Symmetry energy investigation with pion production from Sn+Sn systems

Abstract

In the past two decades, pions created in the high density regions of heavy ion collisions have been predicted to be sensitive at high densities to the symmetry energy term in the nuclear equation of state, a property that is key to our understanding of neutron stars. In a new experiment designed to study the symmetry energy, the multiplicities of negatively and positively charged pions have been measured with high accuracy for central ${}^{132}$Sn+${}^{124}$Sn, ${}^{112}$Sn+${}^{124}$Sn, and ${}^{108}$Sn+${}^{112}$Sn collisions at $E/A=270\mathrm{MeV}$ with the S$\pi$RIT Time Projection Chamber. While the uncertainties of individual pion multiplicities are measured to 4\%, those of the charged pion multiplicity ratios are measured to 2\%. We compare these data to predictions from seven major transport models. The calculations reproduce qualitatively the dependence of the multiplicities and their ratios on the total neutron to proton number in the colliding systems. However, the predictions of the transport models from different codes differ too much to allow extraction of reliable constraints on the symmetry energy from the data. This finding may explain previous contradictory conclusions on symmetry energy constraints obtained from pion data in Au+Au system. These new results call for better understanding of the differences among transport codes, and new observables that are more sensitive to the density dependence of the symmetry energy.

8 pages, 4 figures, 1 table (accepted for publication in PLB)

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Cited by in corpus (28)

• Dense Nuclear Matter Equation of State from Heavy-Ion Collisions
• Probing the Symmetry Energy with the Spectral Pion Ratio
• Constraints on Nuclear Symmetry Energy Parameters
• Impact of NICER's Radius Measurement of PSR J0740+6620 on Nuclear Symmetry Energy at Suprasaturation Densities
• Application of machine learning in the determination of impact parameter in the ${}^{132}$Sn+${}^{124}$Sn system
• Constraining nuclear symmetry energy with the charge radii of mirror-pair nuclei
• Observing Supernova Neutrino Light Curves with Super-Kamiokande. II. Impact of the Nuclear Equation of State
• Symmetry energy extracted from the S$\pi$RIT pion data in Sn+Sn systems
• Deblurring for Nuclei: 3D Characteristics of Heavy-Ion Collisions
• Determining impact parameters of heavy-ion collisions at low-intermediate incident energies using deep learning with convolutional neural network
• Bayesian model averaging for nuclear symmetry energy from effective proton-neutron chemical potential difference of neutron-rich nuclei
• Studies of the equation-of-state of nuclear matter by heavy-ion collisions at intermediate energy in the multi-messenger era
• Isoscaling in central Sn+Sn collisions at 270 MeV/u
• Collision integral with momentum-dependent potentials and its impact on pion production in heavy-ion collisions
• Auxiliary Function Approach for Determining Symmetry Energy at Supra-saturation Densities
• Constraining nucleon effective masses with flow and stopping observables from the S$\pi$RIT experiment
• Charged pion production from Au + Au collisions at $\sqrt{s_{NN}}=2.4$ GeV in the Relativistic Vlasov-Uehling-Uhlenbeck model
• Effects of the momentum dependence of nuclear symmetry potential on pion observables in Sn + Sn collisions at 270 MeV/nucleon
• Impact of quadrupole deformation on intermediate-energy heavy-ion collisions
• Neutron-proton differential transverse flow in ${}^{132}$Sn + ${}^{124}$Sn collisions at 270 MeV/nucleon
• Necessity of selfconsistent calculations for the electromagnetic field in probing the nuclear symmetry energy using pion observables in heavy-ion collisions
• Neutron Star Radii from Laboratory Experiments
• Nucleon-$\Delta$ elastic cross section in isospin-asymmetric nuclear medium with inclusion of scalar-isovector $\delta$ meson field
• In-medium effects of nucleon-nucleon cross sections in heavy-ion collisions
• Toward a Unified Understanding of the Dense Matter Equation of State
• Isospin blocking and its effects in heavy-ion collisions
• Quark-Meson Coupling Model in Heavy-Ion Collision Simulations
• Transport Model Comparison Studies of Intermediate-Energy Heavy-Ion Collisions