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Dai, L. R., Oset, E., Feijoo, A., Molina, R., Roca, L., Martinez Torres, A., et al. (2022). Masses and widths of the exotic molecular B-(s)(()*B-)((s))(*()) states. Phys. Rev. D, 105(7), 074017–11pp.
Abstract: We study the interaction of the doubly bottom systems BB, B*B, BsB, B-s*B, B*B*, B*B-S, B*B-s*, BsBs, BsBs*, B-s*B-s* by means of vector meson exchange with Lagrangians from an extension of the local hidden gauge approach. The full s-wave scattering matrix is obtained implementing unitarity in coupled channels by means of the Bethe-Salpeter equation. We find poles below the channel thresholds for the attractively interacting channels B*B in I = 0, B-s*B – B*B-s in I = 1/2, B* B* in I = 0, and B-s*B* in I = 1/2, all of them with J(P) = 1(+). For these cases the widths are evaluated identifying the dominant source of imaginary part. We find binding energies of the order of 10-20 MeV, and the widths vary much from one system to the other: of the order of 10-100 eV for the B* B system and B-s*B – B* B-s, about 6 MeV for the B*B* system and of the order of 0.5 MeV for the B-s*B* system.
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Song, J., Dai, L. R., & Oset, E. (2022). How much is the compositeness of a bound state constrained by a and r(0)? The role of the interaction range. Eur. Phys. J. A, 58(7), 133–10pp.
Abstract: We present an approach that allows one to obtain information on the compositeness of molecular states from combined information of the scattering length of the hadronic components, the effective range, and the binding energy. We consider explicitly the range of the interaction in the formalism and show it to be extremely important to improve on the formula of Weinberg obtained in the limit of very small binding and zero range interaction. The method allows obtaining good information also in cases where the binding is not small. We explicitly apply it to the case of the deuteron and the D-s0* (2317) and D-s1* (2460) states and determine simultaneously the value of the compositeness within a certain range, as well as get qualitative information on the range of the interaction.
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Li, J. T., Lin, J. X., Zhang, G. J., Liang, W. H., & Oset, E. (2022). The (B)over-bar(s)(0) -> J/psi pi(0)eta decay and the a(0)(980)- f(0)(980) mixing. Chin. Phys. C, 46(8), 083108–6pp.
Abstract: We study the (B) over bar (0)(s) -> J/psi f(0)(980) and (B) over bar (0)(s) -> J/psi a(0)(980) reactions, and pay attention to the different sources of isospin violation and mixing of f(0)(980) and a(0)(980) resonances where these resonances are dynamically generated from meson-meson interactions. We fmd that the main cause of isospin violation is isospin breaking in the meson-meson transition T matrices, and the other source is that the loops involving kaons in the production mechanism do not cancel due to the different masses of charged and neutral kaons. We obtain a branching ratio for a(0)(980) production of the order of 5 x 10(-6) . Future experiments can address this problem, and the production rate and shape of the pi(0)eta mass distribution will definitely help to better understand the nature of scalar resonances.
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Dai, L. R., Molina, R., & Oset, E. (2022). Looking for the exotic X-0(2866) and its J(P)=1(+) partner in the (B)over-bar(0) -> D-(*) + K- K-(*)0 reactions. Phys. Rev. D, 105(9), 096022–7pp.
Abstract: We propose two reactions, (B) over bar (0) -> (KD+K-)-D-0 and (B) over bar (0) -> K*D-0*K-+(-), which have been already measured at Belle, to look into the J(P) = 0(+), X-0(2866) state and a 1(+) partner of molecular D*(K) over bar* nature by looking at the D+K- and D*K-+(-) invariant mass distributions, respectively. Very clear peaks over the background are predicted and the branching ratios for the production of these states are evaluated to facilitate the task of determining the needed statistics for their observation. We conclude that with the upgrade of Belle II clear peaks should be seen in both reactions for the two resonances discussed.
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Ikeno, N., Molina, R., & Oset, E. (2022). Zcs states from the D*s over bar D* and J=psi K* coupled channels: Signal in B+ -> J=psi phi K+ decay. Phys. Rev. D, 105(1), 014012–13pp.
Abstract: We study the D*s over bar D* system in connection with the J=psi K* in coupled channels and observe that, within reasonable values of the cutoff used to regularize the loops, the system does not develop a bound state. However, the JP = 2+ channel has enough attraction to create a strong cusp structure that shows up in the J=psi K+ invariant mass distribution in the B+ -> J=psi phi K+ decay at the D*s over bar D* threshold. Such structure is results should stimulate further measurements around this region, given the fact that cusp effects provide as valuable information on hadron dynamics as resonances themselves.
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