  The Monte Carlo toy model of Bose-Einstein correlations is considered to make
a best choice from different reference distributions. It occurs that the
minimal bias in the Bose-Einstein correlation parameters estimation is provided
by the reference sample which is being emulated from a real sample by the turn
of all vectors in an event by a random angle in the transverse plane. It
proposed to use similar approach in the analysis of two-dimensional
correlation. To make the analysis less dependent on a reference sample, new
definition of azimuthal angle difference is implemented as the angle between
vectors in the transverse plane. Then one-dimensional correlation of azimuthal
angles can be studied without a reference sample subtraction. The ridge in
two-dimensional correlation appears if an appropriate cut in pair invariant
masses is applied.
