Charge and Matter Form Factors of Two-Neutron Halo Nuclei in Halo Effective Field Theory at Next-to-leading-order

TL;DR

This paper employs halo effective field theory at next-to-leading order to calculate charge and matter form factors of two-neutron halo nuclei, providing insights into their structure and radii with experimental agreement.

Contribution

It introduces NLO calculations of form factors for halo nuclei using EFT, including predictions for radii and neutron configurations, and compares results with existing models and experiments.

Findings

Agreement with experimental radii measurements

Predictions for radii based on neutron-core scattering effective range

Consistency with analytical predictions in the unitary limit

Abstract

Using halo effective field theory (EFT), an expansion in $R_{core}/R_{halo}$, where $R_{core}$ is the radius of the core and $R_{halo}$ the radius of the halo nucleus, we calculate the charge and neutron form factors of the two-neutron halo nuclei $^{11}$Li, $^{14}$Be, and $^{22}$C to next-to-leading-order (NLO) by treating them as an effective three-body system. From the form factors we extract the point charge and point matter radii, inter-neutron distance, and neutron opening angle. Agreement is found with existing experimental extractions. Results are given for the point charge and point matter radii for arbitrary neutron core scattering effective range, $\rho_{cn}$, that can be used for predictions once $\rho_{cn}$ is measured. Estimates for $\rho_{cn}$ are also used to make NLO predictions. Finally, our point charge radii are compared to other halo-EFT predictions, and setting the core mass equal to the neutron mass our point charge radius is found to agree with an analytical prediction in the unitary limit.