Measurement of Decay Parameters for ${\Xi }^{-}\to \Lambda {\pi }^{-}$ Decay

Abstract

Based on 1.35 million polarized ${\Xi }^{-}$ events, we measure the parameter ${\varphi }_{\Xi }$ to be $-1.61^{\circ }\pm 2.66^{\circ }\pm 0.37^{\circ }$ for ${\Xi }^{-}\to \Lambda {\pi }^{-}$ decay. New results for the parameters ${\beta }_{\Xi }$ and ${\gamma }_{\Xi }$ are also presented. Assuming that the CP-violating phase-shift difference is negligible, we deduce the strong phase-shift difference between the P-wave and S-wave amplitudes of the $\Lambda \pi$ final state to be $3.17^{\circ }\pm 5.28^{\circ }\pm 0.73^{\circ }$. This strong phase-shift difference reduces the theoretical uncertainty in estimating the level of CP violation in $\Xi$-hyperon decay.

To be published in Physical Review Letters

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• Lambda and Antilambda polarization in Au-Au collisions at RHIC
• Meson-baryon scattering to one-loop order in heavy baryon chiral perturbation theory
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• 70 Years of Hyperon Spectroscopy: A review of strange $\Xi$, $\Omega$ baryons, and the spectrum of charmed and bottom baryons
• Antihyperon polarization in high-energy inclusive reactions
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• Low energy kaon-hyperon interaction
• Remarks on strong phase shifts in weak nonleptonic baryon decays
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• Low energy pion-${\Lambda }_b$ interaction