used to constrain the parameter space of SUSY models.

This paper is structured as follows. The definition of the razor variables is given in Section \[sec:prd-razor\]. The trigger and offline event selection are discussed in Section \[sec:datana\]. The features of the signal and background kinematic distributions are described in Section \[sec:mc-ana\]. In Section \[sec:BKG2011\] we describe the sources of SM background, and in Section \[sec:fits\] the analytic model used to characterize this background in the signal regions. Systematic uncertainties are discussed in Section \[sec:systematics\]. The interpretation of the results is presented in Section \[sec:INTERP2011\] in terms of exclusion limits on squark and gluino production in the context both of the constrained minimal SUSY model (CMSSM) [@Chamseddine:1982jx; @Barbieri:1982eh; @Hall:1983iz] and for some simplified model spectra (SMS) [@ArkaniHamed:2007fw; @Alwall-2; @Alwall-1; @Alwall:2008va; @Alves:2011wf]. Section \[sec:summary\] contains a summary. For the CMSSM, exclusion limits are provided as a function of the universal scalar and fermion mass values at the unification scale, respectively denoted ${\ensuremath{m_0}\xspace}$ and ${\ensuremath{m_{1/2}}\xspace}$. For the SMS, limits are provided in terms of the masses of the produced SUSY partner and the LSP.

The razor approach\[sec:prd-razor\]
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The razor kinematic variables are designed to be sensitive to processes involving the pair-production of 