Pairing dynamics and solitonic excitations in collisions of medium-mass, identical nuclei

TL;DR

This paper investigates the collision dynamics of medium-mass superfluid nuclei using advanced density functional theory, revealing new solitonic excitations, altered barrier behaviors, and dynamic pairing phenomena near the Coulomb barrier.

Contribution

It introduces the application of TDSLDA to study superfluid nuclear collisions, uncovering solitonic excitations and dynamic pairing effects not previously reported.

Findings

Solitonic excitations increase the Coulomb barrier for capture.

Pairing field dynamics lead to slower shape evolution at the barrier.

Post-collision pairing correlations can be dynamically enhanced.

Abstract

We present results of collisions of $^{90}$Zr+$^{90}$Zr and $^{96}$Zr+$^{96}$Zr obtained within time-dependent density functional theory (TDDFT) extended to superfluid systems, known as time-dependent superfluid local density approximation (TDSLDA). We discuss qualitatively new features occurring in collisions of two superfluid nuclei at energies in the vicinity of the Coulomb barrier. We show that a \textit{solitonic excitation} -- an abrupt pairing phase distortion -- reported previously [P.~Magierski et al., Phys. Rev. Lett. \textbf{119}, 042501 (2017)], increases the barrier for capture generating effective repulsion between colliding nuclei. Moreover we demonstrate that pairing field leads to qualitatively different dynamics at the Coulomb barrier which manifests itself in a slower evolution of deformation towards a compact shape. Last but not least, we show that magnitude of pairing correlations can be dynamically enhanced after collision. We interpret it as a dynamically induced $U(1)$ symmetry breaking, which leads to large-amplitude oscillations of pairing field and bear similarity to the pairing Higgs mechanism.