Probing neutron-proton dynamics by pions

Abstract

The Pauli blocking for the nucleon(s) in the final state of two-particle collisions and particle decays was found to be incorrect with the blocking probability too small by a factor of 4, in the code of a hadronic cascade model (JAM) employed in our original publication. This affects, in principle, the NN ↔ N and → Nπ processes in the main calculations of the original paper which combines the antisymmetrized molecular dynamics (AMD) and JAM. The results of the usual JAM simulations, which are shown mainly as a reference case without a mean field, are also affected.We revise all the figures (Figs. 1-10) with the corrected numerical results for completeness, although most of the changes are small and do not influence the statements and conclusions in the original paper except for the following point.The approximate equalityρ,p is not as good as in the original paper because the − / ++ production ratio is now higher than (N/Z) 2 ρ,p . However, the updated results even strengthen our statement since the correlation between − / ++ and (N/Z) 2 ρ,p is stronger than in our paper as seen in Fig. 8 and in the comparison of Figs. 6 and 7(b). The final π − /π + ratio is also significantly higher than in the original paper. This problem of Pauli blocking was found during the work for the transport code comparison [1]. The JAM results shown in Ref.[1] were performed after this correction and are therefore not affected.

Cluster production within antisymmetrized molecular dynamics

“…In our previous works [10,16,17], it was necessary to introduce a reduction factor for the overall cluster-formation probabilities to reproduce multifragmentation data. In the present work, however, such a reduction factor does not seem necessary any longer when the momentum fluctuation is taken into account (see Sec.…”

“…Through the momentum and energy conservation, the fluctuation acts as pressure to reduce the expansion of the emitting source and/or it lowers the internal energy of the emitting source on average. Due to these effects, the two-nucleon collision process with clusters can be done without artificial adjustments, and the cluster-cluster binding process can be done with a relatively natural way, compared to the previous studies [10,16,17]. …”

“…[23] as described in Ref. [17]. The decays of excited fragments at the end of the AMD calculation were calculated by a statistical decay code.…”

“…In this subsection, we will discuss the impacts of clusters in the dynamics of 132 Sn + 124 Sn central collisions at 300 MeV/nucleon by employing the result of the AMD calculation with cluster correlations of Ref. [17]. The details of this calculation are different from Sec.…”

“…A recent calculation by this model demonstrates that collision dynamics is influenced by the clusters [15]. On the other hand, in the antisymmetrized molecular dynamics (AMD) approach, we have introduced cluster correlations by improving the two-nucleon collision procedure [16][17][18]. The aims of this article are to report the present status of this approach and to demonstrate the importance of clusters in the studies of heavy-ion collisions.…”