“Tweezers” to study nuclear interactions

Researchers from North Carolina State University and the Ruhr-Universität Bochum have developed numerical “tweezers” that can pin a nucleus in place, enabling them to study how interactions between protons and neutrons produce forces between nuclei. They found that the strength of local interactions determines whether or not these nuclei attract or repel each other, shedding light on the parameters that control attraction or repulsion in quantum bound states.

“Ultimately we want to understand how nuclear forces determine nuclear structure by studying how nuclei attract or repel one another,” says Dean Lee, professor of physics at NC State and corresponding author of a paper describing the work. “So we needed a way to hold particles in place and move them around relative to one another in order to measure attraction or repulsion.”

The full press release can be found here.

Effective Forces Between Quantum Bound States

Authors: Alexander Rokash, Evgeny Epelbaum and Hermann Krebs, Institut fur Theoretische Physik II, Ruhr-Universität Bochum, Germany; Dean Lee, North Carolina State University

Published: June 9, 2017, Physical Review Letters

Abstract: Recent ab initio lattice studies have found that the interactions between alpha particles (4He nuclei) are sensitive to seemingly minor details of the nucleon-nucleon force such as interaction locality. In order to uncover the essential physics of this puzzling phenomenon without unnecessary complications, we study a simple model involving two-component fermions in one spatial dimension. We probe the interaction between two bound dimers for several different particle-particle interactions and measure an effective potential between the dimers using external point potentials which act as numerical tweezers. We find that the strength and range of the local part of the particle-particle interactions play a dominant role in shaping the interactions between the dimers and can even determine the overall sign of the effective potential.