The pentaquark component is included in the proton wave functions to study phi meson production proton-antiproton annihilation reactions. With all possible configurations of the uuds subsystem proposed for describing the strangeness spin and magnetic
moment of the proton, we estimate the branching ratios of the annihilation reactions at rest proton-antiproton to phi + X (X=pi, eta, rho, omega) from atomic proton-antiproton S- and P-wave states by using effective quark line diagrams incorporating the 3P0 model. The best agreement of theoretical prediction with the experimental data is found when the pentaquark configuration of the proton wave function takes the flavor-spin symmetry, [4]_FS [22]_F [22]_S.
Partial decay widths of various decay channels of the X(1835) are evaluated in the 3P0 quark model, assuming that the X(1835) is a nucleon-antinucleon bound state. It is found that the decays to rho+rho, omega+omega and pion+a0(1450) dominate over ot
her channels, and that the product branching fractions of J/psi to pion+pion+eta and J/psi to pion+pion+eta are in the same order. We suggest that the X(1835) may be searched in the pion+a0(1450) channel.
Apparent channel-dependent violations of the OZI rule in nucleon-antinucleon annihilation reactions are discussed in the presence of an intrinsic strangeness component in the nucleon. Admixture of strange-antistrange quark pairs in the nucleon wave f
unction enables the direct coupling to the phi-meson in the annihilation channel without violating the OZI rule. Three forms are considered in this work for the strangeness content of the proton wave function, namely, the uud cluster with a strange-antistrange sea quark component, kaon-hyperon clusters based on a simple chiral quark model, and the pentaquark picture. Nonrelativistic quark model calculations reveal that the strangeness magnetic moment and the strangeness contribution to the proton spin from the first two models are consistent with recent experimental data. For the third model, the uuds subsystem with the configurations FS[31]F[211]S[22] and FS[31]F[31]S[22] leads to negative values for the strangeness magnetic moment and the strangeness contribution to the proton spin. With effective quark line diagrams incorporating the 3P0 quark model we give estimates for the branching ratios of the proton-antiproton annihilation reactions at rest to two mesons. Results for the branching ratios of phi-meson production from atomic proton-antiproton s-wave states are for the first and third model found to be strongly channel dependent, in good agreement with measured rates.
The antiproton-deuteron atoms are studied in models of various realistic, popular nucleon-antinucleon potentials. The small energy shifts and decay widths of the atoms, which stem from the short-ranged strong interactions between the antiproton and d
euteron, are evaluated in a well-established, accurate approach based on the Sturmian functions. The investigation reveals that none of the employed potentials, which reproduce the nucleon-antinucleon scattering data quite well, is able to reproduce the experimental data of the energy shifts of the 2p antiproton-deuteron atomic states. The energy shifts of the 2p antiproton-deuteron atomic states are very sensitive to the nucleon-antinucleon strong interactions, hence the investigation of the antiproton-deuteron atoms is expected to provide a good platform for refining the nucleon-antinucleon interaction, especially at zero energy.
