Research Papers in Physics and Astronomy
Date of this Version
Eur. Phys. J. C (2020) 80:641 https://doi.org/10.1140/epjc/s10052-020-8210-5
Starting from a general effective Lagrangian for lepton flavor violation (LFV) in quark-lepton transitions, we derive constraints on the effective coefficients from the high-mass tails of the dilepton processes pp → ℓkℓl (with k ≠ l). The current (projected) limits derived in this paper from LHC data with 36 fb−1 (3 ab−1) can be applied to generic new physics scenarios, including the ones with scalar, vector and tensor effective operators. For purely left-handed operators, we explicitly compare these LHC constraints with the ones derived from flavor-physics observables, illustrating the complementarity of these different probes. While flavor physics is typically more constraining for quark-flavor violating operators, we find that LHC provides the most stringent limits on several flavor-conserving ones. Furthermore, we show that dilepton tails offer the best probes for charmquark transitions at current luminosities and that they provide competitive limits for tauonic b → d transitions at the highluminosity LHC phase. As a by-product, we also provide general numerical expressions for several low-energy LFV processes, such as the semi-leptonic decays K → πℓ±k ℓ∓l , B → πℓ±k ℓ∓l and B → K(∗)ℓ±k ℓ∓l .
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