PRECISE SIMULATION OF THE INITIAL-STATE QCD ACTIVITY ASSOCIATED WITH Z-BOSON PRODUCTION IN HADRON COLLISIONS

Abstract

The [Formula: see text] distribution of the Z/γ* → ℓ+ℓ- production in hadron collisions is simulated using a leading-order event generator, GR@PPA. The initial-state parton shower (PS), which simulates the multiple QCD-radiation effects in the initial state, plays the dominant role in this simulation. The simulation in the default setting agrees with the high-statistics measurement by ATLAS at LHC with the precision at the level of 5%. The observed systematic deviation, which can be attributed to the effects of ignored higher-order contributions, can be reduced by adjusting the arbitrary energy scales in the simulation. The agreement at the level of 1% can be achieved over a very wide range without introducing any modification in the implemented naive leading-logarithmic (LL) PS.