Polarization analysis of ${\chi }_{cJ}$ decay into octet baryonic pairs

Abstract

This work presents a comprehensive analysis of polarization transfer in the decays \(\chi_{cJ}\) (\(J=0,1,2\)) to octet baryon-antibaryon pairs within a polarized electron-positron collision environment. Using the spin density matrix formalism, we trace the polarization from the initial beams through the production chain \(e^+e^- \to \psi(2S) \to \gamma \chi_{cJ}\) to the final-state baryon-antibaryon system. The helicity amplitude analysis for \(\chi_{c1} \to B\bar{B}\) confirms the universal angular distribution parameter \(\alpha = -1/3\), as dictated by the charge-conjugation helicity selection rule. For \(\chi_{c2}\) decays, \(\alpha\) and the transverse polarization depend on two independent amplitudes, and our quark-model calculations agree with existing data. We demonstrate that the longitudinal beam polarization \(P_z\) modifies the spin observables for \(\chi_{c1}\) and \(\chi_{c2}\), offering new experimental handles at future polarized facilities like the Super \(\tau\)-Charm Facility(STCF) to test decay mechanisms and explore baryonic spin entanglement as a quantum information resource.

Comments: to be published in Chinese Physics C