scholarly journals Quantifying the Effect of Initial Fluctuations on Isospin-Sensitive Observables from Heavy-Ion Collisions at Intermediate Energies

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2172
Author(s):  
Yongjia Wang ◽  
Zepeng Gao ◽  
Qingfeng Li
Keyword(s):  
Symmetry Energy ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Yield Ratio ◽  
Quantum Molecular Dynamics ◽  
Intermediate Energies ◽  
Ion Collisions ◽  
Protons And Neutrons ◽  
Charged Pions ◽  
Sensitive Observables

Initial fluctuation is one of the ingredients that washes fingerprints of the nuclear symmetry energy on observables in heavy-ion collisions. By artificially using the same initial nuclei in all collision events, the effect of the initial fluctuation on isospin-sensitive observables, e.g., the yield ratio of free neutrons with respect to protons Nn/Np, 3H/3He yield ratio, the yield ratio between charged pions π−/π+, and the elliptic flow ratio or difference between free neutrons and protons v2n/v2p (v2n-v2p), are studied within the ultrarelativistic quantum molecular dynamics (UrQMD) model. In practice, Au + Au collisions with impact parameter b = 5 fm and beam energy Elab = 400 MeV/nucleon are calculated. It is found that the effect of the initialization on the yields of free protons and neutrons is small, while for the yield of pions, the directed and elliptic flows are found to be apparently influenced by the choice of initialization because of the strong memory effects. Regarding the isospin-sensitive observables, the effect of the initialization on Nn/Np and 3H/3He is negligible, while π−/π+ and v2n/v2p (v2n-v2p) display a distinct difference among different initializations. The fingerprints of symmetry energy on π−/π+ and v2n/v2p can be either enhanced or reduced when different initializations are utilized.

PROBING THE SYMMETRY ENERGY AT SUPRA-SATURATION DENSITIES FROM PION EMISSION IN HEAVY-ION COLLISIONS

2010 ◽  
Vol 19 (08n09) ◽  
pp. 1686-1693 ◽  
Author(s):  
ZHAO-QING FENG ◽  
GEN-MING JIN
Keyword(s):  
Symmetry Energy ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Measured Data ◽  
Quantum Molecular Dynamics ◽  
Nuclear Symmetry Energy ◽  
Potential Term ◽  
Ion Collisions ◽  
Pion Emission ◽  
Fopi Collaboration

Within the framework of the improved isospin dependent quantum molecular dynamics (ImIQMD) model, the emission of pion in heavy-ion collisions in the region 1 A GeV as a probe of nuclear symmetry energy at supra-saturation densities is investigated systematically, in which the pion is considered to be mainly produced by the decay of resonances Δ(1232) and N *(1440). The π-/π+ yields are calculated for selected Skyrme parameters SkP, SLy6, Ska and SIII, and also for the cases of different stiffness of symmetry energy with the parameter SLy6. Preliminary results compared with the measured data by the FOPI collaboration favor a hard symmetry energy of the potential term proportional to (ρ/ρ0)γs with γs = 2.

Isospin effects on pt-differential flow in heavy ion collisions at intermediate energies

2014 ◽  
Vol 23 (10) ◽  
pp. 1450062
Author(s):  
Rubina Bansal ◽  
Anupriya Jain ◽  
Suneel Kumar
Keyword(s):  
Density Dependence ◽  
Symmetry Energy ◽  
Heavy Ion Collisions ◽  
Dominant Role ◽  
Heavy Ion ◽  
Nucleon Nucleon ◽  
Transverse Flow ◽  
Intermediate Energies ◽  
Ion Collisions ◽  
Isospin Dependence

This paper aims to study the role of isospin degree of freedom in heavy-ion collisions through the transverse momentum (pt), neutron to proton ratio and system mass dependence of pt-differential transverse flow. Our study shows that (pt)-differential transverse flow dependence can act as sensitive probe to study symmetry energy and its density dependence compared to the energy of vanishing flow. Symmetry energy and its density dependence play a dominant role over the isospin-dependence of nucleon–nucleon cross-section at Fermi energy.

scholarly journals PROBING THE SYMMETRY ENERGY AT HIGH BARYON DENSITY WITH HEAVY ION COLLISIONS

2010 ◽  
Vol 19 (08n09) ◽  
pp. 1664-1674 ◽  
Author(s):  
V. GRECO ◽  
M. COLONNA ◽  
M. DI TORO ◽  
H. H. WOLTER
Keyword(s):  
Symmetry Energy ◽  
Heavy Ion Collisions ◽  
Theoretical Models ◽  
Heavy Ion ◽  
Baryon Density ◽  
Momentum Dependence ◽  
Physical Mechanisms ◽  
Ion Collisions ◽  
Protons And Neutrons ◽  
The Difference

The nuclear symmetry energy at densities above saturation density (ρ0 ~ 0.16fm-3) is poorly constrained theoretically and very few relevant experimental data exist. Its study is possible through Heavy Ion Collisions (HIC) at energies E/A > 200 MeV , particularly with beams of neutron-rich radioactive nuclei. The energy range implies that the momentum dependence of the isospin fields, i.e. the difference of the effective masses on protons and neutrons, also has to be investigated before a safe constraint on E sym (ρ) is possible. We discuss the several observables which have been suggested, like n/p emission and their collective flows and the ratio of meson yields with different isospin projection, π-/π+ and K0/K+. We point out several physical mechanisms that should be included in the theoretical models to allow a direct comparison to the more precise experiments which will be able to distinguish the isospin projection of the detected particles: CSR/Lanzhou, FAIR/GSI, RIBF/RIKEN, FRIB/MSU.

scholarly journals MEDIUM EFFECTS ON CHARGED PION RATIO IN HEAVY ION COLLISIONS

2010 ◽  
Vol 19 (08n09) ◽  
pp. 1763-1772 ◽  
Author(s):  
CHE MING KO ◽  
YONGSEOK OH ◽  
JUN XU
Keyword(s):  
Nuclear Matter ◽  
Symmetry Energy ◽  
Heavy Ion Collisions ◽  
Wave Interaction ◽  
Heavy Ion ◽  
Nuclear Medium ◽  
Nuclear Symmetry Energy ◽  
Ion Collisions ◽  
Charged Pions ◽  
Positively Charged

We have recently studied in the delta-resonance–nucleon-hole model the dependence of the pion spectral function in hot dense asymmetric nuclear matter on the charge of the pion due to the pion p-wave interaction in nuclear medium. In a thermal model, this isospin-dependent effect enhances the ratio of negatively charged to positively charged pions in neutron-rich nuclear matter, and the effect is comparable to that due to the uncertainties in the theoretically predicted stiffness of nuclear symmetry energy at high densities. This effect is, however, reversed if we also take into account the s-wave interaction of the pion in nuclear medium as given by chiral perturbation theory, resulting instead in a slightly reduced ratio of negatively charged to positively charged pions. Relevance of our results to the determination of the nuclear symmetry energy from the ratio of negatively to positively charged pions produced in heavy ion collisions is discussed.

scholarly journals Symmetry energy dependence of light fragment production in heavy-ion collisions

2015 ◽  
Vol 88 ◽  
pp. 00021
Author(s):  
H. H. Wolter ◽  
M. Zielinska-Pfabe ◽  
P. Decowski ◽  
M. Colonna
Keyword(s):  
Energy Dependence ◽  
Symmetry Energy ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Light Fragment ◽  
Ion Collisions ◽  
Fragment Production
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