Three-Nucleon Dynamics in the dp breakup collisions at 190 MeV/nucleon using the WASA detector at COSY-Jülich

TL;DR

Addressing how three-nucleon forces and relativistic dynamics affect the breakup reaction $^{1}$H$(d,pp)n$ at intermediate energies, the paper reports high-precision differential cross sections measured with WASA-at-COSY at $E_d\approx190$ MeV/n and compares them to NN-only, 3NF-inclusive, Coulomb-enabled, and relativistic theories, projecting predictions onto the experimental bins. The authors analyze 189 configurations to quantify agreement and find significant Coulomb effects at forward angles, while 3NF effects are generally small; relativistic CD-Bonn calculations tend to underpredict the data, with notable exceptions in tails and coplanar configurations. The results provide stringent tests of few-nucleon force models and highlight where current descriptions of 3NF and relativistic dynamics require refinement. Overall, the study motivates development of fully relativistic, consistent three-nucleon force frameworks and further comprehensive breakup measurements.

Abstract

The differential cross section for the $^{1}$H$(d,pp)n$ breakup reaction at deuteron beam energy of 380 MeV has been determined with high precision for 189 angular configurations of outgoing protons in the region of forward laboratory angles. The cross section data were compared to theoretical predictions based on the state-of-the-art nucleon-nucleon potentials, combined with a three-nucleon force, the Coulomb interaction or carried out in a relativistic approach. In the region of the lowest differential cross section, the discrepancy between the data and the theoretical predictions is observed, also in the case of relativistic calculations.

Figures (21)

• Figure 1: (Color online) Schematic view of the detection system.
• Figure 2: Particle identification spectra of particles stopped in (a) 3rd layer and (b) 4th layer of FRH. Loci of protons and deuterons are clearly visible.
• Figure 3: (Color online) $E_1$ vs. $E_2$ coincidence spectrum of the two protons registered at $\theta _1$=5$^{\circ}\pm$ 1$^{\circ}$, $\theta _2$=9$^{\circ}\pm$ 1$^{\circ}$, and $\varphi _{12}$=100$^{\circ}\pm$ 5$^{\circ}$. The solid line shows a three-body kinematical curve, calculated for the central values of experimental angular ranges.
• Figure 4: (Color online) Experimental differential cross section of the deuteron-proton elastic scattering at the incident-beam energies: 108 MeV, 120 MeV, 150 MeV, 170 MeV, 190 MeV Ermisch2003Ermisch2005, 155 MeV Kuroda64 and 250 MeV Hatanaka2002 presented as ln($\sigma$) in a function of $q$ for two scattering angles, specified in the panels. Two lines in the lower panel show linear fits including (dashed line) or excluding (solid line) the point for the highest beam energy of 250 MeV.
• Figure 5: (Color online) Determination of the integrated luminosity. The integrated luminosity values were calculated independently for each deuteron scattering angle. Each set of points and corresponding average (horizontal line) corresponds to a different way of determining elastic scattering cross section used for normalization, as specified in the legend. Two additional dashed lines present the systematic uncertainty of the final result. For more detais see the text.