  We present a detailed study of the same-sign top pair production mediated by
a non-universal $Z^\prime$ including production and decay at the Large Hadron
Collider (LHC) at the QCD next-to-leading order (NLO) level, using the narrow
width approximation and helicity amplitudes method. We find that the QCD NLO
corrections can loose the constraint on the model parameters and reduce the
dependence of the total cross sections on the factorization scale
significantly. We also study the signature and backgrounds of the process at
the NLO level. In order to suppress the backgrounds, we further investigate the
difference between the production rates of the positively and negatively
charged dilepton at the LHC, and find that the same-sign dilepton signal of the
new physics could be discovered more easily.
