Approximating the production of a vector boson plus multijets at hadron colliders

We give approximations to the matrix element squared for the production of a vector boson accompanied by an arbitrary number of jets. Only subprocesses containing one and two quark-antiquark pairs are estimated. Approximate cross sections and kinematical distributions are compared to those obtained from the known exact tree-level matrix elements for $W$ plus four and three jets and $Z$ plus three jets using all subprocesses, and an agreement at the ∼30% level is found. The approximations are simple and can be rapidly evaluated on a computer, saving an order of magnitude in CPU time compared to using the tree-level exact matrix elements. Estimates of the cross sections for $W$ plus five jets and the $Z$ plus four jets, as well as their kinematical distributions are also given.