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Comment on Neutron-Proton Spin-Correlation Parameter A_{ZZ} at 68 Mev

R. Machleidt·I. Slaus
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Abstract

We present two arguments indicating that the large value for the $ε_1$ mixing parameter at 50 MeV, which the Basel group extracted from their recent $A_{zz}$ measurement, may be incorrect. First, there are nucleon-nucleon (NN) potentials which predict the $ε_1$ at 50 MeV substantially below the Basel value and reproduce the Basel $A_{zz}$ data accurately. Second, the large value for $ε_1$ at 50 MeV proposed by the Basel group can only be explained by a model for the NN interaction which is very unrealistic (no $ρ$-meson and essentially a point-like $πNN$ vertex) and overpredicts the $ε_1$ in the energy range where it is well determined (150--500 MeV) by a factor of two.

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R. Machleidt, I. Slaus. 1993-03-27. Comment on Neutron-Proton Spin-Correlation Parameter A_{ZZ} at 68 Mev. https://doi.org/10.1103/physrevlett.72.2664

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