We investigate the effects of two-body currents on magnetic dipole moments of medium-mass and heavy nuclei using the valence-space in-medium similarity renormalization group with chiral effective ...field theory interactions and currents. Focusing on near doubly magic nuclei from oxygen to bismuth, we have found that the leading two-body currents globally improve the agreement with experimental magnetic moments. Moreover, our results show the importance of multishell effects for Ca 41 , which suggest that the Z = N = 20 gap in Ca 40 is not as robust as in Ca 48 . The increasing contribution of two-body currents in heavier systems is explained by the operator structure of the center-of-mass dependent Sachs term. Published by the American Physical Society 2024
A direct measurement of the decay width of the excited 0 + 1 state of 6 Li using the relative self-absorption technique is reported. Our value of ... provides sufficiently low experimental ...uncertainties to test modern theories of nuclear forces. The corresponding transition rate is compared to the results of ab initio calculations based on chiral effective field theory that take into account contributions to the magnetic dipole operator beyond leading order. This enables a precision test of the impact of two-body currents that enter at next-to-leading order. (ProQuest: ... denotes formula omitted.)
A direct measurement of the decay width of the excited $0^+_1$ state of 6Li using the relative self-absorption technique is reported. Our value of $Γ_{γ,0^{+}_{1}} → 1^{+}_{1}$ = 8.17 ...(14)stat.(11)syst. eV provides sufficiently low experimental uncertainties to test modern theories of nuclear forces. The corresponding transition rate is compared to the results of ab initio calculations based on chiral effective field theory that take into account contributions to the magnetic dipole operator beyond leading order. This allows for a precision test of the impact of two-body currents that enter at next-to-leading order.
A direct measurement of the decay width of the excited 0_{1}^{+} state of ^{6}Li using the relative self-absorption technique is reported. Our value of ...Γ_{γ,0_{1}^{+}→1_{1}^{+}}=8.17(14)_{stat.}(11)_{syst.} eV provides sufficiently low experimental uncertainties to test modern theories of nuclear forces. The corresponding transition rate is compared to the results of ab initio calculations based on chiral effective field theory that take into account contributions to the magnetic dipole operator beyond leading order. This enables a precision test of the impact of two-body currents that enter at next-to-leading order.
Neutron matter is an important many-body system that provides valuable constraints for the equation of state (EOS) of neutron stars. Neutron-matter calculations employing chiral effective field ...theory (EFT) interactions have been extensively used for this purpose. Among the various many-body methods, quantum Monte Carlo (QMC) methods stand out due to their nonperturbative nature and the achievable precision. However, QMC methods require local interactions as input, which leads to the appearance of stronger regulator artifacts as compared to non-local interactions. To circumvent this, we employ large-cutoff interactions derived within chiral EFT (400 MeV \(\leq \Lambda_c \leq\) 700 MeV) for studies of pure neutron matter. These interactions have been adjusted to nucleon-nucleon scattering phase shifts, the triton binding energy, as well as the triton beta-decay half life. We find that regulator artifacts significantly decrease with increasing cutoff, leading to a significant reduction of uncertainties in the neutron-matter EOS. We discuss implications for the symmetry energy and demonstrate how our new calculations lead to a reduction in the theoretical uncertainty of predicted neutron-star radii by up to 30% for low-mass stars.
Many-body approaches for atomic nuclei generally rely on a basis expansion of the nuclear states, interactions, and current operators. In this work, we derive the representation of the magnetic ...dipole operator in plane-wave and harmonic-oscillator basis states, as needed for Faddeev calculations of few-body systems or many-body calculations within, e.g., the no-core shell model, the in-medium renormalization group, coupled-cluster theory, or the nuclear shell model. We focus in particular on the next-to-leading-order two-body contributions derived from chiral effective field theory. We provide detailed benchmarks and also comparisons with quantum Monte Carlo results for three-body systems. The derived operator matrix elements represent the basic input for studying magnetic properties of atomic nuclei based on chiral effective field theory.
We investigate the effects of two-body currents on magnetic dipole moments of medium-mass and heavy nuclei using the valence-space in-medium similarity renormalization group with chiral effective ...field theory interactions and currents. Focusing on near doubly magic nuclei from oxygen to bismuth, we have found that the leading two-body currents globally improve the agreement with experimental magnetic moments. Moreover, our results show the importance of multi-shell effects for \(^{41}\)Ca, which suggest that the \(Z=N=20\) gap in \(^{40}\)Ca is not as robust as in \(^{48}\)Ca. The increasing contribution of two-body currents in heavier systems is explained by the operator structure of the center-of-mass dependent Sachs term.
Phys. Rev. Lett. 126, 102501 (2021) A direct measurement of the decay width of the excited $0^+_1$ state of
$^6$Li using the relative self-absorption technique is reported. Our value of
...$\Gamma_{\gamma, 0^+_1 \to 1^+_1} = 8.17(14)_\mathrm{stat.}(11)_\mathrm{syst.}
\mathrm{eV}$ provides sufficiently low experimental uncertainties to test
modern theories of nuclear forces. The corresponding transition rate is
compared to the results of ab initio calculations based on chiral effective
field theory that take into account contributions to the magnetic dipole
operator beyond leading order. This enables a precision test of the impact of
two-body currents that enter at next-to-leading order.
PDF