the steepest exponential fall-off. Backgrounds with energetic neutrinos from $\PW/\cPZ$ boson and top-quark production exhibit a slower fall-off and resemble each other closely in the asymptotic regime. Thus, razor signals are characterized by peaks in the (${\ensuremath{M_R}\xspace}$, ${\ensuremath{R^2}\xspace}$) plane on top of exponentially falling SM background distributions. Any SUSY search based on razor variables is then more similar to a “bump-hunt”, e.g., a search for heavy resonances decaying to two jets [@Harris:2011bh], than to a traditional SUSY search. This justifies the use of a shape analysis, based on an analytic fit of the background, as described in Section \[sec:fits\].

Razor megajet reconstruction
----------------------------

The razor megajets are defined by dividing the reconstructed jets of each event into two partitions. Each partition contains at least one jet. The megajet four-momenta are defined as the sum of the four-momenta of the assigned jets. Of all the possible combinations, the one that minimizes the sum of the squared-invariant-mass values of the two megajets is selected. In simulated event samples, this megajet algorithm is found to be stable against variations in the jet definition and it provides an unbiased description of the visible part of the two decay chains in SUSY signal events. The 