Systematics in charged Higgs search in ATLAS

The charged light MH+ <Mtop MSSM Higgs boson production via t->bH+ and the subsequent decay into H+->csbar or H+ ->taunu has been studied for the ATLAS experiment. The first channel, dominating at low tan beta region (<1), is explored in the final state with 4 jets and one lepton and missing energy; the second, at high er tan beta region (>3), is searched in two leptons and two jets and missing ener gy final state. The study has been performed using a realistic detector simulation of the s ignal and the SM backgrounds. The discovery sensitivity and the upper limit on BR(t->gt;b H+) as function of MH+ , assuming the Br(H->csbar)=1 or Br(H->taunu)=1, were discussed for different luminosity and center of mass energy scenarios: at root(s)=10 TeV with integrated luminosity=~200 pb-1 and at root(s) = 7 TeV with integrated luminosity = 1 fb-1, obtained using a rescaling tecnique. The main focus of the present paper is on the impact of systematics on these results.