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Molina, R., Xiao, C. W., Liang, W. H., & Oset, E. (2024). Correlation functions for the N*(1535) and the inverse problem. Phys. Rev. D, 109(5), 054002–10pp.
Abstract: The N*(1535) can be dynamically generated in the chiral unitary approach with the coupled channels, K0E+; K+E0; K+A, and eta p. In this work, we evaluate the correlation functions for every channel and face the inverse problem. Assuming the correlation functions to correspond to real measurements, we conduct a fit to the data within a general framework in order to extract the information contained in these correlation functions. The bootstrap method is used to determine the uncertainties of the different observables, and we find that, assuming errors of the same order than in present measurements of correlation functions, one can determine the scattering length and effective range of all channels with a very good accuracy. Most remarkable is the fact that the method predicts the existence of a bound state of isospin 12 nature around the mass of the N*(1535) with an accuracy of 6 MeV. These results should encourage the actual measurement of these correlation functions (only the K+A one is measured so far), which can shed valuable light on the relationship of the N*(1535) state to these coupled channels, a subject of continuous debate.
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Xiao, C. W., Dias, J. M., Dai, L. R., Liang, W. H., & Oset, E. (2024). Triangle singularity in the J/ψ → ϕ π+ a−0(π−η) ,ϕ π− a+0(π+η) decays. Phys. Rev. D, 109(7), 074033–11pp.
Abstract: We study the J= psi -> phi pi + a 0 ( 980 ) – ( a – 0 -> pi – eta ) decay, evaluating the double mass distribution in terms of the pi – eta and pi + a – 0 invariant masses. We show that the pi – eta mass distribution exhibits the typical cusp structure of the a 0 ( 980 ) seen in recent high statistics experiments, and the pi + a – 0 spectrum shows clearly a peak around M inv ( pi + a – 0 ) = 1420 MeV, corresponding to a triangle singularity. When integrating over the two invariant masses we find a branching ratio for this decay of the order of 10 – 5 , which is easily accessible in present laboratories. We also call attention to the fact that the signal obtained is compatible with a bump experimentally observed in the eta pi + pi – mass distribution in the J= psi -> phi eta pi + pi – decay and encourage further analysis to extract from there the phi pi + a – 0 and phi pi – a + 0 decay modes.
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Xiao, C. W., Nieves, J., & Oset, E. (2019). Prediction of hidden charm strange molecular baryon states with heavy quark spin symmetry. Phys. Lett. B, 799, 135051–10pp.
Abstract: We have studied the meson-baryon S-wave interaction in the isoscalar hidden-charm strange sector with the coupled-channels, eta(c)Lambda, J/psi Lambda, (D) over bar Xi(c), (D) over bar (s)Lambda(c), (D) over bar Xi(c)', (D) over bar*Lambda(c), (D) over bar*Xi(c)', (D) over bar*Xi*(c) in J(p) = 1/2(-), J/psi Lambda, (D) over bar*Xi(c), (D) over bar (s)*Lambda(c), (D) over bar*Xi(c)', (D) over bar Xi(c)*, (D) over bar*Xi(c)* in 3/2(-) and (D) over bar*Xi(c)* in 5/2(-). We impose constraints of heavy quark spin symmetry in the interaction and obtain the non vanishing matrix elements from an extension of the local hidden gauge approach to the charm sector. The ultraviolet divergences are renormalized using the same meson-baryon-loops regulator previously employed in the non-strange hidden charm sector, where a good reproduction of the properties of the newly discovered pentaquark states is obtained. We obtain five states of 1/2(-), four of 3/2(-) and one of 5/2(-), which could be compared in the near future with forthcoming LHCb experiments. The 5/2(-), three of the 3/2(-) and another three of the 1/2(-) resonances are originated from isoscalar (D) over bar (()*())Xi(c)' and (D) over bar (()*()) Xi(c)* interactions. They should be located just few MeV below the corresponding thresholds (4446, 4513, 4588 and 4655 MeV), and would be SU(3)-siblings of the isospin 1/2 (D) over bar (()*())Sigma(()(c)*()) quasi-bound states previously found, and that provided a robust theoretical description of the P-c(4440), P-c(4457) and P-c(4312) LHCb exotic states. The another two 1/2(-) and 3/2(-) states obtained in this work are result of the (D) over bar (()*())Xi(c)- D-s(()*()) Lambda(c) coupled-channels isoscalar interaction, are significantly broader than the others, with widths of the order of 15 MeV, being (D) over bar (()(s)*())Lambda(c) the dominant decay channel.
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Feijoo, A., Wang, W. F., Xiao, C. W., Wu, J. J., Oset, E., Nieves, J., et al. (2023). A new look at the P-cs states from a molecular perspective. Phys. Lett. B, 839, 137760–7pp.
Abstract: We have a look at the P-cs states generated from the interaction of (D) over bar(*)Xi(c)('*) coupled channels. We consider the blocks of pseudoscalar-baryon (1/2(+) , 3/2(+)) and vector-baryon (1/2(+), 3/2(+)), and find 10 resonant states coupling mostly to (D) over bar Xi(c), <(D)*over bar>*Xi(c), (D) over bar Xi(c)' <(DA novel aspect of the work is the realization that the <(Dover bar>Xi(c), (Dover bar>(s) Lambda(c) or (Dover bar>*Xi(c), D-s*Lambda(c) channels, with a strong transition potential, collaborate to produce a larger attraction than the corresponding states <(Dover bar>Xi(c), <(Dover bar>Lambda(c) or (D) over bar*Xi(c), (D) over bar*Lambda(c) appearing in the generation of the strangenessless P-c states, since in the latter case the transition potential between those channels is zero. The extra attraction obtained in the (D) over bar Xi(c), (D) over bar* Xi(c) pairs preclude the association of the P-cs(4338) state coupling mostly to (D) over bar*Xi(c) while the P-cs(4459) is associated to the state found that couples mostly to (D) over bar Xi(c)'. Four more states appear, like in other molecular pictures, and some of the states are degenerate in spin. Counting different spin states we find 10states, which we hope can be observed in the near future.
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Dote, A., Bayar, M., Xiao, C. W., Hyodo, T., Oka, M., & Oset, E. (2013). A narrow quasi-bound state of the DNN system. Nucl. Phys. A, 914, 499–504.
Abstract: We have investigated a charmed system of DNN (composed of two nucleons and a D meson) by a complementary study with a variational calculation and a Faddeev calculation with fixed-center approximation (Faddeev-FCA). In the present study, we employ a DN potential based on a vector-meson exchange picture in which a resonant A(c)(2595) is dynamically generated as a DN quasi-bound state, similarly to the A(1405) as a (K) over barN one in the strange sector. As a result of the study of variational calculation with an effective DN potential and three kinds of NN potentials, the DNN(J(pi) =0(-), I = 1/2) is found to be a narrow quasi-bound state below A(c)(2595)N threshold: total binding energy similar to 225 MeV and mesonic decay width similar to 25 MeV. On the other hand, the J(pi) =1(-) state is considered to be a scattering state of A(c)(2595) and a nucleon. These results are essentially supported by the Faddeev-FCA calculation. By the analysis of the variational wave function, we have found a unique structure in the DNN(J(pi) = 0, I = 1/2) such that the D meson stays around the center of the total system due to the heaviness of the D meson.
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