We show that the four-zero texture of Hermitian quark mass matrices can survive current experimental tests: it is able to yield sufficiently large predictions for the flavor mixing parameter $|V_{ ub}/V_{ cb}|$ and the CP-violating parameter $\sin 2\beta$, without fine-tuning of the input values of quark masses, provided the (2,2), (2,3) and (3,3) elements of up and down mass matrices roughly satisfy a geometrical hierarchy. The successful relations $|V_{ us}| \approx \sqrt{ m_u/m_c + m_d/m_s}$ and $|V_{ td}/V_{ ts}| \approx \sqrt{ m_d/m_s}$ obtained previously from the six-zero texture of Hermitian quark mass matrices remain unchanged in the new ansatz.
Categories: hep-ph