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Abstract Incoherent eta electro-production off the deuteron in the D13(1520) resonance region is studied in the impulse approximation. This means that for the electromagnetic production operator only the elementary operator for eta electro-production off the nucleon, N(e,e’)N is included, neglecting possible two nucleon contributions and, furthermore, that eta and nucleon hadronic rescattering in the final state is neglected. This approximation corresponds to the so-called and often used spectator model in which the eta production takes place on a single nucleon inside the deuteron while the other nucleon acts merely as a spectator. As elementary operator the unitary isobar model MAID 2000 is taken which gives a very good description of the elementary production process on a nucleon. Since the elementary MAID amplitude is given in the eta-nucleon center-of-mass frame, it is transformed to an arbitrary reference frame by parametrizing it in terms of Lorentz-invariant functions. We study the semi-exclusive structure functions RL, RT,RLT, and RTT by observing eta electro-production off the deuteron in the unitary isobar model. With emphasis on nucleon resonance excitation where D13 (1520) resonance region is of interest, where only the final eta is detected and which depend on the invariant mass W or the energy transfer k0, the squared four momentum transfer K2and the eta angle, is calculated for various kinematic settings of k0 and K2as function of in the final hadronic center-of-mass frame, a few values for K2 and have been selected for the presentation of the results. The results show a strong effect of D13(1520) resonance especially at the forward angles.labk0. |