Determination of ${\chi }_b$ spin in the decays ${\chi }_{b0,2}\to \psi \psi$ and ${\chi }_{b0,2}\to \text{JP}\text{JP}\to 2({\mu }^{+}{\mu }^{-})$

The decays ${\chi }_{b0,2}\to \psi \psi$ and ${\chi }_{b0,2}\to \psi \psi \to 2({\mu }^{+}{\mu }^{-})$ are considered. It is shown that with the help of $\psi$-meson angular distributions and the distributions by final muon kinematical variables it is possible to determine the spin of the decaying ${\chi }_b$-meson. These distributions can also give an additional information about $\psi$-meson wave functions.