Antikaon–nucleon interaction and Λ(1405) in chiral SU(3) dynamics

Abstract

The properties of the Λ(1405) resonance are key ingredients for determining the antikaon-nucleon interaction in strangeness nuclear physics, and the novel internal structure of the Λ(1405) is of great interest in hadron physics, as a prototype case of a baryon that does not fit into the simple threequark picture. We show that a quantitative description of the antikaonnucleon interaction with the Λ(1405) is achieved in the framework of chiral SU(3) dynamics, with the help of recent experimental progress. Further constraints on theKN subthreshold interaction are provided by analyzing πΣ spectra in various processes, such as the K − d → πΣn reaction and the Λ c → ππΣ decay. The structure of the Λ(1405) is found to be dominated by an antikaon-nucleon molecular configuration, based on its wavefunction derived from a realisticKN potential and the compositeness criteria from a model-independent weak-binding relation.

K−N amplitudes below threshold constrained by multinucleon absorption

“…At threshold, the precise measurement of strong-interaction level shift and width of the 1s state in the kaonic atom of hydrogen by the SIDDHARTA collaboration [1,2] provides an important constraint on the K − p interaction, in addition to three previously known threshold branching ratios. However, as shown recently [3,4] the resulting K − N scattering amplitudes appear to be strongly model dependent when extrapolating to energies below threshold and also with respect to their pole content. Moreover, for the K − n amplitude different models predict widely different results both below threshold and above.…”

“…Section 3 provides results, showing that only two of the six sets of K − N amplitudes are acceptable when fractions of single-nucleon vs. multinucleon absorption are considered in kaonic atoms studies. The two acceptable sets of amplitudes turn out to be quite similar, and in section 4 we discuss in detail the interplay between the single-nucleon amplitudes and the full optical potential based on these two sets of amplitudes. Radial sensitivities of kaonic atom observables are re-examined, and remarks are made on the role that 'subthreshold kinematics' plays in absorption-at-rest calculations.…”

Pole structure of theΛ(1405)in a recent QCD simulation

“…The accurate kaonic hydrogen measurements by DEAR and SIDDHARTA [29,30], together with total cross section data and threshold branching ratios, are successfully described in the framework of chiral SU (3) coupled-channels dynamics with input based on the NLO meson-baryon effective Lagrangian [31][32][33][34][35][36][37][38]. Dispersion relations can be used to perform the necessary resummation of the chiral perturbation theory amplitudes at any order [39].…”

Triangle singularities in $$B^-\rightarrow D^{*0}\pi ^-\pi ^0\eta $$ B - → D ∗ 0 π - π 0 η and $$B^-\rightarrow D^{*0}\pi ^-\pi ^+\pi ^-$$ B - → D ∗ 0 π - π + π -

“…[3] followed by many studies which are summarized in Refs. [4,5]. The spectrum of the low-lying scalar mesons, such as the f 0 (980) or a 0 (980) mesons, is also discussed in this picture [6][7][8], while the possible explanation as tetraquark states is also discussed in Refs.…”