High-$p_T$ dilepton tails and flavor physics

We investigate the impact of flavor-conserving, non-universal quark-lepton contact interactions on the dilepton invariant mass distribution in processes at the LHC. After recasting the recent ATLAS search performed at 13 TeV with 36.1 fb of data, we derive the best up-to-date limits on the full set of 36 chirality-conserving four-fermion operators contributing to the processes and estimate the sensitivity achievable at the HL-LHC. We discuss how these high- measurements can provide complementary information to the low- rare meson decays. In particular, we find that the recent hints on lepton-flavor universality violation in transitions are already in mild tension with the dimuon spectrum at high- if the flavor structure follows minimal flavor violation. Even if the mass scale of new physics is well beyond the kinematical reach for on-shell production, the signal in the high- dilepton tail might still be observed, a fact that has been often overlooked in the present literature. In scenarios where new physics couples predominantly to third generation quarks, instead, the HL-LHC phase is necessary in order to provide valuable information.