Systematic study of three-nucleon force effects in the cross section of the deuteron-proton breakup at 130 MeV

Abstract

High-precision cross-section data of the deuteron-proton breakup reaction at 130 MeV are presented for 72 kinematically complete configurations. The data cover a large region of the available phase space, divided into a systematic grid of kinematical variables. They are compared with theoretical predictions, in which the full dynamics of the three-nucleon (3N) system is obtained in three different ways: realistic nucleon-nucleon (NN) potentials are combined with model 3N forces (3NF's) or with an effective 3NF resulting from explicit treatment of the -isobar excitation. Alternatively, the chiral perturbation theory approach is used at the next-to-next-to-leading order with all relevant NN and 3N contributions taken into account. The generated dynamics is then applied to calculate cross-section values by rigorous solution of the 3N Faddeev equations. The comparison of the calculated cross sections with the experimental data shows a clear preference for the predictions in which the 3NF's are included. The majority of the experimental data points are well reproduced by the theoretical predictions. The remaining discrepancies are investigated by inspecting cross sections integrated over certain kinematical variables. The procedure of global comparisons leads to establishing regularities in disagreements between the experimental data and the theoretically predicted values of the cross sections. They indicate deficiencies still present in the assumed models of the 3N system dynamics.

Dynamics of Three-Nucleon System Studied in Deuteron–Proton Breakup Experiments

“…The significance of the 3NF for a correct description of the differential cross section has been confirmed [14,15]. On the other hand, certain discrepancies are observed for the tensor analyzing powers of the breakup reaction at the same beam energies, even if (or when) the 3NF is included in the calculations [16].…”

“…Significant progress in this respect has been achieved in recent years, and currently the calculations combining 3NF and Coulomb interactions are available [23] as well as relativistic calculations including 3NFs [22]. Coulomb effects turned out to be surprisingly large [15,24]. Therefore, an experiment probing the part of the phase space that is particularly sensitive to the Coulomb interaction was conducted at FZ-Jülich.…”

Investigations of Few-Nucleon System Dynamics in Medium Energy Domain

“…In the kinematical region of small polar angles significant discrepancies between the measured and predicted cross sections were found [8]. The inconsistency was accounted for the Coulomb interaction.…”

“…The 1 H (d, pp)n breakup reactions were studied in different phase space regions with the use of three detection systems: the SALAD and BINA at KVI [8][9][10][11] and the Germanium Wall (GeWall) at FZ-Jülich [12]. Results of the analyzing powers were obtained with the use of the BINA and SALAD apparatuses at polarized deuteron beam energies of 100 and 130 MeV, respectively.…”

3H at Next-to-Next-to-Next-to Leading Order of the Chiral Expansion

“…This problem is absent for the nuclear forces derived in the framework of chiral effective field theory [5], where 3NF occurs for the first time at next-to-next-to leading order (N 2 LO) of the chiral expansion. This force was used in few-body calculations and the quality of the description of the data was as good as with the so-called realistic nuclear forces [6,7]. That calls for the inclusion of higher order terms of the chiral NN and 3N interactions.…”