Unique mass texture for quarks and leptons

Texture specific quark mass matrices which are Hermitian and hierarchical are examined in detail. In the case of texture 6 zero matrices, out of sixteen possibilities examined by us, none is able to fit the low energy data (LED), for example, $|V_{\mathrm{us}}|=0.2196\mathrm{}\pm 0.0023,$ $|V_{\mathrm{cb}}|=0.0395\mathrm{}\pm 0.0017,$ $|V_{\mathrm{ub}}{/V}_{\mathrm{cb}}|=0.08\mathrm{}\pm 0.02,$ and $|V_{\mathrm{td}}|$ lies in the range 0.004–0.014 (PDG). Similarly none of the 32 texture 5 zero mass matrices considered is able to reproduce the LED. In particular, the latest data from CERN LEP regarding $|V_{\mathrm{ub}}{/V}_{\mathrm{cb}}|=(0.093\mathrm{}\pm 0.016)$ rules out all of them. In the texture 4 zero case, we find that there is a unique texture structure for U and D mass matrices which is able to fit the data.