The Bearable Compositeness of Leptons
Résumé
Partial compositeness as a theory of flavor in the lepton sector is assessed. We begin presenting the first systematic analysis of neutrino mass generation in this context, and identifying the distinctive mass textures. We then update the bounds from charged lepton flavor and CP violating observables. We put forward a U(1)$^{3}$ × CP symmetry of the composite sector, in order to allow the new physics to be not far above the TeV scale. This hypothesis effectively suppresses the new contributions to the electron EDM and μ → eγ, by far the most constraining observables, and results in a novel pattern of flavor violation and neutrino masses. The CP violation in the elementary-composite mixing is shown to induce a CKM phase of the correct size, as well as order-one phases in the PMNS matrix. We compare with the alternative possibility of introducing multiple scales of compositeness for leptons, that also allow to evade flavor and CP constraints. Finally, we examine violations of lepton flavor universality in B-meson semi-leptonic decays. The neutral-current anomalies can be accommodated, predicting strong correlations among different lepton flavors, with a few channels close to the experimental sensitivity.
Mots clés
Beyond Standard Model
Technicolor and Composite Models
Neutrino Physics
Effective Field Theories
lepton: composite
neutrino: mass
neutrino: mass generation
neutrino: mass: texture
CP: violation
CKM matrix
B: semileptonic decay
lepton: flavor: violation
lepton: universality: violation
lepton number: violation
electron: electric moment
numerical calculations
new physics
Fichier principal
Frigerio2018_Article_TheBearableCompositenessOfLept.pdf (1.24 Mo)
Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte