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For the case of two light flavors we propose the stringy description of thesystem made of one heavy and one light quark-antiquark pair, with the aim ofexploring the two lower-lying Born-Oppenheimer potentials as a function of aseparation of the heavy quark-antiquark pair. Our analysis reveals threecritical separations related to the processes of string reconnection, breakingand junction annihilation. In particular, for the ground state potential onlythe process of string reconnection matters. We find that a tetraquark statemakes the dominant contribution to the potential of the first excited state atsmall separations, and this is the big difference with the $QQ\bar q\barq$-quark system where it does so to the ground state potential. Another bigdifference is the emergence of the full diquark picture $[Qq][\bar Q\bar q]$rather than the partial picture $QQ[\bar q\bar q]$ for the tetraquark state. Onthe other hand, the scales of string junction annihilation, below which thesystems can be thought of mainly as the compact tetraquarks, are very close forboth cases and become almost the same if the phenomenological rule$E_{QQ}=\frac{1}{2} E_{Q\bar Q}$ holds. The same is also true for the screeninglengths whose values are in agreement with lattice QCD.

Towards a Stringy Description for the $Q\bar Q q\bar q$-Quark System