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Gauging the accidental symmetries of the standard model, and implications for the flavor anomalies

Published version
Peer-reviewed

Type

Article

Change log

Authors

Altmannshofer, Wolfgang 
Davighi, Joe 
Nardecchia, Marco 

Abstract

We explore the possibility that lepton family numbers and baryon number are such good symmetries of Nature because they are the global remnant of a spontaneously broken gauge symmetry. An almost arbitrary linear combination of these symmetries (together with a component of global hypercharge) can be consistently gauged, if the Standard Model (SM) fermion content is augmented by three chiral SM singlet states. Within this framework of U(1) extensions of the SM one generically expects flavour non-universality to emerge in the charged leptons, in such a way that naturally prevents lepton flavour violation, by aligning the mass and weak eigenbases. For quarks, all the SM Yukawa couplings responsible for their observed masses and mixings arise at the renormalisable level. We perform fits to show that models in this class can explain RK(∗) and the other neutral current B anomaly data if we introduce a heavy vector-like quark to mediate the required quark flavour violation, while simultaneously satisfying other constraints from direct Z searches at the LHC, Bs meson mixing, a number of electroweak precision observables, and neutrino trident production. Within this symmetry-motivated framework of models, we find interesting implications for the flavour anomalies; notably, any axial couplings of the Z to electrons and muons must be flavour universal, with the flavour universality violation arising solely from the vector-like couplings. We also comment on the generation of neutrino masses in these models.

Description

Keywords

hep-ph, hep-ph

Journal Title

PHYSICAL REVIEW D

Conference Name

Journal ISSN

2470-0010
2470-0029

Volume Title

101

Publisher

American Physical Society (APS)
Sponsorship
Science and Technology Facilities Council (ST/P000681/1)
STFC (ST/T000694/1)