Angular analysis of the $e^+ e^- to D^{(*) pm} D^{* mp}$ process near the open charm threshold using initial-state radiation

We report a new measurement of the exclusive $e^+ e^- to D^{(*) pm} D^{*mp}$ cross sections as a function of the center-of-mass energy from the $D^{(*) pm} D^{* mp}$ threshold through $sqrt{s}=6.0$ GeV with initial-state radiation. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of $951$ fb$^{-1}$. The accuracy of the cross section measurement is increased by a factor of two over the first Belle study. We perform the first angular analysis of the $e^+ e^- to D^{* pm} D^{* mp}$ process and decompose this exclusive cross section into three components corresponding to the $D^*$ helicities.