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Register a new userPauli rearrangement potential for a scattering state with the interaction in chiral effective field theory
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M. Kohno
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The Pauli rearrangement potential given by the second-order diagram is evaluated for a nucleon optical model potential (OMP) with $G$ matrices of the nucleon-nucleon interaction in chiral effective field theory. The results obtained in nuclear matter are applied for $^{40}$Ca in a local-density approximation. The repulsive effect is of the order of 5MeV at the normal density. The density dependence indicates that the real part of the microscopic OMP becomes shallower in a central region, but is barely affected in a surface area. This improves the overall resemblance of the microscopic OMP to the empirical one.
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We compute the isospin-asymmetry dependence of microscopic optical model potentials from realistic chiral two- and three-body interactions over a range of resolution scales $Lambda simeq 400-500$,MeV. We show that at moderate projectile energies, $E_{rm inv} = 110 - 200$,MeV, the real isovector part of the optical potential changes sign, a phenomenon referred to as isospin inversion. We also extract the strength and energy dependence of the imaginary isovector optical potential and find no evidence for an analogous phenomenon over the range of energies, $E leq 200$,MeV, considered in the present work. Finally, we compute for the first time the leading corrections to the Lane parametrization for the isospin-asymmetry dependence of the optical potential and observe an enhanced importance at low scattering energies.
The $Lambda N$ and $Sigma N$ interactions are considered at next-to-leading order in SU(3) chiral effective field theory. Different options for the low-energy constants that determine the strength of the contact interactions are explored. Two variants are analysed in detail which yield equivalent results for $Lambda N$ and $Sigma N$ scattering observables but differ in the strength of the $Lambda N to Sigma N$ transition potential. The influence of this difference on predictions for light hypernuclei and on the properties of the $Lambda$ and $Sigma$ hyperons in nuclear matter is investigated and discussed. The effect of the variation in the potential strength of the $Lambda N$-$Sigma N$ coupling (also called $Lambda -Sigma$ conversion) is found to be moderate for the considered $^3_Lambda rm H$ and $^4_Lambda rm He$ hypernuclei but sizable in case of the matter properties. Further, the size of three-body forces and their relation to different approaches to hypernuclear interactions is discussed.
We have calculated the explicit form of the real and imaginary parts of the effective potential for uniform magnetic fields which interact with spin-1/2 fermions through the Pauli interaction. It is found that the non-vanishing imaginary part develops for a magnetic field stronger than a critical field, whose strength is the ratio of the fermion mass to its magnetic moment. This implies the instability of the uniform magnetic field beyond the critical field strength to produce fermion pairs with the production rate density $w(x)=frac{m^{4}}{24pi}(frac{|mu B|}{m}-1)^{3}(frac{|mu B|}{m}+3)$ in the presence of Pauli interaction.
Born in the aftermath of core collapse supernovae, neutron stars contain matter under extraordinary conditions of density and temperature that are difficult to reproduce in the laboratory. In recent years, neutron star observations have begun to yield novel insights into the nature of strongly interacting matter in the high-density regime where current theoretical models are challenged. At the same time, chiral effective field theory has developed into a powerful framework to study nuclear matter properties with quantified uncertainties in the moderate-density regime for modeling neutron stars. In this article, we review recent developments in chiral effective field theory and focus on many-body perturbation theory as a computationally efficient tool for calculating the properties of hot and dense nuclear matter. We also demonstrate how effective field theory enables statistically meaningful comparisons between nuclear theory predictions, nuclear experiments, and observational constraints on the nuclear equation of state.
Song et al. [Phys. Rev. C 102, 065208 (2020)] presented results for the $Lambda_c N$ interaction based on an extrapolation of lattice simulations by the HAL QCD Collaboration at unphysical quark masses to the physical point via covariant chiral effective field theory. We point out that their predictions for the $^3D_1$ partial wave disagree with available lattice results. We discuss the origin of that disagreement and present a comparison with predictions from conventional (non-relativistic) chiral effective field theory.
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