Precision test of a Fermion mass texture

Texture zeros in the quark Yukawa matrices generally lead to precise and simple expressions for CKM matrix elements in terms of ratios of quark masses. Using the new data on b-decays we test a particularly promising texture zero solution and show that it is at best approximate. We analyse the approximate texture zero structure and show it is consistent with experiment. We investigate the implications for the CKM unitarity triangle, measurements at BaBar and BELLE as well as for the theories which invoke family symmetries. (C) 2001 Elsevier Science B.V. All rights reserved.