Gamow-Teller rasonances and Δ production in nuclei

The giant Gamow-Teller states in nuclei are studied through the (3He,t) reaction at energies from 600 MeV to 2.3 GeV. The Gamow-Teller transition in the quark picture can lead to the excitation of the nucleon to the Δ-resonance. At 3He energies above 1.5 GeV the direct Δ excitation is observed both for the proton and for nuclei. The problem of missing strength in the observed Gamow-Teller states is addressed both in terms of mixing of the 1p - 1h states into 2p - 2h states and in terms of a renormalization through admixture of the Δ excitation. 9 refs., 34 figs. (author)