The impact of energy conservation in transport models on the π−/π+ multiplicity ratio in heavy-ion collisions and the symmetry energy

Cozma, M.D.

doi:10.1016/j.physletb.2015.12.015

Cited by 78 publications

(117 citation statements)

References 47 publications

(48 reference statements)

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“…Because the interpretation of the FOPI pion ratios [45] is not yet conclusive (see, e.g., Refs. [46,47,48]), this observable is presently unique as a terrestrial source of information for the EoS of asymmetric matter at high densities.…”

Section: Discussionmentioning

confidence: 99%

Symmetry energy and density

Trautmann¹,

Cozma²,

Russotto³

2016

Proceedings of 54th International Winter Meeting on Nuclear Physics — PoS(BORMIO2016)

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The nuclear equation-of-state is a topic of highest current interest in nuclear structure and reactions as well as in astrophysics. In particular, the equation-of-state of asymmetric matter and the symmetry energy representing the difference between the energy densities of neutron matter and of symmetric nuclear matter are not sufficiently well constrained at present. The density dependence of the symmetry energy is conventionally expressed in the form of the slope parameter L describing the derivative with respect to density of the symmetry energy at saturation. Results deduced from nuclear structure and heavy-ion reaction data are distributed around a mean value L = 60 MeV. Recent studies have more thoroughly investigated the density range that a particular observable is predominantly sensitive to. Two thirds of the saturation density is a value typical for the information contained in nuclear-structure data. Higher values exceeding saturation have been shown to be probed with meson production and collective flows at incident energies in the range of up to about 1 GeV/nucleon.From the measurement of the elliptic-flow ratio of neutrons with respect to light charged particles in recent experiments at the GSI laboratory, a new more stringent constraint for the symmetry energy at suprasaturation density has been deduced. It confirms, with a considerably smaller uncertainty, the moderately soft to linear density dependence of the symmetry energy previously deduced from the FOPI-LAND data. Future opportunities offered by FAIR will be discussed.

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Section: Discussionmentioning

confidence: 99%

Symmetry energy and density

Trautmann¹,

Cozma²,

Russotto³

2016

Proceedings of 54th International Winter Meeting on Nuclear Physics — PoS(BORMIO2016)

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“…Heavy-ion collision dynamics is simulated using an upgraded version [15] of the Tübingen quantum molecular dynamics Model (QMD) transport model [23,24] which provides a semiclassical framework for the description of such reactions and accounts for relevant quantum aspects such as stochastic scattering and Pauli blocking of nucleons. It includes the production of all nucleonic resonances with masses below 2 GeV, in total 11 N * and 10 ∆ resonances.…”

Section: The Model a The Transport Modelmentioning

confidence: 99%

“…Another important conclusion of the study in Ref. [15] was that for the standard choice for the strength of the isovector ∆(1232) potential, equal to that of the nucleon, an almost perfect agreement between the pion and elliptic flow extracted SE constraints could be obtained.…”

Section: Introductionmentioning

confidence: 96%

“…[15], where a transport model which enforces the conservation of the total energy of the entire system during heavy-ion reactions has been developed. A restriction of the model to the so-called local energy conservation scenario, which resembles the models of Refs.…”

Section: Introductionmentioning

confidence: 99%

“…To achieve this goal, the model of Ref. [15] is further improved by including the optical potential of pions in nuclear matter, both the so-called S-and P -wave components [18,19]. All the relevant details of this development are presented in Sec.…”

Section: Introductionmentioning

confidence: 99%

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Constraining the density dependence of the symmetry energy using the multiplicity and average pT ratios of charged pions

Cozma

2017

Phys. Rev. C

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The charged pion multiplicity ratio in intermediate energy heavy-ion collisions, a probe of the density dependence of symmetry energy above the saturation point, has been proven in a previous study to be extremely sensitive to the strength of the isovector ∆(1232) potential in nuclear matter. As there is no knowledge, either from theory or experiment, about the magnitude of this quantity, the extraction of constraints on the slope of the symmetry energy at saturation by using exclusively the mentioned observable is hindered at present. It is shown that, by including the ratio of average pT of charged pions pin the list of fitted observables, the noted problem can be circumvented. A realistic description of this observable requires accounting for the interaction of pions with the dense nuclear matter environment by the incorporation of the so called S-wave and P -wave pion optical potentials. This is performed within the framework of a quantum molecular dynamics transport model that enforces the conservation of the total energy of the system. It is shown that constraints on the slope of the symmetry energy at saturation density and the strength of the ∆(1232) potential can be simultaneously extracted. A symmetry energy with a value of the slope parameter L > 50 MeV is favored, at 1σ confidence level, from a comparison with published FOPI experimental data. A precise constraint will require experimental data more accurate than presently available, particularly for the charged pion multiplicity ratio, and better knowledge of the density and momentum dependence of the pion potential for the whole range of these two variables probed in intermediate energy heavy-ion collisions.

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Collective Motion and the Asymmetric-Matter Equation-of-State

Trautmann

2020

Discoveries at the Frontiers of Science

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The impact of energy conservation in transport models on the π−/π+ multiplicity ratio in heavy-ion collisions and the symmetry energy

Cited by 78 publications

References 47 publications

Symmetry energy and density

Symmetry energy and density

Constraining the density dependence of the symmetry energy using the multiplicity and average pT ratios of charged pions

Collective Motion and the Asymmetric-Matter Equation-of-State

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