${\Sigma }^{+}$ and ${\bar{\Sigma }}^{-}$ polarization in the $J/\psi$ and $\psi (3686)$ decays

Abstract

From $1310.6\times 10^6$ $J/\psi$ and $448.1\times 10^6$ $\psi (3686)$ events collected with the BESIII experiment, we report the first observation of ${\Sigma }^{+}$ and ${\bar{\Sigma }}^{-}$ spin polarization in $e^{+}{e}^{-}\to J/\psi (\psi (3686))\to {\Sigma }^{+}{\bar{\Sigma }}^{-}$ decays. The relative phases of the form factors $\Delta \Phi$ have been measured to be $(-15.5\pm 0.7\pm 0.5{)}^{\circ }$ and $(21.7\pm 4.0\pm 0.8{)}^{\circ }$ with $J/\psi$ and $\psi (3686)$ data, respectively. The non-zero value of $\Delta \Phi$ allows for a direct and simultaneous measurement of the decay asymmetry parameters of ${\Sigma }^{+}\to p{\pi }^0({\alpha }_0=-0.998\pm 0.037\pm 0.009)$ and ${\bar{\Sigma }}^{-}\to \bar{p}{\pi }^0({\bar{\alpha }}_0=0.990\pm 0.037\pm 0.011)$, the latter value being determined for the first time. The average decay asymmetry, $({\alpha }_0-{\bar{\alpha }}_0)/2$, is calculated to be $-0.994\pm 0.004\pm 0.002$. The CP asymmetry $A_{\mathrm{CP},\mathrm{\Sigma }}=({\alpha }_0+{\bar{\alpha }}_0)/({\alpha }_0-{\bar{\alpha }}_0)=-0.004\pm 0.037\pm 0.010$ is extracted for the first time, and is found to be consistent with CP conservation.

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Cited by in corpus (32)

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• Study of CP violation in hyperon decays at Super Charm-Tau Factories with a polarized electron beam
• Observation of ${\Xi }^{-}$ Hyperon Transverse Polarization in $\psi (3686)\to {\Xi }^{-}{\bar{\Xi }}^{+}$
• Measurement of $\Lambda$ baryon polarization in $e^{+}{e}^{-}\to \Lambda \bar{\Lambda }$ at $\sqrt{s}=3.773$ GeV
• Strong and weak $CP$ tests in sequential decays of polarized ${\Sigma }^0$ hyperons
• First simultaneous measurement of ${\Xi }^0$ and ${\bar{\Xi }}^0$ asymmetry parameters in $\psi (3686)$ decay
• Test of $CP$ Symmetry in Hyperon to Neutron Decays
• Determination of the ${\Sigma }^{+}$ Timelike Electromagnetic Form Factors
• Predicted $\Lambda \bar{\Lambda }$ and ${\Xi }^{-}{\bar{\Xi }}^{+}$ decay modes of the charmoniumlike $Y(4230)$
• Study of $e^{+}{e}^{-}\to {\Sigma }^0\overline{\Sigma }{}^0$ and ${\Sigma }^{+}\overline{\Sigma }{}^{-}$ by Initial State Radiation Method at Belle
• Production and decay of polarized hyperon-antihyperon pairs
• Measurements of the branching fractions of $\psi (3686)\to {\bar{\Sigma }}^0\Lambda +c.c.$ and ${\chi }_{cJ(J=0,1,2)}\to \Lambda \bar{\Lambda }$
• Precision Measurement of the Decay ${\Sigma }^{+}\to p\gamma$ in the Process $J/\psi \to {\Sigma }^{+}{\bar{\Sigma }}^{-}$
• Production and decay of hyperons in a transversely polarized electron-positron collider
• Probing hyperon electric dipole moments with a full angular analysis
• Prospects to study hyperon-nucleon interactions at BESIII
• Semileptonic decays of spin-entangled baryon-antibaryon pairs
• $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$ cross sections and the ${\Lambda }_c^{+}$ electromagnetic form factors within the extended vector meson dominance model
• Understanding oscillating features of the timelike nucleon electromagnetic form factors within the extending vector meson dominance model
• The effective radius for production of baryon-antibaryon pairs from $\psi$ decays
• Observation of the decay ${\chi }_{cJ}\to {\Omega }^{-}{\bar{\Omega }}^{+}$
• Stringent test of $CP$ symmetry in ${\Sigma }^{+}$ hyperon decays
• The electromagnetic form factors and spin polarization of ${\Lambda }_c^{+}$ in the process $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$
• Tests of CP symmetry in entangled hyperon anti-hyperon pairs at BESIII
• ${\Sigma }^{+}\to p{\ell }^{+}{\ell }^{-}$ decays within the standard model and beyond
• Baryon decays $J/\psi \to B\bar{B}$ within the QCD factorisation framework
• First measurement of ${\Sigma }^{+}n\to \Lambda p$ and ${\Sigma }^{+}n\to {\Sigma }^{0}p$ cross sections via ${\Sigma }^{+}$-nucleus scattering at an electron-positron collider
• Revisit prompt $J/\psi$ production in associated with Higgs Boson via gluon fusion at the LHC
• Observation of Transverse Polarization and Determination of Psionic Form Factors of the $\Lambda$ Hyperon at $\sqrt{s}=3.773$ GeV
• Isospin violating decays of vector charmonia
• A description of charmonia decays $J/\psi \to B\bar{B}$ within the QCD factorisation framework
• Observation of $\Xi (1530{)}^0$ Polarization and Determination of Its Electric and Magnetic Moments in $\psi (3686)\to \Xi (1530{)}^0\bar{\Xi }(1530{)}^0$