Pion production in rare-isotope collisions

Tsang, M. B.; Estee, J.; Setiawan, H.; Lynch, W. G.; Barney, J.; Chen, M. B.; Cerizza, G.; Danielewicz, Paweł; Hong, Jun Sung; Morfouace, P.; Shane, R.; Tangwancharoen, S.; Zhu, K.; Isobe, T.; Kurata-Nishimura, M.; Łukasik, J.; Murakami, T.; Chajęcki, Z.

doi:10.1103/physrevc.95.044614

Cited by 40 publications

(29 citation statements)

References 35 publications

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“…Similar methodology can be used to extract the symmetry pressure. Experimental efforts are already underway to extract the EoS of asymmetric matter at this density region [58][59][60][61].…”

Section: Laboratory Observable Sensitive To the Tidal Deformabilitymentioning

confidence: 99%

Insights on Skyrme parameters from GW170817

Tsang

Danielewicz

et al. 2019

Physics Letters B

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The binary neutron-star merger event, GW170817, has cast a new light on nuclear physics research. Using a neutron-star model that includes a crust equation of state (EoS), we calculate the properties of a 1.4 solar-mass neutron star. The model incorporates more than 200 Skyrme energy density functionals, which describe nuclear matter properties, in the outer liquid core region of the neutron star. We find a power-law relation between the neutron-star tidal deformability, Λ, and the neutron-star radius, R. Without an explicit crust EoS, the model predicts smaller R and the difference becomes significant for stars with large radii. To connect the neutron star properties with nuclear matter properties, we confront the predicted values for Λ, against the Taylor expansion coefficients of the Skyrme interactions. There is no pronounced correlation between Skyrme parameters in symmetric nuclear matter and neutron star properties.However, we find the strongest correlation between Λ and Ksym, the curvature of the density dependence of the symmetry energy at saturation density. At twice the saturation density, our calculations show a strong correlation between Λ and total pressure providing guidance to laboratory nucleus-nucleus collision experiments.

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Section: Laboratory Observable Sensitive To the Tidal Deformabilitymentioning

confidence: 99%

Insights on Skyrme parameters from GW170817

Tsang

Danielewicz

et al. 2019

Physics Letters B

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“…In the past [9,40,67,68], for energies of 300 MeV -2 GeV per nucleon, where pions are produced, the code pBUU was mostly used with the time step in the range ∆t = 0.2-0.3 fm/c, usually with longer time steps at the lower energies and shorter at the higher. The scheme for pion and ∆ production for that energy range was largely unchanged since the code was put together in 1991 [40], except that in the late 90s the ∆ and pion production cross sections and rates were switched to those from Ref.…”

Section: Pbuumentioning

confidence: 99%

Comparison of heavy-ion transport simulations: Collision integral with pions and Δ resonances in a box

Ono

Colonna

et al. 2019

Phys. Rev. C

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Background: Simulations by transport codes are indispensable for extracting valuable physical information from heavy-ion collisions. Pion observables such as the π − /π + yield ratio are expected to be sensitive to the symmetry energy at high densities.Purpose: To evaluate, understand and reduce the uncertainties in transport-code results originating from different approximations in handling the production of ∆ resonances and pions. Methods:We compare ten transport codes under controlled conditions for a system confined in a box, with periodic boundary conditions, and initialized with nucleons at saturation density and at 60 MeV temperature. The reactions N N ↔ N∆ and ∆ ↔ N π are implemented, but the Pauli blocking and the mean-field potential are deactivated in the present comparison. Thus these are cascade calculations including pions and ∆ resonances. Results are compared to those from the two reference cases of a chemically equilibrated ideal gas mixture and of the rate equation. Results:For the numbers of ∆ and π, deviations from the reference values are observed in many codes, and they depend significantly on the size of the time step. These deviations are tied to different ways in ordering the sequence of reactions, such as collisions and decays, that take place in the same time step. Better agreements with the reference values are seen in the reaction rates and the number ratios among the isospin species of ∆ and π. Both the reaction rates and the number ratios are, however, affected by the correlations between particle positions, which are absent in the Boltzmann equation, but are induced by the way particle scatterings are treated in many of the transport calculations. The uncertainty in the transport-code predictions of the π − /π + ratio, after letting the existing ∆ resonances decay, is found to be within a few percent for the system initialized at n/p = 1.5. Conclusions:The uncertainty in the final π − /π + ratio in this simplified case of particles in a box is sufficiently small so that it does not strongly impact constraining the high-density symmetry energy from heavy-ion collisions. Most of the sources of

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“…While the constraint on Psym is within the expected bounds, it is clear that more accurate measurements designed to isolate the symmetry energy or symmetry pressure are needed. Experimental efforts are already underway to extract this quantity [39][40][41]. Using a neutron-star model that incorporates more than 200 Skyrme energy density functionals documented in [42][43][44] as EoS in the liquid core region of the neutron star, one can correlate the properties of neutron star with that of nuclei [45].…”

Section: Symmetry Pressure At High Densitymentioning

confidence: 99%

Symmetry energy constraints from GW170817 and laboratory experiments

et al. 2019

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The LIGO-Virgo collaboration detection of the binary neutron-star merger event, GW170817, has expanded efforts to understand the Equation of State (EoS) of nuclear matter. These measurements provide new constraints on the overall pressure, but do not elucidate its origins, by not distinguishing the contribution to the pressure from symmetry energy which governs much of the internal structure of a neutron star. By combining the neutron star EoS extracted from the GW170817 event and the EoS of symmetric matter from nucleus-nucleus collision experiments, we extract the symmetry pressure, which is the difference in pressure between neutron and nuclear matter over the density region from 1.20 to 4.50. While the uncertainties in the symmetry pressure are large, they can be reduced with new experimental and astrophysical results.

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Pion production in rare-isotope collisions

Cited by 40 publications

References 35 publications

Insights on Skyrme parameters from GW170817

Insights on Skyrme parameters from GW170817

Comparison of heavy-ion transport simulations: Collision integral with pions and Δ resonances in a box

Symmetry energy constraints from GW170817 and laboratory experiments

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