The Role of Tensor Force in Heavy-Ion Fusion Dynamics

TL;DR

This paper incorporates tensor force into TDHF theory to study its impact on heavy-ion fusion, revealing significant effects on fusion barriers and cross sections, mainly due to shifts in vibrational states and nucleon transfer.

Contribution

It introduces a microscopic implementation of tensor force in TDHF to analyze its role in heavy-ion fusion dynamics, including effects on fusion barriers and transfer processes.

Findings

Tensor force significantly affects fusion barriers and cross sections.

Effects are linked to shifts in vibrational states and nucleon transfer.

Tensor force does not notably influence near-barrier dissipation.

Abstract

The tensor force is implemented into the time-dependent Hartree-Fock (TDHF) theory so that both exotic and stable collision partners, as well as their dynamics in heavy-ion fusion, can be described microscopically. The role of tensor force on fusion dynamics is systematically investigated for $^{40}\mathrm{Ca}+\mathrm{^{40}Ca}$, $^{40}\mathrm{Ca}+\mathrm{^{48}Ca}$, $^{48}\mathrm{Ca}+\mathrm{^{48}Ca}$, $^{48}\mathrm{Ca}+\mathrm{^{56}Ni}$, and $^{56}\mathrm{Ni}+\mathrm{^{56}Ni}$ reactions which vary by the total number of spin-unsaturated magic numbers in target and projectile. A notable effect on fusion barriers and cross sections is observed by the inclusion of tensor force. The origin of this effect is analyzed. The influence of isoscalar and isovector tensor terms is investigated with the T$IJ$ forces. These effects of tensor force in fusion dynamics are essentially attributed to the shift of low-lying vibration states of colliding partners and nucleon transfer in the asymmetric reactions. Our calculations of above-barrier fusion cross sections also show that tensor force does not significantly affect the dynamical dissipation at near-barrier energies.