Oset, E. et al, Albaladejo, M., Nieves, J., Fernandez-Soler, P., & Sun, Z. F. (2016). Weak decays of heavy hadrons into dynamically generated resonances. Int. J. Mod. Phys. E, 25(1), 1630001–105pp.
Abstract: In this paper, we present a review of recent works on weak decay of heavy mesons and baryons with two mesons, or a meson and a baryon, interacting strongly in the final state. The aim is to learn about the interaction of hadrons and how some particular resonances are produced in the reactions. It is shown that these reactions have peculiar features and act as filters for some quantum numbers which allow to identify easily some resonances and learn about their nature. The combination of basic elements of the weak interaction with the framework of the chiral unitary approach allow for an interpretation of results of many reactions and add a novel information to different aspects of the hadron interaction and the properties of dynamically generated resonances.
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Albertus, C., Hernandez, E., & Nieves, J. (2014). Exclusive c -> s, d Semileptonic Decays of Spin-1/2 and Spin-3/2 cb Baryons. Few-Body Syst., 55(8-10), 767–771.
Abstract: We present results for exclusive semileptonic decay widths of ground state spin-1/2 and spin-3/2 cb baryons corresponding to a c -> s, d transition at the quark level. The relevance of hyperfine mixing in spin-1/2 cb baryons is shown. Our form factors are compatible with heavy quark spin symmetry constraints obtained in the infinite heavy quark mass limit.
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Guo, F. K., Hidalgo-Duque, C., Nieves, J., Ozpineci, A., & Pavon Valderrama, M. (2014). Detecting the long-distance structure of the X(3872). Eur. Phys. J. C, 74(5), 2885–10pp.
Abstract: We study the decay within a molecular picture for the state. This decay mode is more sensitive to the long-distance structure of the resonance than its and decays, which are mainly controlled by the details of the wave function at short distances. We show that the final state interaction can be important, and that a precise measurement of this partial decay width can provide valuable information on the interaction strength between the charm mesons.
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Albaladejo, M., Guo, F. K., Hidalgo-Duque, C., Nieves, J., & Pavon Valderrama, M. (2015). Decay widths of the spin-2 partners of the X(3872). Eur. Phys. J. C, 75(11), 547–26pp.
Abstract: We consider the X(3872) resonance as a J(PC) = 1(++) D (D) over bar* hadronic molecule. According to heavy quark spin symmetry, there will exist a partner with quantum numbers 2(++), X-2, which would be a D*(D) over bar* loosely bound state. The X-2 is expected to decay dominantly into D (D) over bar, D (D) over bar* and (D) over barD* in d-wave. In this work, we calculate the decay widths of the X-2 resonance into the above channels, as well as those of its bottom partner, X-b2, the mass of which comes from assuming heavy flavor symmetry for the contact terms. We find partial widths of the X-2 and X-b2 of the order of a few MeV. Finally, we also study the radiative X-2 -> D (D) over bar*gamma. and X-b2 -> (B) over bar B*gamma decays. These decay modes are more sensitive to the long-distance structure of the resonances and to the D (D) over bar* or B (B) over bar* final state interaction.
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Fernandez-Soler, P., Sun, Z. F., Nieves, J., & Oset, E. (2016). The rho(omega) B*(B) interaction and states of J=0, 1, 2. Eur. Phys. J. C, 76(2), 82–12pp.
Abstract: In this work, we study systems composed of a rho/omega and B* meson pair. We find three bound states in isospin, spin-parity channels (1/2, 0(+)), (1/2, 1(+)), and (1/2, 2(+)). The state with J = 2 can be a good candidate for the B-2*(5747). We also study the rho B system, and a bound state with mass 5728 MeV and width around 20 MeV is obtained, which can be identified with the B-1(5721) resonance. In the case of I = 3/2, one obtains repulsion and, thus, no exotic (molecular) mesons in this sector are generated in the approach.
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Albaladejo, M., Nieves, J., Oset, E., & Jido, D. (2016). Ds0*(2317) and DK scattering in B decays from BaBar and LHCb data. Eur. Phys. J. C, 76(6), 300–8pp.
Abstract: We study the experimental DK invariant mass spectra of the reactions B+ -> (D) over bar (DK+)-D-0-K-0, B-0 -> D-(DK+)-K-0 (measured by the BaBar collaboration) and B-s -> pi(+DK-)-K-0 measured by the LHCb collaboration), where an enhancement right above the threshold is seen. We show that this enhancement is due to the presence of D-s0*(2317), which is a D K bound state in the I (J(P)) = 0(0(+)) sector. We employ a unitarized amplitude with an interaction potential fixed by heavy meson chiral perturbation theory. We obtain a mass M-Ds0* = 2315(-17) (+12 +10)(-5) MeV, and we also show, by means of theWeinberg compositeness condition, that the DK component in the wave function of this state is P-DK = 70(-6 -8)(+4 +4) %, where the first (second) error is statistical (systematic).
