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Martinez Torres, A., Khemchandani, K. P., Nielsen, M., Navarra, F. S., & Oset, E. (2013). Exploring the D* rho system within QCD sum rules. Phys. Rev. D, 88(7), 074033–14pp.
Abstract: We present a study of the D* rho system made by using the method of QCD sum rules to determine the mass of possible resonances generated in the same system. Using isospin and spin projectors, we investigate the different configurations and obtain evidences for three D* mesons with isospin I = 1/2, spin S = 0, 1, 2 and with masses 2500 +/- 67, 2523 +/- 60, and 2439 +/- 119 MeV, respectively. The last state can be associated with D-2*(2460) ( spin 2) listed by the Particle Data Group, while one of the first two might be related to D* (2640), with unknown spin parity. In the case of I = 3/2 we also find evidences of three states with spin 0, 1, and 2, respectively, with masses 2467 +/- 82, 2420 +/- 128, and 2550 +/- 56 MeV. The results for the sector I = 1/2 and S 0, 1, 2, are intriguingly similar to a previous study of the D* rho system based on effective field theories, supporting in this way a molecular picture for the resonances D* (2640) and D-2* (2460), while the results for I = 3/2 hint towards the existence of exotic mesons since a multiquark configuration is required to get the quantum numbers of the states found.
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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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Garzon, E. J., Molina, R., Hosaka, A., & Oset, E. (2014). Strategies for an accurate determination of the X(3872) energy from QCD lattice simulations. Phys. Rev. D, 89(1), 014504–9pp.
Abstract: We develop a method to determine accurately the binding energy of the X( 3872) from lattice data for the D (D) over bar* interaction. We show that, because of the small difference between the neutral and charged components of the X( 3872), it is necessary to differentiate them in the energy levels of the lattice spectrum if one wishes to have a precise determination of the the binding energy of the X( 3872). The analysis of the data requires the use of coupled channels. Depending on the number of levels available and the size of the box, we determine the precision needed in the lattice energies to finally obtain a desired accuracy in the binding energy.
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Martinez Torres, A., Khemchandani, K. P., Navarra, F. S., Nielsen, M., & Oset, E. (2014). Reanalysis of the e(+)e(-) -> (D*(D*)over-bar)(+/-)pi(-/+) reaction and the claim for the Z(c)(4025) resonance. Phys. Rev. D, 89(1), 014025–9pp.
Abstract: In this paper we study the reaction e(+)e(-) -> (D*(D*) over bar (+/-)pi(-/+) in which the BESIII collaboration has claimed the existence of a 1(+) resonance, named Z(c)(4025), in the (D*(D*) over bar invariant mass spectrum with a mass around 4026 MeV and width close to 26 MeV. We determine the (D*(D*) over bar invariant mass distribution and find that although the explanation considered by the BESIII collaboration is plausible, there are others which are equally possible, like a 2(+) resonance or a bound state. Even more, we find that the data can be explained without the existence of a resonance/bound state. In view of the different possible interpretations found for the BESIII data, we try to devise a strategy which could help in identifying the origin of the signal reported by the BESIII collaboration. For this, we study the dependence of the (D*(D*) over bar spectrum considering the different options as a function of the total center-of-mass energy. We arrive at the conclusion that increasing the center-of-mass energy from 4.26 GeV to 4.6 GeV can be useful to distinguish between a resonance, a bound state or just a pure background as being responsible for the signal found. This information should be useful for future experiments.
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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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Aceti, F., Bayar, M., Oset, E., Martinez Torres, A., Khemchandani, K. P., Dias, J. M., et al. (2014). Prediction of an I=1 D(D)over-bar* state and relationship to the claimed Z(c)(3900), Z(c)(3885). Phys. Rev. D, 90(1), 016003–13pp.
