Uchino, T., Liang, W. H., & Oset, E. (2016). Baryon states with hidden charm in the extended local hidden gauge approach. Eur. Phys. J. A, 52(3), 43–16pp.
Abstract: The s-wave interaction of (D) over bar Lambda(c), (D) over bar Sigma(c),(D) over bar*Lambda(c), (D) over bar*Sigma(c) and (D) over bar Sigma(c)*, (D) over bar*Sigma(c)*, is studied within a unitary coupled channels scheme with the extended local hidden gauge approach. In addition to the Weinberg-Tomozawa term, several additional diagrams via the pion exchange are also taken into account as box potentials. Furthermore, in order to implement the full coupled channels calculation, some of the box potentials which mix the vector-baryon and pseudoscalar-baryon sectors are extended to construct the effective transition potentials. As a result, we have observed six possible states in several angular momenta. Four of them correspond to two pairs of admixture states, two of (D) over bar Sigma(c) – (D) over bar*Sigma(c) with J – 1/2, and two of (D) over bar Sigma(c)* – (D) over bar*Sigma(c)* with J = 3/2. Moreover, we find a (D) over bar*Sigma(c) resonance which couples to the (D) over bar Lambda(c) channel and one spin degenerated bound state of (D) over bar*Sigma(c)* with J = 1/2, 5/2.
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Oset, E., Bayar, M., Dote, A., Hyodo, T., Khemchandani, K. P., Liang, W. H., et al. (2016). Two-, Three-, Many-body Systems Involving Mesons. Multimeson Condensates. Acta Phys. Pol. B, 47(2), 357–365.
Abstract: In this paper, we review results from studies with unconventional many-hadron systems containing mesons: systems with two mesons and one baryon, three mesons, some novel systems with two baryons and one meson, and finally, systems with many vector mesons, up to six, with their spins aligned forming states of increasing spin. We show that in many cases, one has experimental counterparts for the states found, while in some other cases, they remain as predictions, which we suggest to be searched in BESIII, Belle, LHCb, FAIR and other facilities.
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Xie, J. J., Liang, W. H., & Oset, E. (2016). (K)over-bar-induced formation of the f(0)(980) and a(0)(980) resonances on proton targets. Phys. Rev. C, 93(3), 035206–8pp.
Abstract: We perform a calculation of the cross section for nine reactions induced by (K) over bar scattering on protons. The reactions studied are K- p -> Lambda pi(+)pi(-), K- p -> Sigma(0)pi(+)pi(-), K- p -> Lambda pi(0)eta, K- p -> Sigma(0)pi(0)eta, K- p -> Sigma(+)pi(-)eta, (K) over bar (0) p -> Lambda pi(+)eta, (K) over bar (0) p -> Sigma(0)pi(+)eta, (K) over bar (0) p -> Sigma(+)pi(+)pi(-), and (K) over bar (0) p -> Sigma+pi(0)eta. We find that in the reactions producing pi(+)pi(-), a clear peak for the f(0)(980) resonance is found, while no trace of f(0)(500) appears. Similarly, in the cases of p. production, a strong peak is found for the a(0)(980) resonance, with the characteristic strong cusp shape. Cross sections and invariant mass distributions are evaluated which should serve, by comparing them with future data, to test the dynamics of the chiral unitary approach used for the evaluations and the nature of these resonances.
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Liang, W. H., Xie, J. J., & Oset, E. (2015). (B)over-bar(0), B- and (B)over-bar(S)(0) decays into J/psi and K (K)over-bar or pi eta. Eur. Phys. J. C, 75(12), 609–8pp.
Abstract: We study the (B) over bar (0)(S) -> J/psi K+ K-, (B) over bar (0) -> J/psi K+ K, B- -> J/psi K+ K-, (B) over bar (0) -> J/psi pi(0)eta(-), decays and compare their mass distributions with those obtained for the (B) over bar (0)(S) -> J/psi pi(+) pi(-) and (B) over bar (0)(S) -> J/psi pi(+)pi(-). The approach followed consist in a factorization of the weak part and the hadronization part into a factor which is common to all the processes. Then what makes the reactions different are some trivial CabibboKobayashi- Maskawa matrix elements and the weight by which the different pairs of mesons appear in a primary step plus their final state interaction. These elements are part of the theory and thus, up to a global normalization factor, all the invariant mass distributions are predicted with no free parameters. Comparison is made with the limited experimental information available. Further comparison of these results with coming LHCb measurements will be very valuable to make progress in our understanding of the meson- meson interaction and the nature of the low lying scalar meson resonances, f(0)(500), f(0)( 980) and a(0)(980).
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Liang, W. H., Xie, J. J., & Oset, E. (2015). (B)over-bar(0) decay into D-0 and f(0)(500), f(0)(980), a(0)(980), rho and (B)over-bar(s)(0) decay into D-0 and kappa(800), K*(0). Phys. Rev. D, 92(3), 034008–9pp.
Abstract: We make predictions for ratios of branching fractions of (B) over bar (0) decays into D-0 and the scalar mesons f(0)(500), f(0)(980), a(0)(980), plus (B) over bar (0)(s) decay into D-0 and kappa(800). We also compare the pi(+)pi(-) production in the scalar channel with that observed in the rho channel and make predictions for the (B) over bar (0)(s) decay into D-0 and K*(892), comparing the strength of this channel with that of kappa(800) production. The work is based on results of the chiral unitary approach where the scalar resonances are generated from the pseudoscalar-pseudoscalar interaction. Up to an arbitrary normalization, the mass distributions and rates for decays into the scalar resonances are predicted with no free parameters. Comparison with experimental data is done when available.
