<p>We propose the first scotogenic neutrino mass model with gauged lepton number <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><msub><mo stretchy="false">)</mo><mi>L</mi></msub></math>, which is spontaneously broken by three units <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Δ</mi><mi>L</mi><mo>=</mo><mn>3</mn></math> down to a residual discrete gauge symmetry <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="double-struck">Z</mi><mn>6</mn></msub></math>. The latter guarantees that neutrinos acquire tiny Dirac masses via a one-loop scotogenic mechanism, simultaneously stabilizing the lightest electrically neutral particle with nontrivial charge under the preserved <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="double-struck">Z</mi><mn>6</mn></msub></math> symmetry. In our model there is a scalar particle identified as weakly interacting massive particle dark matter (DM) candidate. We analyzed its compatibility with the existing data on direct DM detection experiments and the DM relic abundance. We also address charged lepton flavor violating decays in our model and find that their predicted rates are within the reach of current experimental sensitivity.</p>

Chile

A.E. Cárcamo Hernández

Mexico

Andrés Enríquez

Sergey Kovalenko

Eduardo Peinado

Carlos Alberto Vaquera-Araujo

Dirac neutrinos and gauged lepton number

We propose an extended Left-Right symmetric model with an additional global U(1) X  symmetry, which collapses to a residual subgroup ℤ 2 after spontaneous symmetry breaking. In this model, the light active neutrino masses are generated via a double seesaw mechanism with the Dirac submatrix arising at one loop. In addition, the masses of the charged fermions of the Standard Model (SM) that are lighter than the top quark are generated at one loop level and the residual ℤ 2 symmetry ensures the stability of the Dark Matter (DM) candidate of the model. To the best of our knowledge our model has the first implementation of the radiative double seesaw mechanism with the Dirac submatrix generated at one loop level. We show that the model can successfully account for the observed pattern of the SM fermion masses and mixing, and that it is compatible with constraints arising from the muon g-2 anomaly, neutrinoless double beta decay and DM.

Paulo Areyuna C.

A. Cárcamo Hernández

Vishnudath K. N.

Sweden

Roman Pasechnik

Iván Schmidt

Left-Right model with radiative double seesaw mechanism

Abstract We propose two versions of radiative linear seesaw models, where electrically charged scalars and vector-like leptons generate the Dirac neutrino mass submatrix at the one- and two-loop levels. In these models, the Standard Model charged lepton masses are generated from a one-loop-level radiative seesaw mechanism mediated by charged exotic vector-like leptons and electrically neutral scalars running in the loops. These models can successfully accommodate the current amount of dark matter and baryon asymmetries observed in the universe, as well as the muon anomalous magnetic moment.

A E Cárcamo Hernández

Yocelyne Hidalgo Velásquez

Nicolás A Pérez-Julve

Ivan Schmidt

Models of Radiative Linear Seesaw with Electrically Charged Mediators

We propose a class of models providing an explanation of the origin of light neutrino masses, the baryon asymmetry of the Universe via leptogenesis and offering viable dark matter candidates. In these models the Majorana masses of the active neutrino are generated by the inverse seesaw mechanism with the lepton number violating right-handed Majorana neutrino masses μ arising at three loops. The latter is ensured by the preserved discrete symmetries, which also guarantee the stability of the dark matter candidate. We focus on one of these models and perform a detailed analysis of the phenomenology of its leptonic sector. The model can successfully accommodate baryogenesis through leptogenesis in both weak and strong washout regimes. The lightest heavy fermion turns out to be a viable dark matter candidate, provided that the entries of the Majorana submatrix μ are in the keV to MeV range. The solutions are consistent with the experimental constraints, accommodating both mass orderings for active neutrinos, in particular charged-lepton flavor violating decays μ → eγ, μ → eee, and the electron-muon conversion processes get sizable rates within future sensitivity reach.

France

Asmaa Abada

United Arab Emirates

Nicolás Bernal

Téssio Melo

Three-loop inverse scotogenic seesaw models

We present a Left-Right symmetric model that provides an explanation for the mass hierarchy of the charged fermions within the framework of the Standard Model. This explanation is achieved through the utilization of both tree-level and radiative seesaw mechanisms. In this model, the tiny masses of the light active neutrinos are generated via a three-loop radiative inverse seesaw mechanism, with Dirac and Majorana submatrices arising at one-loop level. To the best of our knowledge, this is the first example of the inverse seesaw mechanism being implemented with both submatrices generated at one- loop level. The model contains a global U(1) X  symmetry which, after its spontaneous breaking, allows for the stabilization of the Dark Matter (DM) candidates. We show that the electroweak precision observables, the electron and muon anomalous magnetic moments as well as the Charged Lepton Flavor Violating decays, μ → eγ, are consistent with the current experimental limits. In addition, we analyze the implications of the model for the 95 GeV diphoton excess recently reported by the CMS collaboration and demonstrate that such anomaly could be easily accommodated. Finally, we discuss qualitative aspects of DM in the considered model.

Cesar Bonilla

H. Lee

R. Pasechnik

Fermion mass hierarchy in an extended left-right symmetric model

We propose a Majoron-like extension of the Standard Model with an extra global <math><mi>U</mi><msub><mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow><mrow><mi>X</mi></mrow></msub></math>-symmetry where neutrino masses are generated through an inverse seesaw mechanism at the 1-loop level. In contrast to the tree-level inverse seesaw, our framework contains dark matter (DM) candidates stabilized by a residual <math><msub><mrow><mi>Z</mi></mrow><mrow><mn>2</mn></mrow></msub></math>-symmetry surviving spontaneous breaking of the <math><mi>U</mi><msub><mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow><mrow><mi>X</mi></mrow></msub></math>-group. We explore the case in which the DM is a Majorana fermion. Furthermore, we provide parameter space regions allowed by current experimental constraints coming from the dark matter relic abundance, (in)direct detection, and charged lepton flavor violation.

