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Forward Rapidity Hadron Production in Deuteron Gold Collisions from Valence Quarks

Jamal Jalilian-Marian

TL;DR

This paper addresses forward-rapidity hadron production in d+Au collisions at RHIC, where the nucleus is treated as a Color Glass Condensate and the deuteron as a dilute valence-quark beam. It applies BK/JIMWLK-evolved dipole cross sections, parameterized by the IIM model, and convolves them with valence-quark PDFs and fragmentation functions to predict low-$p_t$ spectra and the nuclear modification factor $R_{dA}$ without free parameters. The results show good agreement with BRAHMS data at $y=3.2$ and low $k_t$, and it provides predictions for neutral pion $R_{dA}$ at $y=3.8$, reinforcing the CGC description of forward-rapidity physics while highlighting current limitations, such as the neglect of gluon production and centrality effects. Overall, the work demonstrates that forward rapidity in RHIC collisions can be described by high gluon density QCD effects encoded in the CGC framework, with a calculable dipole-based approach.

Abstract

We consider hadron production in deuteron gold collisions at RHIC in the forward rapidity region. Treating the target nucleus as a Color Glass Condensate and the projectile deuteron as a dilute system of valence quarks, we obtain good agreement with the BRAHMS minimum bias data on charged hadron production in the forward rapidity ($y=3.2$) and low $p_t$ region. We provide predictions for neutral pion production in minimum bias deuteron gold collisions in the forward rapidity region, $y=3.8$, measured by the STAR collaboration at RHIC.

Forward Rapidity Hadron Production in Deuteron Gold Collisions from Valence Quarks

TL;DR

This paper addresses forward-rapidity hadron production in d+Au collisions at RHIC, where the nucleus is treated as a Color Glass Condensate and the deuteron as a dilute valence-quark beam. It applies BK/JIMWLK-evolved dipole cross sections, parameterized by the IIM model, and convolves them with valence-quark PDFs and fragmentation functions to predict low- spectra and the nuclear modification factor without free parameters. The results show good agreement with BRAHMS data at and low , and it provides predictions for neutral pion at , reinforcing the CGC description of forward-rapidity physics while highlighting current limitations, such as the neglect of gluon production and centrality effects. Overall, the work demonstrates that forward rapidity in RHIC collisions can be described by high gluon density QCD effects encoded in the CGC framework, with a calculable dipole-based approach.

Abstract

We consider hadron production in deuteron gold collisions at RHIC in the forward rapidity region. Treating the target nucleus as a Color Glass Condensate and the projectile deuteron as a dilute system of valence quarks, we obtain good agreement with the BRAHMS minimum bias data on charged hadron production in the forward rapidity () and low region. We provide predictions for neutral pion production in minimum bias deuteron gold collisions in the forward rapidity region, , measured by the STAR collaboration at RHIC.

Paper Structure

This paper contains 3 sections, 6 equations, 4 figures.

Table of Contents

  1. Introduction
  2. Scattering of quarks on a Color Glass Condensate
  3. Discussion

Figures (4)

  • Figure 1: The invariant yield of charged hadrons at $y=3.2$ at RHIC in proton-proton collisions at $\sqrt{s}=200$ GeV. The normalization is a fit to the data.
  • Figure 2: The invariant yield of charged hadrons at $y=3.2$ at RHIC in minimum bias deuteron-nucleus collisions at $\sqrt{s}=200$ GeV.
  • Figure 3: The nuclear modification factor for charged hadrons at $y=3.2$ in minimum bias deuteron-nucleus collisions at RHIC, $\sqrt{s}=200$ GeV.
  • Figure 4: The nuclear modification factor for neutral pions at $y=3.8$ in minimum bias deuteron-nucleus collisions at RHIC, $\sqrt{s}=200$ GeV.