Abstract
We present a general class of operators resembling compact tetraquarks which have a range of colour-flavour-spin structures, transform irreducibly under the symmetries of the lattice and respect other relevant symmetries. These constructions are demonstrated in lattice QCD calculations with light quarks corresponding to mπ = 391 MeV. Using the distillation framework, correlation functions involving large bases of meson-meson and tetraquark operators are computed in the isospin-1 hidden-charm and doubly-charmed sectors, and finite-volume spectra are extracted with the variational method. We find the spectra are insensitive to the addition of tetraquark operators to the bases of meson-meson operators. For the first time, through using diverse bases of meson-meson operators, the multiple energy levels associated with meson-meson levels which would be degenerate in the non-interacting limit are extracted reliably. The number of energy levels in each spectrum is found to be equal to the number of expected non-interacting meson-meson levels in the energy region considered and the majority of energies lie close to the non-interacting levels. Therefore, there is no strong indication for any bound state or narrow resonance in the channels we study.
Highlights
Hybrid mesons and threshold cusps, can be found in refs. [3,4,5,6,7,8]
We present a general class of operators resembling compact tetraquarks which have a range of colour-flavour-spin structures, transform irreducibly under the symmetries of the lattice and respect other relevant symmetries
We have described the construction of a general class of operators resembling compact tetraquarks which have a range of different diquark-anti-diquark structures, transform irreducibly under the symmetries of the lattice and respect other relevant symmetries
Summary
Hybrid mesons and threshold cusps, can be found in refs. [3,4,5,6,7,8]. As well as hidden-charm ccqqconfigurations, doubly-charmed ccqqtetraquarks have been hypothesised [9,10,11,12], but there are currently no experimental candidates for these. The Hadron Spectrum Collaboration has developed a range of interpolating operators resembling quark-antiquark [16, 17] and meson-meson [18, 19] structures which transform irreducibly under the symmetries of the lattice and efficiently interpolate the states of interest These operators have proven very successful in recent computations of finitevolume spectra which are used to determine scattering amplitudes [18,19,20,21,22,23,24,25,26]. The main goal of this work is to develop a very general class of operators with compact tetraquark structures, which transform irreducibly under the symmetries of the lattice and which respect other relevant symmetries We will test these constructions in lattice QCD computations of spectra in hidden-charm and doubly-charmed channels. Appendices present some additional properties of diquark and tetraquark operators, give quark model interpretations of the diquark structures and list the operators used to calculate the finite-volume spectra
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
