The full lepton flavor of the littlest Higgs model with T-parity

• Published in: The journal of high energy physics Vol. 2019; no. 7; pp. 1 - 45
• Main Authors: del Aguila, Francisco, Ametller, Lluis, Illana, Jose Ignacio, Santiago, Jose, Talavera, Pere, Vega-Morales, Roberto
• Format: Journal Article Publication
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.07.2019; Springer Nature B.V; Springer; SpringerOpen
• Subjects: Beyond Standard Model; Broken symmetry; Classical and Quantum Gravitation; Couplings; Effective Field Theories; Elementary Particles; Fermions; Flavor (particle physics); Física; Higgs Physics; High energy physics; Large Hadron Collider; Leptons; Mathematical models; Misalignment; Momentum transfer; Parameters; Parity; Particle beams; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Theoretical Physics; Relativity Theory; String Theory; Supersymmetry; Àrees temàtiques de la UPC; Effective Field Theories; Beyond Standard Model; Higgs Physics
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP07(2019)154

A bstract We re-examine lepton flavor violation (LFV) in the Littlest Higgs model with T-parity (LHT) including the full T-odd (non-singlet) lepton and Goldstone sectors. The heavy leptons induce two independent sources of LFV associated with the couplings necessary to give masses to the T-odd mirror fermions and to their partners in right-handed SO(5) multiplets, respectively. The latter, which have been neglected in the past, can be decoupled from gauge mediated processes but not from Higgs mediated ones and must therefore also be included in a general analysis of LFV in the LHT. We also further extend previous analyses by considering on-shell Z and Higgs LFV decays together with the LFV processes at low momentum transfer. We show that current experimental limits can probe the LHT parameter space up to global symmetry breaking scales f ∼ 10 TeV. For lower f values ≳ 1 TeV, μ − e transitions require the misalignment between the heavy and the Standard Model charged leptons to be ≲ 1%. Future LFV experiments using intense muon beams should be sensitive to misalignments below the per mille level. For τ LFV transitions, which could potentially be observed at Belle II and the LHC as well as future lepton colliders, we find that generically they can not discriminate between the LHT and supersymmetric models though in some regions of parameter space this may be possible.