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$ np \leftrightarrow dγ$ reactions calculated up to $E_γ=20$ MeV

Mamoon A. Sharaf, Weijie Du, Andrey M. Shirokov

TL;DR

This work computes electromagnetic dipole transition cross sections for the reactions $np \rightarrow d\gamma$ and $d\gamma \rightarrow np$ over a broad energy range using the LENPIC nucleon-nucleon interaction up to N4LO and electromagnetic dipole operators up to N2LO from χEFT. A novel adaptation of the Efros method is employed to describe continuum states in an oscillator basis, enabling ab initio continuum calculations and providing a pathway toward NCSM-based reaction theory. The authors determine a deuteron bound state with $E_B=-2.2232$ MeV, and report $Q=0.2723$ fm$^2$ and $A_s=0.8846$ fm$^{-1/2}$, calculating cross sections up to $E=17.78$ MeV and $E_ ext{γ}=20$ MeV with ~1% uncertainties in most channels. The results generally agree with experimental data and other theories, validating the Efros adaptation for future light-nucleus continuum studies and highlighting the method’s potential for ab initio predictions in continuum-reaction contexts.

Abstract

We calculate the electromagnetic dipole transition cross sections for the $np \rightarrow dγ$ and $ dγ\rightarrow np$ reactions over a broad range of energies. We use the LENPIC nucleon-nucleon interaction obtained from chiral effective field theory ($χ$EFT) up to next-to-next-to-next-to-next-to-leading order (N4LO) and effective electromagnetic dipole transition operators obtained from the same $χ$EFT up to N2LO. Our results agree with existing experiments. We get results at energies for which experimental data and/or modern theoretical calculations have not been reported. In this study, we utilize a new approach, namely, our adaptation of the Efros [V. D. Efros, Phys. Rev. C 99, 034620 (2019)] method that is prospective for future many-body applications in calculations of bound and continuum state wave functions.

$ np \leftrightarrow dγ$ reactions calculated up to $E_γ=20$ MeV

TL;DR

This work computes electromagnetic dipole transition cross sections for the reactions and over a broad energy range using the LENPIC nucleon-nucleon interaction up to N4LO and electromagnetic dipole operators up to N2LO from χEFT. A novel adaptation of the Efros method is employed to describe continuum states in an oscillator basis, enabling ab initio continuum calculations and providing a pathway toward NCSM-based reaction theory. The authors determine a deuteron bound state with MeV, and report fm and fm, calculating cross sections up to MeV and MeV with ~1% uncertainties in most channels. The results generally agree with experimental data and other theories, validating the Efros adaptation for future light-nucleus continuum studies and highlighting the method’s potential for ab initio predictions in continuum-reaction contexts.

Abstract

We calculate the electromagnetic dipole transition cross sections for the and reactions over a broad range of energies. We use the LENPIC nucleon-nucleon interaction obtained from chiral effective field theory (EFT) up to next-to-next-to-next-to-next-to-leading order (N4LO) and effective electromagnetic dipole transition operators obtained from the same EFT up to N2LO. Our results agree with existing experiments. We get results at energies for which experimental data and/or modern theoretical calculations have not been reported. In this study, we utilize a new approach, namely, our adaptation of the Efros [V. D. Efros, Phys. Rev. C 99, 034620 (2019)] method that is prospective for future many-body applications in calculations of bound and continuum state wave functions.
Paper Structure (4 sections, 13 equations, 3 figures, 2 tables)

This paper contains 4 sections, 13 equations, 3 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Basic Equations
  3. Results
  4. Conclusions

Figures (3)

  • Figure 1: a), b) Capture cross section plotted as a function of $E$. The separate $M1$ and $E1$ contributions are plotted and the results are compared with experimental data and with those from other theoretical calculations with different $NN$ interactions as well as with the $1/k$ dependence of the $M1$ capture cross section at low energies. Most of the calculated uncertainties are not visible at this scale. c) Capture cross section at $E=1.2625 \cdot 10^{-8}$ MeV compared with different experimental data and theoretical calculations.
  • Figure 2: Photodisintegration cross section plotted as a function of $E_{\gamma}$. For comparison, the experimental data as well as other theoretical results are also shown.
  • Figure S1: Absolute value of the a) $s$-wave bound state amplitude $|\breve{d}_{n1}(E_{B})|$ and b) $d$-wave bound state amplitude $|\breve{d}_{n2}(E_{B})|$ obtained via $S$-matrix pole location with $v=118$ at interaction truncation $N_{\textrm{max}}=120$ using the set of eigenfunction SRFs given in Eq. \ref{['eq25']} as compared with the exact result.