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 Physics , 2001, DOI: 10.1088/0253-6102/48/4/024 Abstract: Systematic and careful studies are made on the properties of the IJ=00 $\pi\pi$ and $K\bar K$ coupled-channel system, using newly derived dispersion relations between the phase shifts and poles and cuts. The effects of nearby branch point singularities to the determination of the $f_0(980)$ resonance are estimated and and discussed.
 Physics , 2001, Abstract: Studies on the IJ=00 $\pi\pi$ and $K\bar K$ coupled--channel system are made using newly derived dispersion relations between the phase shifts and poles and cuts. It is found that the $\sigma$ resonance must be introduced to explain the experimental phase shifts, after evaluating the cut contribution. The effects of nearby branch point singularities to the determination of the $f_0(980)$ resonance are also carefully clarified.
 P. Zenczykowski Physics , 1999, DOI: 10.1016/S0370-2693(99)00806-0 Abstract: Coupled-channel final-state-interaction effects for D and B weak decays into \pi \pi and K \bar{K} are discussed in a Regge framework. It is found that the inclusion of coupled-channel effects significantly affects the results obtained previously in a quasi-elastic approximation. It is also shown that in the isospin I=0 channel the inelastic final-state transitions (\pi \pi)_{I=0} --> (K \bar{K})_{I=0} dramatically influence the phase of the B^0 --> (K \bar{K})_{I=0} amplitude.
 Physics , 2011, DOI: 10.1103/PhysRevC.84.054006 Abstract: A dynamical coupled-channel study of K* K*bar state with isospin 0 and omega phi state is performed within both the chiral SU(3) quark model and the extended chiral SU(3) quark model by solving a resonating group method (RGM) equation. The model parameters are taken from our previous work, which gave a satisfactory description of the energies of the octet and decuplet baryon ground states, the binding energy of the deuteron, the nucleon-nucleon (NN) scattering phase shifts, and the hyperon-nucleon (YN) cross sections. The results show that the interactions of K* K*bar states are attractive, which consequently result in K* K*bar bound states with the binding energies of about 10-70 MeV, and contrarily, no omega phi bound state is obtained. The channel coupling effect of K* K*bar and omega phi is found to be considerably large, which makes the binding of K* K*bar 5-45 MeV deeper. The plausible interpretation of f_0(1710) and X(1812) being K* K*bar dominated states is briefly discussed.
 Physics , 2007, DOI: 10.1103/PhysRevC.76.044004 Abstract: Coupled-channel three-body calculations of an $I=1/2$, $J^{\pi}=0^-$ $\bar{K}NN$ quasi-bound state in the $\bar{K}NN - \pi \Sigma N$ system were performed and the dependence of the resulting three-body energy on the two-body $\bar{K}N - \pi \Sigma$ interaction was investigated. Earlier results of binding energy $B_{K^-pp} \sim 50 -70$ MeV and width $\Gamma_{K^-pp} \sim 100$ MeV are confirmed [N.V. Shevchenko {\it et al.}, Phys. Rev. Lett. {\bf 98}, 082301 (2007)]. It is shown that a suitably constructed energy-independent complex $\bar{K}N$ potential gives a considerably shallower and narrower three-body quasi-bound state than the full coupled-channel calculation. Comparison with other calculations is made.
 Physics , 2015, Abstract: We present a unitary multichannel model for $\bar{K}N$ 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 $\Lambda^*$ and $\Sigma^*$ 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 on $\bar{K}N$ scattering mandatory to make progress in the assessment of the hyperon spectrum.
 Physics , 2015, DOI: 10.1007/s10751-015-1152-x Abstract: We have investigated a prototype of kaonic nuclei, "$K^-pp$", with a coupled-channel Complex Scaling Method (ccCSM). Combining the ccCSM with Feshbach projection method, we can handle a coupled-channel problem effectively as a single-channel problem. By using an energy-dependent chiral SU(3)-based $\bar{K}N$ potential, the $K^-pp$ ($J^\pi=0^-$ and $T=1/2$) is obtained to be shallowly bound with the binding energy of 20-30 MeV. The mesonic decay width depends on the interaction parameters and ansatz; the decay width is ranging from 20 to 65 MeV. In case of $J^\pi=1^-$ state, no three-body $\bar{K}NN$ resonant states are found.
 Physics , 1999, DOI: 10.1016/S0370-2693(99)00909-0 Abstract: A coupled channel analysis of the centrally produced K+K- and pi+pi- final states has been performed in pp collisions at an incident beam momentum of 450 GeV/c. The pole positions and branching ratios to pipi and KK of the f0(980), f0(1370), f0(1500) and f0(1710) have been determined. A systematic study of the production properties of all the resonances observed in the pi+pi- and K+K- channels has been performed.
 Physics , 2013, DOI: 10.1103/PhysRevC.88.055204 Abstract: A coupled-channel effective Lagrangian model respecting unitary and gauge invariance is applied to the combined analysis of the $(\pi,\gamma) N \to K\Sigma$ reactions for the center of mass energies up to 2 GeV. The recent photoproduction data obtained by the CLAS, CBELSA, LEPS, and GRAAL groups are included into our calculations with the aim to extract the resonance couplings to the $K\Sigma$ state. Both resonances and background contributions are found to be important to reproduce a correct shape of the angular distributions and polarization observables. Our description to the data is of good quality. The extracted properties of isospin $I = 3/2$ resonances are discussed in detail while the $I = 1/2$ resonances are largely determined by the non-strangeness channels.
 Physics , 2015, Abstract: The meson-baryon interaction in s-wave in the strangeness S=-1 sector has been studied, employing a chiral SU(3) Lagrangian up to next-to-leading order (NLO) and implementing unitarization in coupled channels. The parameters of the Lagrangian have been fitted to a large set of experimental data in different two-body channels, paying special attention to the $\bar{K} N \rightarrow K \Xi$ reaction, which is particularly sensitive to the NLO terms. With the aim of improving the model in the $K\Xi$ production channels, effects of the high spin hyperon resonances $\Sigma(2030)$ and $\Sigma(2250)$ have been taken into account phenomenologically.
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