Polarization phenomena in hyperon-nucleon scattering

Ishikawa, S.; Tanifuji, M.; Iseri, Y.; Yamamoto, Yasuo

doi:10.1103/physrevc.69.034001

Cited by 6 publications

(3 citation statements)

References 23 publications

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“…Final examples of observables that are sensitive to our model 3NFs are spin-dependent total cross section differences in n − d scattering, σ L and σ T [26,27]. These observables are particularly interesting because they are related directly to the imaginary part of n-d scattering amplitudes at forward angle by the optical theorem.…”

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Spin-dependent three-nucleon force effects on nucleon-deuteron scattering

Ishikawa

2007

Phys. Rev. C

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We construct a phenomenological three-nucleon force (3NF) model that gives a good description of polarization observables in elastic nucleon-deuteron (N -d) scattering at a low energy together with a realistic nucleon-nucleon force and a 3NF arising from the exchange of two pions. Parameters of the model, which consists of spinindependent, spin-orbit, and tensor components, are determined to reproduce the three-nucleon binding energy and polarization observables in N -d scattering at 3 MeV. Predictions of the 3NF model on N -d polarization observables at higher energies are examined, and the effects of each component on the observables are investigated. As is well known, modern two-nucleon force (2NF) models have a deficiency in explaining the binding energies of three-nucleon (3N) systems, and this problem is successfully solved by introducing a 3NF arising from the exchange process of two pions among three nucleons, which is called the two-pion-exchange (2π E) 3NF [1,2]. However, such combinations of the 2NFs and the 2π E-3NF that reproduce the 3N binding energy do not necessarily explain polarization observables in 3N scattering systems such as vector or tensor analyzing powers in elastic N -d scattering. See, e.g., Table III of Ref. [3], where calculations of observables with and without a 2π E-3NF are compared in terms of χ 2 with experimental data below 30 MeV of incident nucleon energy in the laboratory system. In spite of recent progress in constructing realistic 3NFs from chiral effective field theory or from heavier-boson-exchange mechanisms, no consensus has been obtained for possible mechanisms of 3NFs consistent with all of the experimental data. On the other hand, model 3NFs with artificial functional forms have been proposed to explain the polarization observables quite well [4][5][6]. These 3NFs have a form that typical components in 2NFs, e.g., central spin-independent, tensor, or spin-orbit components, are modified in the presence of third nucleon. [See Eq. (1) below.]In this paper, we introduce such a phenomenological 3NF to resolve the discrepancies of a 2NF and the 2π E-3NF at a low energy, and we examine whether it is still valid for N -d observables at higher energies up to 30 MeV. Since it may not be so difficult to understand what physical process is simulated by the spin dependence of each component, we expect that the present study will provide some hint of which characteristics of more realistic 3NFs should be studied.Our 3N calculations are based on a formalism to solve the Faddeev equations in coordinate space as integral equations [7,8]. For scattering states below the 3N breakup threshold energy, effects of the long-range Coulomb force between two * ishikawa@hosei.ac.jp protons are exactly treated [9]. Calculations for energies above the 3N breakup threshold are formulated in Ref. [10]. 3N partial wave states for which 2NFs and 3NFs act, are restricted to those with total two-nucleon angular momenta j 6 for bound state calculations, and j 3 for scattering state calculations. The ...

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“…In Ref. [27], it is pointed out that the difference σ T − σ L is proportional to the imaginary part of a tensor component in the n-d scattering amplitudes at forward angle. As Fig.…”

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Spin-dependent three-nucleon force effects on nucleon-deuteron scattering

Ishikawa

2007

Phys. Rev. C

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“…In Ref. [16], we showed that effects of tensor interactions are prominent in the difference of ∆σ T − ∆σ L . As expected, differences of tendency in tensor components of the 3NFs are significantly observed in Fig.…”

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confidence: 93%