${{\boldsymbol D}_{{1}}{(2420)}^{\pm}}$ POLARIZATION AMPLITUDE A$_{{{\boldsymbol D}_{{1}}}}$
INSPIRE search
A polarization amplitude A$_{{{\mathit D}_{{1}}}}$ is a parameter that depends on the initial polarization of the ${{\mathit D}_{{1}}}$ and is sensitive to a possible ${\mathit S}{\mathrm -wave}$ contribution to its decay. For ${{\mathit D}_{{1}}}$ decays the helicity angle, $\theta _{h}$, distribution varies like 1 + A$_{{{\mathit D}_{{1}}}}$cos $^2\theta _{h}$, where $\theta _{h}$ is the angle in the ${{\mathit D}^{*}}$ rest frame between the two pions emitted by the ${{\mathit D}_{{1}}}$ $\rightarrow$ ${{\mathit D}^{*}}{{\mathit \pi}}$ and the ${{\mathit D}^{*}}$ $\rightarrow$ ${{\mathit D}}{{\mathit \pi}}$ .
Unpolarized ${{\mathit D}_{{1}}}$ decaying purely via ${\mathit D}{\mathrm -wave}$ is predicted to give A$_{{{\mathit D}_{{1}}}}$ = 3.