Determination of the ${\Sigma }^{+}$ Timelike Electromagnetic Form Factors

Abstract

Based on data samples collected with the BESIII detector at the BEPCII collider, the process $e^{+}{e}^{-}\to {\Sigma }^{+}{\bar{\Sigma }}^{-}$ is studied at center-of-mass energies $\sqrt{s}$ = 2.3960, 2.6454, and 2.9000 GeV. Using a fully differential angular description of the final state particles, both the relative magnitude and phase information of the ${\Sigma }^{+}$ electromagnetic form factors in the timelike region are extracted. The relative phase between the electric and magnetic form factors is determined to be $\sin \Delta \Phi$ = -0.67~$\pm$~0.29~(stat)~$\pm$~0.18~(syst) at $\sqrt{s}$ = 2.3960 GeV, $\Delta \Phi$ = 55${}^{\circ }$~$\pm$~19${}^{\circ }$~(stat) $\pm$~14${}^{\circ }$~(syst) at $\sqrt{s}$ = 2.6454 GeV, and 78${}^{\circ }$~$\pm$~22${}^{\circ }$~(stat) $\pm$~9${}^{\circ }$~(syst) at $\sqrt{s}$ = 2.9000 GeV. For the first time, the phase of the hyperon electromagnetic form factors is explored in a wide range of four-momentum transfer. The evolution of the phase along with four-momentum transfer is an important input for understanding its asymptotic behavior and the dynamics of baryons.

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Cited by in corpus (5)

• 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
• Observation of $\Xi (1530{)}^0$ Polarization and Determination of Its Electric and Magnetic Moments in $\psi (3686)\to \Xi (1530{)}^0\bar{\Xi }(1530{)}^0$
• Time-like electromagnetic form factors of $\Lambda ,\Sigma$ and ${\Xi }^{+}$ in a light-front quark model
• Accessing baryon-antibaryon generalized distribution amplitudes in $e^{\pm }\gamma \to e^{\pm }B\bar{B}$