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Liang, W. H., Molina, R., Xie, J. J., Doring, M., & Oset, E. (2015). Predictions for the X(YZ) and X(YZ) with X(4160), Y(3940), Z(3930). Eur. Phys. J. A, 51(5), 58–7pp.
Abstract: We investigate the decay of and with R being the , , resonances. Under the assumption that these states are dynamically generated from the vector-vector interaction, as has been concluded from several theoretical studies, we use a reaction mechanism of quark production at the elementary level, followed by hadronization of one final pair into two vectors and posterior final state interaction of this pair of vector mesons to produce the resonances. With this procedure we are able to predict five ratios for these decays, which are closely linked to the dynamical nature of these states, and also predict the order of magnitude of the branching ratios which we find of the order of , well within the present measurable range. In order to further test the dynamical nature of these resonances we study the and decays close to the and thresholds and make predictions for the ratio of the mass distributions in these decays and the decay widths. The measurement of these decays rates can help unravel the nature of these resonances.
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Liang, W. H., Uchino, T., Xiao, C. W., & Oset, E. (2015). Baryon states with open charm in the extended local hidden gauge approach. Eur. Phys. J. A, 51(2), 16–14pp.
Abstract: In this paper we examine the interaction of DN and D* N states, together with their coupled channels, by using an extension of the local hidden gauge formalism from the light meson sector, which is based on heavy quark spin symmetry. The scheme is based on the use of the impulse approximation at the quark level, with the heavy quarks acting as spectators, which occurs for the dominant terms where there is the exchange of a light meson. The pion exchange and the Weinberg-Tomozawa interactions are generalized and with this dynamics we look for states generated from the interaction, with a unitary coupled channels approach that mixes the pseudoscalar-baryon and vector-baryon states. We find two states with nearly zero width, which are associated to the I > (c) (2595) and I > (c) (2625). The lower state, with J (P) = 1/2(-), couples to DN and D* N, and the second one, with J (P) = 3/2(-), to D* N. In addition to these two I > (c) states, we find four more states with I = 0, one of them nearly degenerate in two states of J (P) = 1/2, 3/2. Furthermore we find three states in I = 1, two of them degenerate in J = 1/2, 3/2.
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Bayar, M., Liang, W. H., & Oset, E. (2014). B-0 and B-s(0) decays into J/psi plus a scalar or vector meson. Phys. Rev. D, 90(11), 114004–9pp.
Abstract: We extend a recent approach to describe the B-0 and B-s(0) decays into J/psi f(0)(500) and J/psi f(0)(980), relating it to the B-0 and B-s(0) decays into J/psi and a vector meson, phi, rho, K*. In addition, the B-0 and B-s(0) decays into J/psi and kappa(800) are evaluated and compared to the K* vector production. The rates obtained are in agreement with the available experiment while predictions are made for the J/psi plus kappa(800) decay.
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Liang, W. H., & Oset, E. (2014). B-0 and B-s(0) decays into J/psi f(0)(980) and J/psi f(0)(500) and the nature of the scalar resonances. Phys. Lett. B, 737, 70–74.
Abstract: We describe the B-0 and B-s(0) decays into J/psi f(0)(500) and J/psi f(0)(980) by taking into account the dominant process for the weak decay of B-0 and B-s(0) into J/psi and a q (q) over bar component. After hadronization of this q (q) over bar component into pairs of pseudoscalar mesons we obtain certain weights for the meson-meson components and allow them to interact among themselves. The final state interaction of the meson-meson components, described in terms of chiral unitary theory, gives rise to the f(0)(980) and f(0)(500) resonances and we can obtain the pi(+)pi(-) invariant mass distributions after the decay of the resonances, which allows us to compare directly to the experiments. We obtain ratios of J/psi f(0)(980) and J/psi f(0)( 500) for each of the B decays in quantitative agreement with experiment, with the f(0)(980) clearly dominant in the B-s(0) decay and the f(0)(500) in the B-0 decay.
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Liang, W. H., Xiao, C. W., & Oset, E. (2014). Baryon states with open beauty in the extended local hidden gauge approach. Phys. Rev. D, 89(5), 054023–15pp.
Abstract: In this paper, we examine the interaction of (B) over barN, (B) over bar Delta, (B) over bar *N, and (B) over bar*Delta states, together with their coupled channels, by using a mapping from the light meson sector. The assumption that the heavy quarks act as spectators at the quark level automatically leads us to the results of the heavy quark spin symmetry for pion exchange and reproduces the results of the Weinberg Tomozawa term, coming from light vector exchanges in the extended local hidden gauge approach. With this dynamics we look for states dynamically generated from the interaction and find two states with nearly zero width, which we associate to the A(b)(5912) and A(b)(5920) states. The states couple mostly to (B) over bar *N, which are degenerate with the Weinberg Tomozawa interaction. The difference of masses between these two states, with J = 1/2 and 3/2, respectively, is due to pion exchange connecting these states to intermediate (B) over barN states. In addition to these two A(b) states, we find three more states with I = 0, one of them nearly degenerate in two states of J = 1/2, 3/2. Furthermore, we also find eight more states in I = 1, two of them degenerate in J = 1/2, 3/2, and another two degenerate in J = 1/2, 3/2, 5/2.
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