Speaker
Description
In the last decades a significant progress have been made in the electroproduction of nucleon resonances $N^\ast$. Form factors associated to the $\gamma^\ast N \to N^\ast$ transition, where $N$ is the nucleon, have been measured in different facilities, at low, intermediate, and large square momentum transfer, $Q^2$, for increasing values of the resonance mass. The new experimental data motivated the development of theoretical models which can be used at intermediate and large $Q^2$. One of these models is the covariant spectator quark model. In the first part of the presentation, we present a summary of the model calculations for several nucleon resonances, including the $\Delta(1232)$, $N(1440)$, $N(1535)$ and $N(1520)$ resonances. In the last part of the presentation, we discuss extensions of the formalism to baryons with strange quarks in the vacuum and in the nuclear medium.
