Precision <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>C</mml:mi><mml:mi>P</mml:mi></mml:math> Symmetry Test and Polarization Analysis in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi mathvariant="normal">Σ</mml:mi><mml:mo>+</mml:mo></mml:msup></mml:math> Decays

A stringent test of CP symmetry in hyperon decays is performed using 1.0×10^{10} J/ψ events and 2.7×10^{9} ψ(3686) events collected by the BESIII experiment. The CP asymmetry in the two-body nonleptonic weak decays Σ^{+}→pπ^{0} and Σ[over ¯]^{-}→p[over ¯]π^{0} is determined to be A_{CP}=-0.0118±0.0083(stat)±0.0028(syst), consistent with CP conservation. The average decay parameter ⟨α_{0}⟩=-0.9869±0.0011(stat)±0.0016(syst) represents the most precise measurement in the baryon sector to date. A model-independent analysis of the hyperon polarization is performed for the first time at J/ψ and ψ(3686) resonances, revealing a clear sign reversal and offering new insight into SU(3) symmetry breaking and baryon internal structure. These results provide the most stringent constraints on CP violation in Σ decays and establish a benchmark for future precision studies.