arXiv:1208.4468v1 [hep-ex] 22 Aug 2012 DESY–12–144 August 2012 Production of the excited charm mesons D 1 and D * 2 at HERA ZEUS Collaboration Abstract The production of the excited charm mesons D 1 (2420) and D ∗ 2 (2460) in ep colli- sions has been measured with the ZEUS detector at HERA using an integrated luminosity of 373 pb −1 . The masses of the neutral and charged states, the widths of the neutral states, and the helicity parameter of D 1 (2420) 0 were determined and compared with other measurements and with theoretical expectations. The measured helicity parameter of the D 0 1 allows for some mixing of S - and D- waves in its decay to D ∗± π ∓ . The result is also consistent with a pure D-wave decay. Ratios of branching fractions of the two decay modes of the D ∗ 2 (2460) 0 and D ∗ 2 (2460) ± states were measured and compared with previous measurements. The fractions of charm quarks hadronising into D 1 and D ∗ 2 were measured and are consistent with those obtained in e + e − annihilations.