Positive pion absorption on3Heusing modern trinucleon wave functions

Abstract

We study pion absorption on 3 He employing trinucleon wave functions calculated from modern realistic N N interactions (Paris, CD Bonn). Even though the use of the new wave functions leads to a significant improvement over older calculations with regard to both cross section and polarization data, there are hints that polarization data with quasifree kinematics cannot be described by just two-nucleon absorption mechanisms.

Meson production in nucleon?nucleon collisions close to the threshold

“…As a result of a systematic study of, for example, both NN and pd induced reactions, a deeper insight into the importance of three-body forces should be gained. For example, a recent microscopic calculation using purely two-body input to calculate the reaction π +3 He → ppp, found that the data [289,290] call for three-body correlations [291], confirming earlier studies [292]. It should be stressed, however, that this field is still in its infancy and a large amount theoretical effort is urgently called for.…”

New parameterization of the trinucleon wave function and its application to the π 3He scattering length

“…1 in reactions with either large momentum transfer or where higher partial waves become relevant, the effect of the second term is expected to be much more pronounced. Indeed, this has been already seen in a recent application of the wave function parametrization to π absorption on 3 He [26].…”

“…E.g., a calculation of quasifree pion absorption on nucleon pairs in 3 He based on the presented parameterization has been reported in Ref. [26].…”

“…It should be stressed, that Eqs. (26) are general and independent of the wave functions used. The error estimate only requires that the Weinberg scheme is applicable to the reactions under investigation.…”