Hidden-beauty charged tetraquarks and heavy quark spin conservation

Assuming the dominance of the spin-spin interaction in a diquark, we point out that the mass difference in the beauty sector M(Z(b)')(+/-) - M(Z(b))(+/-) scales with quark masses as expected in QCD, with respect to the corresponding mass difference M(Z(c)')(+/-) - M(Z(c))(+/-). Notably, we show that the decays Upsilon(10890) -> Upsilon(nS)pi(+)pi(-) and Upsilon(10890) -> (h(b)(1P), h(b)(2P))pi(+)pi(-) are compatible with heavy quark spin conservation if the contributions of Z(b), Z(b)' intermediate states are taken into account, Upsilon(10890) being either a Upsilon(5S) or the beauty analog of Y-c(4260). Belle results on these decays support the quark spin wave function of the Z states as tetraquarks. We also consider the role of light quark spin nonconservaton in Z(b),Z(b)' decays into BB* and B*B*. Indications of possible signatures of the still missing X-b resonance are proposed.