New investigation of the neutron-neutron and neutron-proton final-state interaction in the<i>n-d</i>breakup reaction

Huhn, V.; Wätzold, L.; Weber, C.; Siepe, A.; Witsch, W. von; Witała, H.; Glöckle, W.

doi:10.1103/physrevc.63.014003

Cited by 83 publications

(60 citation statements)

References 34 publications

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“…Unfortunately, nn scattering is only poorly known experimentally. There is only one datum for the scattering length, which is still controversal [24,25,26,27,28,29,30,31]. AV18 is adjusted to a nn = −18.82 fm, whereas for CD-Bonn 2000 a nn results in −18.97 fm.…”

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Three-nucleon bound states using realistic potential models

et al. 2003

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The bound states of 3 H and 3 He have been calculated using the Argonne v18 plus the Urbana threenucleon potential. The isospin T = 3/2 state have been included in the calculations as well as the n-p mass difference. The 3 H-3 He mass difference has been evaluated through the charge dependent terms explicitly included in the two-body potential. The calculations have been performed using two different methods: the solution of the Faddeev equations in momentum space and the expansion on the correlated hyperspherical harmonic basis. The results are in agreement within 0.1% and can be used as benchmark tests. Results for the CD-Bonn interaction are also presented. It is shown that the 3 H and 3 He binding energy difference can be predicted model independently.In the last years great efforts have been made to improve the description of the nucleon-nucleon (N N ) interaction. A new generation of potentials including explicitly charge independence and charge symmetry breaking (CIB,CSB) terms appeared. These interactions describe the N N scattering data below T lab = 300 MeV with a nearly perfect χ 2 /datum≈ 1. The CD-Bonn [1] and Argonne v 18 (AV18) [2] interactions also provide a neutron-neutron (nn) force, which has been adjusted to the experimental nn scattering length, whereas the Nijmegen interactions [3] are fitted only to proton-proton and proton-neutron data. Recently, the CD-Bonn potential has been updated to CD-Bonn 2000 [4]. In this paper we only present results for the AV18 and CD-Bonn 2000 interactions. Both are quite different from each other in their functional form, but their description of the N N data is almost equally accurate. Therefore a comparison of the results will give insights into the model dependence of our understanding of the three-nucleon (3N ) bound states.Following for example the notation of Ref.[2], all these N N potentials can be put in the general formThe short range part v R (N N ) of all of these interactions includes a certain number of parameters (around 40), which are determined by a fitting procedure to the N N scattering data and the deuteron binding energy (BE), whereas the long range part is represented by the one-pion-exchange potential v π (N N ) and an electromagnetic part v EM (N N ). For AV18, v EM (pp) consists of the one-and twophoton Coulomb terms plus the Darwin-Foldy term, vacuum polarization and magnetic moment interactions. The v EM (np) interaction includes a Coulomb term due to the neutron charge distribution in addition to the magnetic moment interaction. Finally, v EM (nn) is given by the magnetic moment interaction only. All these terms take into account the finite size of the nucleon charge distributions. The v EM (N N ) for CD-Bonn is much simpler:is given by the Coulomb force of point protons, whereas v EM (np) = v EM (nn) = 0. As it is well known, when these interactions are used to describe the 3N bound state, an underbinding of about 0.5 MeV to 0.9 MeV depending on the model is obtained (see for example Ref. [5]). The local potentials lead to less bin...

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Three-nucleon bound states using realistic potential models

et al. 2003

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“…However, in some cases such an estimation is facilitated by the fact that the reaction mechanism is known. For example, the reaction nd → (nn)p, one of the prime sources of the nn scattering length, can be analyzed by means of rigorous Faddeev calculations [16][17][18]. Reactions involving the pion such as πd, π − d → γ nn or γ d → π + nn, which can be used to extract the πN and nn scattering lengths, respectively, can be tackled by chiral perturbation theory in a well-controlled way in the relevant near-threshold regime [19,20].…”

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Extraction of scattering lengths from final-state interactions

2005

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A recently proposed method, based on dispersion theory, that allows the scattering length of a hadronic two-body system to be extracted from corresponding final-state interactions is generalized to the situation where the Coulomb interaction is present. The steps required in a concrete practical application are discussed in detail. In addition a thorough examination of the accuracy of the proposed method is presented and a comparison is made with results achieved with other methods such as the Jost-function approach based on the effective-range approximation. Deficiencies of the latter method are pointed out. The reliability of the dispersion theory method for also extracting the effective range is investigated.

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“…Fig. 3a presents this experimental spectrum in comparison [6], -16.5 ± 0.9 [7], -17.6 ± 0.4 [8], -18.7 ± 0.6 [9], -18.8 ± 0.4 [10]. …”

Section: Experiments and Resultsmentioning

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Determination of Energy of n n-Singlet Virtual State in $$\varvec{d+{{}^{2}}}\hbox {H}\varvec{\rightarrow p+p+n+n}$$ d + 2

et al. 2017

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Determination of energy of nn-singlet virtual state in d+ 2 H  p+ p +n+n reactionAbstract The nn final state interaction has been investigated in d+ 2 H(pp) S +(nn) S p+p+n+n reaction going through a formation and breakup of singlet diproton and dineutron in the intermediate state.In the kinematically complete experiment performed at Ed =15 MeV two proton and neutron were detected at angles close to those of emission of (pp) S and (nn) S systems. Simulation of the reaction showed that the shape of neutron energy (timing) spectrum depends on εnn − the energy of virtual 1 S0 state of nn-system. The most likely value εnn = 0.076 ± 0.006MeV was obtained by fitting procedure using the experimental data and simulations. This low value of εnn evidently indicates on effective enhancement of nn-interaction in the intermediate state of studied reaction.

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New investigation of the neutron-neutron and neutron-proton final-state interaction in then-dbreakup reaction

Cited by 83 publications

References 34 publications

Three-nucleon bound states using realistic potential models

Three-nucleon bound states using realistic potential models

Extraction of scattering lengths from final-state interactions

Determination of Energy of n n-Singlet Virtual State in $$\varvec{d+{{}^{2}}}\hbox {H}\varvec{\rightarrow p+p+n+n}$$ d + 2

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