{ital pp}{r_arrow}{ital pp}{pi}{sup 0} reaction near threshold: A chiral power counting approach

Journal Article · Sat Jun 01 04:00:00 EDT 1996 · Physical Review, C

DOI:https://doi.org/10.1103/PhysRevC.53.2661· OSTI ID:286153

Cohen, T D; Friar, J L; Miller, G A; van Kolck, U ^[1]

---

1. Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)

We use power-counting arguments as an organizing principle to apply chiral perturbation theory, including an explicit {Delta}, to the {ital pp}{r_arrow}{ital pp}{pi}{sup 0} reaction near threshold. There are two lowest-order leading mechanisms expected to contribute to the amplitude with similar magnitudes: an impulse term, and a {Delta}-excitation mechanism. We examine formally subleading but potentially large mechanisms, including pion-rescattering and short-ranged contributions. We show that the pion-rescattering contribution is enhanced by off-shell effects and has a sign opposite to that of a recent estimate based on a PCAC pion interpolating field. Our result is that the impulse term interferes destructively with the pion-rescattering and {Delta}-excitation terms. In addition, we have modeled the short-ranged interaction using {sigma} and {omega} exchange mechanisms. A recoil correction to the impulse approximation is small. The total amplitude obtained including all of these processes is found to yield cross sections substantially smaller than the measured ones. {copyright} {ital 1996 The American Physical Society.}

• DOE Contract Number: FG06-88ER40427; FG02-93ER40762
• OSTI ID: 286153
• Journal Information: Physical Review, C, Journal Name: Physical Review, C Journal Issue: 6 Vol. 53; ISSN PRVCAN; ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
CHIRAL SYMMETRY
CROSS SECTIONS
EXCITATION
IMPULSE APPROXIMATION
OMEGA PARTICLES
PARTICLE PRODUCTION
PCAC THEORY
PERTURBATION THEORY
PIONS NEUTRAL
PROTON-PROTON INTERACTIONS
PROTONS
RESCATTERING
SIGMA PARTICLES