Abstract: We study here the interaction of D (D) over bar* in the isospin I = 1 channel in light of recent theoretical advances that allow us to combine elements of the local hidden gauge approach with heavy quark spin symmetry. We find that the exchange of light q (q) over bar is Okubo-Zweig-Iizuka (OZI) suppressed and thus we concentrate on the exchange of heavy vectors and of two pion exchange. The latter is found to be small compared to the exchange of heavy vectors, which then determines the strength of the interaction. A barely D (D) over bar* bound state decaying into eta(c)rho and pi J/psi is found. At the same time we reanalyze the data of the BESIII experiment on e(+)e(-) -> pi(+/-)(D (D) over bar*)(-/+), from where a Z(c)(3885) state was claimed, associated to a peak in the (D (D) over bar*)(-/+) invariant mass distribution close to threshold, and we find the data compatible with a resonance with mass around 3875 MeV and width around 30 MeV. We discuss the possibility that this and the Z(c)(3900) state found at BESIII, reconfirmed at 3894 MeV at Belle, or 3885 MeV at CLEO, could all be the same state and correspond to the one that we find theoretically.
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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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Xie, J. J., & Oset, E. (2014). (B)over-bar(0) and (B)over-bar(s)(0) decays into J/psi and f(0)(1370), f(0)(1710), f(2)(1270), f(2)'(1525), K-2*(1430). Phys. Rev. D, 90(9), 094006–7pp.
Abstract: We make predictions for the ratios of branching fractions of (B) over bar (0) and (B) over bar (0)(s) decays into J/psi and the scalar mesons f(0)(1370), f(0)(1710) or tensor mesons f(2)(1270), f(2)'(1525), K-2*(1430). The theoretical approach is based on results of chiral unitary theory where these resonances are shown to be generated from the vector meson-vector meson interaction. Eight independent ratios can be predicted, and comparison is made with the recent data on (B) over bar (0)(s) decay into J/psi f(2)'(1525) versus the (B) over bar (0)(s) decay into J/psi f(2)(1270).
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Dias, J. M., Aceti, F., & Oset, E. (2015). Study of B<(B)over bar>* and B*<(B)over bar>* interactions in I=1 and relationship to the Z(b)(10610), Z(b)(10650) states. Phys. Rev. D, 91(7), 076001–14pp.
Abstract: We use the local hidden gauge approach in order to study the B (B) over bar* and B*(B) over bar* interactions for isospin I = 1. We show that both interactions via one light meson exchange are not allowed by the Okubo-ZweigIizuka rule and, for that reason, we calculate the contributions due to the exchange of two pions, interacting and noninteracting among themselves, and also due to the heavy vector mesons. Then, to compare all these contributions, we use the potential related to the heavy vector exchange as an effective potential corrected by a factor which takes into account the contribution of the other light meson exchanges. In order to look for poles, this effective potential is used as the kernel of the Bethe-Salpeter equation. As a result, for the B (B) over bar* interaction we find a loosely bound state with mass in the range 10587-10601 MeV, very close to the experimental value of the Z(b)(10610) reported by the Belle Collaboration. For the B*(B) over bar* case, we find a cusp at 10650 MeV for all spin J = 0, 1, 2 cases.
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Dai, L. R., Xie, J. J., & Oset, E. (2015). Study of the f(2)(1270), f '(2)(1525), and (K)over-bar(2)*(1430), f(0)(1370) and f(0)(1710) production from psi(nS) and Upsilon(nS) decays. Phys. Rev. D, 91(9), 094013–6pp.
Abstract: Based on previous studies that support the important role of the f(2)(1270), f'(2)(1525), and (K) over bar (2)*(1430) resonances in the J/psi[psi(2S)] -> phi(omega)VV decays, we make an analysis of the analogous decays of Upsilon(1S) and Upsilon(2S), taking into account recent experimental data. In addition, we study the J/psi and psi(2S) radiative decays and we also made predictions for the radiative decay of Upsilon(1S) and Upsilon(2S) into gamma f(2)(1270), gamma f(2)'(1525), gamma f(0)(1370) and gamma f(0)(1710) comparing with the recent results of a CLEO experiment. We can compare our results for ratios of decay rates with eight experimental ratios and find agreement in all but one case, where experimental problems are discussed.
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