scholarly journals Minimal dirac neutrino mass models from $$\hbox {U}(1)_{\mathrm{R}}$$ gauge symmetry and left–right asymmetry at colliders

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
Sudip Jana ◽  
P. K. Vishnu ◽  
Shaikh Saad
Keyword(s):  
Dark Matter ◽  
Neutrino Mass ◽  
Discrete Symmetry ◽  
Tree Level ◽  
Mass Generation ◽  
Abelian Gauge ◽  
Dirac Neutrino ◽  
Left Right Asymmetry ◽  
Minimal Realizations ◽  
The Right

Abstract In this work, we propose minimal realizations for generating Dirac neutrino masses in the context of a right-handed abelian gauge extension of the Standard Model. Utilizing only $$U(1)_R$$U(1)R symmetry, we address and analyze the possibilities of Dirac neutrino mass generation via (a) tree-level seesaw and (b) radiative correction at the one-loop level. One of the presented radiative models implements the attractive scotogenic model that links neutrino mass with Dark Matter (DM), where the stability of the DM is guaranteed from a residual discrete symmetry emerging from $$U(1)_R$$U(1)R. Since only the right-handed fermions carry non-zero charges under the $$U(1)_R$$U(1)R, this framework leads to sizable and distinctive Left–Right asymmetry as well as Forward–Backward asymmetry discriminating from $$U(1)_{B-L}$$U(1)B-L models and can be tested at the colliders. We analyze the current experimental bounds and present the discovery reach limits for the new heavy gauge boson $$Z^{\prime }$$Z′ at the LHC and ILC. Furthermore, we also study the associated charged lepton flavor violating processes, dark matter phenomenology and cosmological constraints of these models.

scholarly journals Relaxing cosmological neutrino mass bounds with unstable neutrinos

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Miguel Escudero ◽  
Jacobo Lopez-Pavon ◽  
Nuria Rius ◽  
Stefan Sandner
Keyword(s):  
Neutrino Mass ◽  
Particle Physics ◽  
Goldstone Boson ◽  
Mass Scale ◽  
Simple Extension ◽  
Type I ◽  
Mass Generation ◽  
Age Of The Universe ◽  
Neutrino Mass Models ◽  
The Right

Abstract At present, cosmological observations set the most stringent bound on the neutrino mass scale. Within the standard cosmological model (ΛCDM), the Planck collaboration reports ∑mv< 0.12 eV at 95 % CL. This bound, taken at face value, excludes many neutrino mass models. However, unstable neutrinos, with lifetimes shorter than the age of the universe τν ≲ tU, represent a particle physics avenue to relax this constraint. Motivated by this fact, we present a taxonomy of neutrino decay modes, categorizing them in terms of particle content and final decay products. Taking into account the relevant phenomenological bounds, our analysis shows that 2-body decaying neutrinos into BSM particles are a promising option to relax cosmological neutrino mass bounds. We then build a simple extension of the type I seesaw scenario by adding one sterile state ν4 and a Goldstone boson ϕ, in which νi→ ν4ϕ decays can loosen the neutrino mass bounds up to ∑mv ∼ 1 eV, without spoiling the light neutrino mass generation mechanism. Remarkably, this is possible for a large range of the right-handed neutrino masses, from the electroweak up to the GUT scale. We successfully implement this idea in the context of minimal neutrino mass models based on a U(1)μ−τ flavor symmetry, which are otherwise in tension with the current bound on ∑mv.

scholarly journals Exploding operators for Majorana neutrino masses and beyond

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
John Gargalionis ◽  
Raymond R. Volkas
Keyword(s):  
Neutrino Mass ◽  
Model Building ◽  
Dominant Role ◽  
New Physics ◽  
Majorana Neutrino ◽  
Effective Field ◽  
Tree Level ◽  
Mass Generation ◽  
Neutrino Mass Models ◽  
Almost All

