Strange-quark-number-dependent response to partonic dynamics in baryon-rich Au+Au collisions

Abstract

We identify a strange-quark-number-dependent hierarchy in the response to explicit partonic dynamics by comparing PHSD5.2 with its hadron--string limit in baryon-rich Au+Au collisions at $\text{snn}=3.0$--$7.2$~GeV. Crossing the local conversion threshold alone does not ensure a visible final-state signal: abundant-hadron flow changes little at 3--4.5~GeV, whereas the fractional yield response becomes ordered at 6.2--7.2~GeV, reaching $S_{|s|=1}\simeq 0.2$--$0.3$, $S_{|s|=2}\simeq 0.65$, and $S_{|s|=3}\simeq 0.93$ at 7.2~GeV. The hierarchy is consistent with an enlarged recombination phase space for strange constituents released from different pre-hadronic sources, but does not by itself establish an increase in the total $s+\bar{s}$ abundance or stronger strange-quark clustering. Since $S_X$ is a model-defined response rather than a direct observable, matched excitation functions of ${\Xi }^{-}/\Lambda$ and ${\Omega }^{-}/\Lambda$, together with high-$m_T$ proton elliptic flow, provide experimentally accessible discriminants between the predicted PHSD and HSD dynamics.

Comments: 7 pages, 6 figures