Hints and Combined Constraints for First Generation Leptoquarks

Abstract

We present a combined analysis of the existing hints for, and constraints on, the first generation fermion couplings of all ten leptoquark (LQ) representations. At the precision frontier we study the bounds from K → πν̄ν, K → πℓ+ℓ−, K0 − K¯0 mixing, D0 − D¯ 0 mixing and parity violation experiments (APV and Qweak), as well as a potential resolution of the Cabibbo Angle Anomaly (CAA) via LQ contributions to the β-decay. Although the CAA could be explained by the LQ representations Φ3,V3, we observe that the necessary parameter space is excluded by other observables barring cancellations between different contributions. On the high-energy side we consider direct searches for single resonant production and pair production of LQs as well as Drell-Yan-like LQ signatures. Particular emphasis is placed on the recent CMS analysis of lepton flavor universality in non-resonant di-lepton pairs. The measured deviations from SM predictions could be a signature of t-channel contributions from Φ͂ 1,Φ2,Φ3,V͂1,V2(κ2RL ≠ 0) or V3