$\alpha$-particle condensate states in $^{16}$O

TL;DR

This paper demonstrates the existence of an $oldsymbol{ ext{alpha}}$-particle condensate state in $ ext{^{16}O}$, characterized by a rotational band with a cluster structure, indicating possible superfluid behavior in nuclear matter.

Contribution

It provides the first unified study of structure and scattering for the $ ext{alpha}+ ext{^{12}C}(0_2^+)$ system, revealing a condensed cluster state near the four-$ ext{alpha}$ threshold.

Findings

Identification of a rotational band with $ ext{alpha}+ ext{^{12}C}(0_2^+)$ structure

Observation of reduced moment of inertia suggesting superfluidity

Agreement with experimental data on $ ext{^{16}O}$ states

Abstract

The existence of a rotational band with the $\alpha$+$^{12}$C($0_2^+$) cluster structure, in which three $\alpha$ particles in $^{12}$C($0_2^+$) are locally condensed, is demonstrated near the four-$\alpha$ threshold of $^{16}$O in agreement with experiment. This is achieved by studying structure and scattering for the $\alpha$+$^{12}$C($0_2^+$) system in a unified way. A drastic reduction (quenching) of the moment of the inertia of the $0^+$ state at 15.1 MeV just above the four-$\alpha$ threshold in $^{16}$O suggests that it could be a candidate for the superfluid state in $\alpha$-particle condensation.