1. Constraints from the 1 / N c Expansion on Properties of Exotic Tetraquark Mesons
- Author
-
Wolfgang Lucha, Dmitri Melikhov, Hagop Sazdjian, Institut de Physique Nucléaire d'Orsay (IPNO), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Quark ,Particle physics ,Meson ,Feynman graph ,High Energy Physics::Lattice ,Flavour ,FOS: Physical sciences ,expansion 1/N: color ,High Energy Physics - Phenomenology (hep-ph) ,quantum chromodynamics ,Bound state ,scattering amplitude: pole ,meson: decay rate ,Physics ,Quantum chromodynamics ,flavor ,High Energy Physics::Phenomenology ,meson: exotic ,Limiting case (mathematics) ,tetraquark ,Composition (combinatorics) ,High Energy Physics - Phenomenology ,bound state ,[PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph] ,High Energy Physics::Experiment ,Tetraquark - Abstract
Scrutinizing the scattering of ordinary mesons in the limiting case of the number of colour degrees of freedom $N_{\rm c}$ of quantum chromodynamics approaching infinity, we formulate Feynman-diagram selection criteria and from these deduce rigorous self-consistency conditions for the manifestation of a tetraquark, a two-quark-two-antiquark bound state, as a pole in the corresponding amplitudes. Our constraints bear rather far-reaching consequences: In particular, all flavour-exotic tetraquarks, composed of four (anti)quarks of disparate flavour, must come in, at least, two variants differing in (and thus readily identifiable by) the large-$N_{\rm c}$ behaviour of their couplings to two ordinary mesons. Quite generally, irrespective of their flavour composition, all tetraquarks prove to be narrow. Their decay rates behave, for large $N_{\rm c},$ like $1/N_{\rm c}^2$ and thus decrease faster than those of ordinary mesons., Comment: 4 pages, 2 figures, contributed to "XVII International Conference on Hadron Spectroscopy and Structure - Hadron2017" (25 - 29 September 2017, Salamanca, Spain)
- Published
- 2018
- Full Text
- View/download PDF