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Magas, V. K., Yamagata-Sekihara, J., Hirenzaki, S., Oset, E., & Ramos, A. (2010). Proton emission off nuclei induced by kaons in flight. Phys. Rev. C, 81(2), 024609–10pp.
Abstract: We study the (K-, p) reaction on nuclei with a 1 GeV/c momentum kaon beam, paying special attention to the region of emitted protons having kinetic energy above 600 MeV, which was used to claim a deeply attractive kaon nucleus optical potential. Our model describes the nuclear reaction in the framework of a local density approach and the calculations are performed following two different procedures: one is based on a many-body method using the Lindhard function and the other is based on a Monte Carlo simulation. The simulation method offers flexibility to account for processes other than kaon quasielastic scattering, such as K- absorption by one and two nucleons, producing hyperons, and allows consideration of final-state interactions of the K-, the p, and all other primary and secondary particles on their way out of the nucleus, as well as the weak decay of the produced hyperons into pi N. We find a limited sensitivity of the cross section to the strength of the kaon optical potential. We also show a serious drawback in the experimental setup-the requirement for having, together with the energetic proton, at least one charged particle detected in the decay counter surrounding the target-as we find that the shape of the original cross section is appreciably distorted, to the point of invalidating the claims made in the experimental paper on the strength of the kaon nucleus optical.
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Malabarba, B. B., Khemchandani, K. P., Martinez Torres, A., & Oset, E. (2023). D1(2420) and its interactions with a kaon: Open charm states with strangeness. Phys. Rev. D, 107(3), 036016–12pp.
Abstract: In this work we present an attempt to describe the X1(2900) found by the LHCb collaboration, in the experimental data on the invariant mass spectrum of D-K+, as a three-meson molecular state of the KpD over line system. We discuss that the interactions in all the subsystems are attractive in nature, with the pD over line interaction generating over line D1(2420) and the Kp resonating as K1(1270). We find that the system can form a three-body state but with a mass higher than that of X1(2900). We investigate the KpD system too, finding that the three-body dynamics generates an isoscalar state, which can be related to D*s1(2860), and an exotic isovector state. This latter state has a mass similar to that of the X0(2900) and X1(2900) states found by LHCb, but a very small width (similar to 7.4 +/- 0.9 MeV) and necessarily requires more than two quarks to describe its properties. We hope that our findings will encourage experimental investigations of the isovector KpD state. Finally, in the pursuit of finding a description for X1(2900), we study the K over line K*D* system where over line K*D* forms 0+, 1+, and 2+ states. We do not find a state that can be associated with X1(2900).
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Martinez Torres, A., Bayar, M., Jido, D., & Oset, E. (2012). Strategy to find the two Lambda (1405) states from lattice QCD simulations. Phys. Rev. C, 86(5), 055201–13pp.
Abstract: Theoretical studies within the chiral unitary approach, and recent experiments, have provided evidence of the existence of two isoscalar states in the region of the Lambda(1405). In this paper we use the same chiral approach to generate energy levels in a finite box. In a second step, assuming that these energies correspond to lattice QCD results, we devise the best strategy of analysis to obtain the two states in the infinite-volume case, with sufficient precision to distinguish them. We find out that by using energy levels obtained with asymmetric boxes and/or with a moving frame, with reasonable errors in the energies, one has a successful scheme to get the two Lambda(1405) poles.
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Martinez Torres, A., Dai, L. R., Koren, C., Jido, D., & Oset, E. (2012). KD, eta Ds interaction in finite volume and the Ds*0(2317) resonance. Phys. Rev. D, 85(1), 014027–11pp.
Abstract: An SU(4) extrapolation of the chiral unitary theory in coupled channels done to study the scalar mesons in the charm sector is extended to produce results in finite volume. The theory in the infinite volume produces dynamically the D-s*0(2317) resonance by means of the coupled channels KD, eta D-s. Energy levels in the finite box are evaluated and, assuming that they would correspond to lattice results, the inverse problem of determining the bound states and phase shifts in the infinite volume from the lattice data is addressed. We observe that it is possible to obtain accurate KD phase shifts and the position of the D-s*0(2317) state, but it requires the explicit consideration of the two coupled channels in the analysis if one goes close to the eta D-s threshold. We also show that the finite volume spectra look rather different in case the D-s*0(2317) is a composite state of the two mesons, or if it corresponds to a non molecular state with a small overlap with the two meson system. We then show that a careful analysis of the finite volume data can shed some light on the nature of the D-s*0(2317) resonance as a KD molecule or otherwise.
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Martinez Torres, A., Garzon, E. J., Oset, E., & Dai, L. R. (2011). Limits to the fixed center approximation to Faddeev equations: The case of the phi(2170). Phys. Rev. D, 83(11), 116002–9pp.
Abstract: The fixed center approximation to the Faddeev equations has been used lately with success in the study of bound systems of three hadrons. It is also important to set the limits of the approach in those problems to prevent proliferation of inaccurate predictions. In this paper, we study the case of the phi(2170), which has been described by means of Faddeev equations as a resonant state of phi and K (K) over bar, and show the problems derived from the use of the fixed center approximation in its study. At the same time, we also expose the limitations of an alternative approach recently proposed.
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