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Dai, L. R., Molina, R., & Oset, E. (2022). Prediction of new T-cc states of D* D* and D-s*D* molecular nature. Phys. Rev. D, 105(1), 016029–12pp.
Abstract: We extend the theoretical framework used to describe the T-cc state as a molecular state of D* D and make predictions for the D* D* and D-s(*) D) systems, finding that they lead to bound states only in the J(P) = 1+ channel. Using input needed to describe the T-cc state, basically one parameter to regularize the loops of the Bethe-Salpeter equation, we find bound states with bindings of the order of MeVand similar widths for the D*D* system, while the D*s D-* system develops a strong cusp around the threshold.
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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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Dai, L. R., Molina, R., & Oset, E. (2022). The (B)over-bar(0)-> D*+ (D)over-bar*K-0(-) reaction to detect the I=0, J(P)=1+ partner of the X-0(2866). Phys. Lett. B, 832, 137219–5pp.
Abstract: We have chosen the (B) over bar (0)-> D*+ (D) over bar*K-0 reaction in order to observe the I= 0, J(P)= 1(+)(R-1) partner state of the X-0(2866) stemming from the D*+ (K) over bar* molecular picture. The reaction proceeds via external emission in the most favored Cabibbo decay mode and one observes the R(1)state as a very strong peak versus the background in the D*+ K- spectrum. The branching ratio for R1production in this reaction is estimated of the order of 4 x10(-3). The method used, applied to the B+-> D- D+ K+ reaction, produces a ratio of signal to background in the D- K+ spectrum in very good agreement with the LHCb experiment that observed the X-0(2866).
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Dai, L. R., & Oset, E. (2024). Dynamical generation of the scalar f0(500), f0(980), and K0*(700) resonances in the Ds+ → K+ π+ π- reaction. Phys. Rev. D, 109(5), 054008–9pp.
Abstract: We develop a model aimed at understanding the three mass distributions of pairs of mesons in the Cabibbo-suppressed D-s(+) – K+pi(+)pi(-) decay recently measured with high statistics by the BESIII collaboration. The largest contributions to the process come from the D-s(+) -> K+ rho(0) and D-s(+) -> K*(0)pi(+) decay modes, but the D-s(+) -> K-0*(1430)pi(+) and D-s(+) -> K+ f(0) (1370) modes also play a moderate role and all of them are introduced empirically. Instead, the contribution of the f(0)(500), f(0)(980) , and K-0*(700) resonances is introduced dynamically by looking at the decay modes at the quark level, hadronizing q (q) over bar over bar pairs to give two mesons, and allowing these mesons to interact, for which we follow the chiral unitary approach, to finally produce the K+ pi(+) pi(-) final state. While the general features of the mass distributions are fairly obtained, we pay special attention to the specific effects created by the light scalar resonances, which are visible in the low mass region of the pi(+) pi(-) (f(0)(500) and K+ pi(-) K+pi-(K-0*(700)) mass distributions and a narrow peak for pi(+) pi(-) distribution corresponding to f(0)(980) excitation. The contribution of these three resonances is generated by only one parameter. We see the agreement found in these regions as further support for the nature of the light scalar states as dynamically generated from the interaction of pseudoscalar mesons.
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Dai, L. R., & Oset, E. (2020). Helicity amplitudes in the (B)over-bar -> D*(nu)over-bar(tau)tau decay with V-A breaking in the quark sector. Eur. Phys. J. A, 56(5), 154–8pp.
Abstract: In view of the recent measurement of the F-D*(L) magnitude in the (B) over bar -> D*(nu) over bar (tau)tau reaction we evaluate this magnitude within the standard model and for a family of models with the gamma(mu) – alpha gamma(mu)gamma(5) current structure for the quarks for different values of a. At the same time we evaluate also the transverse contributions, M = -1, M = +1, and find that the difference between the M = -1 and M = +1 contributions is far more sensitive to changes in a than the longitudinal component. These findings should be looked as an incentive to measure the transverse helicities which are bound to be a far more sensitive magnitude to possible new physics than F-D*(L).
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