Rapidity dependence of deuteron production in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV

TL;DR

This study measures proton and deuteron production over a wide rapidity range in high-energy Au+Au collisions, analyzing coalescence parameters and phase-space densities to understand particle formation and rapidity dependence.

Contribution

It provides new measurements of coalescence parameters and phase-space densities at various rapidities, revealing similarities between protons and anti-protons near mid-rapidity and differences from lower energy results.

Findings

Protons and anti-protons have similar coalescence parameters near mid-rapidity.

Little variation of coalescence parameters with rapidity from 0 to 3.

Strong dependence of parameters on transverse momentum at all rapidities.

Abstract

We have measured the distributions of protons and deuterons produced in high energy heavy ion Au+Au collisions at RHIC over a very wide range of transverse and longitudinal momentum. Near mid-rapidity we have also measured the distribution of anti-protons and anti-deuterons. We present our results in the context of coalescence models. In particular we extract the "volume of homogeneity" and the average phase-space density for protons and anti-protons. Near central rapidity the coalescence parameter $B_2(p_T)$ and the space averaged phase-space density $<f> (p_T)$ are very similar for both protons and anti-protons. For protons we see little variation of either $B_2(p_T)$ or the space averaged phase-space density as the rapidity increases from 0 to 3. However both these quantities depend strongly on $p_T$ at all rapidities. These results are in contrast to lower energy data where the proton and anti-proton phase-space densities are different at $y$=0 and both $B_2$ and $f$ depend strongly on rapidity.