Study of continuumD*+spin alignment

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