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Naturalising the Third Family Hypercharge Model for Neutral Current $B-$Anomalies

Published version
Peer-reviewed

Type

Article

Change log

Authors

Allanach, BC 
Davighi, Joe 

Abstract

We consider a deformation of the Third Family Hypercharge Model, which arguably makes the model more natural. Additional non-zero charges of the spontaneously broken, family-dependent U(1)F gauge symmetry are assigned to the second family leptons, and the third family leptons' charges are deformed away from their hypercharges in such a way that the U(1)F gauge symmetry remains anomaly-free. Second family U(1)F lepton charges allow a Z coupling to muons without having to assume large charged lepton mixing, which risks violating tight lepton flavour violation bounds. In this deformed version, only the bottom and top Yukawa couplings are generated at the renormalisable level, whereas the tauon Yukawa coupling is absent. The Z mediates a beyond the Standard Model contribution to an effective (b¯s)(μ¯μ) vertex in the combination C9=−9C10 and is able to fit the apparent discrepancy between Standard Model predictions in flavour changing neutral-current Bmeson decays and their measurements, whilst simultaneously avoiding current constraints from direct Z searches and other measurements, when 0.8 TeV<MZ<12.5 TeV.

Description

Keywords

hep-ph, hep-ph, hep-ex

Journal Title

European Physical Journal C: Particles and Fields

Conference Name

Journal ISSN

1124-1861
1434-6052

Volume Title

79

Publisher

Springer Nature
Sponsorship
Science and Technology Facilities Council (ST/P000681/1)
This work has been partially supported by STFC consolidated Grant ST/P000681/1. JD has been supported by The Cambridge Trust.