Spin-isospin selectivity in three-nucleon forces

TL;DR

This study presents precise measurements of the deuteron breakup reaction using polarized protons, revealing discrepancies with theoretical models and highlighting the need for improved three-nucleon force descriptions.

Contribution

It provides new experimental polarization data for deuteron breakup and tests the isospin sensitivity of three-nucleon force models against state-of-the-art calculations.

Findings

Significant discrepancies between data and Faddeev calculations for certain kinematics.

Current models do not fully describe polarization data across isospin states.

Experimental data highlight the need for refined three-nucleon force modeling.

Abstract

Precision data are presented for the break-up reaction, $^2{\rm H}(\vec p,pp)n$, within the framework of nuclear-force studies. The experiment was carried out at KVI using a polarized-proton beam of 190 MeV impinging on a liquid-deuterium target and by exploiting the detector, BINA. Some of the vector-analyzing powers are presented and compared with state-of-the-art Faddeev calculations including three-nucleon forces effect. Significant discrepancies between the data and theoretical predictions were observed for kinematical configurations which correspond to the $^2{\rm H}(\vec p,^2$He$)n$ channel. These results are compared to the $^2{\rm H}(\vec p,d)p$ reaction to test the isospin sensitivity of the present three-nucleon force models. The current modeling of two and three-nucleon forces is not sufficient to describe consistently polarization data for both isospin states.