Abstract
We analyze joint angular distributions of a charmonium decay to the $\Xi\bar\Xi$ pair using the $\Xi\to\Lambda\pi\to p\pi^-\pi$ weak decay chain for the cascade and the charge conjugated mode for the anticascade. The decays allow a direct comparison of the baryon and antibaryon decay properties and a sensitive test of CP symmetry in the strange baryon sector. We show that all involved decay parameters can be determined separately in vector and (pseudo)scalar charmonia decays into $\Xi\bar\Xi$ due to the spin correlations between the weak decay chains. Contrary to the recently measured $e^+e^-\to J/\psi\to \Lambda\bar\Lambda$ process, the transverse polarization of the cascade is not needed and has almost no impact on the uncertainties of the decay parameters.
Highlights
The decays allow a direct comparison of the baryon and antibaryon decay properties and a sensitive test of conjugation parity (CP) symmetry in the strange baryon sector
We show that all involved decay parameters can be determined separately in vector andscalar charmonia decays into ΞΞdue to the spin correlations between the weak decay chains
The ongoing experimental studies of the combined charge conjugation parity (CP) symmetry violation in particle decays aim to find effects that are not expected in the Standard Model (SM), such that new dynamics is revealed
Summary
The ongoing experimental studies of the combined charge conjugation parity (CP) symmetry violation in particle decays aim to find effects that are not expected in the Standard Model (SM), such that new dynamics is revealed. The main decay modes of the ground state hyperons are weak transitions into a baryon and a pseudoscalar meson like Λ → pπ−, branching fraction B ≈ 64%, and Ξ− → Λπ−, B ≈ 100% [7]. They involve two amplitudes: parity conserving to the relative p state, and parity violating to the s state. The best limit for CP violation in the strange baryon sector was obtained by comparing the Ξ− and Ξþ decay chains of unpolarized Ξ baryons at the HyperCP (E871) experiment [8] by determining the asymmetry AΞΛ 1⁄4ðαΛαΞ −αΛαΞ Þ= ðαΛαΞ þαΛαΞ Þ. The method allows for a direct comparison of the decay parameters of the charge conjugate decay modes and a test of the CP symmetry
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