Data driven flavour model
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Regular Article - Theoretical Physics
Data driven flavour model F. Arias-Aragón1,a , C. Bouthelier-Madre2,3,b , J. M. Cano1,c , L. Merlo1,d 1
Departamento de Física Teórica and Instituto de Física Teórica UAM/CSIC, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain 2 Departamento de Física Teórica, Universidad de Zaragoza, 50009 Zaragoza, Spain 3 Instituto de Biocomputación y Física de Sistemas Complejos, Universidad de Zaragoza, 50018 Zaragoza, Spain
Received: 30 March 2020 / Accepted: 25 August 2020 © The Author(s) 2020
Abstract A bottom-up approach has been adopted to identify a flavour model that agrees with present experimental measurements. The charged fermion mass hierarchies suggest that only the top Yukawa term should be present at the renormalisable level. Similarly, describing the lightness of the active neutrinos through the type-I Seesaw mechanism, right-handed neutrino mass terms should also be present at the renormalisable level. The flavour symmetry of the Lagrangian including the fermionic kinetic terms and only the top Yukawa is then a combination of U (2) and U (3) factors. Once considering the Majorana neutrino terms, the associated symmetry is O(3). Lighter charged fermion and active neutrino masses and quark and lepton mixings arise considering specific spurion fields à la Minimal Flavour Violation. The associated phenomenology is investigated and the model turns out to have almost the same flavour protection as the Minimal Flavour Violation in both quark and lepton sectors. Promoting the spurions to dynamical fields, the associated scalar potential is also studied and a minimum is identified such that fermion masses and mixings are correctly reproduced. Very precise predictions for the Majorana phases follow from the minimisation of the scalar potential and thus the neutrinoless-double-beta decay may represent a smoking gun for the model.
Contents 1 Introduction . . . . . . . . . . . . . . . 2 Data driven flavour model . . . . . . . . 3 Phenomenological analysis . . . . . . . 3.1 Phenomenology in the quark sector .
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a e-mail:
[email protected] (corresponding author)
b e-mail:
[email protected]
c e-mail:
[email protected]
d e-mail:
[email protected]
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3.1.1 Dimension 6 operators and bounds on the NP scale . . . . . . . . . . . . . . . . . . 3.2 Phenomenology in the lepton sector . . . . . . 3.2.1 Dimension 6 operators and prospects for LFV and 0ν2β decay . . . . . . . . . . . 4 Flavon scalar potential . . . . . . . . . . . . . . . . 4.1 The quark sector . . . . . . . . . . . . . . . . 4.1.1 Minimisation of the scalar potential . . . 4.2 The lepton sector . . . . . . . . . . . . . . . . 4.2.1 Minimisation of the scalar potential . . . 5 Conclusions . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . .
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1 Introduction The seek of an explanation for the heterogeneity of fermion masses and mixings is nowadays one
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