Search for Lepton Flavour Violating Decays of Heavy Resonances and Quantum Black Holes to electron/muon Pairs in pp Collisions at a centre of mass energy of 8 TeV

A search for heavy states decaying into the e$\mu$ final state has been performed using an integrated luminosity of $19.7~\text{fb}^{-1}$ of $8\,\text{TeV}$ proton-proton collision data recorded with the CMS detector at the LHC. No evidence for physics beyond the Standard Model is observed in the invariant mass spectrum of selected e$\mu$ pairs. 95$\%$ CL upper limits are set on the cross section times branching ratio of different signals arising in theories of new physics with lepton flavour violation in interactions involving charged leptons. In the framework of TeV-scale quantum gravity from a renormalization of Newton's constant, exclusion limits are set on the production threshold of quantum black holes for threshold masses below $1.99\,\text{TeV}$, and in extra-dimensional models the bounds range from $2.36\,\text{TeV}$ for one extra dimension to $3.63\,\text{TeV}$ for six extra dimensions. Scenarios of resonant tau sneutrino LSP production in R-parity violating supersymmetry are excluded for LSP masses below $1.28\,\text{TeV}$ for couplings $\lambda_{132}=\lambda'_{311}=0.01$ and below $2.11\,\text{TeV}$ for $\lambda_{132}=0.05$ and $\lambda'_{311}=0.1$.