PHYSICAL REVIEW D VOLUME 27. NUMBER 3 1 FEBRUARY 1983 Test of color gauge theories in two-photon interactions Kyung Hyun Cho, Seung Kee Han, and Jae Kwan Kim Department of Physics, Korea Advanced Institute of Science and Technology, P.O. Box 150, Chongyangni, Seoul 131, Korea (Received 1 October 1982) The lowest-order diagrams for the process e+e--e+e-yy +e+e-+ two jets + X are calculat- ed explicitly in the broken color gauge theory. The experimental data are consistent with the theoretical calculations with the gluon mass m, = 0.2-0.3 GeV. In recent years, quantum chromodynamics (QCD) has been a main tool in the perturbative calculations involving strong interactions.' But also there have been efforts to analyze many processes of strong- interaction physics in the broken color gauge theory of Pati and Salam2 to determine whether the color symmetry is exact or not. Due to the canceling me~hanism,~ one-photon processes like e'e- annihi- lation or electroproduction do not produce distinctive differences between these two models. The two- photon process of Compton ~cattering,~ on the other hand, gives a considerable difference and has been analyzed successfully in the broken color gauge theory. In this sense, it is natural that another two- photon processS e+e-+e+e-yy +e+e-+ two jets + X appears as a good testing ground for the color sym- metry and the quark charges. Recently the experimental data of this process have been reported697 and compared with the lowest-order QCD calculation. But the dynamical calculation of this process is lacking in the broken color gauge theory and ocly charge-factor analysiss using simple group-theoretical arguments has been made. Howev- er, Lipkin9 has pointed out that the possibility of the color brightening in the two-photon processes below the color threshold in the above charge-factor analysis is incorrect since the color-oscillation effect is not properly taken care of. Therefore, in this Communication we calculate dynamically the color- charge effect only above the color threshold in the double-equivalent-photon approximationlo (DEPA), since the color-charge effect is absent below the color threshold. The results are compared with the avail- able experimental data. In the broken color gauge theory, integrally charged gluons contribute in addition to quarks with integer charge, and the intermediate photon A. is ac- companied by its orthogonal color gauge partner 0, with the mass m,. We now write down the initial- spin-averaged cross section of the lowest-order Feyn- mann diagrams shown in Fig. 1: and 2 684 01983 The American Physical Society