Level densities in deformed nuclei beyond the mean-field approximation

Nuclear level densities are important inputs to the Hauser-Feshbach theory of compound nucleus reactions. Microscopic calculations of level densities often rely on the mean-field approximation, which underestimates level densities in deformed nuclei [1]. The static-path plus random-phase approximation (SPA+RPA) includes large-amplitude thermal fluctuations and small-amplitude time-dependent quantal fluctuations beyond the mean field [2,3]. We investigate how much of the rotational enhancement of the level density is recovered in the SPA+RPA by benchmarking the level densities calculated with a quadrupole-quadrupole interaction against exact results calculated with the auxiliary-field Monte Carlo method [4].

[1] Y. Alhassid et al., Phys. Rev. C 93, 044320 (2016).

[2] H. Attias and Y. Alhassid, Nucl. Phys. A 625, 565 (1997).

[3] B. Lauritzen et al., Phys. Lett. B 246, 329 (1990).

[4] Y. Alhassid, in Emergent Phenomena in Atomic Nuclei from Large-Scale Modeling: a Symmetry-Guided Perspective, ed. by K. D. Launey (World Scientific, Singapore, 2017), pp. 267-268.