Flavorful leptoquarks at the LHC and beyond: spin 1

Abstract

Evidence for electron-muon universality violation that has been revealed in b → sℓℓ transitions in the observables RKK∗ by the LHCb Collaboration can be explained with spin-1 leptoquarks in SU(2)L singlet V1 or triplet V3 representations in the O(1 − 10) TeV range. We explore the sensitivity of the high luminosity LHC (HL-LHC) and future proton-proton colliders to V1 and V3 in the parameter space connected to RKK∗-data. We consider pair production and single production in association with muons in different flavor benchmarks. Reinterpreting a recent ATLAS search for scalar leptoquarks decaying to bμ and jμ, we extract improved limits for the leptoquark masses: for gauge boson-type leptoquarks (κ = 1) we obtain MV1> 1.9 TeV, MV1> 1.9 TeV, and MV1> 1.7 TeV for leptoquarks decaying predominantly according to hierarchical, flipped and democratic quark flavor structure, respectively. Future sensitivity projections based on extrapolations of existing ATLAS and CMS searches are worked out. We find that for κ = 1 the mass reach for pair (single) production of V1 can be up to 3 TeV (2.1 TeV) at the HL-LHC and up to 15 TeV (19.9 TeV) at the FCC-hh with s = 100 TeV and 20 ab−1. The mass limits and reach for the triplet V3 are similar or higher, depending on flavor. While there is the exciting possibility that leptoquarks addressing the RKK∗-anomalies are observed at the LHC, to fully cover the parameter space pp-collisions beyond the LHC-energies are needed.