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Cincioglu, E., Nieves, J., Ozpineci, A., & Yilmazer, A. U. (2016). Quarkonium Contribution to Meson Molecules. Eur. Phys. J. C, 76(10), 576–25pp.
Abstract: Starting from a molecular picture for the X(3872) resonance, this state and its J(PC) = 2(++) heavy-quark spin symmetry partner [X-2(4012)] are analyzed within a model which incorporates possible mixings with 2P charmonium (c (c) over bar) states. Since it is reasonable to expect the bare chi(c1)(2P) to be located above the D (D) over bar* threshold, but relatively close to it, the presence of the charmonium state provides an effective attraction that will contribute to binding the X(3872), but it will not appear in the 2(++) sector. Indeed in the latter sector, the chi(c2)(2P) should provide an effective small repulsion, because it is placed well below the D*(D) over bar* threshold. We show how the 1(++) and 2(++) bare charmonium poles are modified due to the D-(*)(D) over bar ((*)) loop effects, and the first one is moved to the complex plane. The meson loops produce, besides some shifts in the masses of the charmonia, a finite width for the 1(++) dressed charmonium state. On the other hand, X(3872) and X-2(4012) start developing some charmonium content, which is estimated by means of the compositeness Weinberg sum rule. It turns out that in the heavy-quark limit, there is only one coupling between the 2P charmonia and the D-(*)(D) over bar ((*)) pairs. We also show that, for reasonable values of this coupling, leading to X(3872) molecular probabilities of around 70-90%, the X2 resonance destabilizes and disappears from the spectrum, becoming either a virtual state or one being located deep into the complex plane, with decreasing influence in the D*(D) over bar* scattering line. Moreover, we also discuss how around 10-30% charmonium probability in the X(3872) might explain the ratio of radiative decays of this resonance into psi(2S) gamma and J/psi gamma Finally, we qualitatively discuss within this scheme, the hidden bottom flavor sector, paying a special attention to the implications for the X-b and Xb(2) states, heavy-quark spin-flavor partners of the X(3872).
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Albaladejo, M., Fernandez-Soler, P., & Nieves, J. (2016). Z(c)(3900): confronting theory and lattice simulations. Eur. Phys. J. C, 76(10), 573–9pp.
Abstract: We consider a recent T -matrix analysis by Albaladejo et al. (Phys Lett B 755: 337, 2016), which accounts for the J/psi pi and D*(D) over bar coupled-channels dynamics, and which successfully describes the experimental information concerning the recently discovered Z(c)(3900)(+/-). Within such scheme, the data can be similarly well described in two different scenarios, where Z(c)(3900) is either a resonance or a virtual state. To shed light into the nature of this state, we apply this formalism in a finite box with the aim of comparing with recent Lattice QCD (LQCD) simulations. We see that the energy levels obtained for both scenarios agree well with those obtained in the single-volume LQCD simulation reported in Prelovsek et al. (Phys Rev D 91: 014504, 2015), thus making it difficult to disentangle the two possibilities. We also study the volume dependence of the energy levels obtained with our formalism and suggest that LQCD simulations performed at several volumes could help in discerning the actual nature of the intriguing Z(c)(3900) state.
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Guo, F. K., Meissner, U. G., Nieves, J., & Yang, Z. (2016). Remarks on the P-c structures and triangle singularities. Eur. Phys. J. A, 52(10), 318–6pp.
Abstract: It was proposed that the narrow P-c(4450) structure observed by the LHCb Collaboration in the reaction Lambda(b) -> J/psi pK might be due to a triangle singularity around the chi(c1)-proton threshold at 4.45 GeV. We discuss the occurrence of a similar triangle singularity in the J/psi p invariant mass distribution for the decay Lambda(b) -> J/psi p pi, which could explain the bump around 4.45 GeV in the data. More precise measurements of this process would provide valuable information towards an understanding of the P-c structures.
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Albaladejo, M., Fernandez-Soler, P., Nieves, J., & Ortega, P. G. (2017). Lowest-lying even-parity (B)over-bar(s) mesons: heavy-quark spin-flavor symmetry, chiral dynamics, and constituent quark-model bare masses. Eur. Phys. J. C, 77(3), 170–9pp.
Abstract: The discovery of the D*(s0)(2317) and D-s1(2460) resonances in the charmed-strange meson spectra revealed that formerly successful constituent quark models lose predictability in the vicinity of two-meson thresholds. The emergence of non-negligible effects due to meson loops requires an explicit evaluation of the interplay between Q (q) over bar and (Q (q) over bar)(q (q) over bar) Fock components. In contrast to the c (s) over bar sector, there is no experimental evidence of J(P) = 0(+), 1(+) bottom-strange states yet. Motivated by recent lattice studies, in this work the heavy-quark partners of the D*(s0)(2317) and D-s1(2460) states are analyzed within a heavy meson chiral unitary scheme. As a novelty, the coupling between the constituent quark-model P-wave (B) over bar (s) scalar and axial mesons and the (B) over bar (()*()) K channels is incorporated employing an effective interaction, consistent with heavy-quark spin symmetry, constrained by the lattice energy levels.
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