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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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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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Liang, W. H., Xiao, C. W., & Oset, E. (2013). Study of eta K(K)over-bar and eta ' K(K)over-bar with the fixed center approximation to Faddeev equations. Phys. Rev. D, 88(11), 114024–10pp.
Abstract: In the present work we investigate the three-body systems of eta K (K) over bar and eta'K (K) over bar, by taking the fixed center approximation to Faddeev equations. We find a clear and stable resonance structure around 1490 MeV in the squared eta K (K) over bar scattering amplitude, which is not sensitive to the renormalization parameters. Conversely, we get only an enhancement effect of the threshold in the eta'K (K) over bar amplitude that indicates the difficulty to bind the eta'K (K) over bar system as a consequence of the eta'K interaction being weaker than the eta K one. We associate the eta K (K) over bar state found to the eta(1475).
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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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Liang, W. H., Bayar, M., & Oset, E. (2017). Lambda(b) -> pi(-)(D-S(-)) Lambda(C)(2595), pi(-)(D-S(-)) Lambda(C)(2625) decays and DN, D*N molecular components. Eur. Phys. J. C, 77(1), 39–9pp.
Abstract: From the perspective that Lambda(C)(2595) and Lambda(C)(2625) are dynamically generated resonances from the DN, D*N interaction and coupled channels, we have evaluated the rates for Lambda(b) -> pi(-)Lambda(C)(2595) and Lambda(b) -> pi(-)Lambda(C)(2625) up to a global unknown factor that allows us to calculate the ratio of rates and compare with experiment, where good agreement is found. Similarly, we can also make predictions for the ratio of rates of the, yet unknown, decays of Lambda(b) -> D-s(-)Lambda(C)(2595) and Lambda(b) -> D-s(-)Lambda(c)(2625) and make estimates for their individual branching fractions.
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