Li, H. P., Zhang, G. J., Liang, W. H., & Oset, E. (2023). Theoretical interpretation of the Ξ(1620) and Ξ(1690) resonances seen in Ξc+ → Ξ-π+π+ decay. Eur. Phys. J. C, 83(10), 954–7pp.
Abstract: We study the Belle reaction Xi(+)(c) -> Xi(-)pi(+)pi(+) looking at the mass distribution of pi(+)Xi, where clear signals for the Xi(1620) and Xi(1690) resonances are seen. These two resonances are generated dynamically from the interaction in coupled channels of pi Xi, (K) over bar Lambda, (K) over bar Xi and eta Xi within the chiral unitary approach. Yet, the weak decay process at the quark level, together with the hadronization to produce pairs of mesons, does not produce the pi pi Xi final state. In order to produce this state one must make transitions from the (K) over bar Lambda, (K) over bar Xi and eta Xi components to pi Xi, and this interaction is what produces the resonances. So, the reaction offers a good test for the molecular picture of these resonances. Adding the contribution of the Xi*(1530) and some background we are able to get a good reproduction of the mass distribution showing the signatures of the two resonances as found in the experiment.
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Dai, L. R., Dias, J. M., & Oset, E. (2018). Disclosing D* (D)over bar* molecular states in the B-c(-) -> pi(-) J/psi omega decay. Eur. Phys. J. C, 78(3), 210–7pp.
Abstract: We study the B-c(-) -> pi(-) J/omega and B-c(-) -> pi(-) D* (D) over bar* reactions and show that they are related by the presence of two resonances, the X(3940) and X(3930), that are of molecular nature and couple most strongly to D* (D) over bar*, but also to J/psi omega. Because of that, in the J/psi omega mass distribution we find a cusp with large strength at the D* (D) over bar* threshold and predict the ratio of strengths between the peak of the cusp and the maximum of the D* (D) over bar* distribution close to D* (D) over bar* threshold, which are distinct features of the molecular nature of these two resonances.
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Dai, L. R., Xie, J. J., & Oset, E. (2016). B-0 -> D-0 D-0 K-0, B+ -> D-0 D-0 K+, and the scalar DD bound state. Eur. Phys. J. C, 76(3), 121–9pp.
Abstract: We study the B-0 decay to D-0 D-0 K-0 based on the chiral unitary approach, which generates the X(3720) resonance, and we make predictions for the D D invariant mass distribution. From the shape of the distribution, the existence of the resonance below threshold could be induced. We also predict the rate of production of the X(3720) resonance to the D D mass distribution with no free parameters.
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Dai, L. R., Wang, G. Y., Chen, X., Wang, E., Oset, E., & Li, D. M. (2019). The B+ -> J/phi omega K+ reaction and D*(D)over-bar* molecular states. Eur. Phys. J. A, 55(3), 36–7pp.
Abstract: We study the B+J/K+ reaction, and show that it is driven by the presence of two resonances, the X(3940) and X(3930), that are of molecular nature and couple most strongly to D*D*, but also to J/. Because of that, in the J/ mass distribution we find a peak related to the excitation of the resonances and a cusp with large strength at the D*D* threshold.
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Sakai, S., Oset, E., & Ramos, A. (2018). Triangle singularities in B- -> K- pi- D(s0)+ and B- -> K- pi- D(s1)+. Eur. Phys. J. A, 54(1), 10–14pp.
