Beam-energy dependence of the relativistic retardation effects of electrical fields on the π-/π+ ratio in heavy-ion collisions
Abstract
In this article we investigate the beam-energy dependence of relativistic retardation effects of electrical fields on the single and double π-/π+ ratios in three heavy-ion reactions with an isospin- and momentum-dependent transport model IBUU11. With the beam energy increasing from 200 to 400 MeV/nucleon, effects of the relativistically retarded electrical fields on the π-/π+ ratio are found to increase gradually from negligible to considerably significant as expected; it is, however, an interesting observation that the relativistic retardation effects of electrical fields on the π-/π+ ratio become gradually insignificant as the beam energy further increases from 400 to 800 MeV/nucleon. That is to say, with the beam energy increasing, the competition of enhanced anisotropic features of retarded electrical fields and reduced duration time of the reactions gets effects of the relativistically retarded electrical fields on the π-/π+ ratio to be maximum around 400 MeV/nucleon. Therefore, the relativistic retardation effects of electrical fields should be carefully considered in heavy-ion collisions at intermediate energy especially around 400 MeV/nucleon when using the π-/π+ ratio as the probe of nuclear symmetry energy. Moreover, we also investigate the isospin dependence of relativistic retardation effects of electrical fields on the π-/π+ ratio in two isobar reaction systems of 96Ru+96Ru and 96Zr+96Zr at the beam energies from 200 to 800 MeV/nucleon. It is shown that the relativistic retardation effects of electrical fields on the π-/π+ ratio are independent of the isospin of reaction. Furthermore, we also examine the double π-/π+ ratio in reactions of 96Zr+96Zr over 96Ru+96Ru at the beam energies from 200 to 800 MeV/nucleon with the static field and retarded field, respectively. It is shown that the double π-/π+ ratio from two reactions is still an effective observable of symmetry energy without the interference of electrical field due to using the relativistic calculation compared to the nonrelativistic calculation.
- Publication:
-
Physical Review C
- Pub Date:
- August 2018
- DOI:
- 10.1103/PhysRevC.98.024618
- arXiv:
- arXiv:1807.05878
- Bibcode:
- 2018PhRvC..98b4618W
- Keywords:
-
- Nuclear Theory;
- High Energy Physics - Phenomenology
- E-Print:
- 8 pages, 7 figures. Abbreviated abstract to meet the criterion of arXiv platform. Accepted for publication in Physical Review C. An extended but necessary complementary study to arXiv:1709.09127