PHYSICAL REVIEW D, cilt.83, sa.1, 2011 (SCI-Expanded)
A new method for calculation of the mixing angle between the hadrons within QCD sum rules is proposed. In this method, the mixing is expressed in terms of quark and gluon degrees of freedom. As an application, the detailed calculation of the mixing angle between heavy cascade baryons Xi(Q) and Xi'(Q), Q = c, b is presented and it is found that the mixing angle between Xi(b) (Xi(c)) and Xi'(b) (Xi'(c)) is given by theta(b) = 6.4 degrees +/- 1.8 degrees (theta(c) = 5.5 degrees +/- 1.8 degrees).