Chiral perturbation theory and the pp{r_arrow}pp{pi}{sup 0} reaction near threshold

Journal Article · Mon Sep 01 04:00:00 EDT 1997 · Physical Review, C

DOI:https://doi.org/10.1103/PhysRevC.56.1246· OSTI ID:560737

Sato, T ^[1]; Lee, T H ^[2]; Myhrer, F; Kubodera, K ^[3]

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1. Department of Physics, Osaka University, Toyonaka, Osaka 560 (Japan)
2. Physics Division, Argonne National Laboratory, Argonne, Illinois 60439-4843 (United States)
3. Department of Physics and Astronomy, University of South Carolina, Columbia, South Carolina 29208 (United States)

A chiral-perturbative consideration of the near-threshold pp{r_arrow}pp{pi}{sup 0} reaction indicates that the pion-rescattering term has a substantial energy and momentum dependence. The existing calculations that incorporate this dependence give pion rescattering contributions significantly larger than those of the conventional treatment, and this enhanced rescattering term interferes destructively with the one-body impulse term, leading to theoretical cross sections that are much smaller than the observed values. However, since the existing calculations are based on coordinate-space representation, they involve a number of simplifying assumptions about the energy-momentum flow in the rescattering diagram, even though the delicate interplay between the one-body and two-body terms makes it desirable to avoid these kinematical assumptions. We carry out here a momentum-space calculation that retains the energy-momentum dependence of the vertices as predicted by chiral perturbation theory. Our improved treatment increases the rescattering amplitude by a factor of {approximately}3 over the value obtained in the r-space calculations. The pp{r_arrow}pp{pi}{sup 0} transition amplitude, which is now dominated by the rescattering term, leads to the cross section much larger than what was reported in the approximate r-space calculations. Thus, the extremely small cross sections obtained in the previous chiral perturbative treatments of this reaction should be considered as an accidental consequence of the approximations employed rather than a general feature. {copyright} {ital 1997} {ital The American Physical Society}

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 560737
• Journal Information: Physical Review, C, Journal Name: Physical Review, C Journal Issue: 3 Vol. 56; ISSN PRVCAN; ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
CHIRAL SYMMETRY
CROSS SECTIONS
ENERGY DEPENDENCE
PARTICLE PRODUCTION
PERTURBATION THEORY
PIONS NEUTRAL
PROTON-PROTON INTERACTIONS
PROTONS
RESCATTERING
TRANSITION AMPLITUDES