Global analysis of μ → e interactions in the SMEFT

Abstract We study current experimental bounds on charged lepton flavor violating (CLFV) μ – e interactions in the model-independent framework of the Standard Model Effective Field Theory (SMEFT). Assuming a generic flavor structure in the quark sector, we consider the contributions of CLFV operators...

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Main Authors: Filippo Delzanno, Kaori Fuyuto, Sergi Gonzàlez-Solís, Emanuele Mereghetti
Format: Article
Language:English
Published: SpringerOpen 2025-07-01
Series:Journal of High Energy Physics
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Online Access:https://doi.org/10.1007/JHEP07(2025)283
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author Filippo Delzanno
Kaori Fuyuto
Sergi Gonzàlez-Solís
Emanuele Mereghetti
author_facet Filippo Delzanno
Kaori Fuyuto
Sergi Gonzàlez-Solís
Emanuele Mereghetti
author_sort Filippo Delzanno
collection DOAJ
description Abstract We study current experimental bounds on charged lepton flavor violating (CLFV) μ – e interactions in the model-independent framework of the Standard Model Effective Field Theory (SMEFT). Assuming a generic flavor structure in the quark sector, we consider the contributions of CLFV operators to low-energy observables, including μ → eγ and μ → e conversion for quark-flavor conserving operators and CLFV meson decays for quark-flavor violating operators. At high energy, we consider limits on CLFV decays of the Higgs and Z bosons and of the top quark, and obtain bounds on operators with light quarks by recasting searches for production of eμ pairs in pp collisions at the Large Hadron Collider (LHC). We connect observables at low- and high-energy by taking into account renormalization group running and matching between CLFV operators. We also discuss the sensitivity of the future Electron-Ion Collider, where the prospective bounds are derived by imposing simple cuts on final state particles. We find that, in a single operator scenario, bounds on purely leptonic operators are dominated by μ → eγ and μ → e conversion. Semileptonic operators with down-type quarks are also dominantly constrained by low-energy observables, while LHC searches lead the bounds on up-type quark-flavor violating operators. Taking simplified multiple-coupling scenarios, we show that it is easy to evade the strongest low-energy bounds from spin-independent μ → e conversion, and that collider searches are competitive and complementary to constraints from spin-dependent μ → e conversion and other low-energy probes.
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spelling doaj-art-eee41f8161ff43eab028382ee3d4b18c2025-08-20T04:01:43ZengSpringerOpenJournal of High Energy Physics1029-84792025-07-012025715110.1007/JHEP07(2025)283Global analysis of μ → e interactions in the SMEFTFilippo Delzanno0Kaori Fuyuto1Sergi Gonzàlez-Solís2Emanuele Mereghetti3Department of Physics, University of California Santa BarbaraTheoretical Division, Los Alamos National LaboratoryTheoretical Division, Los Alamos National LaboratoryTheoretical Division, Los Alamos National LaboratoryAbstract We study current experimental bounds on charged lepton flavor violating (CLFV) μ – e interactions in the model-independent framework of the Standard Model Effective Field Theory (SMEFT). Assuming a generic flavor structure in the quark sector, we consider the contributions of CLFV operators to low-energy observables, including μ → eγ and μ → e conversion for quark-flavor conserving operators and CLFV meson decays for quark-flavor violating operators. At high energy, we consider limits on CLFV decays of the Higgs and Z bosons and of the top quark, and obtain bounds on operators with light quarks by recasting searches for production of eμ pairs in pp collisions at the Large Hadron Collider (LHC). We connect observables at low- and high-energy by taking into account renormalization group running and matching between CLFV operators. We also discuss the sensitivity of the future Electron-Ion Collider, where the prospective bounds are derived by imposing simple cuts on final state particles. We find that, in a single operator scenario, bounds on purely leptonic operators are dominated by μ → eγ and μ → e conversion. Semileptonic operators with down-type quarks are also dominantly constrained by low-energy observables, while LHC searches lead the bounds on up-type quark-flavor violating operators. Taking simplified multiple-coupling scenarios, we show that it is easy to evade the strongest low-energy bounds from spin-independent μ → e conversion, and that collider searches are competitive and complementary to constraints from spin-dependent μ → e conversion and other low-energy probes.https://doi.org/10.1007/JHEP07(2025)283Lepton Flavour Violation (charged)SMEFT
spellingShingle Filippo Delzanno
Kaori Fuyuto
Sergi Gonzàlez-Solís
Emanuele Mereghetti
Global analysis of μ → e interactions in the SMEFT
Journal of High Energy Physics
Lepton Flavour Violation (charged)
SMEFT
title Global analysis of μ → e interactions in the SMEFT
title_full Global analysis of μ → e interactions in the SMEFT
title_fullStr Global analysis of μ → e interactions in the SMEFT
title_full_unstemmed Global analysis of μ → e interactions in the SMEFT
title_short Global analysis of μ → e interactions in the SMEFT
title_sort global analysis of μ e interactions in the smeft
topic Lepton Flavour Violation (charged)
SMEFT
url https://doi.org/10.1007/JHEP07(2025)283
work_keys_str_mv AT filippodelzanno globalanalysisofmeinteractionsinthesmeft
AT kaorifuyuto globalanalysisofmeinteractionsinthesmeft
AT sergigonzalezsolis globalanalysisofmeinteractionsinthesmeft
AT emanuelemereghetti globalanalysisofmeinteractionsinthesmeft