Heavy Baryon Spectroscopy
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avy Baryon Spectroscopy V. O. Galkina, * and R. N. Faustova aInstitute
of Cybernetics and Informatics in Education, Federal Research Center “Computer Science and Control”, Russian Academy of Sciences, Moscow, 119333 Russia *e-mail: [email protected] Received December 20, 2019; revised January 16, 2020; accepted January 29, 2020
Abstract—A review of theoretical predictions for the mass spectra of heavy baryons, obtained within the relativistic quark model and the quark–diquark picture, is given. A detailed comparison is made with experimental data, including recent measurements of the LHCb Collaboration. Good agreement between the theoretical results and the experiment was found. Possible quantum numbers of excited states of heavy baryons are discussed. DOI: 10.1134/S1063779620040292
1. INTRODUCTION Nikolai Nikolaevich Bogolyubov has always conducted research at the forefront of theoretical and mathematical physics. The very next year after M. Gell-Mann and G. Zweig proposed the constituent quark model in 1964, he lectured on this model at Lomonosov Moscow State University. Following the contribution of Bogolyubov to the development of the composite picture of hadrons, we developed a relativistic quark model [1–4]. This model is based on a quasi-potential approach in quantum field theory with a quasi-potential motivated by quantum chromodynamics. Hadrons are considered as bound states of constituent quarks and are described by a single-time wave function satisfying a three-dimensional relativistically invariant Schrödinger-type equation. The quasi-potential of the interaction consists of the perturbative part: the one-gluon exchange potential, and the nonperturbative confining part, which linearly increases with distance. The Lorentz structure of the confining interaction is chosen as a mixture of scalar and vector interactions. The vertex of the long-range vector interaction contains an additional Pauli term (anomalous chromomagnetic quark moment), which leads to the vanishing of the spin-dependent chromomagnetic interaction at large distances. In the past few years, significant experimental progress has been made in the study of spectroscopy of heavy baryons. Many new excited states of heavy baryons have been discovered. A significant contribution was made by the LHCb Collaboration [5–10]. This is due to the fact that heavy baryons are abundantly produced at the Large Hadron Collider (LHC). In this paper, these new experimental data are compared with the predictions of the relativistic quark–diquark model of baryons [2–4].
2. RELATIVISTIC QUARK–DIQUARK MODEL OF BARYONS A heavy baryon is described as a relativistic bound state of a heavy quark and a light diquark. Thus, a very complex relativistic three-body problem is reduced to solving two substantially simpler two-body problems. First, the properties of the diquark are calculated. A diquark is a bound two-quark system; therefore, it is not a point object. As a result, its interaction with gluons is smeared by a form factor, which can be calculated as the overlap
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