Search for leptoquarks coupling to third generation quarks

Three of the most significant measured deviations from standard model predictions, the anomalous magnetic moment of the muon, the enhanced decay rate $\overline{B}\to D^{(*)} \tau \overline{\nu}$ and hints of lepton universality violation in $\overline{B}\to \overline{K} \ell^+ \ell^-$ decays, can be explained through the existence of leptoquarks with large couplings to third generation quarks and masses at the TeV scale. These states can be probed at the CERN LHC in high energy pp collisions. A first search is presented for the pair production of leptoquarks coupling to a top quark and a muon using data at a centre-of-mass energy of $13\,\mathrm{TeV}$, corresponding to an integrated luminosity of $35.9\,\mathrm{fb}^{-1}$ as recorded by the CMS experiment. Combined with previous results for leptoquark decays into $\mathrm{t}\tau$ and $\mathrm{b}\nu$, this search allows for the first time to cover the full allowed parameter space of leptoquark couplings to third generation quarks. Scalar leptoquarks decaying exclusively into $\mathrm{t}\mu$, $\mathrm{t}\tau$ and $\mathrm{b}\nu$ can be excluded up to masses of $1420$, $900$ and $1080\,\mathrm{GeV}$, respectively. Leptoquarks can be excluded up to masses of $900\,\mathrm{GeV}$ for all possible combinations of branching fractions to these final states.