Search for pair production of third-generation scalar leptoquarks and stops

A search for pair production of heavy scalar particles is presented using events from a data sample of pp collisions corresponding to an integrated luminosity of 19.7 fb$^{-1}$, collected by the CMS detector at the LHC with $\sqrt{s}=8$ TeV. The number of observed events is found to be in agreement with the standard model prediction. A 95\% CL limit is set on the scalar particle pair production cross section times decay branching fraction. Third generation scalar leptoquarks with masses below 740 GeV are excluded at the 95\% CL, assuming 100\% braching fraction for the leptoquark decay to pair of a $\tau$ lepton and a b quark. This limit also directly constrains supersymmetric top partners, stops, decaying via an R-parity violating coupling $\lambda^{\prime}_{333}$. A limit is also set on the cross section times branching fraction for stop pair production decaying via a mixture of both R-parity conserving and violating couplings. Stop quarks in this model with masses below 576 GeV are excluded at the 95\% CL.