Explicit algebraic characterization of Mueller matrices.

A general explicit algebraic characterization of Mueller matrices is presented in terms of the non-negativity of a set of leading principal minors of the coherency matrix C(A) associated with the arrow form M(A) of a given Mueller matrix M. This result is also formulated through a set of four characteristic Stokes vectors. The particular cases of Mueller matrices with zero degree of polarizance and symmetric Mueller matrices are analyzed.