A quark model is applied to the spectrum of baryons containing heavy quarks. The model gives masses for the known heavy baryons that are in agreement with experiment, but for the doubly-charmed baryon Ξcc, the model prediction is too heavy. Mixing between the ΞQ and Ξ′Q states is examined and is found to be small for the lowest lying states. In contrast with this, mixing between the Ξbc and Ξ′bc states is found to be large, and the implication of this mixing for properties of these states is briefly discussed. We also examine heavy-quark spin-symmetry multiplets, and find that many states in the model can be placed in such multiplets. We compare our predictions with those of a number of other authors.

We examine the decays of nonstrange baryons to the final states ∆π, N ρ, N η, N η ′ , N ω, N 1 2 + (1440)π, and ∆ 3 2 + (1600)π, in a relativized pair-creation ( 3 P 0 ) model which has been developed in a previous study of the N π 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.

The strong decays of excited nonstrange baryons into the final states ⌳K, ⌺K, and for the first time into ⌳(1405)K, ⌳(1520)K, ⌺(1385)K, ⌳K*, and ⌺K*, are examined in a relativized quark pair creation model. The wave functions and parameters of the model are fixed by previous calculations of N and N, etc., decays. Our results show that it should be possible to discover several new negative parity excited baryons and confirm the discovery of several others by analyzing these final states in kaon production experiments. We also establish clear predictions for the relative strengths of certain states to decay to ⌳(1405)K and ⌳(1520)K, which can be tested to determine if a three-quark model of the ⌳(1405)K is valid. Our results compare favorably with the results of partial wave analyses of the limited existing data for the ⌳K and ⌺K channels. We do not find large ⌺K decay amplitudes for a substantial group of predicted and weakly established negative-parity states, in contrast to the only previous work to consider decays of these states into the strange final states ⌳K and ⌺K.

Abstract. The composite nature of baryons manifests itself in the existence of a rich spectrum of excited states, in particular in the important mass region 1-2 GeV for the light-flavoured baryons. The properties of these resonances can be identified by systematic investigations using electromagnetic and strong probes, primarily with beams of electrons, photons, and pions. After decades of research, the fundamental degrees of freedom underlying the baryon excitation spectrum are still poorly understood. The search for hitherto undiscovered but predicted resonances continues at many laboratories around the world. Recent results from photo-and electroproduction experiments provide intriguing indications for new states and shed light on the structure of some of the known nucleon excitations. The continuing study of available data sets with consideration of new observables and improved analysis tools have also called into question some of the earlier findings in baryon spectroscopy. Other breakthrough measurements have been performed in the heavy-baryon sector, which has seen a fruitful period in recent years, in particular at the B factories and the Tevatron. First results from the LHC indicate rapid progress in the field of bottom baryons. In this review, we discuss the recent experimental progress and give an overview of theoretical approaches.