Bastián Díaz Sáez

Juan Marchant González

Dark matter from a radiative inverse seesaw majoron model

Motivated by the recent muon anomalous magnetic moment (g-2) measurement at FERMILAB and non-zero neutrino masses, we propose a model based on the <math><mi>S</mi><mi>U</mi><msub><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow><mrow><mi>C</mi></mrow></msub><mo>×</mo><mi>S</mi><mi>U</mi><msub><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow><mrow><mi>L</mi></mrow></msub><mo>×</mo><mi>U</mi><msub><mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow><mrow><mi>X</mi></mrow></msub></math> (3-3-1) gauge symmetry. The most popular 3-3-1 models in the literature require the presence of a scalar sextet to address neutrino masses. In our work, we show that we can successfully implement an one-loop linear seesaw mechanism with right-handed neutrinos, and vector-like fermions to nicely explain the active neutrino masses, and additionally reproduce the recent Muon g-2 result, in agreement with existing bounds.

Brazil

Farinaldo S. Queiroz

Yoxara S. Villamizar

An extended 3-3-1 model with radiative linear seesaw mechanism

We propose a scotogenic model for generating neutrino masses through a three-loop seesaw. It is a minimally extended inert doublet model with a spontaneously broken global symmetry U(1)′ and a preserved ℤ2 symmetry. The three-loop suppression allows the new particles to have masses at the TeV scale without fine-tuning the Yukawa couplings. The model leads to a rich phenomenology while satisfying all the current constraints imposed by neutrinoless double-beta decay, charged-lepton flavor violation, and electroweak precision observables. The relatively large Yukawa couplings lead to sizable rates for charged lepton flavor violation processes, well within future experimental reach. The model could also successfully explain the W mass anomaly and provides viable fermionic or scalar dark matter candidates.

Antonio Cárcamo Hernández

Japan

Takashi Toma

Phenomenological and cosmological implications of a scotogenic three-loop neutrino mass model

It is well-known that at tree-level the d = 5 Weinberg operator can be generated in exactly three different ways, the famous seesaw models. In this paper we study the related question of how many phenomenologically consistent 1-loop models one can construct at d=5. First, we discuss that there are two possible classes of 1-loop neutrino mass models, that allow avoiding stable charged relics: (i) models with dark matter candidates and (ii) models with “exits”. Here, we define “exits” as particles that can decay into standard model fields. Considering 1-loop models with new scalars and fermions, we find in the dark matter class a total of (115+203) models, while in the exit class we find (38+368) models. Here, 115 is the number of DM models, which require a stabilizing symmetry, while 203 is the number of models which contain a dark matter candidate, which maybe accidentally stable. In the exit class the 38 refers to models, for which one (or two) of the internal particles in the loop is a SM field, while the 368 models contain only fields beyond the SM (BSM) in the neutrino mass diagram. We then study the RGE evolution of the gauge couplings in all our 1-loop models. Many of the models in our list lead to Landau poles in some gauge coupling at rather low energies and there is exactly one model which unifies the gauge couplings at energies above 1015 GeV in a numerically acceptable way.

Carolina Arbeláez

Germany

Ricardo Cepedello

Juan Helo

Spain

Martin Hirsch

How many 1-loop neutrino mass models are there?

We consider the lepton-flavor violating (LFV) lepton-quark dimension-6 operators and analyze their contributions to the LFV leptonic decays of vector, pseudoscalar, and scalar neutral mesons  $$M\rightarrow \ell _1 \ell _2$$  <math> <mrow> <mi>M</mi> <mo>→</mo> <msub> <mi>ℓ</mi> <mn>1</mn> </msub> <msub> <mi>ℓ</mi> <mn>2</mn> </msub> </mrow> </math>   as well as to  $$\mu (\tau ) \rightarrow \ell ee, \ell \gamma \gamma $$  <math> <mrow> <mi>μ</mi> <mo>(</mo> <mi>τ</mi> <mo>)</mo> <mo>→</mo> <mi>ℓ</mi> <mi>e</mi> <mi>e</mi> <mo>,</mo> <mi>ℓ</mi> <mi>γ</mi> <mi>γ</mi> </mrow> </math>   decays. These operators contribute to the purely leptonic processes via quark loop. On the basis of quark-hadron duality, we relate these loops to the appropriate meson-exchange contributions. In this way, we extract lower bounds on the individual scales of the studied LFV operators from the experimental and phenomenological limits on the leptonic decays of mesons and leptons. As a byproduct, we shall obtain new limits on the LFV leptonic decays of flavored mesons from the experimental bounds on the three-body lepton decays. We study the effects of QED and QCD radiative corrections to the LFV lepton-quark operators in question. We derive for them the one-loop matrix of the RGE evolution and examine its effect on the previously derived tree-level limits on these operators. We show that the QED corrections are particularly relevant due to operator mixing. Specifically, for some of them the limits on their individual LFV scales improve by up to 3 orders of magnitude.

Marcela González

Nicolás Neill

Jonatan Vignatti

RGE effects on the LFV scale from meson decays