Massive c(bar c)g-Production in Diffractive DIS

We calculate the cross section for q(\bar q)g-production in diffractive DIS with finite fermion masses and zero momentum transfer. The calculation is done in the leading log(1/x_p) approximation and is valid for the region of high diffractive masses (small beta). We apply our cross section formula to diffractive charm production at HERA: in a Monte-Carlo-Simulation of diffractive D*+- meson production we include both massive q(\bar q)- and massive q(\bar q)g-production, and we compare with preliminary H1 results. After adjusting an infrared cutoff parameter of our model which affects the overall normalization of the cross section we find reasonable agreement with the data. In particular, the slope of the beta-distribution can be reproduced.