Jülich hyperon-nucleon model revisited

Abstract

A one-boson-exchange model for the hyperon-nucleon ( N, N ) interaction is presented. The model incorporates the standard one boson exchanges of the lowest pseudoscalar and vector meson multiplets with coupling constants fixed by SU(6) flavor symmetry relations. As the main new feature of the model, the contributions in the scalar-isoscalar (σ ) and vector-isovector (ρ) exchange channels are now constrained by a microscopic model of correlated ππ and KK exchange. Additional short-ranged ingredients of the model in the scalar-isovector (a 0 ) and scalar-isospin-1/2 (κ) channels are likewise viewed as arising from meson-meson correlations but are treated phenomenologically. With this model a satisfactory reproduction of the available hyperon-nucleon data can be achieved.

Hyperon–nucleon interactions—a chiral effective field theory approach

“…Although our Λp scattering lengths differ significantly from those of [19,24], the Y N interaction based on chiral EFT also yields a correctly bound hypertriton, see Table 4.3. Our singlet Σ + p scattering length is about half as large as the values found for the Y N potentials in [19,24]. Similar to those models and other Y N interactions, the value of the triplet Σ + p scattering length is rather small.…”

“…It is expected that this prob- lem for the Y N interaction can be solved by the derivative contact terms in a NLO calculation, just like in the NN case. Our 3 S 1 Σ + p phase shift is repulsive like in [19], but contrary to [24]. We remark that the P -waves are the result of pseudoscalar meson exchange only, since we only have contact terms in the S-waves.…”

“…These data have also been used in [19,24] and are listed in Table 4.2 (see below). The higher energy total cross sections and differential cross sections are then predictions of the LO chiral EFT, which contains five free parameters.…”

“…For this purpose we have multiplied the strong potential with an exponential regulator function. We used a cut-off in the .., 700 MeV, the dashed curve is the Jülich '04 model [19], and the solid curve is the Nijmegen NSC97f model [24]. The Nijmegen ǫ 1 phase shown here has an other sign convention than in Ref.…”

“…Following [17,18,19], we will neglect the contribution from η meson exchange. The spin space part of the one-pseudoscalar-meson-exchange potential resulting from the interaction Lagrangian Eq.…”