* FíSICA NUCLEAR * Seminario

Hola  a Todos,

les copio info del seminario de los martes.

saludos

Rolo

_______________________--

Dear Colleagues,

 

Please join us for our next Rising Researchers seminar tomorrow (June 18th) at 10:30 AM Pacific Time by Matthias Heinz --- Technische Universität Darmstadt.

 

The seminar is fully virtual. Please find the Zoom link below.

 

Title: Improved ab initio nuclear structure of neutron-rich calcium isotopes

 

Abstract:

 

Ab initio nuclear structure theory aims to predict the structure of atomic nuclei from "first principles," employing systematically improvable approximations in the determination of inter-nucleon potentials and in the solution of the many-body Schrödinger equation. Over the past decade, the in-medium similarity renormalization group (IMSRG) has been established as a powerful and flexible method to approaching the many-body problem. The IMSRG solves for a unitary transformation that approximately diagonalizes the Hamiltonian (or produces an effective interaction within a valence space for shell model applications). This approximation can be systematically relaxed by including higher-body operators in the many-body solution. Recently, we have worked on extending the IMSRG to the next order, the IMSRG(3) with normal-ordered three-body operators. The IMSRG(3) truncation is formally more involved and also computationally substantially more expensive than the IMSRG(2), the well-established truncation used in applications so far. We have shown, however, that the most expensive terms in the IMSRG(3) can be truncated with little effect on the improved accuracy of the many-body solution, allowing the IMSRG(3) to be approximated at a reasonable computational cost comparable to other high fidelity nuclear structure methods like coupled cluster with approximate triples (CCSDT-1).

 

A key advantage of the IMSRG is its ability to interface with the shell model via the derivation of an effective valence space Hamiltonian (and consistent effective operators). This allows the IMSRG to describe open-shell nuclei easily, and this has been used to perform comprehensive studies of all isotopes up to iron. In calcium isotopes, the IMSRG(2) describes ground-state energies quite well, but struggles to quantitatively reproduce the spectra of calcium-48, a doubly-magic nucleus. Additionally, the trends in the charge radii of neutron-rich calcium are so far unexplained by ab initio methods. I will discuss the improved description of the structure of neutron-rich calcium isotopes made possible by the IMSRG(3) and what this means for existing discrepancies to experimental trends.

 

Zoom link:

https://us06web.zoom.us/j/85077701870

 

Sincerely,

 

Rising Researchers Seminar Series Committee