$SU(2)_L$ deconstruction and flavour (non)-universality

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Main Authors: Capdevila, Bernat, Crivellin, Andreas, Lizana, Javier M., Pokorski, Stefan
Format: Preprint
Published: 2024
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author Capdevila, Bernat
Crivellin, Andreas
Lizana, Javier M.
Pokorski, Stefan
author_facet Capdevila, Bernat
Crivellin, Andreas
Lizana, Javier M.
Pokorski, Stefan
contents We study two-site deconstructions of the $SU(2)_L$ gauge group factor of the SM. Models based on this approach can explain the hierarchies of the quark masses and CKM mixing between third and light families if these fields are localised on different sites by the presence of hierarchical new physics scales. The model leads to an accidental global $U(2)_q\times U(3)_u\times U(3)_d$ flavour symmetry which prevents dangerously large effects in flavour observables, making a TeV extension of the SM possible. Given the structure of the PMNS matrix in the neutrino sector, we explore different possibilities for the arrangement of the leptons on the two sites, and consider different models with $U(2)_{\ell}$ or $U(3)_{\ell}$ flavour symmetries. The phenomenology of the models is mostly governed by a massive vector triplet of $SU(2)_L$. We study the interesting interplay between LHC searches and precision observables. In particular, one of the models can give a sizeable lepton flavour universal effect in the Wilson coefficient $C_9$ while naturally suppressing contributions to $C_{10}$, as suggested by current $b\to s\ell^+\ell^-$ data, predicting simultaneously a mild positive shift in the $W$ boson mass.
format Preprint
id arxiv_https___arxiv_org_abs_2401_00848
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle $SU(2)_L$ deconstruction and flavour (non)-universality
Capdevila, Bernat
Crivellin, Andreas
Lizana, Javier M.
Pokorski, Stefan
High Energy Physics - Phenomenology
We study two-site deconstructions of the $SU(2)_L$ gauge group factor of the SM. Models based on this approach can explain the hierarchies of the quark masses and CKM mixing between third and light families if these fields are localised on different sites by the presence of hierarchical new physics scales. The model leads to an accidental global $U(2)_q\times U(3)_u\times U(3)_d$ flavour symmetry which prevents dangerously large effects in flavour observables, making a TeV extension of the SM possible. Given the structure of the PMNS matrix in the neutrino sector, we explore different possibilities for the arrangement of the leptons on the two sites, and consider different models with $U(2)_{\ell}$ or $U(3)_{\ell}$ flavour symmetries. The phenomenology of the models is mostly governed by a massive vector triplet of $SU(2)_L$. We study the interesting interplay between LHC searches and precision observables. In particular, one of the models can give a sizeable lepton flavour universal effect in the Wilson coefficient $C_9$ while naturally suppressing contributions to $C_{10}$, as suggested by current $b\to s\ell^+\ell^-$ data, predicting simultaneously a mild positive shift in the $W$ boson mass.
title $SU(2)_L$ deconstruction and flavour (non)-universality
topic High Energy Physics - Phenomenology
url https://arxiv.org/abs/2401.00848