Abstract Building UV completions of lepton-number-violating effective operators has proved to be a useful way of studying and classifying models of Majorana neutrino mass. In this paper we describe and implement an algorithm that systematises this model-building procedure. We use the algorithm to generate computational representations of all of the tree-level completions of the operators up to and including mass-dimension 11. Almost all of these correspond to models of radiative neutrino mass. Our work includes operators involving derivatives, updated estimates for the bounds on the new-physics scale associated with each operator, an analysis of various features of the models, and a look at some examples. We find that a number of operators do not admit any completions not also generating lower-dimensional operators or larger contributions to the neutrino mass, ruling them out as playing a dominant role in the neutrino-mass generation. Additionally, we show that there are at most five models containing three or fewer exotic multiplets that predict new physics that must lie below 100 TeV. Accompanying this work we also make available a searchable database containing all of our results and the code used to find the completions. We emphasise that our methods extend beyond the study of neutrino-mass models, and may be useful for generating completions of high-dimensional operators in other effective field theories. Example code: ref. [37].

AN SU(2)L×U(1)L×U(1)R MODEL WITH FINITE DIRAC NEUTRINO MASSES

1993 ◽  
Vol 08 (10) ◽  
pp. 895-902 ◽  
Author(s):  
SUBHASH RAJPOOT
Keyword(s):  
Standard Model ◽  
Discrete Symmetry ◽  
Lepton Number ◽  
Tree Level ◽  
Neutrino Masses ◽  
Charged Scalar ◽  
Dirac Neutrino ◽  
Left Handed ◽  
The Standard Model ◽  
The One

An SU(2)L×U(1)L×U(1)R model of electroweak interactions is presented in which the conventional fermions of the standard model are left-handed doublets under SU(2)L× U(1)L and are right-handed singlets under U(1) R . The triangle anomalies are canceled by adding vector-like singlet fermions. Neutrinos are massless at the tree level due to a discrete symmetry and acquire tiny finite masses at the one-loop level due to the exchange of two charged scalar singlets. The singlet scalars carry two units of lepton number.

scholarly journals A hybrid seesaw model and hierarchical neutrino flavor structures based on A4 symmetry

2021 ◽  
Author(s):  
Mayumi Aoki ◽  
Daiki Kaneko
Keyword(s):  
Dark Matter ◽  
Neutrino Mass ◽  
Mass Matrix ◽  
Hierarchical Structures ◽  
Double Beta Decay ◽  
Tree Level ◽  
Dark Matter Candidate ◽  
Flavor Symmetry ◽  
Seesaw Model ◽  
Majorana Phases

Abstract We propose a hybrid seesaw model based on A4 flavor symmetry, which generates a large hierarchical flavor structure. In our model, tree-level and one-loop seesaw mechanisms predict different flavor structures in the neutrino mass matrix, and generate a notable hierarchy among them. We find that such a hierarchical structure gives a large effective neutrino mass which can be accessible by next-generation neutrinoless double beta decay experiments. Majorana phases can also be predictable. The A4 flavor symmetry in the model is spontaneously broken to the Z2 symmetry, leading to a dark matter candidate which is assumed to be a neutral scalar field. The favored mass region of the dark matter is obtained by numerical computations of the relic abundance and the cross section of the nucleon. We also investigate the predictions of the several hierarchical flavor structures based on A4 symmetry for the effective neutrino mass and the Majorana phases, and find the characteristic features depending on the hierarchical structures.

scholarly journals Neutrino lines from DM decay induced by high-scale seesaw interactions

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Rupert Coy ◽  
Thomas Hambye
Keyword(s):  
Dark Matter ◽  
Gauge Symmetry ◽  
Neutrino Mass ◽  
Gauge Boson ◽  
High Scale ◽  
Abelian Gauge ◽  
Neutrino Telescopes ◽  
The Stability ◽  
Accidental Symmetry

Abstract If the stability of the dark matter (DM) particle is due to an accidental symmetry, nothing prevents UV physics from destabilising it by inducing DM decays suppressed by powers of the UV scale. The seesaw physics, presumably at the origin of neutrino mass, could induce such a decay. We show that if the seesaw scale lies around the usual Weinberg operator scale, the induced DM decay could generically lead to neutrino lines whose intensity is of the order of the present sensitivity of neutrino telescopes. We illustrate this possibility with models in which the DM is made of the gauge boson(s) of an abelian or non-abelian gauge symmetry.

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