  We provide a theoretical study of a novel variable introduced in
  Ref. \cite{WV} to study the transverse momentum of the Z boson at hadron
colliders. The variable we consider has experimental advantages over the
standard $p_T$ distribution enabling more accurate measurement at low $p_T$. We
provide an all orders perturbative estimate for this variable at the
next-to--leading logarithmic accuracy and compare the results to those for the
standard $p_T$ distribution. We test our resummation, at the two-loop level, by
comparing its expansion to fixed-order perturbative estimates and find
agreement with our expectations.

High Energy Physics - Phenomenology