Hyperon III: $$K^{-}p - \pi \varSigma $$ coupled-channel dynamics in the $$\varLambda (1405)$$ mass region

Anisovich, A. V.; Sarantsev, A.; Nikonov, V. A.; Burkert, Volker; Schumacher, R. A.; Thoma, U.; Klempt, E.

doi:10.1140/epja/s10050-020-00142-8

Cited by 38 publications

(30 citation statements)

References 56 publications

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“…[69]. In a recent update, these authors also included a second pole in their model [70]. They found that the second pole does not considerably worsen the description of the considered data but still they prefer the solution with one pole.…”

Section: Where Do We Stand?mentioning

confidence: 99%

Two-Pole Structures in QCD: Facts, Not Fantasy!

Meißner

2020

Symmetry

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The two-pole structure refers to the fact that particular single states in the spectrum as listed in the PDG tables are often two states. The story began with the Λ ( 1405 ) , when in 2001, using unitarized chiral perturbation theory, it was observed that there are two poles in the complex plane, one close to the K ¯ p and the other close to the π Σ threshold. This was later understood combining the SU(3) limit and group-theoretical arguments. Different unitarization approaches that all lead to the two-pole structure have been considered in the mean time, showing some spread in the pole positions. This fact is now part of the PDG book, although it is not yet listed in the summary tables. Here, I discuss the open ends and critically review approaches that cannot deal with this issue. In the meson sector, some excited charm mesons are good candidates for such a two-pole structure. Next, I consider in detail the D 0 * ( 2300 ) , which is another candidate for this scenario. Combining lattice QCD with chiral unitary approaches in the finite volume, the precise data of the Hadron Spectrum Collaboration for coupled-channel D π , D η , D s K ¯ scattering in the isospin I = 1 / 2 channel indeed reveal its two-pole structure. Further states in the heavy meson sector with I = 1 / 2 exhibiting this phenomenon are predicted, especially in the beauty meson sector. I also discuss the relation of these two-pole structures and the possible molecular nature of the states under consideration.

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Section: Where Do We Stand?mentioning

confidence: 99%

Two-Pole Structures in QCD: Facts, Not Fantasy!

Meißner

2020

Symmetry

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“…This raised a debate on the one-pole versus two-pole structure of (1405) state, see, e.g., Refs. [55][56][57][58][59]. Note that the mentioned studies finding only a single pole have some deficiencies as detailed e.g.…”

Section: Introductionmentioning

confidence: 99%

The $${\varvec{\Lambda (1405)}}$$ in resummed chiral effective field theory

et al. 2021

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We study the unitarized meson–baryon scattering amplitude at leading order in the strangeness $$S=-1$$ S = - 1 sector using time-ordered perturbation theory for a manifestly Lorentz-invariant formulation of chiral effective field theory. By solving the coupled-channel integral equations with the full off-shell dependence of the effective potential and applying subtractive renormalization, we analyze the renormalized scattering amplitudes and obtain the two-pole structure of the $$\Lambda (1405)$$ Λ ( 1405 ) resonance. We also point out the necessity of including higher-order terms.

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“…In this context the appearance of a very detailed analysis of all available experimental data in a somewhat extended energy range together with a comprehensive compilation of the (1405) related literature has to be mentioned [24]. From our point of view this analysis is a polite rejection of any relevance of the second pole in the reproduction of data.…”

Section: About the Acceptance Of The Potentialmentioning

confidence: 99%

Lessons from Fitting the Lowest Order Energy Independent Chiral Based $$\bar{K}N$$ Potential to Experimental Data

Révai

2020

Few-Body Syst

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It is shown, that fitting parameters of a $$\bar{K}N$$ K ¯ N interaction model to different sets of experimental data can lead to physical conclusions which might provide a deeper insight into the physics of this multichannel system. The available experimental data are divided into three parts: the “classical” set consisting of the low-energy $$K^-p$$ K - p cross sections and the threshold branching ratios, the SIDDHARTA 1s level shift in kaonic hydrogen and the CLAS photoproduction data. We have fitted the parameters of the potential to different combinations of these data. We found, that the two poles corresponding to the $$I=0$$ I = 0 nuclear quasi-bound state $$(\Lambda (1405))$$ ( Λ ( 1405 ) ) and to the $$K^-p$$ K - p 1s atomic level seem to resist to their simultaneous reproduction at the right place, though a more or less satisfactory compromise can be achieved. Potentials with the $$\Lambda (1405)$$ Λ ( 1405 ) pole pinned down close to the PDG value fail to reproduce the classical two-body data with an acceptable accuracy. We also added comments on two papers criticizing the potential used in the fits.

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Hyperon III: $$K^{-}p - \pi \varSigma $$ coupled-channel dynamics in the $$\varLambda (1405)$$ mass region

Cited by 38 publications

References 56 publications

Two-Pole Structures in QCD: Facts, Not Fantasy!

Two-Pole Structures in QCD: Facts, Not Fantasy!

The $${\varvec{\Lambda (1405)}}$$ in resummed chiral effective field theory

Lessons from Fitting the Lowest Order Energy Independent Chiral Based $$\bar{K}N$$ Potential to Experimental Data

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