The differential cross section for the process Z/gamma* -> ll (l = e, mu) as a function of dilepton invariant mass is measured in pp collisions at root s = 7 TeV at the LHC using the ATLAS detector. The measurement is performed in the e and mu channels for invariant masses between 26 GeV and 66 GeV using an integrated luminosity of 1.6 fb(-1) collected in 2011 and these measurements are combined. The analysis is extended to invariant masses as low as 12 GeV in the muon channel using 35 pb(-1) of data collected in 2010. The cross sections are determined within fiducial acceptance regions and corrections to extrapolate the measurements to the full kinematic range are provided. Next-to-next-to-leading-order QCD predictions provide a significantly better description of the results than next-to-leading-order QCD calculations, unless the latter are matched to a parton shower calculation.
Aad, G., Abajyan, T., Abbott, B., Abdallah, J., Abdel Khalek, S., Abdinov, O., et al. (2014). Measurement of the low-mass Drell-Yan differential cross section at root s=7 TeV using the ATLAS detector. JOURNAL OF HIGH ENERGY PHYSICS, 06(6), 1-45 [10.1007/JHEP06(2014)112].