t(t)over-barb(b)over-bar as a probe of new physics at the LHC

We study the t (t) over barb (b) over bar b final state at the LHC as a probe of new physics that couples mainly to the third generation of quarks. We analyze new physics simplified models with resonances of spin-0, -1 and -2. The sensitivity of the final states t (t) over barb (b) over bar , t (t) over bart (t) over bar , b (b) over barb (b) over bar and t (t) over bar on each of these models is used to identify an important region in parameter space that is still not excluded and where t (t) over barb (b) over bar is the most sensitive final state. We indicate possible experimental hints and discuss potential issues of observables that rely mainly on Monte Carlo predictions. A new observable is proposed that, at the price of requiring more statistics, reduces the impact of Monte Carlo predictions. We use preliminary 13 TeV results to give a raw estimate on the discovery reach and propose simple improvements on the observables.