Semileptonic decays of heavy tetraquarks

There exist heavy tetraquark states QQ bar q bar q in the heavy quark limit. These states are stable with respect to strong interactions and hence must decay weakly. It is shown that the semileptonic decay depends on a single Isgur-Wise form factor, which can be expressed in terms of the Isgur-Wise form factors which govern the semileptonic decays of the Qqq and QQq baryons