X(1835), X(2120), and X(2370) in flux tube models

Nonstrange hexaquark state q(3)(q) over bar (3) spectrum is systematically studied by using the Gaussian expansion method in flux tube models with a six-body confinement potential. All the model parameters are fixed by baryon properties, so the calculation of hexaquark state q3 (q) over bar3 is parameter-free. It is found that some ground states of q(3)(q) over bar (3) are stable against disintegrating into a baryon and an anti-baryon. The main components of X(1835) and X(2370), which are observed in the radiative decay of J/psi by BES collaboration, can be described as compact hexaquark states N-8(N) over bar (8) and Delta(8)(Delta) over bar (8) with quantum numbers I(G)J(PC) = 0(+)0(-+), respectively. These bound states should be color confinement resonances with three-dimensional configurations similar to a rugby ball, however, X(2120) can not be accommodated in this model approach.