Orateur
Description
The objective of the so-called ab initio approach to nuclear structure is to provide an accurate and universal description of nuclear systems from first principles [1]. In this context, solving the many-body Schrödinger equation requires systematically improvable many-body methods. Over the past 20 years, the development of novel expansion methods displaying a mild computational scaling with systems size have allowed access to mid-mass closed-shell nuclei. Such methods typically expand the exact ground-state wave-function around a reference/unperturbed Slater determinant and include correlations through elementary particle-hole excitations. This can be obtained from perturbative techniques [2] or from non-perturbative approaches such as coupled-cluster (CC) theory [3]. While closed-shell nuclei are well under control, the extension to open-shell nuclei remains a major challenge.
Only very recently, a novel many-body method coined as Bogoliubov coupled cluster (BCC) theory [4] has been formulated that extends the standard coupled cluster scheme to singly open-shell nuclei. This is achieved by breaking particle-number symmetry of the unperturbed state as a way to already incorporate crucial static correlations into it. In my talk I will present recent results obtained for the ground-state of oxygen isotopes based on nuclear interaction models derived from chiral effective field theory.
Once fully implemented, the non-perturbative (equation-of-motion) BCC method will allow for high-precision ab initio calculations of ground and excited states in medium-mass nuclei.
[1] H. Hergert, Front. Phys. 8, 379 (2020)
[2] A. Tichai, R. Roth, T. Duguet, Front Phys. 8, 164 (2020)
[3] G. Hagen, T. Papenbrock, M. Hjort-Jensen, D. J. Dean, Rep. Prog. Phys. 77, 9 (2014)
[4] A. Signoracci, T. Duguet, G. Hagen, G. Jansen, Phys. Rev. C 91, 064320 (2015)
