  We explore in detail the physics potential of a measurement of the ttbar
invariant mass distribution. First, we assess the accuracy of the best
available predictions for this observable and find that in the low invariant
mass region, the shape is very well predicted and could be used to perform a
top mass measurement. Second, we study the effects of a heavy s-channel
resonance on the ttbar invariant mass distribution, in a model independent way.
We provide the necessary Monte Carlo tools to perform the search and outline a
simple three-step analysis.
