Timelike nucleon electromagnetic form factors: All about interference of isospin amplitudes

Abstract

A striking feature of the timelike nucleon electromagnetic form factors, investigated in $e^{+}{e}^{-}\to N\bar{N}$ annihilation reactions, is the modulation by local structures of small magnitude and oscillatory form, showing up above $N\bar{N}$ threshold. Starting from an isospin decomposition of the proton and neutron form factors it is shown that such structures are the natural consequence of the interference of a large and a small amplitudes, resulting in a sinusoidal behavior as a function of the "invariant energy" if the relative phase shift varies with energy. Thus, periodic oscillations superimposed on a smooth background will be observed. In this scenario, an equal size of the modulation for neutron and proton discovered by recent BESIII data evidently implies the particular isoscalar or isovector nature of these local structures, or their orthogonal interference, hence specifies their origin as excited vector mesons whose widths are tied to the modulation frequency.We clarify that the phase difference of modulation between neutron and proton as BESIII data found, but not the modulation itself, is the evidence of an imaginary part of the timelike nucleon electromagnetic form factors, which is associated with the rescattering processes.

7 pages, 2 figures

References in corpus (11)

• Dispersion analysis of the nucleon form factors including meson continua
• New insights into the nucleon's electromagnetic structure
• The electromagnetic form factors of the proton in the timelike region
• Nucleon Electromagnetic Form Factors in the Timelike Region
• Periodic interference structures in the time-like proton form factor
• Time- and Spacelike Nucleon Electromagnetic Form Factors beyond Relativistic Constituent Quark Models
• High-precision determination of the electric and magnetic radius of the proton
• Measurement of the cross section for $e^{+}{e}^{-}\to \Lambda \bar{\Lambda }$ and evidence of the decay $\psi (3770)\to \Lambda \bar{\Lambda }$
• New fit of time-like proton electromagnetic form factors from $e^{+}{e}^{-}$ colliders
• Study of $e^{+}{e}^{-}\to p\bar{p}$ in the vicinity of $\psi (3770)$
• Light unflavor vector meson spectroscopy around the mass range of $2.4\sim 3$ GeV and possible experimental evidence

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• Electromagnetic form factors of neutron and neutral stange hyperons in the oscillating view of point
• New insights into the oscillation of the nucleon electromagnetic form factors
• Understanding oscillating features of the timelike nucleon electromagnetic form factors within the extending vector meson dominance model
• Compared analysis of time-like hyperon form factors
• The electromagnetic form factors and spin polarization of ${\Lambda }_c^{+}$ in the process $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$
• Measurement of ${\Sigma }^{+}$ transverse polarization in $e^{+}{e}^{-}$ collisions at $\sqrt{s}=3.68-3.71$ GeV
• Accessing baryon-antibaryon generalized distribution amplitudes in $e^{\pm }\gamma \to e^{\pm }B\bar{B}$