Three-Nucleon Force and theAyPuzzle in Intermediate Energyp→

Abstract

New vector analyzing-power data on p-->+d elastic scattering at E(p) = 150 and 190 MeV have been measured. These are presented together with existing data and with recent d-->+p vector and tensor analyzing power data at E(d) = 270 MeV. The strong negative extremum of both vector analyzing powers A(p)(y) and A(d)(y) at straight theta(c.m.) approximately 80 degrees -120 degrees is underestimated by Faddeev calculations using modern NN forces. Inclusion of the Tucson-Melbourne 3N force shifts the minima upwards, but with conflicting results for A(p)(y), and leading to a good description for A(d)(y). An A(p)(y) puzzle, previously thought to exist at energies E(N)</=30 MeV only, appears to exist also at intermediate energies.

Ndelastic scattering as a tool to probe properties of3Nforces

“…The tremendous advance in computational resources allowed in recent years to make exact predictions for three-nucleon scattering using nuclear forces in all their complexities [21]. Also experimentally one can access nowadays spin observables in Nd scattering where in the initial states the deuteron and / or the nucleon is polarized and after the reaction also the polarization of the outgoing particles can be measured [22,[24][25][26][27][28][29][30]. This leads to a very rich spectrum of observables in Nd elastic scattering and the Nd break-up processes.…”

Chiral 3NF and neutron-deuteron scattering

“…This is the case e.g. for the nucleon analyzing power A y [16,21] and for the deuteron tensor analyzing powers [16]. In both cases the data cannot be reproduced by pure 2N force predictions either.…”

Nuclear Collective Motion

“…The recently developed no-core shell model, employing the e ective i n teraction calculated (in the large con guration space) from the NNforce, has recently reached 12 C. Figure 6 shows the result of the no-core shell-model calculations 34] for positive and negative-parity states of 12 C. In a parallel development, Bloch-Horowitz equations have been solved for very light systems 35], and an e ort has been under way 36] to marry the numerical methods of the shell model 24 Mg in the full sd shell (with the dimension of the model space approaching 30,000). Today, this can be done in a few seconds on a modern workstation.…”

“…21{23] for recent applications). In the parallel development 24,25], ab initio calculations describing the scattering of few-body systems have brought new insights into the nature of the three-nucleon force. While the very light n uclei can nowadays be described as A-body systems bound by a f r e e NNforce augmented by a NNNforce, the conceptual framework of larger nuclei is still that of the independent particle model.…”