Collisions
173
Fig. 13.8 Integrated v 2 determined from v 2 {4} versus collision centrality for STAR and ALICE
data. Predictions from VISHNU for different η/s are also displayed
Fig. 13.9 v 2 versus p T for 0–5% and 20–30% collision centralities for Cu+Au collisions at
√
s NN =
200 GeV. v 2 is determined using event plane or scalar product is indicated in the figure. Predictions of
hydrodynamics calculations using Glauber initial conditions with η/s = 0.08–0.16 are also displayed
data. Ratio of v 2 /v 2 (hydro fit) in the central collisions reproduces K results whereas
deviations are seen for other particle species. The measured v 2 ( p T ) for pions is more
than those of theoretically calculated for p T < 1 GeV/c and also proton elliptic flow
is significantly underestimated. It overestimates v 2 ( p T ) for multi-strange baryons.
The φ meson does not follow mass ordering in case of VISHNU. This may be due
to small hadronic interaction cross section.
Figure 13.11 compares the v 2 probability distribution for Pb-Pb collisions at
2.76 TeV (ATLAS data) for 20–25% central events [25, 38] with the eccentricity
distribution, P(( 2 / 2 ), obtained using IP-Glasma [39]. Reasonably good agreement is seen. The IP-Glasma model [40, 41] describes well the initial conditions for
173
Fig. 13.8 Integrated v 2 determined from v 2 {4} versus collision centrality for STAR and ALICE
data. Predictions from VISHNU for different η/s are also displayed
Fig. 13.9 v 2 versus p T for 0–5% and 20–30% collision centralities for Cu+Au collisions at
√
s NN =
200 GeV. v 2 is determined using event plane or scalar product is indicated in the figure. Predictions of
hydrodynamics calculations using Glauber initial conditions with η/s = 0.08–0.16 are also displayed
data. Ratio of v 2 /v 2 (hydro fit) in the central collisions reproduces K results whereas
deviations are seen for other particle species. The measured v 2 ( p T ) for pions is more
than those of theoretically calculated for p T < 1 GeV/c and also proton elliptic flow
is significantly underestimated. It overestimates v 2 ( p T ) for multi-strange baryons.
The φ meson does not follow mass ordering in case of VISHNU. This may be due
to small hadronic interaction cross section.
Figure 13.11 compares the v 2 probability distribution for Pb-Pb collisions at
2.76 TeV (ATLAS data) for 20–25% central events [25, 38] with the eccentricity
distribution, P(( 2 / 2 ), obtained using IP-Glasma [39]. Reasonably good agreement is seen. The IP-Glasma model [40, 41] describes well the initial conditions for