A polarization amplitude A$_{{{\mathit D}_{{2}}}}$ is a parameter that depends on the initial polarization of the ${{\mathit D}_{{2}}}$. For ${{\mathit D}_{{2}}}$ decays the helicity angle, ${{\mathit \theta}_{{H}}}$, distribution varies like 1 + A$_{{{\mathit D}_{{2}}}}$ cos $^2{{\mathit \theta}_{{H}}}$, where ${{\mathit \theta}_{{H}}}$ is the angle in the ${{\mathit D}^{*}}$ rest frame between the two pions emitted by the ${{\mathit D}_{{2}}}$ $\rightarrow$ ${{\mathit D}^{*}}{{\mathit \pi}}$ and ${{\mathit D}^{*}}$ $\rightarrow$ ${{\mathit D}}{{\mathit \pi}}$ .

VALUE EVTS DOCUMENT ID TECN  COMMENT • • We do not use the following data for averages, fits, limits, etc. • • $-1.16$ $\pm0.35$ 2.3k 1 ABRAMOWICZ 2013 ZEUS ${{\mathit e}^{\pm}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit D}^{(*)+}}{{\mathit \pi}^{-}}{{\mathit X}}$ $\text{consistent with -1}$ 243k DEL-AMO-SANCH.. 2010 P BABR ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit D}^{+}}{{\mathit \pi}^{-}}{{\mathit X}}$ $-0.74$ ${}^{+0.49}_{-0.38}$ 2 AVERY 1994 C CLE2 ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit D}^{*+}}{{\mathit \pi}^{-}}{{\mathit X}}$ 1  From the combined fit of the ${{\mathit M}}$( ${{\mathit D}^{+}}{{\mathit \pi}^{-}}$ ) and ${{\mathit M}}$( ${{\mathit D}^{*+}}{{\mathit \pi}^{-}}$ ) distributions. 2  Systematic uncertainties not estimated.

References:

ABRAMOWICZ 2013 NP B866 229 Production of the Excited Charm Mesons ${{\mathit D}_{{1}}}$ and ${{\mathit D}_{{2}}^{*}}$ at HERA DEL-AMO-SANCHEZ 2010P PR D82 111101 Observation of New Resonances Decaying to ${{\mathit D}}{{\mathit \pi}}$ and ${{\mathit D}^{*}}{{\mathit \pi}}$ in Inclusive ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions near $\sqrt {s }$ = 10.58 GeV AVERY 1994C PL B331 236 Production and Decay of ${{\mathit D}_{{1}}{(2420)}^{0}}$ and ${{\mathit D}_{{2}}^{*}{(2460)}^{0}}$