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Liang, W. H., Oset, E., & Xie, Z. S. (2017). Semileptonic Lambda(b) -> (nu)over-bar(l) l Lambda(c)(2595) and Lambda(b) -> (nu)over-bar(l)l Lambda(c)(2625) decays in the molecular picture of Lambda(c)(2595) and Lambda(c)(2625). Phys. Rev. D, 95(1), 014015–8pp.
Abstract: We evaluate the partial decay widths for the semileptonic Lambda(b) -> (nu) over bar (l) l Lambda(c)(2595) and Lambda(b) -> (nu) over bar (l)l Lambda(c)(2625) decays from the perspective that these two Lambda(c)* resonances are dynamically generated from the DN and D*N interaction with coupled channels. We find that the ratio of the rates obtained for these two reactions is compatible with present experimental data and is very sensitive to the D*N coupling, which becomes essential to obtain agreement with experiment. Together with the results obtained for the Lambda(b) -> pi(-)Lambda(c)* reactions, it gives strong support to the molecular picture of the two Lambda(c)* resonances arid the important role of the DN component neglected in prior studies of the Lambda(c)(2595) from the molecular perspective.
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Debastiani, V. R., Aceti, F., Liang, W. H., & Oset, E. (2017). Revising the f(1)(1420) resonance. Phys. Rev. D, 95(3), 034015–10pp.
Abstract: We have studied the production and decay of the f(1) (1285) into pi a(0)(980) and K* (K) over bar as a function of the mass of the resonance and find a shoulder around 1400 MeV, tied to a triangle singularity, for the pi a(0)(980) mode, and a peak around 1420 MeV with about 60 MeV width for the K* (K) over bar mode. Both of these features agree with the experimental information on which the f(1)(1420) resonance is based. In addition, we find that if the f(1)(1420) is a genuine resonance, coupling mostly to K* (K) over bar as seen experimentally, one finds unavoidably about a 20% fraction for pi a(0)(980) decay of this resonance, in drastic contradiction with all experiments. Altogether, we conclude that the f(1)(1420) is not a genuine resonance, but the manifestation of the pi a(0)(980) and K* (K) over bar decay modes of the f(1)(1285) at higher energies than the nominal one.
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Sakai, S., Oset, E., & Liang, W. H. (2017). Abnormal isospin violation and a(0) – f(0) mixing in the D-s(+) -> pi(+) pi(0)a(0)(980)(f(0)(980)) reactions. Phys. Rev. D, 96(7), 074025–11pp.
Abstract: We have chosen the reactions D-s(+) -> pi(+) pi(0)a(0)(980)(f(0)(980)) investigating the isospin violating channel D-s(+) -> pi+ pi(0)f(0)(980). The reaction was chosen because by varying the pi(0)a(0)(980)(f(0)(980)) invariant mass one goes through the peak of a triangle singularity emerging from D-s(+) -> pi(K) over bar *K, followed by (K) over bar* -> (K) over bar pi(0) and the further merging of K (K) over bar to produce the a(0)(980) or f(0)(980). We found that the amount of isospin violation had its peak precisely at the value of the pi(0)a(0)(980)(f(0)(980)) invariant mass where the singularity has its maximum, stressing the role of the triangle singularities as a factor to enhance the mixing of the f(0)(980) and a(0)(980) resonances. We calculate absolute rates for the reactions and show that they are within present measurable range. The measurement of these reactions would bring further information into the role of triangle singularities in isospin violation and the a(0) – f(0) mixing, in particular, and shed further light into the nature of the low energy scalar mesons.
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Debastiani, V. R., Dias, J. M., Liang, W. H., & Oset, E. (2018). Molecular Omega(c) states generated from coupled meson-baryon channels. Phys. Rev. D, 97(9), 094035–11pp.
Abstract: We have investigated Omega(c) states that are dynamically generated from the meson-baryon interaction. We use an extension of the local hidden gauge to obtain the interaction from the exchange of vector mesons. We show that the dominant terms come from the exchange of light vectors, where the heavy quarks are spectators. This has as a consequence that heavy quark symmetry is preserved for the dominant terms in the (1/m(Q)) counting, and also that the interaction in this case can be obtained from the SU(3) chiral Lagrangians. We show that for a standard value for the cutoff regulating the loop, we obtain two states with J(P) = 1/2(-) and two more with J(P) = 3/2(-), three of them in remarkable agreement with three experimental states in mass and width. We also make predictions at higher energies for states of vector-baryon nature.
