Covariant calculation of strange decays of baryon resonances

Abstract

We present results for kaon decay widths of baryon resonances from a relativistic study with constituent quark models. The calculations are done in the point-form of Poincare-invariant quantum mechanics with a spectator-model decay operator. We obtain covariant predictions of the Goldstone-boson-exchange and a variant of the one-gluon-exchange constituent quark models for all kaon decay widths of established baryon resonances. They are generally characterized by underestimating the available experimental data. In particular, the widths of kaon decays with increasing strangeness in the baryon turn out to be extremely small. We also consider the nonrelativistic limit, leading to the familiar elementary emission model, and demonstrate the importance of relativistic effects. It is found that the nonrelativistic approach evidently misses sensible influences from Lorentz boosts and some essential spin-coupling terms.Comment: 6 pages, 3 table

Baryon resonances and strong decays⋆

“…We have considered the direct predictions of CQMs without any additional fitting of the results. The findings obtained within the PFSM approach [7,8,9] are surprisingly similar to the ones in the framework of the Bethe-Salpeter equation [10,11]. The defects hint to missing contributions.…”

“…In such a framework, the baryon states will receive a finite width leading to a more realistic description of the excited resonances. Of course, such a procedure will [7,8,9]. Only established resonances (with at least three-star status) are included.…”

“…From the comprehensive relativistic studies of π, η, and K decay widths [7,8,9] a classification of light and strange baryon resonances into SU (3) flavor multiplets is suggested as given in Tables 1 and 2. While in most instances the octet and decuplet assignments agree with the ones by the PDG [12], there occur also some differences.…”

“…Recently, we performed covariant calculations of the π, η, and K decay widths employing relativistic CQMs within the so-called point-form spectator model (PFSM) [7,8,9]. The direct predictions for partial decay widths produced a completely different pattern.…”

Baryon Masses and Hadronic Decay Widths with Explicit Pionic Contributions

“…Along constituent-quark models resonances have hitherto usually been considered as excited bound states rather than as genuine resonances with finite decay widths. Covariant predictions for decay widths of baryons have shown shortcomings usually underestimating data from phenomenology [1][2][3][4]. A possible remedy consists in coupling to decay channels and thereby including mesonic degrees of freedom explicitly.…”