Speaker
Description
Fluctuations of charged-particle multiplicities are sensitive observables proposed to probe the Quantum Chromodynamics (QCD) phase structure, such as searching for a possible critical point at high baryochemical potential ($\mu_B$), where enhanced fluctuations are theoretically expected. Recent measurements of proton multiplicity fluctuations across the $\sqrt{s_{NN}} = 3$–27 GeV range in Au+Au collisions reveal intriguing trends~\cite{STAR:2025zdq,STAR:FXT2025}. On the other hand, a comprehensive study of the fluctuation of relative particle yields has not yet been systematically explored in the high-$\mu_B$ regime ($\mu_B\gtrsim$400). The observable $\nu_{dyn}$ offers a robust measure of dynamical fluctuations in particle species ratios and serves as an indicator of how different particle yields are correlated~\cite{Pruneau:2002yf}.
In this presentation, we report a systematic study of $\nu_{dyn}$ for identified particle pairs in Au+Au collisions spanning $\sqrt{s_{NN}} = 3-27$ GeV ($\mu_B\sim750-150$ MeV). The analysis uses STAR BES-II data, incorporating results from both fixed-target and collider configurations.
Results will be presented as a function of collision centrality and collision energy. Model calculations will be used as reference baselines to provide insight into the trends observed in the data.
\begin{thebibliography}{99}
\bibitem{STAR:2025zdq}
B.~E.~Aboona \textit{et al.} [STAR], Phys. Rev. Lett. \textbf{135} (2025) no.14, 142301
\bibitem{STAR:FXT2025}
Z.~Sweger [for STAR Collaboration], QM 2025 talk
\bibitem{Pruneau:2002yf}
C.~Pruneau, S.~Gavin and S.~Voloshin, Phys. Rev. C \textbf{66}, 044904 (2002)
\end{thebibliography}
| Is the talk given on behalf of the Collaboration? | yes |
|---|---|
| Topic area | Critical Point |