Heavy ion collisions at intermediate energies in a quark-gluon exchange framework

Heavy ion collisions at intermediate energies can be studied in the context of the Vlasov-Uehling-Uhlenbeck (VUU) model. One of the main features in this model is the nucleon-nucleon (NN) cross section in the collisional term. Quark interchange plays a role in the NN interaction and its effect can be observed in the cross section. We explore the possibility that quark interchange effects can appear in observables at energies lower than RHIC.Comment: To appear in the Proceedings of VIII Hadron Physics 200

Searching for a dark matter coupling to the Standard Model with a Stueckelberg extension

We investigate a double extension to the Standard Model (SM). A first extension introduces, via minimal coupling, a massive $Z'$ boson. This enlarged SM is coupled to a dark matter sector through the Stueckelberg mechanism by a $A'$ boson. However, the $A'$ boson does not interact directly with the SM fermions. In our study, we found that the $A'$ is a massless photon-like particle in dark sector. Constraints on the mass for $Z'$ and corrections to $Z$ mass are obtained.Comment: Presented at IWARA 2011. "Fifth International Workshop on Astronomy and Relativistic Astrophysics" Jo\~ao Pessoa, Brazil, October 9 to 12, 201

Glueball-glueball scattering in a constituent gluon model

In this work we use a mapping technique to derive in the context of a constituent gluon model an effective Hamiltonian that involves explicit gluon degrees of freedom. We study glueballs with two gluons using the Fock-Tani formalism. In the present work we consider two possibilities for $0^{++}$: (i) as a pure $s\bar{s}$ and calculate, in the context of a quark interchange picture, the cross-section; (ii) as a glueball where a new calculation for this cross-section is made, in the context of the constituent gluon model, with gluon interchange.Comment: Proceedings of the International Workshop IX Hadron Physics and VII Relativistic Aspects of Nuclear Physics (HADRON-RANP 2004

Quark interchange effects in the KN interaction

We study the short range repulsion in the KN system due to quark-gluon exchange. Phase shifts for spin-spin, color Coloumb and spin-orbit interactions are presented

Meson decay in a corrected 30P3^P_0 model

Extensively applied to both light and heavy meson decay and standing as one of the most successful strong decay models is the $3^P_0$ model, in which $q\bar{q}$ pair production is the dominant mechanism. The pair production can be obtained from the non-relativistic limit of a microscopic interaction Hamiltonian involving Dirac quark fields. The evaluation of the decay amplitude can be performed by a diagrammatic technique for drawing quark lines. In this paper we use an alternative approach which consists in a mapping technique, the Fock-Tani formalism, in order to obtain an effective Hamiltonian starting from same microscopic interaction. An additional effect is manifest in this formalism associated to the extended nature of mesons: bound-state corrections. A corrected $3^P_0$ is obtained and applied, as an example, to $b_{1}\to\omega\pi$ and $a_{1}\to\rho\pi$ decays.Comment: 3 figures. To appear in Physical Review