Compact Flavour-Exotic Tetraquarks in Large-Ν<sub>c</sub> QCD - To Be or Not to Be?

Author(s)
Dmitri Melikhov, Wolfgang Lucha, Hagop Sazdjian
Abstract

We analyse exotic tetraquark mesons - bound states formed by two quarks and two antiquarks - for the specific case of four different quark flavours within the framework of a well-defined limit of quantum chromodynamics characterized by the correlated growth without bound of the number of colour degrees of freedom and approach to zero of the coupling constant of the strong interactions. On the one hand, the assumption that the tetraquarks of the kind defined above show up, as poles in the amplitudes for the scattering of two ordinary mesons with flavour quantum numbers that match those of these tetraquarks, already at lowest possible order in an expansion in inverse powers of the number of colours implies the existence of two types of flavour-exotic tetraquarks, distinguishable by their dominant transitions to two ordinary mesons. On the other hand, we are aware of merely a single, unique colour-singlet arrangement of two quarks and two antiquarks capable of tolerating a compact flavour-exotic tetraquark, a bound state of colour-antisymmetric diquark and antidiquark. In view of these two clearly contradictory observations, we are led to the plausible conclusion that, within the considered limiting case of quantum chromodynamics, a conceivable explanation of the riddle might consist in the non-existence of any flavour-exotic tetraquarks in form of narrow states.

Organisation(s)
Particle Physics
External organisation(s)
Österreichische Akademie der Wissenschaften (ÖAW), Universität Wien, Lomonosov Moscow State University (MSU), Institut de Physique Nucléaire, CNRS-IN2P3
Journal
Proceedings of Science (PoS)
Volume
336
No. of pages
7
DOI
https://doi.org/10.22323/1.336.0087
Publication date
09-2019
Peer reviewed
Yes
Austrian Fields of Science 2012
103012 High energy physics
Keywords
ASJC Scopus subject areas
Physics and Astronomy(all)
Portal url
https://ucris.univie.ac.at/portal/en/publications/compact-flavourexotic-tetraquarks-in-largec-qcd--to-be-or-not-to-be(4de8be0d-3b09-4a21-a204-f5bb15627f2a).html