Unintegrated parton distributions and electroweak boson production at hadron colliders

We describe the use of doubly-unintegrated parton distributions in hadron-hadron collisions, using the (z, kt)-factorisation prescription where the transverse momentum of the incoming parton is generated in the last evolution step. We apply this formalism to calculate the transverse momentum (PT ) distributions of produced W and Z bosons and compare the predictions to Tevatron Run 1 data. We find that the observed PT distributions can be generated almost entirely by the leading order q1 q2 → W,Z subprocesses, using known and universal doubly-unintegrated quark distributions. We also calculate the PT distribution of the Standard Model Higgs boson at the LHC, where the dominant production mechanism is by gluon-gluon fusion.