Centrality dependence of charged hadron transverse momentum spectra in d+Au collisions at sqrt(s_NN) = 200 GeV

TL;DR

The results provide important information for discriminating between different models for the suppression of high-p(T) hadrons observed in Au+Au collisions.

Abstract

We have measured transverse momentum distributions of charged hadrons produced in d+Au collisions at sqrt(s_NN) = 200 GeV. The spectra were obtained for transverse momenta 0.25 < p_T < 6.0 GeV/c, in a pseudorapidity range of 0.2 < eta < 1.4 in the deuteron direction. The evolution of the spectra with collision centrality is presented in comparison to p+pbarcollisions at the same collision energy. With increasing centrality, the yield at high transverse momenta increases more rapidly than the overall particle density, leading to a strong modification of the spectral shape. This change in spectral shape is qualitatively different from observations in Au+Au collisions at the same energy. The results provide important information for discriminating between different models for the suppression of high-p_T hadrons observed in Au+Au collisions.

Figures (4)

• Figure 1: Invariant yield of charged hadrons, $\frac{h^+ + h^-}{2}$, as a function of $p_T$ for four centrality bins. Only statistical errors are shown.
• Figure 2: The relative yield of d+Au to UA1 $p+\bar{p}$ data at $p_T = 1, 2, 3 \hbox{and} 4$ GeV/c is shown as a function of the integrated yield $dN/d\eta$ for the four $E_{\it Ring}$ centrality bins. The ratio d+Au/$p+\bar{p}$ has been normalized to unity at $p_T = 0.5$ GeV/c. The triangles indicate the values for $p+\bar{p}$. The brackets indicate the systematic errors on the relative yield (90% C.L.). The systematic error on $dN/d\eta$ is 12%.
• Figure 3: Nuclear modification factor $R_{\it dAu}$ as a function of $p_T$ for four bins of centrality. For the most central bin, the spectral shape for central Au+Au data relative to $p+\bar{p}$ is shown for comparison. The shaded area shows the uncertainty in $R_{\it dAu}$ due to the systematic uncertainty in $\langle N_{\it coll} \rangle$ and the UA1 scale error (90% C.L.). The brackets show the systematic uncertainty of the d+Au spectra measurement (90% C.L.).
• Figure 4: Nuclear modification factor $R_{\it dAu}$ as a function of centrality in four bins of transverse momentum. The brackets indicate the point-to-point systematic error, dominated by the uncertainty in the number of collisions for each centrality bin. The grey band shows the overall scale uncertainty at each $p_T$. Systematic errors are at 90% C.L.