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When studying tetraquark states using the method of QCD sum rules, we findsome tetraquark currents, such as $\bar u_L \gamma_\mu d_L~\bar d_L \gamma^\muu_L$ and $\bar u_L \gamma_\mu d_L~\bar d_R \gamma^\mu u_R$, etc. We calculatetheir correlation functions using the method of operator product expansion, andfind that non-perturbative QCD effects do not contribute much to them. Thisindicates the possible existence of tetraquark states composed of bare quarkswith abnormally small masses. We study the possible assignment of the $X17$ assuch a state. We argue that the Atomki experiments might observe a new type ofnuclear decay process, where sea quarks take away the extra energy of thenucleus. A unique feature of this tetraquark assignment is that we predict twoalmost degenerate states with significantly different widths.

Is the $X17$ composed of four bare quarks?