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Molina, R., Ikeno, N., & Oset, E. (2023). Sequential single pion production explaining the dibaryon “d*(2380)” peak. Chin. Phys. C, 47(4), 041001–10pp.
Abstract: In this study, we investigate the two step sequential one pion production mechanism, that is, np(I=0)->pi(-)pp followed by the fusion reaction pp ->pi(+)d, to describe the np ->pi(+)pi(-)d reaction with in state I = 0 . In this reaction, a narrow peak identified with a “ d(2380) ” dibaryon has been previously observed. We discover that the second reaction step pp ->pi(+)d is driven by a triangle singularity that determines the position of the peak of the reaction and the high strength of the cross section. The combined cross section of these two mechanisms produces a narrow peak with a position, width, and strength, that are compatible with experimental observations within the applied approximations made. This novel interpretation of the peak accomplished without invoking a dibaryon explains why this peak has remained undetected in other reactions.
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Ikeno, N., Dai, L. R., & Oset, E. (2020). Meson exchange between initial and final state and the R-D ratio in the B-bar -> D nu-bar l (nu_tau-bar tau) reactions. Eur. Phys. J. A, 56(2), 73–12pp.
Abstract: We perform a calculation of the strong interaction effects between the B and D mesons in the B -> D nu l reaction, as a crossing process of reactions with BD in the final state, where the strong interaction between the mesons leads to a bound BD state. We find corrections to the tree level amplitude of the order of 15-25%. We further see the effect of the corrections studied in the R-D ratio for the rates of B -> D nu and B. D decays and find corrections of the order of 10%. Given the claims of 1.5% precision in this ratio from fits to data within the standardmodel, any theoretical model aiming at describing this ratio within the same precision must take into account the corrections described in the present work.
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Ikeno, N., Bayar, M., & Oset, E. (2018). Semileptonic decay of B-c(-) into X (3930), X (3940), X (4160). Eur. Phys. J. C, 78(5), 429–7pp.
Abstract: We study the semileptonic decay of B-c(-) meson into & Unknown;l(-) and the isospin zero X (3930) (2(++)), X(3940) (0(++)), X (4160) (2(++)) resonances. We look at the reaction from the perspective that these resonaces appear as dynamically generated from the vector-vector interaction in the charm sector, and couple strongly to D*& Unknown;D* and D-s*& Unknown;D-s*. We also look into the B-c(-) -> & Unknown;(l)l(-) D*& Unknown;* and B-c(-) -> & Unknown;(l)l(-) D-s*& Unknown;(s)* reactions close to threshold and relate the D*& Unknown;* and D-s*& Unknown;(s)* mass distribution to the rate of production of the X resonances.
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Bayar, M., Ikeno, N., & Oset, E. (2020). Analysis of the psi (4040) and psi (4160) decay into D-(*()) (D)over-bar(()*()), D-s(()*()) (D)over-bar(s)(()*()). Eur. Phys. J. C, 80(3), 222–9pp.
Abstract: We have performed an analysis of the e+e--> D(*) data in the region of the psi(4040) and psi(4160) resonances which have a substantial overlap and require special care. By using the P-3(0) model to relate the different D(*)(D) over bar(*) production modes, we make predictions for production of these channels and compare with experiment and other theoretical approaches. As a side effect we find that these resonances qualify largely as c (c) over bar states and theweight of the meson-meson components in the wave function is very small.
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Toledo, G., Ikeno, N., & Oset, E. (2021). Theoretical study of the D-0 -> K-pi(+)eta reaction. Eur. Phys. J. C, 81(3), 268–11pp.
Abstract: We develop a model to study the D-0 -> K-pi(+)eta weak decay, starting with the color favored external emission and Cabibbo favored mode at the quark level. A less favored internal emission decay mode is also studied as a source of small corrections. Some pairs of quarks are allowed to hadronize producing two pseudoscalar mesons, which posteriorly are allowed to interact to finally provide the K-pi(+)eta state. The chiral unitary approach is used to take into account the final state interaction of pairs of mesons, which has as a consequence the production of the kappa (K-0*(700)) and the a(0)(980) resonances, well visible in the invariant mass distributions. We also introduce the (K) over bar*(0)eta production in a phenomenological way and show that the s-wave pseudoscalar interaction together with this vector excitation mode are sufficient to provide a fair reproduction of the experimental data. The model provides the relative weight of the a(0)(980) to the kappa excitation, and their strength is clearly visible in the low energy part of the K pi spectrum.
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