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Debastiani, V. R., Dias, J. M., Liang, W. H., & Oset, E. (2018). Omega(-)(b) -> (Xi(+)(c) K-)pi(-) decay and the Omega(c) states. Phys. Rev. D, 98(9), 094022–8pp.
Abstract: We study the weak decay Omega(-)(b) -> (Xi(+)(c) K-)pi(-), in view of the narrow Omega(c) states recently measured by the LHCb Collaboration and later confirmed by the Belle Collaboration. The Omega(c) (3050) and Omega(c) (3090) are described as meson-baryon molecular states, using an extension of the local hidden gauge approach in coupled channels. We investigate the Xi D, Xi(c)(K) over bar, and. Xi '(c) (K) over bar invariant mass distributions making predictions that could be confronted with future experiments, providing useful information that could help determine the quantum numbers and nature of these states.
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Yu, Q. X., Liang, W. H., Bayar, M., & Oset, E. (2019). Line shape and D-(*())(D)over-bar(()*()) probabilities of psi(3770) from the e(+) e(-) -> D(D)over-bar reaction. Phys. Rev. D, 99(7), 076002–17pp.
Abstract: We have performed a calculation of the D (D) over bar, D (D) over bar*, D*(D) over bar, D*(D) over bar* components in the wave function of the psi(3770). For this we make use of the P-3(0) model to find the coupling of psi(3770) to these components, that with an elaborate angular momentum algebra can be obtained with only one parameter. Then we use data for the e(+)e(-) -> D (D) over bar reaction, from where we determine a form factor needed in the theoretical framework, as well as other parameters needed to evaluate the meson-meson self-energy of the psi(3770). Once this is done we determine the Z probability to still have a vector core and the probability to have the different meson components. We find Z about 80%-85%, and the individual meson-meson components are rather small, providing new empirical information to support the largely q (q) over bar component of vector mesons, and the psi(3770) in particular. A discussion is done of the meaning of the terms obtained for the case of the open channels where the concept of probability cannot be strictly used.
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Liang, W. H., Sakai, S., & Oset, E. (2019). Theoretical description of the J/psi -> eta(eta ')h(1)(1380), J/psi -> eta(eta ')h(1)(1170) and J/psi -> pi(0)b(1) (1235)(0) reactions. Phys. Rev. D, 99(9), 094020–10pp.
Abstract: We have made a study of the J/psi -> eta'h(1), eta h(1) [with h(1) being /11(1170) and h(1)(1380)1 and P/psi ->pi(0)b(1) 171(1235)(0) assuming the axial vector mesons to be dynamically generated from the pseudoscalar-vectormeson interaction. We have taken the needed input from previous studies of the J/psi -> phi pi pi, omega pi pi reactions. We obtain fair agreement with experimental data and provide an explanation on why the recent experiment on J/psi -> eta'h(1)(1380), h(1)(1380) -> K*K-+(-) + c.c. observed in the K+K-pi(0) mode observes the peak of the h(1)(1380) at a higher energy than its nominal mass.
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Ikeno, N., Dias, J. M., Liang, W. H., & Oset, E. (2019). chi(c1) decays into a pseudoscalar meson and a vector-vector molecule. Phys. Rev. D, 100(11), 114011–7pp.
Abstract: We evaluate ratios of the chi(c1) decay rates to eta (eta', K-) and one of the f(0) (1370), f(0) (1710), f(2) (1270), f(2)'(1525), K-2*(1430) resonances, which in the local hidden gauge approach are dynamically generated from the vector-vector interaction. With the simple assumption that the chi(c1) is a singlet of SU(3), and the input from the study of these resonances as vector-vector molecular states, we describe the experimental ratio B(chi(c1)-> eta f(2) (1270))/B(chi(c1) -> eta'f(2)' (1525)) and make predictions for six more ratios that can be tested in future experiments.
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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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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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