Combined Constraints On First Generation Leptoquarks

In this article we perform a combined analysis of low energy precision constraints and LHC searches for leptoquarks which couple to first generation fermions. Considering all ten leptoquark representations, five scalar and five vector ones, we study at the precision frontier the constraints from K -> pi nu nu, K -> pi e(+)e(-), K-0 - (K) over bar (0) and D-0 - (D) over bar (0) mixing, as well as from experiments searching for parity violation (atomic parity violation experiments and Qweak). We include LHC searches for s-channel single resonant production, pair production and Drell-Yan-like signatures of leptoquarks. Interestingly, we find that the recent nonresonant dilepton analysis of ATLAS provides stronger bounds than the resonant searches recasted so far to constrain t-channel production of leptoquarks. Taking into account all these bounds, we observe that none of the leptoquark representations can address the so-called "Cabibbo-angle anomaly" via a direct contribution to superallowed beta decays.