Tyler and I, along with our collaborators at MIT, Old Dominion, Penn State, Tel Aviv, and Jefferson Lab have just published an article in Physical Review Letters on the quark structure of free neutrons. Whereas free protons are easy to study (using my favorite technique, electron scattering!), neutrons decay with a lifetime of about 15 minutes, and can’t be practically made into a target. Instead, we learn about the neutron by scattering from nuclei, like deuterium or helium, and try to account for any effects that come from nuclear binding. One problematic effect is that the nuclear environment seems to change the structure of protons and neutrons, which we’ve given the name “The EMC Effect.”
In this work, first-authored by MIT graduate student Efrain Segarra, we looked at electron-scattering data from lots of different nuclei, including heavy nuclei, where the EMC Effect is large. Then, using the model developed in one of our recent papers, in which the EMC Effect stems only from short-range correlated proton-neutron pairs, we inferred what the free neutron structure must be to explain the data. This has consequences for the results of the MARATHON Experiment, which will hopefully be published soon.
Our paper is a quick read, and I hope you enjoy it.