Photoproduction of the Λ(1405) on the proton and nuclei

We study the gamma p --> K+ Lambda(1405) reaction at energies close to threshold using a chiral unitary model where the resonance is generated dynamically from K(-)p interaction with other channels constructed from the octets of baryons and mesons. Predictions are made for cross sections into several channels and it is shown that the detection of the K+ is sufficient to determine the shape and strength of the Lambda(1405) resonance. The determination of the resonance properties in nuclei requires instead the detection of the resonance decay channels. Pauli blocking effects on the resonance, which have been shown to be very important for the resonance at rest in the nucleus, are irrelevant here where the resonance is produced with a large momentum. The nuclear modifications here would thus offer information on the resonance and K- nucleus dynamics complementary to the one offered so far by K- atoms. (C) 1999 Elsevier Science B.V. All rights reserved.