The K¯N Interaction in Higher Partial Waves

Abstract

We present a chiral K¯N interaction model that has been developed and optimized in order to account for the experimental data of inelastic K¯N reaction channels that open at higher energies. In particular, we study the effect of the higher partial waves, which originate directly from the chiral Lagrangian, as they could supersede the role of high-spin resonances employed in earlier phenomenological models to describe meson-baryon cross sections in the 2 GeV region. We present a detailed derivation of the partial wave amplitudes that emerge from the chiral SU(3) meson-baryon Lagrangian up to the d-waves and next-to-leading order in the chiral expansion. We implement a nonperturbative unitarization in coupled channels and optimize the model parameters to a large pool of experimental data in the relevant energy range where these new contributions are expected to be important. The obtained results are encouraging. They indicate the ability of the chiral higher partial waves to extend the description of the scattering data to higher energies and to account for structures in the reaction cross-sections that cannot be accommodated by theoretical models limited to the s-waves.

SU(3) flavor symmetry considerations for the $\bar{K}N$ coupled channels system

“…This also follows a recent trend of extending the available chirally motivated KN models to energies much higher than those dominated by the Λ(1405), see e.g. [17,18,19].…”

K̅N interaction, p-wave terms

“…By contrary, since our models explore higher energies, it is reasonable to consider these additional contributions. Actually, as we show in [28] and in the present manuscript, they play a relevant role mainly in the KN transitions to the ηΛ, ηΣ 0 , and KΞ channels. It should be mentioned that there is a reduction of the number of LECs since the the g 3 monomial cancells after the hermitian conjugation (h.c.) transformation in Eq.…”

“…In Ref. [28], as we expected, the inclusion of partial waves higher than the L = 0 reveal more information about the physics behind the NLO terms of the chiral Lagrangian. In particular, the focus was put on p-wave contributions whose effect is proved to be non-negligible in order to describe the ηΛ, ηΣ 0 , K 0 Ξ 0 and K + Ξ − production reactions.…”

“…This collection of experimental data has been employed to constrain the models developed in the study, the technical details of the data treatment as well as the fitting procedure can be found in Ref. [28]. Actually, three models were introduced in [28] to discuss the effects of the new elements, two new and a third one already developed in [26].…”

“…[28]. Actually, three models were introduced in [28] to discuss the effects of the new elements, two new and a third one already developed in [26]. Being the two new models the natural extension of the old one in two steps.…”