0000000000666676
AUTHOR
Francesca Aceti
Isospin breaking and f(0)(980)-a(0)(980) mixing in the eta(1405) -> pi(0)f(0)(980) reaction
We make a theoretical study of the eta(1405) -> pi(0)f(0)(980) and eta(1405) -> pi(0)a(0)(980) reactions with an aim to determine the isospin violation and the mixing of the f(0)(980) and a(0)(980) resonances. We make use of the chiral unitary approach where these two resonances appear as composite states of two mesons, dynamically generated by the meson-meson interaction provided by chiral Lagrangians. We obtain a very narrow shape for the f(0)(980) production in agreement with a BES experiment. As to the amount of isospin violation, or f(0)(980) and a(0)(980) mixing, assuming constant vertices for the primary eta(1405) -> pi K-0 (K) over bar and eta(1405) -> pi(0)pi(0)eta production, we f…
Composite nature of the Lambda (1520) resonance
Recently, the Weinberg compositeness condition of a bound state was generalized to account for resonant states and higher partial waves. We apply this extension to the case of the Lambda (1520) resonance and quantify the weight of the meson-baryon components in contrast to other possible genuine building blocks. This resonance was theoretically obtained from a coupled channels analysis using the s-wave pi Sigma* and K Xi* and the d-wave (K) over bar N and pi Sigma channels, applying the techniques of the chiral unitary approach. We obtain the result that this resonance is essentially dynamically generated from these meson-baryon channels, leaving room for only 15% weight of other kinds of c…
Prediction of a Z(c)(4000) state and relationship with the claimed Z(c)(4025)
After discussing the OZI suppression of one light meson exchange in the interaction of with isospin I = 1 , we study the contribution of the two-pion exchange to the interaction and the exchange of heavy vectors, J/psi for diagonal transitions and D-* for transitions of to J/psi rho. We find these latter mechanisms to be weak, but enough to barely bind the system in J = 2 with a mass around 4000 MeV, while the effect of the two-pion exchange is a net attraction, though weaker than that from heavy-vector exchange. We discuss this state and try to relate it to the Z (c) (4025) state, above the threshold, claimed in an experiment at BES from an enhancement of the distribution close to threshol…
Prediction of an I=1 D(D)over-bar* state and relationship to the claimed Z(c)(3900), Z(c)(3885)
We study here the interaction of D (D) over bar* in the isospin I = 1 channel in light of recent theoretical advances that allow us to combine elements of the local hidden gauge approach with heavy quark spin symmetry. We find that the exchange of light q (q) over bar is Okubo-Zweig-Iizuka (OZI) suppressed and thus we concentrate on the exchange of heavy vectors and of two pion exchange. The latter is found to be small compared to the exchange of heavy vectors, which then determines the strength of the interaction. A barely D (D) over bar* bound state decaying into eta(c)rho and pi J/psi is found. At the same time we reanalyze the data of the BESIII experiment on e(+)e(-) -> pi(+/-)(D (D) o…
The K K bar π decay of the f1 (1285) and its nature as a K* K bar - cc molecule
We investigate the decay of f1 (1285) → πK K bar with the assumption that the f1 (1285) is dynamically generated from the K* K bar - cc interaction. In addition to the tree level diagrams that proceed via f1 (1285) →K* K bar - cc → πK K bar , we take into account also the final state interactions of K K bar → K K bar and πK → πK. The partial decay width and mass distributions of f1 (1285) → πK K bar are evaluated. We get a value for the partial decay width which, within errors, is in fair agreement with the experimental result. The contribution from the tree level diagrams is dominant, but the final state interactions have effects in the mass distributions. The predicted mass distributions …
Interaction of hadrons and tests for the nature of resonances
El propósito de esta Tesis es contribuir al extenso esfuerzo que se ha hecho, en las ultimas décadas, a fin de entender la estructura de las partículas hadrónicas, uno de los temas más importantes en física hadrónica. En los años 50, el desarrollo de los aceleradores de partículas reveló la existencia de una gran cantidad de nuevas resonancias. La proliferación de partículas, poco después, manifestó un patrón, y un esquema de organización para describirlo se hizo necesario. Al principio, se encontró una solución generalizando el concepto de isospín con el modelo de Fermi-Yang de 1959, en el que el protón y el neutrón aparecen como bloques fundamentales y las otras partículas como sus combin…
X(3872) -> J/psi gamma decay in the D(D)over-bar* molecular picture
From a picture of the X(3872) where the resonance is a bound state of D (D) over bar*- c.c., we evaluate the decay width into the J/psi gamma channel, which is sensitive to the internal structure of this state. For this purpose we evaluate the loops through which the X(3872) decays into its components, and the J/psi and the photon are radiated from these components. We use the local hidden gauge approach extrapolated to SU(4) with a particular SU(4) breaking. The radiative decay involves anomalous couplings, and we obtain acceptable values which are compared to experiments and results of other calculations. Simultaneously, we evaluate the decay rate for the X(3872) into J/psi omega and J/ps…
Study of B* and B** interactions in I=1 and relationship to the Z(b)(10610), Z(b)(10650) states
We use the local hidden gauge approach in order to study the B (B) over bar* and B*(B) over bar* interactions for isospin I = 1. We show that both interactions via one light meson exchange are not allowed by the Okubo-ZweigIizuka rule and, for that reason, we calculate the contributions due to the exchange of two pions, interacting and noninteracting among themselves, and also due to the heavy vector mesons. Then, to compare all these contributions, we use the potential related to the heavy vector exchange as an effective potential corrected by a factor which takes into account the contribution of the other light meson exchanges. In order to look for poles, this effective potential is used …