Measurement of the Z boson transverse momentum: direct and using phi* variable with ATLAS

A measurement of angular correlations in Drell-Yan lepton pairs via the phi* observable at the LHC using ATLAS data at sqrt{s}=7 TeV is presented. This variable probes the same physics as the Z/gamma* boson transverse momentum p_T with a better experimental resolution, especially for low transverse momenta. The measurement using phi* and the direct measurement of p_T are compared to predictions based on QCD calculations and predictions from different Monte Carlo event generators.