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  • Open Access

Two-body currents at finite momentum transfer and applications to M1 transitions

C. Brase1,2,3,*, T. Miyagi1,2,3,4,†, J. Menéndez5,6,‡, and A. Schwenk1,2,3,§

  • *Contact author: catharina.brase@tu-darmstadt.de
  • †Contact author: miyagi@nucl.ph.tsukuba.ac.jp
  • ‡Contact author: menendez@fqa.ub.edu
  • §Contact author: schwenk@physik.tu-darmstadt.de
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Phys. Rev. C 113, 014317 – Published 20 January, 2026

DOI: https://doi.org/10.1103/4tky-t2h1

Abstract

We explore the impact of two-body currents (2BCs) at finite momentum transfer with a focus on magnetic-dipole properties in Ca48 and Ti48. To this end, we derive a multipole decomposition of 2BCs to fully include the momentum-transfer dependence in ab initio calculations. As application, we investigate the effects of 2BCs on the strong M1 transition at 10.23 MeV in Ca48 using the valence-space in-medium similarity renormalization group (VS-IMSRG) with a set of nonimplausible interactions as well as the 1.8/2.0 (EM) interaction. Experiments, such as (e,e′) and (γ,n), disagree on the magnetic-dipole strength B(M1) for this transition. Our VS-IMSRG results favor larger B(M1) values similar to recent coupled-cluster calculations. However, for this transition there are larger cancellations between the leading pion-in-flight and seagull 2BCs, so that future calculations including higher-order 2BCs are important. For validation of our results, we investigate additional observables in Ca48 as well as M1 transitions in Ti48. For these, our results agree with experiment. Finally, our results show that for medium-mass nuclei 2BC contributions to M1 and Gamow-Teller transitions are, as expected, very different. Therefore, using similar quenching factors for both in phenomenological calculations is not supported from first principles.

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Physics Subject Headings (PhySH)

Corrections

27 January, 2026

Correction: Figure 3 contained an incorrect data point and has been replaced.

Article Text

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Outline

Information

Phys. Rev. C 113, 014317– Published 20 January, 2026
  • Received 11 April 2025
  • Revised 30 September 2025
  • Accepted 18 November 2025
  • Corrected 27 January 2026
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