The theory of a compound, large-angle atom beam splitter [A. Zh. Muradyan, A. A. Poghosyan, and P. R. Berman, Phys. Rev. A 68, 033604 (2003)] is generalized to allow for initial-state deflection. Atoms are prepared in an initial state by an off-resonant standing-wave field and then subject to two-standing-wave fields that couple the initial state to a final state. By a proper choice of parameters, atoms in the initial state can be deflected or split as a result of the interactions with the fields. The role of relaxation is considered.
The stability of antiproton-hydrogen compound states
(pH) is investigated theoretically. The
pH compound state has decay channels of atomic electron detachment $(\ensuremath{\rightarrow}{e}^{\ensuremath{-}}+\overline{p}p)$ and hadronic pair $(\overline{p}\text{\ensuremath{-}}p)$ annihilation, and hence it cannot be permanently stable even if the dissociation channel $(\ensuremath{\rightarrow}\overline{p}+\mathrm{H})$ is energetically closed. In this paper, information on the metastable
pH states at energies below the dissociation limit is obtained by analyzing low-energy resonances in ${e}^{\ensuremath{-}}+\overline{p}p$ scattering. The scattering calculation is carried out by using an R-matrix method, which also allows for the annihilation channel simultaneously. The metastable states are found to be identified as vibrational levels supported by a Born-Oppenheimer (BO) potential. The energy-level widths attributed to the electron detachment and the annihilation are also calculated using a model based on the BO picture.