Prospects for exclusion or discovery of a third generation leptoquark decaying into a $\tau$ lepton and a b quark with the upgraded CMS detector at the HL-LHC

Projections for searches for production of third generation leptoquarks (LQs) in proton-proton collisions at a center-of-mass energy of 14 TeV are presented. The projections use simulated data samples corresponding to integrated luminosities of 300 and 3000 $\mathrm{fb}^{-1}$. The analysis utilizes the DELPHES simulation package for the upgraded CMS detector at the High-Luminosity LHC, and considers both the single production channel, with a final state consisting of one b quark and two $\tau$ leptons, and the pair production channel, producing two b quarks and two $\tau$ leptons. In both cases, only $\tau$ leptons that decay hadronically are considered. Assuming a Yukawa coupling of one for the LQ-b-$\tau$ vertex, the expected 95$\%$ confidence level mass limit is 732 and 1130 GeV for integrated luminosities of 300 and 3000 $\mathrm{fb}^{-1}$ for singly-produced LQs. The corresponding limits for pair production are 1249 (1518) GeV. Discovery sensitivity (5$\sigma$) is expected to be reached for masses below 800 (1000) GeV for the single production channel and 1200 (1500) GeV for the pair production channel in the 300 (3000) $\mathrm{fb}^{-1}$ scenario. Limits are calculated both assuming negligible systematic uncertainties and utilizing ones extrapolated from searches at 13 TeV.