Speaker
Description
Currently, the nature of the baryon number carrier remains debated. Although it is conventionally assumed to be carried by quarks, an alternative model suggests that the baryon number is instead carried by a Y-shaped gluon configuration called the baryon junction. This has significant ramifications for baryon emission at mid-rapidity in nuclear collisions. In this work, we accurately extract the chemical potential differences ($\Delta\mu = \mu_\text{Zr+Zr} - \mu_\text{Ru+Ru}$) between isobaric $_{44}^{96}$Ru+$_{44}^{96}$Ru and $_{40}^{96}$Zr+$_{40}^{96}$Zr collision systems at $\sqrt{s_{NN}}=200$GeV, based on charged particle yields in these collisions and electric charge difference ($\Delta Q$) between the two recently measured by the STAR collaboration. Utilizing Bayesian inference with THERMUS thermal model, we show that baryon and strange chemical potential differences ($\Delta \mu_B$ and $\Delta \mu_S$) are positive, while $\Delta \mu_Q$ is negative across all centralities. We find that $\Delta\mu_B/\Delta\mu_Q=-0.96\pm0.02$ in head-on collisions, which is close to the expected value of -1 for decoupled electric charge carried by quarks and baryon number. Furthermore, the dependence of mid-rapidity hyperon yields on beam rapidity demonstrates flavor independence, with $\Lambda$, $\Xi$, and $\Omega$ baryons exhibiting similar transport behavior. This is also consistent with the baryon junction picture as a junction is composed of flavorless gluons and the resultant baryon formed around the junction should be flavor blind. These results challenge the conventional assumption about baryon number being carried by quarks.
