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arXiv · 2409.06492

Beam energy dependence of net-hyperon yield and its implication on baryon transport mechanism

Chun Yuen Tsang·Rongrong Ma·Prithwish Tribedy·Zhangbu Xu
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Abstract

In the constituent quark model, each quark inside a baryon carries 1/3 unit of the baryon number. An alternative picture exists where the center of a Y-shaped topology of gluon fields, called the baryon junction, carries a unit baryon number. Studying baryon transport over a large rapidity gap ($\delta y$) in nuclear collisions provides a possible tool to distinguish these two pictures. A recent analysis of global data on net-proton yield at mid-rapidity in Au+Au collisions showed an exponential dependence on $\delta y$ and the exponential slope does not vary with event centrality, favoring the baryon junction picture. Since junctions are flavor blind, hyperons -- baryons containing valence strange quarks -- are expected to exhibit a similar behavior as the proton. This study aims to test this prediction by analyzing hyperon yields in Au+Au collisions at various energies. We observe that net-hyperon yields, after correcting for the strangeness production suppression, adhere to the expected exponential form. The extracted slope parameters for net-$\Lambda$, net-$\Xi$ and net-$\Omega$ are consistent with each other and with those of net-proton within uncertainties, and exhibit no centrality dependence, further substantiating the baryon junction picture. Various implementations of the \texttt{PYTHIA} event generator, primarily based on valence quarks for baryon transport, are unable to simultaneously describe the slope parameters for all baryons.

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Chun Yuen Tsang, Rongrong Ma, Prithwish Tribedy, Zhangbu Xu. 2024-09-10. Beam energy dependence of net-hyperon yield and its implication on baryon transport mechanism. https://doi.org/10.1016/j.physletb.2024.139205

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