The structure of the Cabibbo-Kobayashi-Maskawa (CKM) matrix is analyzed from the standpoint of a composite model. A model is constructed with three families of quarks, by taking tensor products of sufficient numbers of spin-1/2 representations and imagining the dominant terms in the mass matrix to arise from spin-spin interactions. Generic results then obtained include the familiar relation $|V_{ us}| = (m_d/m_s)^{ 1/2} - (m_u/m_c)^{ 1/2}$, and a less frequently seen relation $|V_{ cb}| = \sqrt{ 2} [(m_s/m_b) - (m_c/m_t)]$. The magnitudes of $V_{ ub}$ and $V_{ td}$ come out naturally to be of the right order. The phase in the CKM matrix can be put in by hand, but its origin remains obscure.
Categories: hep-ph