PARAMETRIZATION OF FLAVOR MIXING IN THE STANDARD MODEL

It is shown that there exist nine different ways to describe the flavo r mixing, in terms of three rotation angles and one CP-violating phase , within the standard electroweak theory of six quarks. For the assign ment of the complex phase there essentially exists a continuum of poss ibilities, if one allows the phase to appear in more than four element s of the mixing matrix. If the phase is restricted to four elements, t he phase assignment is uniquely defined. If one imposes the constraint that the phase disappears in a natural way in the chiral limit in whi ch the masses of the u and d quarks are turned off, only three of the nine parametrizations are acceptable. In particular the ''standard'' p arametrization advocated by the Particle Data Group is not permitted. One parametrization, in which the CP-violating phase is restricted to the light quark sector, stands up as the most favorable description of the flavor mixing. [S0556-2821(98)00803-0].