Open charm production and $\Lambda_{c}^{+}/D^{0}$ ratio in pp and Au+Au collisions at the RHIC

TL;DR

This study uses an improved multi-phase transport model to analyze open charm hadron production and the $ ext{Lambda}_c^+/ ext{D}^0$ ratio in proton-proton and gold-gold collisions at 200 GeV, comparing results with experimental data.

Contribution

It demonstrates the importance of coalescence in charm baryon production and evaluates the relative roles of coalescence and fragmentation mechanisms in heavy-ion collisions.

Findings

AMPT model results agree with STAR data.

Fragmentation alone underestimates charm baryon enhancement.

Coalescence plus fragmentation reproduces observed trends.

Abstract

We study open charm hadrons production in pp and Au+Au collisions at $\sqrt{s_{\mathrm{NN}}} = 200$~GeV using an improved a multi-phase transport (AMPT) model. Specifically, we show the transverse-momentum spectra and nuclear modification factors $R_{\mathrm{AA}}$ of $D^{0}$ mesons and $\Lambda_{c}^{+}$ baryons, as well as the $\Lambda_{c}^{+}/D^{0}$ ratio in pp and Au+Au collisions. The results obtained from the AMPT model simulations are compared with the STAR experimental data and found to be consistent. We further investigate the $\Lambda_{c}^{+}/D^{0}$ ratio by evaluating contributions from coalescence, fragmentation, and the combined coalescence+fragmentation mechanisms, and we find that fragmentation alone underestimates the pronounced enhancement in Au+Au relative to pp at low and intermediate $p_{\mathrm{T}}$, whereas the coalescence+fragmentation mechanism reproduces the observed trend significantly better. These results indicate that coalescence plays a key role in charm baryon productions and helps constrain the relative importance of different hadronization mechanisms in the ultra-relativistic nuclear collisions.