Axial change in pion production and absorption

Journal Article · Sun Oct 01 04:00:00 EDT 1995 · Bulletin of the American Physical Society

OSTI ID:255425

Niskanen, J A ^[1]

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1. Univ. of Helsinki (Finland)

The unexpectedly large pp {r_arrow} pp{sup pi}cross section at threshold reopened the question of the axial charge in nuclear systems. The standard treatment of the one-nucleon axial charge (the Galilean invariance term), s-wave pion rescattering and the {Delta}(1232) contribution gave only 20-30 % of the experimental result. There have been two suggestions to solve this problem discussed in this talk. Lee and Riska proposed heavy meson exchange with intermediate NN pair obtained from NN potentials. More recently an off-shell pion rescattering model via a exchange has been proposed, where the off-shell nature destroys the delicate cancellation of the a exchange and the pair term as required by chiral symmetry. Both approaches contribute surprisingly much and are able to raise the cross section to the experimental value. Appreciable effects are expected also in pion absorption on nucleon pairs in nuclei. Further, the effect of these mechanisms in the better known and understood pp {r_arrow} d{pi}{sup +} reaction is discussed, since this process has not much space for large new contributions.

• OSTI ID: 255425
• Report Number(s): CONF-9510116--
• Journal Information: Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 10 Vol. 40; ISSN BAPSA6; ISSN 0003-0503
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ABSORPTION
AXIAL-VECTOR CURRENTS
CHARGE-EXCHANGE INTERACTIONS
CHIRAL SYMMETRY
CROSS SECTIONS
PARTICLE PRODUCTION
PIONS
PROTON-PROTON INTERACTIONS