Elliptic Flow and the Nuclear Equation of State

TL;DR

This paper uses heavy-ion collision data to constrain the nuclear equation of state at high densities, favoring a moderately soft to linear density dependence, with implications for understanding asymmetric nuclear matter.

Contribution

It provides new experimental constraints on the nuclear equation of state at suprasaturation densities using collective flow measurements.

Findings

Neutron and hydrogen flow ratios constrain the EoS.

Data favor a moderately soft to linear density dependence.

Higher energy data could extend understanding to higher densities.

Abstract

New constraints for the nuclear equation of state at suprasaturation densities have been obtained by measuring collective particle flows in heavy-ion reactions at relativistic energies. Ratios and differences of neutron and hydrogen flows in 197Au + 197Au collisions at 400 MeV/nucleon were used in studies of the asymmetric-matter equation of state. The comparison with predictions of transport models favors a moderately soft to linear density dependence, consistent with ab-initio nuclear matter theories. Model predictions suggest that comprehensive data sets collected at higher bombarding energies will provide information on the asymmetric-matter equation of state in the density range up to two or three times the saturation value.