Quark Models of Baryon Masses and Decays

The description of baryon resonance masses and decays in the constituent quark model is outlined, with emphasis on the potential-model approach combined with the 3P0 pair-creation model of strong decays. This approach allows the estimation of branching fractions for baryon states missing in pion nucleon elastic scattering analyses but expected to be present in electromagnetic production. Prospects for the discovery of hybrid baryons are discussed. A subjective list of the most important corrections required to this approach is presented.Comment: 10 pages, 5 figures. Invited contribution to the COSY Workshop on Baryon Excitations, Juelich, 2-3 May 200

Language learning as psycho-social support: translanguaging space as safe space in superdiverse refugee settings

This paper explores language learning for displaced people in the countries bordering Syria and attempts to establish a link between the concept of translanguaging and the concept of safe spaces used by NGOs. The paper uses the term ‘displaced people’ as it is this feature of being dis-placed that the paper seeks to explore through the lens of superdiversity and its connections to spaces for translanguaging. The concept of superdiversity helps us understand the stratification and multiplication of the processes and effects of migration which lead to heightened complexity, while the concept of translanguaging has been incorporated into this heuristic to help understand how people communicate in these superdiverse settings. The main finding is that monolingual ideologies of language learning pervade the safe spaces which one NGO provides, though the aim is not to single out this one NGO for criticism when the majority of NGOs visited orient to similar monolingual outlooks which disregard home languages at a time when vulnerable adults, adolescents and children need to draw on all of the language resources in their repertoires to make sense of their new surroundings

Structure of baryons in a relativistic quark model

Baryonic excitation spectra, electroweak and strong decay properties are discussed within a relativistically covariant constituent quark model based on the instantaneous approximation to the three-body Bethe-Salpeter equation.Comment: 7 pages, 2 figures, Contribution to the Proceedings of the 17th International IUPAP Conference on Few-Body Problems in Physics, Durham, North Carolina, USA, 5-10 June 200

Interpretation of the Theta+ as an isotensor pentaquark with weakly decaying partners

The Theta+(1540), recently observed at LEPS, DIANA and CLAS, is hypothesized to be an isotensor resonance. This implies the existence of a multiplet where the Theta++, Theta+ and Theta0 have isospin-violating strong decays, and the Theta+++ and Theta- have weak decays and so are long-lived. Production mechanisms for these states are discussed. The J^P assignment of the Theta is most likely 1/2^- or 3/2^-.Comment: references added, section on pentaquark model revised, 11 pages, LaTeX, accepted for publication in Physics Letters

Quark Models of Baryon Masses and Decays

The application of quark models to the spectra and strong and electromagnetic couplings of baryons is reviewed. This review focuses on calculations which attempt a global description of the masses and decay properties of baryons, although recent developments in applying large N_c QCD and lattice QCD to the baryon spectrum are described. After outlining the conventional one-gluon-exchange picture, models which consider extensions to this approach are contrasted with dynamical quark models based on Goldstone-boson exchange and an algebraic collective-excitation approach. The spectra and electromagnetic and strong couplings that result from these models are compared with the quantities extracted from the data and each other, and the impact of various model assumptions on these properties is emphasized. Prospects for the resolution of the important issues raised by these comparisons are discussed.Comment: 91 page review article; 25 figures, 9 tables; submitted to Progress in Particle and Nuclear Physic

Quasi-Two-Body Decays of Nonstrange Baryons

We examine the decays of nonstrange baryons to the final states $\Delta\pi$, $N\rho$, $N\eta$, $N\eta^\prime$, $N\omega$, $N1/2^+(1440)\pi$, and $\Delta3/2^+(1600)\pi$, in a relativized pair-creation($^3P_0$) model which has been developed in a previous study of the $N\pi$ decays of the same baryon states. As it is our goal to provide a guide for the possible discovery of new baryon states at CEBAF and elsewhere, we examine the decays of resonances which have already been seen in the partial-wave analyses, along with those of states which are predicted by the quark model but which remain undiscovered. The level of agreement between our calculation and the available widths from the partial-wave analyses is encouraging.Comment: 41 pages, CEBAF-TH-93-1