High-p_T Tomography of d+Au and Au+Au at SPS, RHIC, and LHC

TL;DR

It is shown that future d+Au data can be used to disentangle the initial and final state effects of nuclear suppression/enhancement pattern in A+A reactions, and predicted competition between nuclear shadowing, Cronin effect, and jet energy loss due to medium-induced gluon radiation.

Abstract

The interplay of nuclear effects on the p_T > 2 GeV inclusive hadron spectra in d+Au and Au+Au reactions at root(s) = 17, 200, 5500 GeV is compared to leading order perturbative QCD calculations for elementary p+p (p-bar+p) collisions. The competition between nuclear shadowing, Cronin effect, and jet energy loss due to medium-induced gluon radiation is predicted to lead to a striking energy dependence of the nuclear suppression/enhancement pattern in A+A reactions. We show that future d+Au data can used to disentangle the initial and final state effects.

Figures (3)

• Figure 1: The ratio of $A$-scaled $p+W/p+Be$ data on $\pi^+,\pi^-$ production at $\sqrt{s}=27.4, 38.8$ GeV from CRON. Calculations for ${\frac{1}{2}} (\pi^+ + \pi^-$) include nuclear shadowing and initial parton broadening as in Eq.(\ref{['cron']}) with $\mu^2 / \lambda = 0.05$ GeV$^2$/fm. The anticipated $\sqrt{s}=200$ GeV $p+W/p+Be$ ratio is also shown.
• Figure 2: The nuclear modification $R_{BA}(p_T)$ due to Cronin effect and shadowing (but not energy loss) for $\pi^0$ in $d+Au$ ($B=d,A=Au$) and central $Au+Au$ ($B=A=Au$) reactions at $\sqrt{s}_{NN} = 17, 200, 5500$ GeV.
• Figure 3: The suppression/enhancement ratio $R_{AA}(p_T)$ ($A=B=Au$) for neutral pions at $\sqrt{s}_{NN}=17$, $200$, $5500$ GeV. Solid (dashed) lines correspond to the smaller (larger) effective initial gluon rapidity densities at given $\sqrt{s}$ that drive parton energy loss. Data on $\pi^0$ production in central $Pb+Pb$ at $\sqrt{s}_{NN}=17.4$ GeV from WA98 NOELOSS and in central $Au+Au$ at $\sqrt{s}_{NN}=130$ GeV PHEN, as well as preliminary data at $200$ GeV PHEN200 from PHENIX and $h^\pm$ central/peripheral data from STAR STAR200 are shown. The sum of estimated statistical and systematic errors are indicated.