Speaker
Description
Time-like hadron electromagnetic form factors are accessible through electron-positron annihilation into a hadron and anti-hadron pair and its time reverse reaction. Large progress was recently done at electron-positron colliders, applying the Initial State Radiation (ISR) method. Precise measurements of the proton form factor, up to s $simeq$ 40 GeV$2$, done by BaBar showed irregularities in the annihilation cross section and in the effective form factor spectra. These structures were recently confirmed by BESIII with both, ISR and beam scan methods. When plotted as a function of the relative momentum of the produced hadrons, this behavior can be fitted by a damped regular oscillation on the top of a monotone decreasing background, favoring a description in terms of an interference between phenomena occurring at the quark scale (0.2 fm) and at the hadron scale (1 fm). A similar analysis done by the BESIII collaboration, highlights such behavior also in the neutron case. Interesting correlations appear among proton, neutron and hyperon form factors.
| speaker affiliation | CEA Saclay, IRFU/DPhN |
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