Coupled-channel model forK¯Nscattering in the resonant region

Abstract

We present a unitary multichannel model forKN scattering in the resonance region that fulfills unitarity. It has the correct analytical properties for the amplitudes once they are extended to the complex-s plane and the partial waves have the right threshold behavior. To determine the parameters of the model, we have fitted single-energy partial waves up to J = 7/2 and up to 2.15 GeV of energy in the center-of-mass reference frame obtaining the poles of the Λ * and Σ * resonances, which are compared to previous analyses. We provide the most comprehensive picture of the S = −1 hyperon spectrum to date. Important differences are found between the available analyses making the gathering of further experimental information onKN scattering mandatory to make progress in the assessment of the hyperon spectrum.

A hidden-charm $$\varvec{S=-1}$$ S = - 1 pentaquark from the decay of $$\varvec{\varLambda _b}$$ Λ b into $$\varvec{J/\psi \, \eta \varLambda }$$ J / ψ η Λ states

“…One state with these characteristics is listed in the PDG compilation [49], the one star Λ(2000), having a width ∼ 100-300 MeV and a branching ratio to the decay into ηΛ of (16 ± 7) %. The recent unitary multichannel model forK N scattering, with parameters fitted to partial waves up to J = 7/2 and up to 2.15 GeV of energy, also gives an s-wave J P = 1/2 − Λ state with similar mass and width properties [50].…”

The Joint Physics Analysis Center website

“…The detailed procedure is described in Ref. [7]. Finally the partial waves are analytically continued on the unphysical sheet and the pole positions are extracted.…”

“…In Ref. [7] we presented a unitary multichannel model forKN scattering in the resonance region that fulfills unitarity. Several coupled channels, indicated in the publication, were considered in the fitting procedure.…”

“…For a detailed relation, in all channels, between the orbital momentum and the partial waves we refer the reader to Ref. [7]. For a given orbital angular momentum , we first remove the phase space factor with the introduction of a diagonal matrix C (s)…”

“…After two years of activities, several papers were published by the JPAC collaboration and its members. The topics covered include the photoproduction of one [4] or two mesons [5] at high energies, elastic scattering with pion [6] and kaon [7,8] and the three-body decays of heavy [9,10] and light [11,12] mesons. Many projects have led to deliverables (such as codes) and a platform, an interactive webpage [13], was created to exchange material within the community.…”