Multiquark Hadrons

This work summarises the salient features of current and planned experiments into multiquark hadrons, describing various inroads to accommodate them within a theoretical framework. At a pedagogical level, authors review the salient aspects of quantum chromodynamics (QCD), the theory of strong interactions, which has been brought to the fore by high-energy physics experiments over recent decades. Compact diquarks as building blocks of a new spectroscopy are presented and confronted with alternative explanations of the XYZ resonances. Ways to distinguish among theoretical alternatives are illustrated, to be tested with the help of high luminosity LHC, electron-positron colliders, and the proposed Tera-Z colliders. Non-perturbative treatments of multiquark hadrons, such as large N expansion, lattice QCD simulations, and predictions about doubly heavy multiquarks are reviewed in considerable detail. With a broad appeal across high-energy physics, this work is pertinent to researchers focused on experiments, phenomenology or lattice QCD.

Table of Contents:
Preface; 1. Introduction; 2. XYZ and Pc phenomenology; 3. Color forces and constituent quark model; 4. Hadron molecules; 5. Light scalar mesons; 6. Mass formulae for P-wave, qq mesons; 7. Compact tetraquarks; 8. The Xu Xd puzzle; 9. Y states as P-wave tetraquarks; 10. Pentaquark models; 11. Tetraquarks in large N QCD; 12. QCD sum rules and lattice QCD; 13. Phenomenology of beauty quark exotics; 14. Hidden heavy avour tetraquarks – overview; 15. Tetraquarks with double heavy quarks; 16. Outlook; Appendix A. Low energy p – n scattering amplitude; Appendix B. Wigner's 6-j symbols; References; Index.

About the Author :
Ahmed Ali is an Emeritus staff member in Theoretical Physics at the high-energy physics laboratory, Deutsches Elektronen-Sychrotron (DESY), Hamburg and an Emeritus Professor of Physics at the University of Hamburg. Working on the phenomenology of high-energy physics, his main research interests are flavor physics, QCD, and multiquark hadrons. He has worked as a scientific associate at CERN for several years and is also a fellow of the American Physical Society. Luciano Maiani is Emeritus Professor of Theoretical Physics at Sapienza University of Rome. He has been president of the Italian Institute for Nuclear Physics (INFN), director-general of CERN in Geneva and president of the Italian National Council for Research (CNR). He is a member of the Italian Lincean Academy and a fellow of the American Physical Society. Antonio D. Polosa is Professor at the Department of Physics in Università degli Studi di Roma 'La Sapienza', Italy. His research focuses primarily exclusive heavy meson decays, high energy hadron collider physics and exotic hadron spectroscopy. He has held positions at the University of Helsinki, CERN, LAPP-TH and INFN-Rome.