We evaluate the mass of the $B_{s0}$ scalar meson and the coupling constant in the $B_{s0} B K$ vertex in the framework of QCD sum rules. We consider the $B_{s0}$ as a tetraquark state to evaluate its mass. We get $m_{B_s0}=(6.04pm 0.08) GeV$, which is bigger than predictions supposing it as a $bbar{s}$ state or a $Bbar{K}$ bound state with $J^{P}=0^+$. To evaluate the $g_{B_{s0}B K}$ coupling we use the three point correlation functions of the vertex, considering $ B_{s0} $ as a normal $bbar{s}$ state. The obtained coupling constant is: $g_{B_{s0} B K} =(16.3 pm 3.2) GeV$. This number is in agreement with light-cone QCD sum rules calculation. We have also compared the decay width of the $BSto BK$ process considering the $BS$ to be a $bbar{s}$ state and a $BK$ molecular state. The width obtained for the $BK$ molecular state is twice as big as the width obtained for the $bbar{s}$ state. Therefore, we conclude that with the knowledge of the mass and the decay width of the $BS$ meson, one can discriminate between the different theoretical proposals for its structure.
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