Blast wave fits to elliptic flow data at $\sqrt{s_{\mathit{\text{NN}}}}=7.7–2760$ GeV

We present blast wave fits to elliptic flow [$v_2\left(p_{\mathrm{T}}\right)$] data in minimum bias collisions from $\sqrt{s_{\mathit{\text{NN}}}}=7.7–200$ GeV at the BNL Relativistic Heavy Ion Collider, and also at the CERN Large Hadron Collider energy of 2.76 TeV. The fits are performed separately for particles and corresponding antiparticles. The mean transverse velocity parameter $\beta$ shows an energy-dependent difference between particles and corresponding antiparticles, which increases as the beam energy decreases. Possible effects of feed down, baryon stopping, antiparticle absorption, and early production times for antiparticles are discussed.

Figure 1

Elliptic flow $v_2$ as a function of transverse momentum $p_{\mathrm{T}}$ for $\text{Au}+\text{Au}$ collisions at $\sqrt{s_{\mathit{\text{NN}}}}=27$ GeV for a selected group of particles. The shaded areas show estimates for the feed-down correction. Solid lines are from blast wave fits and dashed lines are predictions by using the fit parameters.

Figure 2

The simultaneous blast wave fits for $v_2$ of (a) particles $(K_s^0,p$, and $\Lambda$) and (b) corresponding antiparticles ($K_s^0,\overline{p}$, and $\overline{\Lambda }$) from 0%–80% central $\text{Au}+\text{Au}$ collisions at $\sqrt{s_{\mathit{\text{NN}}}}=7.7$–200 GeV and for combined $v_2$ of particles and antiparticles (${\pi }^{\pm },K^{\pm },p+\overline{p}$, and $\Lambda +\overline{\Lambda }$) from 0%–60% central $\text{Pb}+\text{Pb}$ collisions at $\sqrt{s_{\mathit{\text{NN}}}}=2.76$ TeV. Solid lines are from blast wave fits and dashed lines are predictions by using the fit parameters.

Figure 3

The transverse expansion velocity $\beta$ as a function of beam energy from 0%–80% central $\text{Au}+\text{Au}$ collisions and 0%–60% central $\text{Pb}+\text{Pb}$ collisions for particles and antiparticles with three different temperatures.

Figure 4

Integrated multiplicity rapidity density of protons, antiprotons, and net protons as a function of the center-of-mass energy. Data are taken from Refs. [27, 34, 35].

Figure 5

$v_2$ as a function of $p_{\mathrm{T}}$ from 0%–80% central $\text{Au}+\text{Au}$ collisions at $\sqrt{s_{\mathit{\text{NN}}}}=11.5$ GeV for the antiparticle group (points) and from 0%–60% central $\text{Pb}+\text{Pb}$ collisions at $\sqrt{s_{\mathit{\text{NN}}}}=2.76$ TeV (bands).