Study of continuumD*+spin alignment

The spin alignment of ${D}^{*+}$ mesons produced in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation at $\sqrt{s}=10.5$ GeV is obtained from a study of the angular distribution of the decay ${D}^{*+}\ensuremath{\rightarrow}{D}^{0}{\ensuremath{\pi}}^{+}$. The alignment is studied as a function of momentum and compared to theoretical predictions. We find an average value of the spin alignment parameter $\ensuremath{\eta}$ of $〈\ensuremath{\eta}〉=0.04\ifmmode\pm\else\textpm\fi{}0.02\ifmmode\pm\else\textpm\fi{}0.01$. We obtain a model-dependent measurement of the probability of producing a vector particle $〈{P}_{V}〉=0.77\ifmmode\pm\else\textpm\fi{}0.02\ifmmode\pm\else\textpm\fi{}0.01$ for $D$ mesons.