Forward hadron production in high energy pA collisions: from RHIC to LHC

TL;DR

The paper applies a unified gluon-saturation framework (KKT) to forward hadron production in pA collisions from RHIC to LHC, targeting π, D and B mesons and the rapidity, centrality, and pT dependence of RpA. It develops and utilizes a dipole amplitude N(r,y) with a saturation scale Q_s(y) and an anomalous dimension γ(r,y) to compute gluon, light-quark, and heavy-quark contributions, including fragmentation effects. The results predict slow rapidity variation of RpA at LHC with a suppression scaling approximately as N_coll^{-(1-γ)}, and reveal mass- and kT-dependent patterns tied to geometric scaling, with heavy quarks showing delayed saturation effects. The work provides testable predictions for forward physics and insights into small-x evolution and saturation in dense nuclear matter.

Abstract

We present a calculation of Pi, D and B mesons production at RHIC and LHC energies based upon the KKT model of gluon saturation. We discuss dependence of the nuclear modification factor on rapidity and transverse momentum.

Figures (5)

• Figure 1: Nuclear modification factor for pion production at RHIC and LHC.
• Figure 2: The diagrams contributing to the quark--anti-quark pair production in the quasi-classical approximation. Disconnected $t$-channel gluon lines imply summation over all possible connections to the adjacent $s$-channel quark and gluon lines. Adopted from Kovchegov:2006qn.
• Figure 3: Nuclear modification factor for open charm production at RHIC and LHC.
• Figure 4: Nuclear modification factor for open beauty production at RHIC and LHC.
• Figure 5: Dependence of the nuclear modification factor on quark mass. Solid line is $R_{pA}$ for quarks (no fragmentation). Geometric scaling is expected to break down at $m_\bot\sim Q_\mathrm{geom}$ and therefore $R_{pA}$ is anticipated to deviate from the solid line towards unity. Dotted lines illustrates a possible behavior of $R_{pA}$.