Constraining the nuclear matter equation of state around twice saturation density

Abstract

Using data on elliptic flow measured by the FOPI collaboration we extract constraints for the equation of state (EOS) of symmetric nuclear matter with the help of the microscopic transport code IQMD. Best agreement between data and calculations is obtained with a ’soft’ equation of state including a momentum dependent interaction. From the model it can be deduced that the characteristic density related to the observed flow signal is around twice saturation density and that both compression within the fireball and the presence of the surrounding spectator matter is necessary for the development of the signal and its sensitivity to the nuclear equation of state.