Meson Spectroscopy In The Framework Of Constituent Quark Models

The complexity of quantum chromodynamics in the non-perturbative domain forces physicist to resort to models in order to describe the phenomena of intermediate energy physics and hence this book develops three different quark models to study light and some heavy mesons: a non relativistic quark model with one-gluon-exchange potential(OGEP) and Instanton-Induced Interaction (III); a semi-relativistic quark model with OGEP and III where the confinement of the quark is modeled with the relativistic harmonic model; a relativistic model where the features of the two previous models are supplemented with the introduction of gluon confinement and thus confined one-gluon-exchange potential (COGEP). Both tensor and spin-orbit parts of the interactions are taken into account in all the three models. It begins with an introduction to the quark model of hadrons covering the SU(3) symmetry in chapter 1 and it discusses in detail the constituent quark models in chapter 2. The three models and a description on decays are developed in chapters 3 and 4. The results and conclusions are presented in chapters 5 and 6. This book predicts mass spectra and certain decays of light and some heavy mesons.

Quantum Chromodynamics (QCD) is the theory of strong interactions. Since the exact form of confinement of quarks from QCD is not known constituent quark modes were developed incorporating the basic features of the QCD. Mesons are the very fundamental particles in hadron physics. Hence, a deep understanding of the internal structure of the mesons is of crucial importance for explaining properties concerning more complex systems. In this work, non-relativistic and relativistic constituent quark models have been developed including instantons as a short range nonperturbative gluonic effect. The total energy or the mass of the meson is obtained by calculating the energy eigen values of the Hamiltonian in the harmonic-oscillator basis.

This workshop proceedings presents interesting lectures on the theoretical and experimental problems which may be studied using the new GeV accelerators. It provides a discussion of ongoing and planned experiments on the CELCIUS, COSY, LEAR, SATURNE and SIS accelerators as well as general descriptions of the experimental techniques applied in these experiments. There is special focus on the meson production mechanism in various reactions, meson spectroscopy and meson decay modes.

The book discusses constituent quarks, diquarks, the massive effective gluons and the problem of scalar isoscalar mesons. The quark-gluonium classification of meson states is also given. Experimentally observed properties of hadrons are presented together with the corresponding theoretical interpretation in the framework of the composite hadron structure. The text includes a large theoretical part, which shows how to treat composite systems (including relativistic ones) with a technique based on spectral integration. This technique provides the possibility of handling hadrons as weakly bound systems of quarks and, at the same time, takes into account confinement. Attention is focused on the composite structure revealing itself in high energy hadron collisions. Fields of applicability of the additive quark model are discussed, as is colour screening in hadronic collisions at high and superhigh energies. Along with a detailed presentation of hadron-hadron collisions, a description of hadron-nucleus collisions is given.

This book is devoted to the investigation of the strongly interacting hadrons — to a quark model operating with effective color particles, constituent quarks, massive effective gluons and diquarks. The study of strong interactions based on effective constituent particles requires a solid ground of experimental data, which we now have at our disposal with the serious progress made in the investigation of hadrons, especially meson states.The present understanding of QCD applied to strong interactions can be distorted by prejudices. Therefore, the way followed by the quark model is to rely on the experiment and to restore the effective Hamiltonian on the basis of QCD on the one hand, and, on the other, of the spectral integral method.Baryon-baryon and antibaryon-baryon interactions are studied with the purpose of unambiguous applications of the written formulae to the interpretation of experimental data — to the observation of new meson and baryon resonances. The technique used is the spin-orbital momentum expansion of the amplitude. This method is our basic approach to the proper treatment of experimental data. The photon-induced reactions are also considered and the problem of form factors is discussed.

In this pedagogical review the authors discuss the theoretical understanding of light hadron spectroscopy in terms of QCD and the quark model. They begin with a summary of the known and surmised properties of QCD and confinement. Following this they review the nonrelativistic quark potential model for q{anti q} mesons and discuss the quarkonium spectrum and methods for identifying q{anti q} states. Finally, they review theoretical expectations for non-q{anti q} states (glueballs, hybrids and multiquark systems) and the status of experimental candidates for these states.