Precision test of quark mass textures: a model-independent approach

Using a Monte Carlo method, we have directly extracted from the available measurements, the hierarchies among the different elements of the quark mass matrices. To do that, we have first introduced a model-independent parameterization for two generic class of models: those based on Abelian symmetries and those inspired by a U(2) horizontal symmetry. So, matrix entries are proportional to some epsilon(t), with epsilon much less than 1 and the t's are different free exponents that we determine from the data through a statistically well defined procedure. We have found that the experimental data poorly constrain the Abelian scenarios. Instead, in non-Abelian scenarios, these t-exponents are strongly constrained by the present data. We have found that contrary to a naive U(2) horizontal symmetry expectation, quark mass matrices turn out to be not symmetric. Two solutions emerge: one with M-32(down) much greater than M-23(down) and M-21(up) much greater than M-12(up); and a second one with slight asymmetries only in the light quark sector, namely M-21(up) < M-12(up) and M-21(down) > M-12(down). (C) 2002 Elsevier Science B.V. All rights reserved.