Search for Pair Production of Third-Generation Scalar Leptoquarks Using Events Produced in pp Collisions at $\sqrt{s}$ = 7 TeV Containing b-jets and Missing Transverse Energy

We perform a search for third generation leptoquarks produced in $\sqrt{s}$ = 7~TeV proton-proton collisions with 1.8~fb$^{-1}$ of data collected by the CMS experiment in 2011 at the CERN Large Hadron Collider. We search for evidence of leptoquarks decaying to a b-quark plus $\nu_{\tau}$, characterized as final state involving events with b-jets and large missing transverse energy. The analysis is using the dimensionless {\it razor} variable $R$, related to the missing transverse energy $\big\slash\hspace{-1.6ex}{E_T}$. The new physics signal is characterized by a broad peak in the distribution of $M_R$, an event-by-event indicator of the heavy particle mass scale. This approach is complementary to $\big\slash\hspace{-1.6ex}{E_T}$-based searches. No significant excess is found and a 95\% confidence level upper limit on the pair-production cross section of third generation scalar leptoquarks is set. Assuming a 100\% branching fraction to $b\nu_{\tau}$ we exclude scalar leptoquarks with masses below $\sim 350$~GeV. Limits as a function of the branching fraction are also given.