Dispersion-theoretical analysis of the electromagnetic form factors of the $\Lambda$ hyperon

Abstract

The electromagnetic form factors of the $\Lambda$ hyperon in the time-like region are determined precisely through a dispersion-theoretical analysis of the world data for the cross section of the annihilation process $e^{+}{e}^{-}\to \bar{\Lambda }\Lambda$. The spectral function is represented by a superposition of narrow and broad vector meson poles. We test different scenarios for the spectral function and obtain a good description of the world data in the time-like region. The uncertainties in the extracted form factors are estimated by means of the bootstrap sampling method. The analytical continuation of the form factors to the space-like region introduces large errors due to the lack of data. When the electric $\Lambda$ radius from chiral perturbation theory is taken as a constraint, the magnetic radius is predicted as $r_M=0.681\pm 0.002$ fm. We also extract various vector meson to baryon coupling constants.

7 pages, 1 figure

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Cited by in corpus (8)

• Determination of the ${\Sigma }^{+}$ Timelike Electromagnetic Form Factors
• Production and decay of polarized hyperon-antihyperon pairs
• Electromagnetic $|G_E/G_M|$ ratios of hyperons at large timelike $q^2$
• Space-like Electromagnetic Form Factors of Lambda- and Sigma-Baryons from Quark-Diquark Faddeev Equations
• $\Lambda \bar{\Lambda }$ final-state interaction in the reactions $e^{+}{e}^{-}\to \varphi \Lambda \bar{\Lambda }$ and $e^{+}{e}^{-}\to \eta \Lambda \bar{\Lambda }$
• Unraveling the structure of $\Lambda$ hyperons with polarized $\Lambda \bar{\Lambda }$ pairs
• Observation of Transverse Polarization and Determination of Psionic Form Factors of the $\Lambda$ Hyperon at $\sqrt{s}=3.773$ GeV
• Baryon Form Factors