Lepton flavor violation and dilepton tails at the LHC

Authors

• Andrei Angelescu, University of Nebraska-Lincoln
• Darius A. Faroughy, Universität Zürich
• Olcyr Sumensari, Università di Padova, Istituto Nazionale Fisica Nucleare

Document Type

Article

Date of this Version

7-19-2020

Citation

Eur. Phys. J. C (2020) 80:641 https://doi.org/10.1140/epjc/s10052-020-8210-5

Comments

Used by permission

Abstract

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 → ℓ_kℓ_l (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 .