Physics Letters B 791 (2019) 210–214
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
Neutrino masses and mixings dynamically generated by a light dark
sector
Enrico Bertuzzo
a
, Sudip Jana
b,c,∗
, Pedro A.N. Machado
c
, Renata Zukanovich Funchal
a
a
Departamento de Física Matemática, Instituto de Física, Universidade de São Paulo, C.P. 66.318, São Paulo, 05315-970, Brazil
b
Department of Physics and Oklahoma Center for High Energy Physics, Oklahoma State University, Stillwater, OK 74078-3072, USA
c
Theory Department, Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510, USA
a r t i c l e i n f o a b s t r a c t
Article history:
Received
15 August 2018
Received
in revised form 19 December 2018
Accepted
16 February 2019
Available
online 19 February 2019
Editor:
B. Grinstein
Keywords:
Neutrino
masses
Inverse
seesaw
Light
dark sector
Neutrinos may be the harbingers of new dark sectors, since the renormalizable neutrino portal allows for
their interactions with hidden new physics. We propose here to use this fact to connect the generation of
neutrino masses to a light dark sector, charged under a new U(1)
D
dark gauge symmetry. We introduce
the minimal number of dark fields to obtain an anomaly free theory with spontaneous breaking of the
dark symmetry, and obtain automatically the inverse seesaw Lagrangian. In addition, the so-called μ-term
of the inverse seesaw is dynamically generated and technically natural in this framework. As a bonus, the
new light dark gauge boson can provide a possible explanation to the MiniBooNE anomaly.
© 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
1. Introduction
One of the most surprising experimental results of the last
decades has been the discovery of tiny neutrino masses and rel-
atively
large neutrino mixings. Although non-vanishing neutrino
masses are a clear indication of physics beyond the Standard Model
(SM), the mechanism and the scales responsible for the neutrino
mass generation remain a total mystery.
It
seems unlikely that the very small neutrino masses are gen-
erated
by the same Higgs mechanism responsible for the masses
of the other SM fermions, since extremely small Yukawa couplings,
of the order of 10
−12
, must be invoked. A more ‘natural’ way to
generate neutrino masses involve the addition of new states that,
once integrated out, generate the dimension five Weinberg opera-
tor
O
5
=
c
LLH H. (1.1)
This is embodied by the so-called seesaw mechanisms [1–4]. The
smallness of neutrino masses relative to the weak scale implies
either that the scale of new physics is very large (making
*
Corresponding author.
E-mail
addresses: bertuzzo@if.usp.br (E. Bertuzzo), sudip.jana@okstate.edu
(S. Jana),
pmachado@fnal.gov (P.A.N. Machado), zukanov@if.usp.br
(R. Zukanovich Funchal).
it impossible to experimentally discriminate the different seesaw
mechanisms), or that the Wilson coefficient c is extremely small
(for instance, coming from loop effects involving singly or doubly
charged scalars [5]).
A
different approach is given by neutrinophilic Two-Higgs-
Doublet
Models [6,7]. In this framework, a symmetry (U (1) or Z
2
)
compels one of the doublets to couple to all SM fermions but neu-
trinos,
hence being responsible for their masses, while the other
Higgs couples to the lepton doublets and right-handed neutrinos.
If the second doublet acquires a vacuum expectation value (vev)
around the eV scale, this leads to small neutrino masses. These
models, however, are either ruled out or severely constrained by
electroweak precision data and low energy flavor physics [8,9].
A
variation of this idea, in which the symmetry is taken to be a
local U(1) and leads to the typical Lagrangian of the inverse see-
saw
scenario, suffers from an accidental lepton number symmetry
that has to be explicitly broken to avoid the presence of a massless
Nambu-Goldstone boson in the spectrum [10]. All aforementioned
models have one of the two following features: (i) The model is
realized at very high scales, or (ii) the model is based on explicit
breaking of lepton number or other symmetries that protect neu-
trino
masses (e.g. in TeV scale type II or inverse seesaw models).
Neutrinos,
however, are the darkest between the SM particles,
in the sense that they can couple through the renormalizable neu-
trino
portal LH operator with generic dark sectors [11]. This fact
has been used in connection to thermal Dark Matter with mass in
the sub-GeV region (see for instance Refs. [12,13]). In this letter we
https://doi.org/10.1016/j.physletb.2019.02.023
0370-2693/
© 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by
SCOAP
3
.