inclusive nature of the megajets allows an estimate of the SM background in the razor plane.

Reconstructed leptons in the final state can be included as visible objects in the reconstruction of the megajets, or they can be treated as invisible, i.e., as though they are escaping weakly interacting particles [@razor2010]. For SM background processes such as $\PW(\ell\cPgn)$+jets, the former choice yields more transversely balanced megajets and lower values of ${\ensuremath{R}\xspace}$. If the leptons are treated as invisible in these processes, the corresponds to the entire $\PW$ boson $\pt$ value, similar to the case of $\cPZ (\cPgn
\cPagn)$+jets events.

Razor variables
---------------

To the extent that the reconstructed pair of megajets accurately reflects the visible portion of the underlying parent particle decays, the kinematics of the event are equivalent to that of the pair production of heavy squarks $\PSq_1$, $\PSq_2$, with $\PSq_i\to \cPq_i \PSGczDo$, where $\PSGczDo$ denotes the LSP and $\cPq_i$ denotes the visible products of the decays as represented by the megajets.

The razor analysis approximates the unknown center-of-mass and parent particle rest frames with a razor frame defined unambiguously from measured quantities in the laboratory frame. Two observables ${\ensuremath{M_R}\xspace}$ and ${\ensuremath{M_\mathrm{T}^R}\xspace}$ estimate the heavy mass scale ${\ensuremath{M_\Delta}\xspace}$. Consider 