Towards precise top mass measurement at LHC

The top quark mass plays an important role in a variety of discussions both within and beyond the Standard Model. However, a precise determination of a theoretically well-defined top quark mass is still missing. Towards a precise determination of a theoretically well-defined top quark mass at the LHC, we propose a method which uses lepton energy distribution and has a boost-invariant nature. We investigate its experimental viability by performing a simulation analysis for ttbar production process and lepton+jets decay channel at the leading order. We estimate several major uncertainties in the top mass determination with this method and they amount to 1.7 GeV with an integrated luminosity of 100 fb^{-1} at sqrt{s}=14 TeV. The uncertainties should be reduced by considering the next-to-leading order corrections to the method.