Role of heavy-meson exchange in pion production near threshold

Horowitz, C. J.; Meyer, H. O.; Griegel, David K.

doi:10.1103/physrevc.49.1337

Cited by 92 publications

(115 citation statements)

References 32 publications

(62 reference statements)

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“…On the other hand, the σ meson exchange, which models the CTPE in the ππ S-wave and provides about 2/3 of this exchange in the low energy N N interaction, plays a relatively more important role. This observation has also been made in the case of N N → N N π reaction [58][59][60]30,31]. Thus, the σ meson exchange provides an efficient means of mediating the large momentum mismatch involved in the meson production reactions in N N collisions, particularly at lower beam momenta.…”

Section: A Cross Section Data For Beam Energy Above 2 Gevmentioning

confidence: 65%

pp→pK+Λreaction in an effective Lagrangian model

Shyam

1999

Phys. Rev. C

128

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We investigate the pp → pK + Λ reaction within an effective Lagrangian model where the contributions to the amplitudes are taken into account within the tree level. The initial interaction between the two nucleons is modeled by the exchange of π, ρ, ω and σ mesons and the ΛK + production proceeds via the excitation of the N * (1650), N * (1710), N * (1720) baryonic resonances. The parameters of the model at the nucleon-nucleon-meson vertices are determined by fitting the elastic nucleon-nucleon scattering with an effective interaction based on the exchange of these four mesons, while those at the resonance vertices are calculated from the known decay widths of the resonances as well as the vector meson dominance model. Available experimental data is described well by this approach. The one-pion-exchange diagram dominates the production process at both higher and lower beam energies. The ρ and ω meson exchanges make negligible contributions. However, the σ-exchange processes contribute substantially to the total cross sections at lower beam energies. The excitation of the N * (1710) and N * (1650) resonances dominate this reaction at beam momenta above and below 3 GeV/c respectively. The interference among the amplitudes of various resonance excitation processes is significant. For beam energies very close to the K + production threshold the hyperon-proton final state interaction effects are quite important. The data is selective about the model used to describe the low energy scattering of the two final state baryons.

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Section: A Cross Section Data For Beam Energy Above 2 Gevmentioning

confidence: 65%

pp→pK+Λreaction in an effective Lagrangian model

Shyam

1999

Phys. Rev. C

128

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“…Indeed the gures shown in refs. 6,7] suggest that the contributions from heavy-meson exchange modify the dependence of the cross section to the right direction. However, it is unlikely that these modi cations will be su cient to remedy the discrepancy observed in our calculation.…”

Section: Discussionmentioning

confidence: 99%

The reaction pp → ppπ0 near threshold

et al. 1995

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We perform a momentum-space calculation of the reaction pp ! pp 0 near threshold. Direct production and pion rescattering are taken into account. For the latter a T-matrix obtained from a microscopic model of the N interaction is employed.The e ects of some approximations commonly used in studies of pp ! pp 0 are discussed. We nd that those approximations overestimate the cross section and also modify its energy dependence. We obtain a signi cant contribution from rescattering, but not nearly enough to describe the data.

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“…were shown to be important for the total (CI) cross section near threshold [21,46,47]. These exchanges correspond to contact interactions in the EFT [20,21].…”

Section: Explicit Form Of Leading Tree-level Operatorsmentioning

confidence: 99%

Survey of charge symmetry breaking operators fordd→απ0

et al. 2004

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The charge-symmetry-breaking amplitudes for the recently observed dd → απ 0 reaction are investigated. Chiral perturbation theory is used to classify and identify the leading-order terms.Specific forms of the related one-and two-body tree level diagrams are derived. As a first step toward a full calculation, a few tree-level two-body diagrams are evaluated at each considered order, using a simplified set of d and α wave functions and a plane-wave approximation for the initial dd state. The leading-order pion-exchange term is shown to be suppressed in this model because of poor overlap of the initial and final states. The higher-order one-body and shortrange (heavy-meson-exchange) amplitudes provide better matching between the initial and final states and therefore contribute significantly and coherently to the cross section. The consequences this might have for a full calculation, with realistic wave functions and a more complete set of amplitudes, are discussed.

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Role of heavy-meson exchange in pion production near threshold

Cited by 92 publications

References 32 publications

pp→pK+Λreaction in an effective Lagrangian model

pp→pK+Λreaction in an effective Lagrangian model

The reaction pp → ppπ0 near threshold

Survey of charge symmetry breaking operators fordd→απ0

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