Size of helium nucleus measured more precisely than ever before Posted by rustoo on Saturday January 30, 2021 @02:33AM from the ethz.ch dept. https://ethz.ch/en/news-and-events/eth-news/news/2021/01/helium-nucleus-measured-more-precisely-than-ever-before.html ( 4 comments | 19 points | on HN )
is the closest work i found in only a few minutes of lazy research on phone screen. “ab initio” is the phrase you can use to index into the literature on this topic.
"(...) the so- called mean charge radius of the helium nucleus is 1.67824 femtometers (...)"