Contribution of the two-photon interaction to the EMC effect

The two-photon contribution to deep inelastic lepton-nucleus scattering is investigated. The resulting contribution is of the order of a few percent of the ratio of the lepton-nucleus cross section per nucleon divided by the lepton-proton cross section, and is restricted to the lowest kinematically allowed values of the proton scaling variable Xsub(lp). The calculated effect is presented as a function of the nucleus charge Z, the incoming lepton laboratory energy Esub(lab), and momentum transfer squared Q2. The γγ contribution increases with Z and with Esub(lab) for fixed Q2. (orig.)