Disconnected contributions to D-meson semi-leptonic decay form factors

We calculate the disconnected contribution to the form factor for the semileptonic decay of a D-meson into a final state, containing a flavor singlet eta meson. We use QCDSF n_f=2+1 configurations at the flavor symmetric point m_u=m_d=m_s and the partially quenched approximation for the relativistic charm quark. Several acceleration and noise reduction techniques for the stochastic estimation of the disconnected loop are tested.