Covalent hadronic molecules induced by shared light quarks

Abstract After examining Feynman diagrams corresponding to the D¯(*)Σc) , )}{{\rm{\Lambda }}}_{c}$?> stretchy="false">)Λc ${D}^{(* )}{\bar{K}}^{* }$?> overflow="scroll">D)K¯* and )}{\bar{D}}^{(* stretchy="false">) hadronic molecular states, we propose a possible binding mechanism induced by shared light quarks. This is similar covalent bond in chemical molecules electrons. We use method of QCD sum rules calculate its light-quark-exchange diagrams, obtained results indicate model-independent hypothesis: interaction attractive when quarks are totally antisymmetric so they obey Pauli principle. build toy model with four parameters formulize this picture estimate energies some possibly-existing molecules. A unique feature that ( I ) J P = (0)1 + $D{\bar{B}}^{* }/{D}^{* }\bar{B}$?> overflow="scroll">DB¯*/D*B¯ much larger than those ${{DD}}^{* }/\bar{B}{\bar{B}}^{* overflow="scroll">DD*/B¯B¯* ones, while (1/2)1/2 $\bar{D}{{\rm{\Sigma }}}_{c}/\bar{D}{{\rm{\Sigma }}}_{b}/B{{\rm{\Sigma }}}_{c}/B{{\rm{\Sigma }}}_{b}$?> overflow="scroll">D¯ΣcΣb/BΣb have energies.