Yu, Q. X., Dias, J. M., Liang, W. H., & Oset, E. (2019). Molecular Xi(bc) states from meson-baryon interaction. Eur. Phys. J. C, 79(12), 1025–13pp.
Abstract: We have studied the meson-baryon interaction in coupled channels with the same quantum numbers of Xi bc. The interaction is attractive in some channels and of sufficient intensity to lead to bound states or resonances. We use a model describing the meson-baryon interaction based on an extrapolation of the local hidden gauge approach to the heavy sector, which has been successfully used in predicting omega c and hidden charm states. We obtain many states, some of them narrow or with zero width, as a consequence of the interaction, which qualify as molecular states in those channels. The success in related sectors of the picture used should encourage the experimental search for such states.
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Sakai, S., Liang, W. H., Toledo, G., & Oset, E. (2020). J/psi -> gamma pi pi, gamma pi(0)eta reactions and the f(0)(980) and a(0)(980) resonances. Phys. Rev. D, 101(1), 014005–9pp.
Abstract: We study the J/psi -> gamma pi(+)pi(-), gamma pi(0)eta reactions from the perspective that they come from the J/psi -> phi(omega)pi(+)pi(-), rho(0)pi(0)eta reactions, where the rho(0), psi, and phi get converted into a photon via vector meson dominance. Using models successfully used previously to study the J/psi -> omega(phi)pi pi reactions, we make determinations of the invariant mass distributions for pi(+)pi(-) in the regions of the f(0)(500), f(0)(980), and for pi(0)eta in the region of the a(0)(980). The integrated differential widths lead to branching ratios below present upper bounds, but they are sufficiently large for future check in updated facilities.
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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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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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Sakai, S., Oset, E., & Guo, F. K. (2020). Triangle singularity in the B-> K- pi X-0 (3872) reaction and sensitivity to the X(3872) mass. Phys. Rev. D, 101(5), 054030–10pp.
Abstract: We have done a study of the B--> K-pi X-0(3872) reaction by means of a triangle mechanism via the chain of reactions: B--> K-D*(0);(D) over bar*(0); D*(0)-> pi D-0(0); D-0(D) over bar*(0)-> X(3872). We show that this mechanism generates a triangle singularity in the pi X-0(3872) invariant mass for a very narrow window of the X(3872) mass, around the present measured values, and show that the peak positions and the shape of the mass distributions arc sensitive to the X(3872) mass, such that a measurement of the reaction can serve to improve on the present values of this mass. In particular, we point out that the X(3872) mass relative to the D-0(D) over bar*(0) threshold may be extracted from the asymmetry of the pi X-0 line shape.
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Liang, W. H., & Oset, E. (2020). Observed Omega(b) spectrum and meson-baryon molecular states. Phys. Rev. D, 101(5), 054033–6pp.
Abstract: We observe that four peaks seen in the high energy part of the Omega(b) spectrum of the recent LHCb experiment are in remarkable agreement with predictions made for molecular Omega(b) states stemming from the meson-baryon interaction, with an approach that applied to the Omega(c) states gives rise to three states in good agreement with experiment in masses and widths. While the statistical significance of the peaks prevents us from claims of states at the present time, the agreement found should be an incentive to look at this experiment with increased statistics to give an answer to this suggestive idea.
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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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Molina, R., Xie, J. J., Liang, W. H., Geng, L. S., & Oset, E. (2020). Theoretical interpretation of the D-s(+) -> pi(+)pi(0)eta decay and the nature of a(0)(980). Phys. Lett. B, 803, 135279–4pp.
Abstract: In a recent paper [I], the BESIII Collaboration reported the so-called first observation of pure W-annihi- lation decays D-s(+) -> a(0)(+) (980)pi(0) and D-s(+) -> a(0)(0)(980)pi(+). The measured absolute branching fractions are, however, puzzlingly larger than those of other measured pure W-annihilation decays by at least one order of magnitude. In addition, the relative phase between the two decay modes is found to be about 0 degrees. In this letter, we show that all these can be easily understood if the a(0)(980) is a dynamically generated state from (K) over barK and pi eta interactions in coupled channels. In such a scenario, the D-s(+) decay proceeds via internal W emission instead of W-annihilation, which has a larger decay rate than W-annihilation. The proposed decay mechanism and the molecular nature of the a(0)(980) also provide a natural explanation to the measured negative interference between the two decay modes.
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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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Liang, W. H., & Oset, E. (2020). Testing the origin of the f1(1420) with the Kbar p -> Lambda(Sigma) K Kbar pi reaction. Eur. Phys. J. C, 80(5), 407–8pp.
Abstract: We study the K¯p→YKK¯π reactions with K¯=K¯0,K− and Y=Σ0,Σ+,Λ, in the region of KK¯π invariant masses of 1200−1550 MeV. The strong coupling of the f1(1285) resonance to K∗K¯ makes the mechanism based on K∗ exchange very efficient to produce this resonance observed in the KK¯π invariant mass distribution. In addition, in all the reactions one observes an associated peak at 1420 MeV which comes from the K∗K¯ decay mode of the f1(1285) when the K∗ is placed off shell at higher invariant masses. We claim this to be the reason for the peak of the K∗K¯ distribution seen in the experiments which has been associated to the “f1(1420)” resonance.
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