Search for high-mass resonances and quantum black holes in the $e\mu$ final state in proton-proton collisions at $\sqrt{s}=13~\mathrm{TeV}$

A search for heavy resonances decaying into $e\mu$ final states has been performed using an integrated luminosity of $2.7~\mathrm{fb}^{-1}$ of $13~\mathrm{TeV}$ 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. Upper limits at $95\%$ CL are set on the cross section times branching ratio of different signal benchmark models foreseeing lepton flavour violation in interactions involving charged leptons. Scenarios of resonant $\tau$ sneutrino production in R-parity violating supersymmetry are excluded for masses below $1.0~\mathrm{TeV}$ for couplings $\lambda_{132}=\lambda_{231}=\lambda'_{311}=0.01$ and below $3.3~\mathrm{TeV}$ for $\lambda_{132}=\lambda_{231}=\lambda'_{311}=0.2$. The observed invariant mass spectrum is also interpreted in terms of the non-resonant signal of Quantum Black Hole (QBH) production in models with extra dimensions. The observed exclusion limits range from $2.5~\mathrm{TeV}$ for one extra dimension to $4.5~\mathrm{TeV}$ for six extra dimensions.