QCD asymmetry and measurement of structure functions of polarized hadron

Polarization phenomena are discussed in the framework of high energy physics. It is shown that in hard processes with a polarized particle the contributions proportional to two-index distribution functions (correlation densities of parton number) have imaginary parts even in a Born subprocess. They represent the source of large single asymmetries. Calculation of such asymmetry in the γP → γX process, which appears to be a good partonometer for correlation densities was conducted