Search for CP Violations in the Production and Decay of the Hyperon-Antihyperon Pairs

This study introduces a complete joint angular distribution analysis for the process $e^{+}e^{-}\to J/ψ\to B(\to B_1π)\bar{B}(\to \bar{B}1π)$ with polarized beams, where $B$ and $B{1}$ are hyperons. We consider both transverse and longitudinal beam polarization and analyze $CP$ violation in the production and decay of hyperons. We present the complete Fisher information matrix for the sensitivities of the weak decay parameters $α_{-},~α_{+},~ϕ_Ξ$ and $\barϕ_Ξ$, the $P$-violating term $F_{A}$, and the EDM $d_{B}$ (derived from the $CP$-violating term $H_{T}$), under the BESIII and STCF statistics. We find that polarization enhances the sensitivity of the parameters. Specifically, longitudinal polarization provides a more significant improvement compared to transverse polarization, with the enhancement being more pronounced for single-step decays than for multistep decays. With the expected statistics from the BESIII experiment, the estimated EDM sensitivities for $Λ$ and $Σ^{+}$ are on the order of $10^{-19}e\rm cm$, while those for $Ξ^{-}$ and $Ξ^{0}$ are $10^{-18}e\rm cm$. The upcoming STCF experiment is expected to improve these estimates by $1-2$ orders of magnitude. Furthermore, $CP$ violation in hyperon decays originates from weak-phase differences among partial-wave amplitudes. Based on a refined isospin analysis, we emphasize the non-negligible contribution of $ΔI = 3/2$ amplitudes to $CP$ violation and advocate for increased theoretical attention to this aspect in future studies..

💡 Research Summary

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This paper presents a comprehensive theoretical framework for studying CP violation and electric dipole moments (EDMs) of hyperons produced in electron‑positron annihilation at the $J/\psi$ resonance. The authors consider both transverse ($P_T$) and longitudinal ($P_L$) beam polarizations and derive the full joint angular distribution for the process
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