Abstract: We study the appearance of structures in the decay of the B- into K-pi D--(s0)+ (2317) and K-pi D--(s1)+ (2460) final states by forming invariant mass distributions of pi D--(s0)+ and pi D--(s1)+ pairs, respectively. The structure in the distribution is associated to the kinematical triangle singularity that appears when the B- -> K- K*(0) D-0 (B- -> K- K*(0) D*(0)) decay process is followed by the decay of the K*(0) into pi(-) K+ and the subsequent rescattering of the K+ D-0 (K+ D*(0)) pair forming the D-s0(+) (2317) (D-s1(+) (2460)) resonance. We find this type of non-resonant peaks at 2850MeV in the invariant mass of pi D--(s0) pairs from B- -> K- pi(-) D-s0(+) (2317) decays and around 3000MeV in the invariant mass of pi D--(s1)+ pairs from B- -> K- pi(-) D-s1(+)(2460) decays. By employing the measured branching ratios of the B- -> K- K*(0) D-0 and B- -> K- K*(0) D*(0) decays, we predict the branching ratios for the processes B- into K-pi D--(s0)+ (2317) K-pi D--(s1)+ (2460), in the vicinity of the triangle singularity peak, to be about 8 x 10(-6) and 1 x 10(-6), respectively. The observation of this reaction would also give extra support to the molecular picture of the D-s0(+)(2317) and D-s1(+)(2460).
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Dai, L. R., & Oset, E. (2018). Polarization amplitudes in VP decay beyond the Standard Model. Eur. Phys. J. A, 54(12), 219–10pp.
Abstract: We study the amplitudes of the -VP decay for the different polarizations of the vector meson V, using a formalism where the mapping from the quark degrees of freedom to the meson ones is done with the P-3(0) model. We extend the formalism to a case, with the operator -5, that can account for different models beyond the Standard Model and study in detail the -K*0K- reaction for the different polarizations of the K*0. The results are shown in terms of the parameter that differs for each model. We find that is very different for each of the third components of the vector spin, M=+/- 1,0, and in particular the magnitude |M=-1 is very sensitive to the parameter, which makes the investigation of this magnitude very useful to test different models beyond the Standard Model.
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Magas, V. K., Yamagata-Sekihara, J., Hirenzaki, S., Oset, E., & Ramos, A. (2010). Proton emission off nuclei induced by kaons in flight. Phys. Rev. C, 81(2), 024609–10pp.
Abstract: We study the (K-, p) reaction on nuclei with a 1 GeV/c momentum kaon beam, paying special attention to the region of emitted protons having kinetic energy above 600 MeV, which was used to claim a deeply attractive kaon nucleus optical potential. Our model describes the nuclear reaction in the framework of a local density approach and the calculations are performed following two different procedures: one is based on a many-body method using the Lindhard function and the other is based on a Monte Carlo simulation. The simulation method offers flexibility to account for processes other than kaon quasielastic scattering, such as K- absorption by one and two nucleons, producing hyperons, and allows consideration of final-state interactions of the K-, the p, and all other primary and secondary particles on their way out of the nucleus, as well as the weak decay of the produced hyperons into pi N. We find a limited sensitivity of the cross section to the strength of the kaon optical potential. We also show a serious drawback in the experimental setup-the requirement for having, together with the energetic proton, at least one charged particle detected in the decay counter surrounding the target-as we find that the shape of the original cross section is appreciably distorted, to the point of invalidating the claims made in the experimental paper on the strength of the kaon nucleus optical.
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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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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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Albaladejo, M., Nielsen, M., & Oset, E. (2015). Ds0*(+/-)(2317) and K D scattering from Bs(0) decay. Phys. Lett. B, 746, 305–310.
Abstract: We study the (B) over bar (0)(s) -> D-s(-)(KD)(+) weak decay, and look at the KD invariant mass distribution, for which we use recent lattice QCD results for the KDinteraction from where the D-s0*(2317) resonance appears as a KD bound state. Since there are not yet experimental data on this reaction, in a second step we propose an analysis method to obtain information on the D-s0* (2317) resonance from the future experimental KD mass distribution in this decay. For this purpose, we generate synthetic data taking a few points from our theoretical distribution, to which we add a 5% or 10% error. With this analysis method, we prove that one can obtain from these “data” the existence of a bound KD state, the KD scattering length and effective range, and most importantly, the KD probability in the wave function of the bound state obtained, which was found to be largely dominant in lattice QCD studies. This means that one can obtain information on the nature of the D-s0*(+) (2317) resonance from the implementation of this experiment, in the line of finding the structure of resonances, which is one of the main aims in hadron spectroscopy.
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