Interactions of confining strings in SU(3) gluodynamics
  We study the interaction energy of the confining strings in the static rectangular tetraquark system in SU(3) gluodynamics. Using a two-state approximation we calculate the energy eigenvalues and corresponding eigenvectors of string states of different geometry. The interactions are studied both for the co-aligned and for the counter-aligned parallel strings as the functions of positions of the tetraquark constituents. We formulate a simple soap-film model and show that with a good accuracy the string interaction energy corresponding to the ground state of the tetraquark system can be described by this soap-film model. 
V. G. Bornyakov, P. Yu. Boyko, M. N. Chernodub, M. I. Polikarpov