Absence of Suppression in Particle Production at Large Transverse Momentum in sqrt(s_NN) = 200 GeV d+Au Collisions

Abstract

Transverse momentum spectra of charged hadrons with p_T < 8 GeV/c and neutral pions with p_T < 10 GeV/c have been measured at mid-rapidity by the PHENIX experiment at RHIC in d+Au collisions at sqrt(s_NN) = 200 GeV. The measured yields are compared to those in p+p collisions at the same sqrt(s_NN) scaled up by the number of underlying nucleon-nucleon collisions in d+Au. The yield ratio does not show the suppression observed in central Au+Au collisions at RHIC. Instead, there is a small enhancement in the yield of high momentum particles.

Figures (4)

• Figure 1: Midrapidity $p_T$ spectra for charged hadrons and $\pi^0$. Total uncertainties are shown. The $\pi^0$ below 5 GeV/$c$ are from minimum bias triggered events, and above from photon triggered. Lines show fits to reference spectra from p+p collisions, and open points show the p+p $\pi^0$ spectrum measured by PHENIX ppg024.
• Figure 2: Nuclear modification factor $R_{\rm{dA}}$ for $\pi^0$ in the PbGl and PbSc calorimeters in minimum bias d+Au. The bands around the data points show systematic errors which can vary with $p_T$, while the shaded band around unity indicates the normalization uncertainty. The nuclear modification factor $R_{\rm{AA}}$ in 10% most central Au+Au collisions is also shown.
• Figure 3: Top: Nuclear modification factor $R_{\rm{dA}}$ for $(h^+ + h^-)/2$ in minimum bias d+Au compared to $R_{\rm{AA}}$ in the 10% most central Au+Au collisions. Inner bands show systematic errors which can vary with $p_T$, and outer bands include also the normalization uncertainty. Bottom: Comparison of $R_{\rm{dA}}$ for $(h^+ + h^-)/2$ and the average of the $\pi^0$ measurements in d+Au. The bar at the left indicates the systematic uncertainty in common for the charged and $\pi^0$ measurements.
• Figure 4: Ratio of $R_{\rm{dA}}$ in minimum bias d+Au and $R_{\rm{pA}}$ from neutron tagged d+Au collisions for $(h^+ + h^-)/2$ and $\pi^0$. The band shows the uncertainty on the number of binary collisions; all other systematic errors cancel.