Role of chiral two-body currents in $^6$Li magnetic properties in light of a new precision measurement with the relative self-absorption technique

TL;DR

This paper reports a precise measurement of the decay width of an excited state in $^6$Li, providing a critical test for modern nuclear force theories, especially the role of two-body currents in magnetic properties.

Contribution

It presents a new high-precision measurement of $^6$Li's excited state decay width, enabling a direct comparison with advanced ab initio chiral EFT calculations including two-body currents.

Findings

Measured decay width: 8.17(14)(11) eV.

Experimental uncertainties are low enough for theory testing.

Results support the significance of two-body currents in nuclear magnetic properties.

Abstract

A direct measurement of the decay width of the excited $0^+_1$ state of $^6$Li using the relative self-absorption technique is reported. Our value of $\Gamma_{\gamma, 0^+_1 \to 1^+_1} = 8.17(14)_\mathrm{stat.}(11)_\mathrm{syst.} \mathrm{eV}$ provides sufficiently low experimental uncertainties to test modern theories of nuclear forces. The corresponding transition rate is compared to the results of ab initio calculations based on chiral effective field theory that take into account contributions to the magnetic dipole operator beyond leading order. This enables a precision test of the impact of two-body currents that enter at next-to-leading order.