Determining the spin of any new particle is critical in identifying the true theory among various extensions of the standard model (SM). The degree of $Z$-boson polarization in any two-body decay process $A\to BZ$ is sensitive to the spin assignments of two new particles $A$ and $B$. Considering all possible spin-0, $1/2$, and 1 combinations in a renormalizable field theory, we demonstrate that $Z$-boson polarization can indeed play a role of a decisive and universal analyzer in distinguishing the different spin assignments.

• Received 28 November 2018

DOI:https://doi.org/10.1103/PhysRevD.98.115037

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Published by the American Physical Society