Measurement of phi* variable in Drell-Yan events in p-p collisions with 8 TeV data

Transverse momentum spectra of vector bosons in Drell-Yan events have always been interesting observables since they test the theoreticaldescription of the process. At lower end the spectrum tests the model ofunderlying event while the high tail can be compared with predictions fromperturbative QCD. However the measurements at LHC are limited due to theresolution in the measurement of momenta of the daughter leptons,electron and muon, in particular. A novel variable phistar has beenproposed recently which uses the angular correlation of the lepton pairsfrom Z decay to probe the transverse momenta the vector boson and hencehas less systematic error.Results from measurements at LHC will be presented in this talk.