We determine rapidity asymmetry in the production of charged pions, protons, and antiprotons for large transverse momentum ($p_T$) for $d+\mathrm{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV. The rapidity asymmetry is defined as the ratio of particle yields at backward rapidity (Au beam direction) to those at forward rapidity ($d$ beam direction). The identified hadrons are measured in the rapidity regions $\left|y\right|<0.5$ and $0.5<\left|y\right|<1.0$ for the $p_T$ range $2.5<p_T<10\mathrm{GeV}/\mathrm{c}$. We observe significant rapidity asymmetry for charged pion and proton+antiproton production in both the rapidity regions. The asymmetry is larger for $0.5<\left|y\right|<1.0$ than for $\left|y\right|<0.5$ and is almost independent of particle type. The measurements are compared to various model predictions employing multiple scattering, energy loss, nuclear shadowing, saturation effects, and recombination and also to a phenomenological parton model. We find that asymmetries are sensitive to model parameters and show model preference. The rapidity dependence of ${\pi }^{-}/{\pi }^{+}$ and $\overline{p}/p$ ratios in peripheral $d+\mathrm{Au}$ and forward neutron-tagged events are used to study the contributions of valence quarks and gluons to particle production at high $p_T$.

• Received 14 September 2006

DOI:https://doi.org/10.1103/PhysRevC.76.054903