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Ikeno, N., Molina, R., & Oset, E. (2022). Zcs states from the D*s over bar D* and J=psi K* coupled channels: Signal in B+ -> J=psi phi K+ decay. Phys. Rev. D, 105(1), 014012–13pp.
Abstract: We study the D*s over bar D* system in connection with the J=psi K* in coupled channels and observe that, within reasonable values of the cutoff used to regularize the loops, the system does not develop a bound state. However, the JP = 2+ channel has enough attraction to create a strong cusp structure that shows up in the J=psi K+ invariant mass distribution in the B+ -> J=psi phi K+ decay at the D*s over bar D* threshold. Such structure is results should stimulate further measurements around this region, given the fact that cusp effects provide as valuable information on hadron dynamics as resonances themselves.
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Ikeno, N., Molina, R., & Oset, E. (2021). Triangle singularity mechanism for the pp -> pi(+)d fusion reaction. Phys. Rev. C, 104(1), 014614–16pp.
Abstract: We develop a model for the pp -> pi(+)d reaction based on the pp -> Delta(1232)N transition followed by Delta(1232) -> pi N' decay and posterior fusion of NN' to give the deuteron. We show that the triangle diagram depicting this process develops a triangle singularity leading to a large cross section of this reaction compared to ordinary fusion reactions. The results of the calculation also show that the process is largely dominated by the pp system in L = 2 and S = 0, which transfers J = 2 to the final pi(+)d system. This feature is shown to be well suited to provide L = 2, S = 1, and J(tot) = 3 for np in the np(I = 0) pi(-)pp reaction followed by the pp -> pi(+)d reaction, which has been proposed recently, as a means of describing the so far assumed dibaryon d* (2380) peak.
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Ikeno, N., Molina, R., & Oset, E. (2021). The Z(cs)(3985) as a threshold effect from the (D)over-bar(s)*D + (D)over-bar(s)D* interaction. Phys. Lett. B, 814, 136120–5pp.
Abstract: We study the e(+)e(-) -> K+(D-s*D--(0) + Ds-D*(0)) reaction recently measured at BESIII, from where a new Z(cs) state has been reported. We study the interaction of (D) over bar D-s* with the coupled channels J/psi K-, K*(-)eta(c), Ds-D*(0), D-s*D--(0) by means of an extension to the charm sector of the local hidden gauge approach. We find that the Ds-D*(0) + D-s*D--(0) combination couples to J/psi K- and K*(-)eta(c), but the Ds-D*(0 ) -D-s*D--(0) combination does not. The coupled channels help to build up strength in the Ds-D*(0) + D-s*D--(0) diagonal scattering matrix close to threshold and, although the interaction is not strong enough to produce a bound state or resonance, it is sufficient to produce a large accumulation of strength at the (D) over bar D-s* threshold in the e(+)e(-) -> K+(D-s*D--(0) + Ds-D*(0)) reaction in agreement with experiment.
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Ikeno, N., Ono, A., Nara, Y., & Ohnishi, A. (2020). Effects of Pauli blocking on pion production in central collisions of neutron-rich nuclei. Phys. Rev. C, 101(3), 034607–9pp.
Abstract: Pauli blocking is carefully investigated for the processes of NN <-> N Delta and Delta -> N pi in heavy-ion collisions, aiming at a more precise prediction of the pi(-)/pi(+) ratio which is an important observable to constrain the high-density symmetry energy. We use the AMD + JAM approach, which combines the antisymmetrized molecular dynamics for the time evolution of nucleons and the Jet AA Microscopic transport model to treat processes for Delta resonances and pions. As is known in general transport-code simulations, it is difficult to treat Pauli blocking very precisely due to unphysical fluctuations and additional smearing of the phase-space distribution function, when Pauli blocking is treated in the standard method of JAM. We propose an improved method in AMD + JAM to use the Wigner function precisely calculated in AMD as the blocking probability. Different Pauli blocking methods are compared in heavy-ion collisions of neutron-rich nuclei, Sn-132+Sn-124, at 270 MeV/nucleon. With the more accurate method, we find that Pauli blocking is stronger, in particular for the neutron in the final state in NN -> N Delta and Delta -> N pi, compared to the case with a proton in the final state. Consequently, the pi(-)/pi(+) ratio becomes higher when the Pauli blocking is improved, the effect of which is found to be comparable to the sensitivity to the high-density symmetry energy.
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Ikeno, N., & Oset, E. (2016). Semileptonic Lambda(c) decay to nu l(+) and Lambda(1405). Phys. Rev. D, 93(1), 014021–7pp.
Abstract: We study the semileptonic decay of Lambda(c) to nu l(+) and Lambda(1405), where the Lambda(1405) is seen in the invariant mass distribution of pi Sigma. We perform the hadronization of the quarks produced in the reaction in order to have a meson baryon pair in the final state and then let these hadron pairs undergo final state interaction from where the Lambda(1405) is dynamically generated. The reaction is particularly suited to study this resonance, because we show that it filters I = 0. It is also free of tree-level pi Sigma production, which leads to a clean signal of the resonance with no background. This same feature has as a consequence that one populates the state of the Lambda(1405) with higher mass around 1420 MeV, predicted by the chiral unitary approach. We make absolute predictions for the invariant mass distributions and find them within the measurable range in present facilities. The implementation of this reaction would allow us to gain insight into the existence of the predicted two Lambda(1405) states and their nature as molecular states.
