Status Report on the Analyses of Proton-Number Cumulants in the STAR Fixed-Target Program
ORAL
Abstract
Fluctuations of net-proton number distributions in heavy-ion collisions are expected to be sensitive to a QCD critical point. These fluctuations are measured through various-order cumulants, $C_n$, of net-proton multiplicity distributions. The collision-energy dependence of net-proton cumulant ratio from Beam Energy Scan I shows a hint of deviation from the baseline between $sqrt{s_{NN}}=$ 19.6~GeV to 7.7~GeV, while the recent proton $C_4/C_2$ value at $sqrt{s_{NN}}=$ 3~GeV from the Fixed-Target program (FXT) at STAR returns to the baseline. These results indicate the importance of filling the gap between $sqrt{s_{NN}}=$ 3.0~GeV and 7.7~GeV. The analyses of the remaining FXT data are ongoing, although analysis of the STAR fixed-target data comes with challenges. A shifting mid-rapidity with beam energy results in acceptance gaps at some energies, and a reliance on time-of-flight particle identification at top FXT energies necessitates a thorough understanding of the effect of precision timing on proton-number cumulants. These and other challenges and techniques used in the analyses of FXT proton cumulants will be presented, and the status of the analyses will be discussed.
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Presenters
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Zachary Sweger
University of California, Davis
Authors
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Zachary Sweger
University of California, Davis