Abstract
The investigation of the fundamental properties of the nucleon is one of the most important topics in the modern hadron physics. Its internal structure and dynamics can be studied through the measurement of electromagnetic form factors which represent the simplest structure observables and serve as a test ground for our understanding of the strong interaction. Since the first attempt to measure the time-like form factors of the neutron, only four experiments published results on its structure from annihilation reactions. Due to the lack of statistics and experimental challenges, no individual determination of the form factors of the neutron has been possible so far. Modern developments of electron-positron colliders and the associated detectors allow to measure the effective FF of the neutron with the process e+e−→nn¯ with unprecedented precision at the BESIII experiment, which is based at the BEPCII collider in Beijing, China. In this report, we review the published results of the form factors on the neutron in the time-like regime, describe the experimental setup, and discuss their impact on our understanding of the strong interaction. Future works at BESIII will help to improve the precision of the neutron FFs and, combined with theoretical progress in this field, help to illuminate the properties of the neutron structure.
Highlights
Introduction published maps and institutional affilThe interaction of the constituents of the proton and the neutron are described by Quantum Chromodynamics (QCD)
The internal structure and dynamics of the nucleon can be parametrized by the electromagnetic (EM) form factors (FFs) [1]
Physical background from the p pfinal state is considered with a dedicated measurement of such and taken into account when deriving the number of signal events, while other processes are considered within the systematics uncertainty
Summary
Experimental access to the neutron structure in the time-like region is very limited. Different q2 -values can only be reached by scanning the beam energy. The process e+ e− → nnγ ISR can be studied using high luminosity data samples at fixed beam energy to analyze the Initial. When performing the analysis of an energy scan, the signal process e+ e− → nnis reconstructed from data samples taken at each beam energy value and the FFs are measured. Lack of statistics in the collected data prevented the individual determination of the FFs. Instead, all previous experiments measured the so-called effective form factor | G n | from the integrated Born cross section n |, which σBnn , under the hypothesis of equal electric and magnetic contributions | GEn | = | G M can be written as v u
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
