|
Dias, J. M., Debastiani, V. R., Xie, J. J., & Oset, E. (2018). Doubly charmed Xi(cc) molecular states from meson-baryon interaction. Phys. Rev. D, 98(9), 094017–11pp.
Abstract: Stimulated by the new experimental LHCb findings associated with the Omega(c) states, some of which we have described in a previous work as being dynamically generated through meson-baryon interaction, we have extended this approach to make predictions for new Xi(cc) molecular states in the C = 2, S = 0, and I = 1/2 sector. These states manifest themselves as poles in the solution of the Bethe-Salpeter equation in coupled channels. The kernels of this equation were obtained using general Lagrangians coming from the hidden local gauge symmetry or massive Yang-Mills theory, and the interactions are dominated by the exchange of light vector mesons. The extension of this approach to the heavy sector stems from the realization that the dominant interaction corresponds to having the heavy quarks as spectators, which implies the preservation of the heavy quark symmetry. As a result, we get several states: three states from the pseudoscalar meson-baryon interaction with J(P) = 1/2(-), and masses around 3840, 4080 and 4090 MeV, and two at 3920 and 4150 MeV for J(P) = 3/2(-). Furthermore, from the vector meson-baryon interaction we get three states degenerate with J(P) 1/2(-) and 3/2(-) from 4220 MeV to 4290 MeV, and two more states around 4280 and 4370 MeV, degenerate with J(P) = 1/2(-), 3/2(-), and 5/2(-).
|
|
|
Chen, H. X., & Oset, E. (2013). pi pi interaction in the rho channel in finite volume. Phys. Rev. D, 87(1), 016014–15pp.
Abstract: The aim of this paper is to investigate an efficient strategy that allows one to obtain pi pi phase shifts and rho meson properties from QCD lattice data with high precision. For this purpose we evaluate the levels of the pi pi system in the rho channel in finite volume using chiral unitary theory. We investigate the dependence on the pi mass and compare this with other approaches which use QCD lattice calculations and effective theories. We also illustrate the errors induced by using the conventional Luscher approach instead of a more accurate one that was recently developed that takes into account exactly the relativistic two-meson propagators. Finally, we make use of this latter approach to solve the inverse problem, getting pi pi phase shifts from “synthetic” lattice data, providing an optimal strategy and showing which accuracy is needed in these data to obtain the rho properties with a desired accuracy.
|
|
|
Jido, D., Oset, E., & Sekihara, T. (2013). The K(-)d -> pi Sigma n reaction revisited. Eur. Phys. J. A, 49(8), 95–11pp.
Abstract: The appearance of some papers dealing with the K(-)d -> pi Sigma n reaction, with some discrepancies in the results and a proposal to measure the reaction at forward n angles at J-PARC justifies to retake the theoretical study of this reaction. We do this in the present paper showing results using the Watson approach and the truncated Faddeev approach. We argue that the Watson approach is more suitable to study the reaction because it takes into account the potential energy of the nucleons forming the deuteron, which is neglected in the truncated Faddeev approach. The paper shows the strength and limitations of both approaches and we perform calculations using four different approximations. Comparison of the results shows that the truncated Faddeev approach produces a strong asymmetry between the energy of the two nucleons of the deuteron, while in the Watson approach this energy is equally shared. From the experimental point of view the results are very valuable since they show that the different approximations share the feature that the peak of the pi Sigma mass distribution is drastically shifted in the presence of the Lambda(1405). Additionally, we also show that in the angle-integrated cross section the threshold cusp effects are basically washed away and all approximations show a clear shape of the Lambda(1405). In this sense, measurements of all these magnitudes in different K- energies are bound to bring new information that sheds new light on the properties and nature of the Lambda(1405) resonance.
|
|
|
Xie, J. J., Albaladejo, M., & Oset, E. (2014). Signature of an h(1) state in the J/psi -> eta h(1) -> eta K*(0)(K)over-bar*(0) decay. Phys. Lett. B, 728, 319–322.
Abstract: The BES data on the J/psi -> eta K*(0)(K) over bar*(0) reaction show a clear enhancement in the K*(0)(K) over bar*(0) mass distribution close to the threshold of this channel. Such an enhancement is usually a signature of an L = 0 resonance around threshold, which in this case would correspond to an h1 state with quantum numbers I-G(J(Pc))= 0(-)(1(+-)). A state around 1800 MeV results from the interaction of the K*TC* using the local hidden gauge approach. We show that the peak observed in J/psi -> eta K*(0)(K) over bar*(0) naturally comes from the creation of this h(1) state with mass and width around 1830 MeV and 110 MeV, respectively. A second analysis, model independent, corroborates the first result, confirming the relationship of the enhancement in the invariant mass spectrum with the h(1) resonance.
|
|
|
Xie, J. J., Dai, L. R., & Oset, E. (2015). The low lying scalar resonances in the D-0 decays into K-s(0) and f(0)(500), f(0)(980), a(0)(980). Phys. Lett. B, 742, 363–369.
Abstract: The D-0 decay into K-s(0) and a scalar resonance, f(0)(500), f(0)(980), a(0)(980), are studied obtaining the scalar resonances from final state interaction of a pair of mesons produced in a first step in the D-0 decay into K-s(0) and the pair of pseudoscalar mesons. This weak decay is very appropriate for this kind of study because it allows to produce the three resonances in the same decay in a process that is Cabibbo-allowed, hence the rates obtained are large compared to those of (B) over bar (0) decays into J/psi and a scalar meson that have at least one Cabibbo-suppressedvertex. Concretely the a(0)(980) production is Cabibbo-allowedhere, while it cannot be seen in the (B) over bar (0)(s) decay into J/psi a(0)(980) and is doubly Cabibbo-suppressedin the (B) over bar (0) decay into J/psi a(0)(980) and has not been identified there. The fact that the three resonances can be seen in the same reaction, because there is no isospin conservation in the weak decays, offers a unique opportunity to test the ideas of the chiral unitary approach where these resonances are produced from the interaction of pairs of pseudoscalar mesons.
|
|
|
Dai, L. R., Pavao, R., Sakai, S., & Oset, E. (2018). Anomalous enhancement of the isospin-violating Lambda(1405) production by a triangle singularity in Lambda(c) ->pi(+)pi(0)pi(0)Sigma(0). Phys. Rev. D, 97(11), 116004–10pp.
