Measuring gamma at LHCb with an Atwood-Dunietz-Soni Method

The selection efficiencies and backgrounds for the two-body Atwood-Dunietz-Soni modes B+- -> D0bar/D0 K+-, where the D0bar/D0 decays to Kpi, KK or pipi, are determined from studies with LHCb's full GEANT based Monte Carlo simulation. These are used with a toy Monte Carlo, and assumptions about the D0bar/D0 -> Kpipipi decay modes, to estimate the precision with which LHCb will be able to measure the CKM angle gamma. For the majority of values of the unknown strong phases in the relevant D0bar/D0 decays, the fits to the toy Monte Carlo data converge and return the input values. Depending on the values of these phases, the precision on gamma from a nominal year of data (2fb-1 integrated luminosity) is in the range 2-6 degrees without the background, and 5-13 degrees with the considered background. In the latter case the background estimate is statistically limited and has a large uncertainty.