Forward neutral pion production in p+p and d+Au collisions at s(NN)**(1/2) = 200-GeV

The collaboration
Phys.Rev.Lett. 97 (2006) 152302, 2006.

Abstract (data abstract)
Measurements of the production of forward $\pi^{0}$ mesons from p+p and d+Au collisions at $\sqrt{s_{NN}}$= 200 GeV are reported. The p+p yield generally agrees with next-to-leading order perturbative QCD calculations. The d+Au yield per binary collision is suppressed as $\eta$ increases, decreasing to ~30% of the p+p yield at $\langle\eta\rangle$= 4.00, well below shadowing expectations. Exploratory measurements of azimuthal correlations of the forward $\pi^{0}$ with charged hadrons at $\eta\approx0$ show a recoil peak in p+p that is suppressed in d+Au at low pion energy. These observations are qualitatively consistent with a saturation picture of the low-x gluon structure of heavy nuclei.

• #### Figure 1

Data from Figure 1

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Inclusive $\pi^{0}$ cross section for p+p collisions versus the leading $\pi^{0}$ energy ($E_{\pi}$) averaged over 5 GeV bins at fixed...

• #### Figure 2

Data from Figure 2

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Inclusive $\pi^{0}$ cross section per binary collision for d+Au collisions, as in Fig. 1. The curves are calculations described in...

• #### Figure 3

Data from Figure 3

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Nuclear modification factor ($R_{dAu}$) for minimum-bias d+Au collisions versus transverse momentum ($p_{T}$). The solid circles are for $\pi^{0}$ mesons. The...

• #### Figure 4 top left

Data from Figure 4 top left

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Coincidence probability versus azimuthal angle difference between the forward $\pi^{0}$ and a leading charged particle at midrapidity with $p_{T}$ >...

• #### Figure 4 bottom left

Data from Figure 4 bottom left

10.17182/hepdata.98968.v1/t5

Coincidence probability versus azimuthal angle difference between the forward $\pi^{0}$ and a leading charged particle at midrapidity with $p_{T}$ >...

• #### Figure 4 top right

Data from Figure 4 top right

10.17182/hepdata.98968.v1/t6

Coincidence probability versus azimuthal angle difference between the forward $\pi^{0}$ and a leading charged particle at midrapidity with $p_{T}$ >...

• #### Figure 4 bottom right

Data from Figure 4 bottom right

10.17182/hepdata.98968.v1/t7

Coincidence probability versus azimuthal angle difference between the forward $\pi^{0}$ and a leading charged particle at midrapidity with $p_{T}$ >...