ATLAS discovery prospects for the charged Higgs in the H+ to tau nu final state

In the Minimal Super-Symmetric model (MSSM), the decay H+ to tau nu can be a dominant decay channel for the light (m(H+) < m(top) ) charged Higgs boson. Through this channel, the ATLAS detector at the Large Hadron Collider (LHC) could either discover the light H+ or improve the current Tevatron upper limits on B(t to bH+). We evaluate the expected ATLAS upper limit for B(t to b H+), assuming B(H+ to tau nu)=1 and an integrated luminosity of 200 pb-1 gathered at sqrt(s)=10 TeV.