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.

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.

Abstract: We analyze theoretically the D+ ye+ pK and D+ pe+ K*7 decays to see the feasibility to check the double pole nature of the axial -vector resonance Kt(1270) predicted by the unitary extensions of chiral perturbation theory (UChPT). Indeed, within UChPT the K1(1270) is dynamically generated from the interaction of a vector and a pseudoscalar meson, and two poles are obtained for the quantum numbers of this resonance. The lower mass pole couples dominantly to 10 and the higher mass pole to pK, therefore we can expect that different reactions weighing differently these channels in the production mechanisms enhance one or the other pole. We show that the different final V P channels in D pe+ V P weigh differently both poles, and this is reflected in the shape of the final vector-pseudoscalar invariant mass distributions. Therefore, we conclude that these decays are suitable to distinguish experimentally the predicted double pole of the Kt(1270) resonance.

Abstract: We analyze the D (D) over bar mass distribution from a recent Belle experiment on the e(+)e(-) -> J/.D (D) over bar reaction, and show that the mass distribution divided by phase sp(c)e does not have a clear peak above the D (D) over bar threshold that justifies the experimental claim of chi(c0)(2P) state from those data. Then we use a unitary formalismwith coupled channels D+ D-, D-0 (D) over bar (0), D-s(D) over bar (s), and eta eta, with some of the interactions taken from a theoretical model, and use the data to fix other parameters. We then show that, given the poor quality of the data, we can get different fits leading to very different D (D) over bar amplitudes, some of them supporting a D (D) over bar bound state and others not. The main conclusion is that the claim for the chi(c0)(2P) state, already included in the PDG, is premature, but refined data can provide very valuable information on the D (D) over bar scattering amplitude. As side effects, we warn about the use of a Breit-Wigner amplitude parameterization close to threshold, and show that the D-s(D) over bar (s) channel plays an important role in this reaction.

Abstract: We evaluate the a(1)(1260) -> pi sigma(f(0)(500)) decay width from the perspective that the a(1)(1260) resonance is dynamically generated from the pseudoscalar-vector interaction and the sigma arises from the pseudoscalar-pseudoscalar interaction. A triangle mechanism with a(1)(1260) -> p pi followed by rho -> pi pi and a fusion of two pions within the loop to produce the sigma provides the mechanism for this decay under these assumptions for the nature of the two resonances. We obtain widths of the order of 13-22 MeV. Present experimental results differ substantially from each other, suggesting that extra efforts should be devoted to the precise extraction of this important partial decay width, which should provide valuable information on the nature of the axial vector and scalar meson resonances and help clarify the role of the ps channel in recent lattice QCD calculations of the a(1).