Uncertainty propagation from the SAM acceptance fraction

Determine how uncertainty in the subensemble acceptance-method fraction propagates to the final-state suppression of the net-proton cumulant ratio $C_4/C_2$, and determine the acceptance fraction self-consistently from STAR rapidity and transverse-momentum acceptance through a systematic scan in $\alpha$.

Background

The calculation converts grand-canonical cumulants into canonical-ensemble cumulants using the subensemble acceptance method, with the acceptance fraction α\alpha fixed phenomenologically from earlier results. Since the canonical cumulants and the inferred rescattering suppression depend sensitively on this parameter, the paper identifies the lack of a dedicated uncertainty analysis as an unresolved issue. The proposed resolution is to determine α\alpha directly from the experimental STAR acceptance and systematically examine how varying it changes the predicted C4/C2C_4/C_2 suppression.

References

Since the CE cumulants depend sensitively on $\alpha$, a dedicated study of the propagation of its uncertainty to the final-state suppression of $C_4/C_2$ is required. A self-consistent determination of $\alpha$ directly from the STAR rapidity and transverse-momentum acceptance, together with a systematic scan in $\alpha$, is left to a forthcoming analysis.

— Hadronic rescattering effects on net-proton cumulants from functional renormalization group calculations  (2608.28299 - Lin et al., 28 Aug 2026) in Section 4, Conclusion and Outlook, subsection “Acceptance fraction in the SAM”