2025/07/21 by Ramalho, G., Peña, M. T., Tsushima, K. +1
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Lattice (hep-lat) #High Energy Physics - Phenomenology (hep-ph) #Nuclear Experiment (nucl-ex)
paper · doi:10.48550/arxiv.2507.15248
In the last few years there has been considerable progress in the study of the electromagnetic form factors of baryons in the timelike region, through electron-positron scattering, with increasing square transfer momentum q2. The modulus of the electric (GE) and magnetic (GM) form factors has been measured for nucleons, hyperons and other baryons at BaBar, CLEO, Belle and BESIII. The novel measurements motivated the extension of a covariant quark model, developed to the spacelike region (q2 ≤ 0), to the timelike region, without any further parameter fitting. The extension is based on asymptotic relations derived from analyticity and unitarity, valid for the large-q2 region. We use the model to make predictions for the effective form factor |G| (combination of GE and GM) and the ratio |GE/GM| for spin 1/2 hyperons at large q2 (above 10 GeV2). Our calculations are in good agreement with the data from CLEO and BESIII for Λ, Σ+ and Ξ- above q2=15 GeV2. Upcoming data for Σ0, Σ- and Ξ- at large q2 may be used to further test our predictions. We also compare our model calculations with the scarce available data for |GE/GM|. We conclude that the present q2 range is not large enough to test our calculations, but that a more definitive test can be made by experiments above q2=20 GeV2.