A3F-CNS Summer School 2020

Alpha-Cluster Structures above Double Shell Closures from Chiral Effective Field Theory

20 Aug 2020, 17:00

15m

Young Scientist Session 4

Speaker

Dr Dong Bai (School of Physics Science and Engineering, Tongji University, Shanghai 200092, China)

Description

$\alpha$-cluster states above double shell closures are important examples of nuclear $\alpha$ clustering. They include ${}^8\text{Be}=\alpha +\alpha$, ${}^{20}\text{Ne}={}^{16}\text{O}+\alpha$, ${}^{44,52}\text{Ti}={}^{40,48}\text{Ca}+\alpha$, ${}^{104}\text{Te}={}^{100}\text{Sn}+\alpha$, ${}^{212}\text{Po}={}^{208}\text{Pb}+\alpha$, etc. Many theoretical and experimental efforts have been made to understand their physical properties.

We develop new cluster models with local potentials to study these $\alpha$-cluster states in the light of chiral effective field theory ($\chi$EFT) [1]. Compared with phenomenological models for nuclear interactions, $\chi$EFT is characterized by its intimate connections to quantum chromodynamics through chiral symmetry breaking [2,3]. Also, its EFT framework provides a systematic way to make improvements and estimate theoretical errors. We obtain the local potentials between $\alpha$ clusters and doubly magic core nuclei by doubly folding their realistic density distributions with soft local chiral nucleon-nucleon potentials at next-to-next-to-leading order proposed in Ref. [4]. To simulate the Pauli blocking between alpha clusters and core nuclei, we adopt a modified version of the Wildermuth condition.

Various physical properties of $\alpha$-cluster states in ${}^8\text{Be}$, ${}^{20}\text{Ne}$, ${}^{44,52}\text{Ti}$, and ${}^{212}\text{Po}$ are studied by our new model. The theoretical results agree well with experimental data and theoretical expectations. We also study ${}^{104}\text{Te}$, which has become a hot topic recently [5,6]. We analyze the available experimental data systematically within our model. The results could be helpful references for future experiments.

[1] D. Bai and Z. Ren, $\alpha$-Cluster Structures above Double Shell Closures from Chiral Effective Field Theory, under review (2020).
[2] E. Epelbaum, H.-W. Hammer, and U. G. Meissner, Rev. Mod. Phys. 81, 1773 (2009).
[3] R. Machleidt and D. R. Entem, Phys. Rept. 503, 1 (2011).
[4] V. Durant, P. Capel, L. Huth, A. B. Balantekin, and A. Schwenk, Phys. Lett. B 782, 668 (2018).
[5] K. Auranen et al., Phys. Rev. Lett. 121, 182501 (2018).
[6] Y. Xiao et al., Phys. Rev. C 100, 034315 (2019).