50 research outputs found
Tetraquark states and spectrum
A general classification of tetraquark states in terms of the spin-flavour,
colour and spatial degrees of freedom has been constructed. The permutational
symmetry properties of both the spin-flavour and orbital parts of the
quark-quark and antiquark-antiquark subsystems are discussed in short. This
classification is model indipendent and useful both for model-builders and
experimentalists. An evaluation of the tetraquark spectrum is obtained from a
generalization of a Iachello mass formula, originally developed for the mesons. The ground state tetraquark nonet is identified with ,
, , .Comment: Invited talk at XI Conference on Problems in Theoretical Nuclear
Physics (Cortona 2006), Cortona, Italy, 11-14 Oct, 200
Spectroscopy of the hidden-charm and tetraquarks
We calculate the spectrum of and
tetraquarks, where , and stand for light (), strange and charm
quarks, respectively, in a relativized diquark model, characterized by
one-gluon-exchange (OGE) plus confining potential. In the diquark model, a
() tetraquark configuration is made up of
a heavy-light diquark, (), and anti-diquark, (). According to our results, 13 charmonium-like observed states can be
accommodated in the tetraquark picture, both in the hidden-charm () and hidden-charm hidden-strange () sectors.Comment: Discussions extended, references adde
Nucleon form factors in a simple three-body quark model
We construct a simple 3-body quark model for the non strange nucleon resonances and we give results for the spectrum, the helicity amplitudes and the transition form factors. All the observables, in particular the transition form factors, are evaluated analytically and the results are compared with those of other models