Minimal flavor violation in the see-saw portal
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Springer
Received: March 31, 2020 Accepted: June 15, 2020 Published: June 30, 2020
Daniele Barducci,a Enrico Bertuzzo,b Andrea Caputoc and Pilar Hernandezc a
Dipartimento di Fisica Universit` a degli Studi di Roma La Sapienza and INFN Sezione di Roma, Piazzale Aldo Moro 5, 00185, Roma, Italy b Instituto de Fisica, Universidade de Sao Paulo, C.P. 66.318, 05315-970 Sao Paulo, Brazil c Institut de F´ısica Corpuscular — CSIC/Universitat de Val`encia, Parc Cient´ıfic de Paterna, Paterna, Spain
E-mail: [email protected], [email protected], [email protected], [email protected] Abstract: We consider an extension of the Standard Model with two singlet leptons, with masses in the electroweak range, that induce neutrino masses via the see-saw mechanism, plus a generic new physics sector at a higher scale, Λ. We apply the minimal flavor violation (MFV) principle to the corresponding Effective Field Theory (νSMEFT) valid at energy scales E Λ. We identify the irreducible sources of lepton flavor and lepton number violation at the renormalizable level, and apply the MFV ans¨atz to derive the scaling of the Wilson coefficients of the νSMEFT operators up to dimension six. We highlight the most important phenomenological consequences of this hypothesis in the rates for exotic Higgs decays, the decay length of the heavy neutrinos, and their production modes at present and future colliders. We also comment on possible astrophysical implications. Keywords: Neutrino Physics, Beyond Standard Model, CP violation ArXiv ePrint: 2003.08391
c The Authors. Open Access, Article funded by SCOAP3 .
https://doi.org/10.1007/JHEP06(2020)185
JHEP06(2020)185
Minimal flavor violation in the see-saw portal
Contents 1 Introduction
1
2 Setting the stage
3
3 Spurion parametrization
5 10
5 Hierarchies between the composed spurions: d=5 operators 5 5.1 Operator ON H 5 5.2 Operator ON B 5 5.3 Operator OW
14 14 15 15
6 Hierarchies between the composed spurions: d=6 operators 6.1 Spurion Sν 6.2 Spurion SN N † 6.3 Spurion Sν † Se 6.4 Additional spurions
16 16 17 17 18
7 Phenomenological implications 7.1 Exotic Higgs decay 7.2 Pair production of RH neutrinos at future lepton facilities 7.3 Searches at FCC-eh and FCC-hh 7.4 Prompt and displaced decays 7.5 Astrophysics
18 19 19 20 20 23
8 Conclusions
23
1
Introduction
The observed pattern of neutrino masses and oscillations parameters [1] calls for the existence of new physics (NP) beyond the Standard Model (SM). One of the simplest solution is to extend the SM with the right-handed (RH) chiral counterparts of the left-handed SM neutrinos, with which the new states can have Yukawa type interactions at the renormalizable level. Being electroweak (EW) singlets, the RH neutrinos NR (also dubbed sterile neutrinos) can have Majorana masses and provide a mechanism that explains the lightness of the observed neutrinos in terms of a large hierarchy between the EW scale v and
–1–
JHEP06(2020)185
4 Connection with the neutrino mass matrix
the Majorana mass scale. This
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