Abstract
Pion exchange is the central ingredient to nucleon-nucleon interactions used in nuclear structure calculations, and one-pion exchange (OPE) enters at leading order in chiral effective field theory. In the 2S+1LJ=1S0 partial wave, however, OPE and a contact term needed for proper renormalization fail to produce the qualitative, and quantitative, features of the scattering phase shifts. Cutoff variation also revealed a surprisingly low breakdown momentum Λb≈330 MeV in this partial wave. Here we show that potentials consisting of OPE, two-pion exchange (TPE), and a single contact address these problems and yield accurate and renormalization group (RG) invariant phase shifts in the S01 partial wave. We demonstrate that a leading-order potential with TPE can be systematically improved by adding a contact quadratic in momenta. For momentum cutoffs Λ 500 MeV, the removal of relevant physics from TPE loops needs to be compensated by additional contacts to keep RG invariance. Inclusion of the Δ isobar degree of freedom in the potential does not change the strong contributions of TPE.
| Original language | English |
|---|---|
| Article number | 024004 |
| Journal | Physical Review C |
| Volume | 106 |
| Issue number | 2 |
| DOIs | |
| State | Published - Aug 2022 |
Funding
We thank Daniel Phillips for insightful and useful discussions. We also thank the participants of the INT program \u201CNuclear Forces for Precision Nuclear Physics (21-1b)\u201D for many useful exchanges and discussions. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Awards No. DE-FG02-96ER40963 and No. DE-SC0018223 (NUCLEI SciDAC-4 collaboration), and Contract No. DE-AC05-00OR22725 with UT-Battelle, LLC (Oak Ridge National Laboratory), the Swedish Research Council Grant No. 2020-005127, the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 758027), by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - Projektnummer 279384907 - CRC 1245, and by the National Science Foundation under Grants No. PHY-1555030 and No. PHY-2111426.