When is “ab initio” not “ab initio”?

by Steven Karataglidis (University of Melbourne/University of Johannesburg)

Tuesday 8 Apr 2025, 16:00 → 17:00 Europe/Zurich

508/1-001 (CERN)

There is much in the literature concerning the use of effective field theories in nuclear structure calculations. Many, though not all, are described as “ab initio”. Ab initio is Latin for “from the beginning”, the implication being that any such theory is starting from first principles and, as such, the theory should be completely predictive and have no adjustable parameters. In fact, I will illustrate that that is not the case, with the reasons having been published in a little known paper from 2008. Therein, we show that there is an inherent convergence problem in all such theories, due to the requirement of truncating what is, in essence, an infinite-dimension Hilbert space of nuclear configurations for a given nucleus to a finite-dimensional one in order to be able to diagonalise, in every practical sense, the (shell-model) Hamiltonian to obtain the spectrum for the nucleus. I will discuss the consequences of such.