High- pT dilepton tails and flavor physics

Abstract

We investigate the impact of flavor-conserving, non-universal quark-lepton contact interactions on the dilepton invariant mass distribution in pp→ℓ+ℓ- processes at the LHC. After recasting the recent ATLAS search performed at 13 TeV with 36.1 fb- 1 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-pT measurements can provide complementary information to the low-pT rare meson decays. In particular, we find that the recent hints on lepton-flavor universality violation in b→ sμ+μ- transitions are already in mild tension with the dimuon spectrum at high-pT 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-pT 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.