Analyticity, crossing, and the absorptive parts of the one-loop contributions to the quark-quark-gluon-gauge-boson four-point function - art. no. 096011

Starting from the known one-loop result for the e(+)e(-)-annihilation proce ss [GRAPHICS] with massless quarks we employ analyticity and crossing to determine the ab sorptive parts of the corresponding one-loop contributions in deep inelasti c scattering (DIS) and in the Drell-Yan (DY) process. Whereas the O(alpha ( 2)(s)) absorptive parts generate a nonmeasurable phase factor in the e(+)e( -)-annihilation channel one obtains measurable phase effects from the one-l oop contributions in the deep inelastic and Drell-Yan cases. We compare our results with the results of previous calculations where the absorptive par ts in DIS and in the DY process were calculated directly in the respective channels. We also present some new results on the dispersive and absorptive contributions of the triangle anomaly graph to the DIS process.