Abstract: The decay of Lambda(+)(c) into pi(+)pi(0) Lambda(1405) with the Lambda(1405) decay into pi(0)Sigma(0) through a triangle diagram is studied. This process is initiated by Lambda(+)(c) -> pi(+) (K) over bar N-*, and then the (K) over bar (*) decays into (K) over bar (pi) and (K) over bar N produce the Lambda(1405) through a triangle loop containing (K) over bar N-* (K) over bar which develops a singularity around 1890 MeV. This process is prohibited by the isospin symmetry, but the decay into this channel is enhanced by the contribution of the triangle diagram, which is sensitive to the mass of the internal particles. We find a narrow peak in the pi(0)Sigma(0) invariant mass distribution, which originates from the (K) over bar amplitude, but is tied to the mass differences between the charged and neutral (K) over bar or N states. The observation of the unavoidable peak of the triangle singularity in the isospin- violating Lambda(1405) production would provide further support for the hadronic molecular picture of the Lambda(1405) and further information on the (K) over bar N interaction.
|
|
|
Albaladejo, M., Nieves, J., Oset, E., Sun, Z. F., & Liu, X. (2016). Can X(5568) be described as a B-s pi, B(K)over-bar resonant state? Phys. Lett. B, 757, 515–519.
Abstract: The DO Collaboration has recently seen a resonant-like peak in the B-s pi invariant mass spectrum, claimed to be a new state called X(5568). Using a B-s pi-B (K) over bar coupled channel analysis, implementing unitarity, and with the interaction derived from Heavy Meson Chiral Perturbation Theory, we are able to reproduce the reported spectrum, with a pole that can be associated to the claimed X(5568) state, and with mass and width in agreement with the ones reported in the experimental analysis. However, if the T-matrix regularization is performed by means of a momentum cutoff, the value for the latter needed to reproduce the spectrum is Lambda = 2.80 +/- 0.04 GeV, which is much larger than a “natural” value Lambda similar or equal to 1 GeV. In view of this, it is difficult to interpret the nature of this new state. This state would not qualify as a resonance dynamically generated by the unitarity loops. Assuming the observed peak to correspond to a physical state, we make predictions for partners in the D, D*, and B* sectors. Their observation (or lack thereof) would shed light into this issue.
|
|
|
Bayar, M., Xiao, C. W., Hyodo, T., Dote, A., Oka, M., & Oset, E. (2012). Energy and width of a narrow I=1/2 DNN quasibound state. Phys. Rev. C, 86(4), 044004–16pp.
Abstract: The energies and widths of DNN quasibound states with isospin I = 1/2 are evaluated in two methods, the fixed center approximation to the Faddeev equation and the variational method approach to the effective one-channel Hamiltonian. The DN interactions are constructed so they dynamically generate the Lambda(c)(2595) (I = 0, J(pi) = 1/2(-)) resonance state. We find that the system is bound by about 250 MeV from the DNN threshold, root s similar to 3500 MeV. Its width, including both the mesonic decay and the D absorption, is estimated to be about 20-40 MeV. The I = 0 DN pair in the DNN system is found to form a cluster that is similar to the Lambda(c)(2595).
|
|
|
Martinez Torres, A., Garzon, E. J., Oset, E., & Dai, L. R. (2011). Limits to the fixed center approximation to Faddeev equations: The case of the phi(2170). Phys. Rev. D, 83(11), 116002–9pp.
Abstract: The fixed center approximation to the Faddeev equations has been used lately with success in the study of bound systems of three hadrons. It is also important to set the limits of the approach in those problems to prevent proliferation of inaccurate predictions. In this paper, we study the case of the phi(2170), which has been described by means of Faddeev equations as a resonant state of phi and K (K) over bar, and show the problems derived from the use of the fixed center approximation in its study. At the same time, we also expose the limitations of an alternative approach recently proposed.
|
|
|
Feijoo, A., Magas, V. K., Ramos, A., & Oset, E. (2016). A hidden-charm S =-1 pentaquark from the decay Lambda(b) into J/psi eta Lambda states. Eur. Phys. J. C, 76(8), 446–12pp.
Abstract: The hidden-charm pentaquark P-c(4450) observed recently by the LHCb collaboration may be of molecular nature, as advocated by some unitary approaches that also predict pentaquark partners in the strangeness S = -1 sector. In this work we argue that a hidden-charm strange pentaquark could be seen from the decay of the Lambda b, just as in the case of the non-strange P-c(4450), but looking into the J/psi eta Lambda decay mode and forming the invariant mass spectrum of J/psi Lambda pairs. In the model presented here, which assumes a standard weak decay topology and incorporates the hadronization process and final-state interaction effects, we find the J/psi eta Lambda final states to be populated with similar strength as the J/psi K- p states employed for the observation of the non-strange pentaquark. This makes the Lambda b -> J/psi eta Lambda decay to be an interesting process to observe a possible strange partner of the P-c(4450). We study the dependence of the J/psi Lambda mass spectra on various model ingredients and on the unknown properties of the strange pentaquark.
|
|