A study of hyperons in nuclear matter based on chiral effective field theory

Abstract

The in-medium properties of a hyperon-nucleon potential, derived within chiral effective field theory and fitted to ΛN and ΣN scattering data, are investigated. Results for the single-particle potentials of the Λ and Σ hyperons in nuclear matter are reported, based on a conventional G-matrix calculation. The Σ-nuclear potential is found to be repulsive, in agreement with phenomenological information. A weak Λ-nuclear spin-orbit interaction can be achieved by an appropriate adjustment of a low-energy constant corresponding to an antisymmetric ΛN-ΣN spin-orbit interaction that arises at next-to-leading order in the effective field theory approach.

Baryon–Baryon Interaction from Chiral Effective Field Theory

“…Recently, we investigated also the properties of our Y N interactions in nuclear matter [4,5]. Specifically, we performed conventional first-order Brueckner calculations based on the standard (gap) choice of the single-particle (s.p.)…”

“…Then results for the in-medium properties of this Y N are presented [4,5]. In particular, the singleparticle potentials for the Λ and Σ hyperons in nuclear matter are evaluated in a conventional G-matrix calculation, and the Scheerbaum factor [6] associated with the hyperon-nucleus spin-orbit interaction is computed.…”

“…Therefore, we investigated also the spin-orbit interaction and, in particular, the role of the antisymmetric spin-orbit force in the Y N system [4]. As mentioned above, the chiral EFT approach yields a potential that contains, besides pseudoscalar meson exchanges, a series of contact interactions with an increasing number of derivatives.…”

“…[3] and, thus, it was simply put to zero in that work. However, its value can be fixed from investigating the properties of the Λ hyperon in nuclear matter and, specifically, it can be utilized to achieve a weak Λ-nuclear spin-orbit potential [4,5]. Afterwards I turn to three-body forces.…”

Foundations of strangeness nuclear physics derived from chiral effective field theory

“…used in Ref. 44 In the so-called continuous choice, the dependence of the energy denominator on the full single-particle energies is retained. This method is computationally more difficult but allows to reliably access the imaginary parts of the single-particle potentials, which is not possible when the gap choice is employed.…”