Angular distribution of leptons from the decay of massive vector bosons

We examine the transverse momentum Q(perpendicular to) dependence of the helicity structure functions for massive vector bosons of mass Q in hadron reactions. We demonstrate that large logarithmic terms of the form ln(Q/Q(perpendicular to)) in the helicity structure functions have the same origin as the logarithmic terms in the angular-integrated cross section. and that they can be resummed to all orders in the strong coupling alpha(s), in the same way as the angular-integrated cross section. As a consequence of current conservation, the resummed part of the helicity structure functions preserves the Lam-Tung relation as a function of Q(perpendicular to) to all orders in alpha(s). (c) 2007 Elsevier B.V. All rights reserved.