The asymmetry parameter $\alpha_-$ of the parity-violating weak decay $\Lambda \rightarrow p \pi^-$ is a result of interference between $s$- and $p$-waves. The BESIII collaboration recently reported a value of $\alpha_-$ as 0.750(9)(4) - which is significantly higher than the current PDG value of 0.642(13).
In the same time, most of the polarization observables (from CLAS measurements) also depend on the value of $\alpha_-$. We show, that a higher value of the decay parameter is obtained when constraints from spin-algebra (Fierz identities) are implemented into the analysis of the photoproduction data.
Such, independently obtained value is significantly closer to the BESIII value than the quoted PDG value and implies also a closer agreement with vanishing matter/antimatter asymetry ratio $(\alpha_-+\alpha_+)/(\alpha_--\alpha_+)$.