  The search for light stops is of paramount importance, both in general as a
promising path to the discovery of beyond the standard model physics and more
specifically as a way of evaluating the success of the naturalness paradigm.
While the LHC experiments have ruled out much of the relevant parameter space,
there are "stop gaps", i.e., values of sparticle masses for which existing LHC
analyses have relatively little sensitivity to light stops. We point out that
techniques involving on-shell constrained M_2 variables can do much to enhance
sensitivity in this region and hence help close the stop gaps. We demonstrate
the use of these variables for several benchmark points and describe the effect
of realistic complications, such as detector effects and combinatorial
backgrounds, in order to provide a useful toolkit for light stop searches in
particular, and new physics searches at the LHC in general.
