Diagrammatic Approach to Meson Production in Proton-Proton Collisions near Threshold
We evaluate the threshold T-matrices for the reactions pp {yields} pp{pi}{sup 0}, pn{pi}{sup +}, pp{eta}, pp{omega},p{Lambda}K{sup +}, and pn {yields} pn{eta} in a relativistic Feynman diagram approach. We employ an effective range approximation to take care of the strong S-wave pN and p{Lambda} final-state interaction. We stress that the heavy baryon formalism is not applicable in the NN-system above {pi}-production threshold due to the large external momentum, {vert_bar}{rvec p}{vert_bar} {approx_equal} {radical}(Mm{sub {pi}}). The magnitudes of the experimental threshold amplitudes extracted from total cross section data, script-A = (2.7{minus}0.3i)fm{sup 4}, script-B = (2.8{minus}1.5i)fm{sup 4}, {vert_bar}script-C{vert_bar} = 1.32 fm{sup 4}, {vert_bar}{Omega}{vert_bar} = 0.53 fm{sup 4}, script-K = {radical}(2{vert_bar}K{sub s}{vert_bar}{sup 2} + {vert_bar}K{sub t}{vert_bar}{sup 2}) = 0.38 fm{sup 4} and {vert_bar}script-D{vert_bar} = 2.3 fm{sup 4} can be reproduced by (long-range) o ne-pion exchange and short-range vector meson exchanges, with the latter giving the largest contributions. Pion loop effects in pp {yields} pp{pi}{sup 0} appear to be small. The presented diagrammatic approach requires further tests via studies of angular distributions and polarization observables.
- Research Organization:
- TU Muenchen, Physik Dept., Garching (DE)
- Sponsoring Organization:
- None (US)
- OSTI ID:
- 784258
- Report Number(s):
- ISBN 1-56396-928-9; ISSN 0094-243X; CODEN APCPCS; ISBN 1-56396-928-9; ISSN 0094-243X; CODEN APCPCS; TRN: US0106019
- Resource Relation:
- Conference: Nuclear Physics at Storage Rings: Fourth International Conference: STORI99, Bloomington, IN (US), 09/12/1999--09/16/1999; Other Information: PBD: 31 Dec 2000
- Country of Publication:
- United States
- Language:
- English
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