Four-Particle Correlations and Quantum Condensates in Nuclear Matter

Starting from a Green function approach to nuclear matter, the formation of bound states and quantum condensates is treated within the cluster-mean field approach. In particular, quartetting in symmetric matter is considered. Nucleonic correlations are of importance in low-density matter, e.g. near the surface of nuclei. Self-conjugate 4n nuclei exhibit an α-like cluster structure. A new α-cluster wave function is proposed which is of the α-particle condensate type. Applications to ¹²C and ¹⁶O show that states of low density close to the three- resp. four-α-particle threshold in both nuclei are possibly of this kind. Furthermore, the occurrence of deformed condensates is discussed. In particular, excited ⁸Be is described as deformed gas-like two-α-particle states.