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Z′models with less-minimal flavour violation


Crivellin, Andreas; Kirk, Fiona; Manzari, Andrea (2019). Z′models with less-minimal flavour violation. arXiv.org 1910.00014, University of Zurich.

Abstract

We study the phenomenology of simplified Z′ models with a global U(2)3 flavour symmetry in the quark sector, broken solely by the Standard Model Yukawa couplings. This flavour symmetry, known as less-minimal flavour violation, protects ΔF=2 processes from dangerously large new physics (NP) effects, and at the same time provides a free complex phase in b→s transitions, allowing for an explanation of the hints for additional direct CP violation in kaon decays (ϵ′/ϵ) and in hadronic B-decays (B→Kπ puzzle). Furthermore, once the couplings of the Z′ boson to the leptons are included, it is possible to address the intriguing hints for NP (above the 5σ level) in b→sℓ+ℓ− transitions. Taking into account all flavour observables in a global fit, we find that ϵ′/ϵ, the B→Kπ puzzle and b→sℓ+ℓ− data can be explained simultaneously. Sizeable CP violation in b→sℓ+ℓ− observables, in particular A8, is predicted, which can be tested in the near future, and an explanation of the B→Kπ and ϵ′/ϵ puzzles leads to effects in di-jet tails at the LHC, that are not far below the current limits. Once b→sℓ+ℓ− is included, cancellations in di-muon tails, possibly by a second Z′, are required by LHC data.

Abstract

We study the phenomenology of simplified Z′ models with a global U(2)3 flavour symmetry in the quark sector, broken solely by the Standard Model Yukawa couplings. This flavour symmetry, known as less-minimal flavour violation, protects ΔF=2 processes from dangerously large new physics (NP) effects, and at the same time provides a free complex phase in b→s transitions, allowing for an explanation of the hints for additional direct CP violation in kaon decays (ϵ′/ϵ) and in hadronic B-decays (B→Kπ puzzle). Furthermore, once the couplings of the Z′ boson to the leptons are included, it is possible to address the intriguing hints for NP (above the 5σ level) in b→sℓ+ℓ− transitions. Taking into account all flavour observables in a global fit, we find that ϵ′/ϵ, the B→Kπ puzzle and b→sℓ+ℓ− data can be explained simultaneously. Sizeable CP violation in b→sℓ+ℓ− observables, in particular A8, is predicted, which can be tested in the near future, and an explanation of the B→Kπ and ϵ′/ϵ puzzles leads to effects in di-jet tails at the LHC, that are not far below the current limits. Once b→sℓ+ℓ− is included, cancellations in di-muon tails, possibly by a second Z′, are required by LHC data.

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Additional indexing

Item Type:Working Paper
Communities & Collections:07 Faculty of Science > Physics Institute
Dewey Decimal Classification:530 Physics
Language:English
Date:2019
Deposited On:06 Jan 2020 15:38
Last Modified:07 Aug 2020 03:40
Series Name:arXiv.org
ISSN:2331-8422
OA Status:Green
Related URLs:https://arxiv.org/abs/1910.00014

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