Diffractive Heavy Quarkonium Photoproduction In COM And LLA QCD

In this dissertation,under the leading-log approximation(LLA)we discuss the con-tribution of color octet mechanism(COM)to diffractive heavy quarkonium photoproduc-tion process.The scattering cross sections of diffractive heavy quarkonium photoproduc-tion by S-wave are calculated and compared with the corresponding cross sections com-puted by color singlet mechanism.We found that the color octet mechanism correction is relatively large.The contribution of color octet mechanism S-wave can be compared with color singlet mechanism,So it is better to be used in heavy quarkonium photoproduction process.Based on the general research method of the derivative process,we combined the Pomeron model with COM model.First,we determined the parameters of the Pomeron model under the COM frame.And then we calculated the cross sections of the diffractive process by combining the Pomeron model with the color octet mechanism under the condition of no destroying the structure of the Pomeron.We found that the cross section is directly proportional to the square of gluon structure function,and it is more sensitive to the change of gluon structure function.So the calculation of diffractive cross section can help to re-scale gluon structure function.This result is of great significance to the small x physics.