English

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

Nuclear Theory 2025-03-07 v2 Nuclear Experiment

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 (δy\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 δy\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-Λ\Lambda, net-Ξ\Xi and net-Ω\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.

Keywords

Cite

@article{arxiv.2409.06492,
  title  = {Beam energy dependence of net-hyperon yield and its implication on baryon transport mechanism},
  author = {Chun Yuen Tsang and Rongrong Ma and Prithwish Tribedy and Zhangbu Xu},
  journal= {arXiv preprint arXiv:2409.06492},
  year   = {2025}
}