Nonspherical Pauli-forbidden states in deformed halo nuclei: Impact on the ${}^7\mathrm{Be}+p$ resonant states in the particle rotor model

TL;DR

This paper introduces a new method using Nilsson states to properly eliminate Pauli forbidden states in deformed halo nuclei models, improving the accuracy of resonant state predictions in ${}^8$B scattering.

Contribution

The study develops a novel approach to treat Pauli forbidden states in the particle rotor model using Nilsson states, enhancing the modeling of deformed halo nuclei.

Findings

Successfully reproduces elastic scattering cross sections

Predicts a low-energy bump in inelastic scattering

Overestimates the bump's position by about 1 MeV

Abstract

Background: An important aspect of reducing nuclear many-body problems to few-body models is the presence of Pauli forbidden (PF) states, which are excluded in fully antisymmetrized calculations. Insufficient treatments of PF states in deformed halo nuclei underscore the need for model refinement. Purpose: We propose a new method utilizing Nilsson states as PF states in the orthogonality condition model, and investigate the impact of PF states on the properties of resonant states. Method: We investigate the scattering states of ${}^8\mathrm{B}$ within the Particle Rotor Model (PRM) framework based on a deformed ${}^7\mathrm{Be}$ core and $p$ two-body model. We compare several methods for eliminating PF states and test them with the experimental data. Results: Our model successfully reproduces the experimental excitation function for elastic scattering cross section by properly eliminating PF states. The same calculation predicts the presence of a low-energy bump in the inelastic scattering excitation function, although its position is overestimated by about 1 MeV compared to experimental data. Conclusion: This study extends the applicability of the PRM, offering a comprehensive approach for exploring structures and reactions of loosely bound nuclei like ${}^8$B. Future integration with the continuum discretized coupled channels (CDCC) method promises to further advance the research.