title: Anomalous bumpy structures in the capture cross sections of antiprotons by helium.
abstract: We investigate the state-specified capture process of antiprotons by helium. Freezing one of the two electrons, we reduce this four-body rearrangement problem into a three-body problem. The capture cross sections are calculated by solving the Chew-Goldberger-type integral equation. Differing from the capture of antiprotons by hydrogen atoms, the bumpy structures are revealed in the total angular momentum dependent capture cross sections. Further analysis shows that the bumps arise from the partial channel closing due to the removal of the energy degeneracy in the antiprotonic helium.
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan. tong@ims.tsukuba.ac.jp
authors.forename: X M
authors.initials: XM
authors.lastname: Tong
authors.forename: K
authors.initials: K
authors.lastname: Hino
authors.forename: N
authors.initials: N
authors.lastname: Toshima