The Possible Heavy Tetraquarks $qQ\bar q \bar Q$, $qq\bar Q \bar Q$ and   $qQ\bar Q \bar Q$
  Assuming X(3872) is a $qc \bar q \bar c$ tetraquark and using its mass as input, we perform a schematic study of the masses of possible heavy tetraquarks using the color-magnetic interaction with the flavor symmetry breaking corrections. 
Ying Cui, Xiao-Lin Chen, Wei-Zhen Deng, Shi-Lin Zhu