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Ikeno, N., Toledo, G., Liang, W. H., & Oset, E. (2023). Consistency of the Molecular Picture of Omega(2012) with the Latest Belle Results. Few-Body Syst., 64(3), 55–6pp.
Abstract: We report the results of the research on the Omega(2012) state based on themolecular picture and discuss the consistency of the picture with the Belle experimental results. We study the interaction of the (K) over bar Xi*, eta Omega(s-wave) and (K) over bar Xi(d-wave) channels within a coupled channel unitary approach, and obtain the mass and the width of the Omega(2012) state and the decay ratio R-Xi(K) over bar(Xi pi(K) over bar). We also present a mechanism for Omega c -> pi(+)Omega(2012) production through an external emission Cabibbo favoredweak decay mode, where the Omega(2012) is dynamically generated from the above interaction. We find that the results obtained by the molecular picture are consistent with all Belle experimental data.
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Ikeno, N., Toledo, G., & Oset, E. (2023). Model independent analysis of femtoscopic correlation functions: An application to the D∗s0(2317). Phys. Lett. B, 847, 138281–6pp.
Abstract: We face the inverse problem of obtaining the interaction between coupled channels from the correlation functions of these channels. We apply the method to the interaction of the (DK+)-K-0, (D+K0), and D-s(+)eta channels, from where the D-s0(& lowast;)(2317) state emerges. We use synthetic data extracted from an interaction model based on the local hidden gauge approach and find that the inverse problem can determine the existence of a bound state of the system with a precision of about 20 MeV. At the same time, we can determine the isospin nature of the bound state and its compositeness in terms of the channels. Furthermore, we evaluate the scattering length and effective range of all three channels, as well as the couplings of the bound state found to all the components. Lastly, the size parameter of the source function, R, which in principle should be a magnitude provided by the experimental teams, can be obtained from a fit to the data with relatively high accuracy. These findings show the value of the correlation function to learn about the meson-meson interaction for systems which are difficult to access in other present facilities.
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Ikeno, N., Toledo, G., & Oset, E. (2020). Molecular picture for the Omega(2012) revisited. Phys. Rev. D, 101(9), 094016–9pp.
Abstract: We conduct a study of the interaction of the (K) over bar Xi*, eta Omega(s-wave), and (K) over bar Xi(d-wave) channels within a coupled channel unitary approach where the transition potential between the (K) over bar Xi* and eta Omega channels is obtained from chiral Lagrangians. The transition potential between (K) over bar Xi*, eta Omega, and (K) over bar Xi is taken in terms of free parameters, which together with a cutoff to regularize the meson-baryon loops are fitted to the Omega(2012) data. We find that all data including the recent Belle experiment on Gamma(Omega*->pi(K) over bar Xi)/Gamma(Omega*->(K) over bar Xi), are compatible with the molecular picture stemming from meson baryon interaction of these channels.
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Ikeno, N., Yamagata-Sekihara, J., Nagahiro, H., Jido, D., & Hirenzaki, S. (2011). Formation of heavy-meson bound states by two-nucleon pick-up reactions. Phys. Rev. C, 84(5), 054609–7pp.
Abstract: We develop a model to evaluate the formation rate of the heavy mesic nuclei in two-nucleon pick-up reactions and apply it to the (6)Li target cases for the formation of heavy meson-alpha bound states, as examples. The existence of the quasideuteron in the target nucleus is assumed in this model. It is found that mesic nuclei formation in recoilless kinematics is possible even for heavier mesons than the nucleon in two-nucleon pick-up reactions. We find the formation rate of the meson-alpha bound states can be around half of the elementary cross sections at the recoilless kinematics with small distortions.
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Liang, W. H., Ikeno, N., & Oset, E. (2020). Upsilon(nl) decay into B(*) (B)over-bar(*). Phys. Lett. B, 803, 135340–6pp.
Abstract: We have evaluated the decay modes of the Upsilon(4s), Upsilon(3d), Upsilon(5s), Upsilon(6s) states into B (B) over bar, B (B) over bar* + c.c., B* (B) over bar*, B-s(B) over bar (s), B-s(B) over bar (s)* + c.c., B-s* (B) over bar (s)* using the P-3(0) model to hadronize the bb vector seed, fitting some parameters to the data. We observe that the Upsilon(4s) state has an abnormally large amount of mesonmeson components in the wave function, while the other states are largely b (b) over bar. We predict branching ratios for the different decay channels which can be contrasted with experiment for the case of the Upsilon(5s) state. While globally the agreement is fair, we call the attention to some disagreement that could be a warning for the existence of more elaborate components in the state.
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