Speaker
Description
The study of the charmed baryons is crucial for investigating the strong and weak interactions in the Standard Model and for gaining insights into the internal structure of baryons. In an $e^+e^-$ experiment the lightest charmed baryon, $\Lambda_c^+$, can be produced in pairs through the single photon annihilation process. This process can be described by two complex electromagnetic form factors. The presence of a non-zero relative phase between these form factors gives rise to a transverse polarization of the charmed baryon and provides additional constraints on the dynamic parameters in the decays. In this article, we present the first observation of the transverse polarization of $\Lambda_{c}^{+}$ in the reaction $e^+e^- \to \Lambda_c^{+}\bar{\Lambda}_c^-$, based on $6.4~\text{fb}^{-1}$ of $e^{+}e^{-}$ annihilation data collected at center-of-mass energies between $4600$ MeV and $4951$ MeV with the BESIII detector.
The decay asymmetry parameters and strong phase shift in the decays $\Lambda_c^+ \to pK_S^0$, $\Lambda\pi^+$, $\Sigma^0\pi^+$, $\Sigma^+\pi^0$ are also simultaneously extracted from the joint angular distributions.
These results are vital for understanding $C\!P$ violation and its role in the matter-antimatter asymmetry of the Universe.
