scholarly journals MUONIUM–ANTIMUONIUM OSCILLATIONS AND MASSIVE MAJORANA NEUTRINOS

2004 ◽  
Vol 19 (04) ◽  
pp. 297-306 ◽  
Author(s):  
T. E. CLARK ◽  
S. T. LOVE
Keyword(s):  
Matrix Element ◽  
Interesting Case ◽  
Neutrino Masses ◽  
Leading Order ◽  
Seesaw Mechanism ◽  
The Standard Model ◽  
Oscillation Process ◽  
Majorana Neutrinos ◽  
Order Matrix Element ◽  
Neutrino Masses And Mixings

The electron and muon number violating muonium–antimuonium oscillation process can proceed provided that neutrinos have nonzero masses and mix among the various generations. Modifying the Standard Model only by the inclusion of singlet right-handed neutrino fields and allowing for general neutrino masses and mixings, the leading order matrix element contributing to this process is computed. For the particularly interesting case where the neutrino masses are generated by a seesaw mechanism with a very large Majorana mass MR≫MW, it is found that both the very light and very heavy Majorana neutrinos each give comparable contributions to the oscillation time scale proportional to [Formula: see text]. Present experimental limits set by the non-observation of the oscillation process sets a lower limit on MR of roughly of order 104 GeV.

scholarly journals GAUGE INVARIANCE OF THE MUONIUM–ANTIMUONIUM OSCILLATION TIME SCALE AND LIMITS ON RIGHT-HANDED NEUTRINO MASSES

2009 ◽  
Vol 24 (05) ◽  
pp. 335-348 ◽  
Author(s):  
BOYANG LIU
Keyword(s):  
Gauge Invariance ◽  
Time Scale ◽  
Mass Scale ◽  
Neutrino Masses ◽  
Leading Order ◽  
Seesaw Mechanism ◽  
The Standard Model ◽  
Oscillation Process ◽  
Majorana Neutrinos ◽  
Order Matrix Element

The gauge invariance of the muonium–antimuonium [Formula: see text] oscillation time scale is explicitly demonstrated in the Standard Model modified only by the inclusion of singlet right-handed neutrinos and allowing for general renormalizable interactions. The seesaw mechanism is exploited resulting in three light Majorana neutrinos and three heavy Majorana neutrinos with mass scale MR≫MW. The leading order matrix element contribution to the [Formula: see text] oscillation process is computed in Rξ gauge and shown to be ξ-independent thereby establishing the gauge invariance to this order. Present experimental limits resulting from the non-observation of the oscillation process sets a lower limit on MR roughly of order 600 GeV.

scholarly journals Complete leading-order standard model corrections to quantum leptogenesis

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Paul Frederik Depta ◽  
Andreas Halsch ◽  
Janine Hütig ◽  
Sebastian Mendizabal ◽  
Owe Philipsen
Keyword(s):  
Standard Model ◽  
Gauge Coupling ◽  
Thermal Bath ◽  
Leading Order ◽  
Boltzmann Equations ◽  
The Standard Model ◽  
Majorana Neutrinos ◽  
Infinite Loop ◽  
First Time ◽  
The Universe

Abstract Thermal leptogenesis, in the framework of the standard model with three additional heavy Majorana neutrinos, provides an attractive scenario to explain the observed baryon asymmetry in the universe. It is based on the out-of-equilibrium decay of Majorana neutrinos in a thermal bath of standard model particles, which in a fully quantum field theoretical formalism is obtained by solving Kadanoff-Baym equations. So far, the leading two-loop contributions from leptons and Higgs particles are included, but not yet gauge corrections. These enter at three-loop level but, in certain kinematical regimes, require a resummation to infinite loop order for a result to leading order in the gauge coupling. In this work, we apply such a resummation to the calculation of the lepton number density. The full result for the simplest “vanilla leptogenesis” scenario is by $$ \mathcal{O} $$ O (1) increased compared to that of quantum Boltzmann equations, and for the first time permits an estimate of all theoretical uncertainties. This step completes the quantum theory of leptogenesis and forms the basis for quantitative evaluations, as well as extensions to other scenarios.

scholarly journals THE PROBLEM OF NEUTRINO MASSES IN EXTENSIONS OF THE STANDARD MODEL

2001 ◽  
Vol 16 (32) ◽  
pp. 5101-5199 ◽  
Author(s):  
ISABELLA MASINA
Keyword(s):  
Proton Decay ◽  
Fine Tuning ◽  
Neutrino Masses ◽  
Flavor Symmetry ◽  
Mixing Angle ◽  
Grand Unified Theories ◽  
Triplet Splitting ◽  
Fermion Masses ◽  
The Standard Model ◽  
Neutrino Masses And Mixings

We review the problem of neutrino masses and mixings in the context of grand unified theories. After a brief summary of the present experimental status of neutrino physics, we describe how the see-saw mechanism can automatically account for the large atmospheric mixing angle. We provide two specific examples where this possibility is realized by means of a flavor symmetry. We then review in some detail the various severe problems which plague minimal GUT models (like the doublet–triplet splitting and proton-decay) and which force us to investigate the possibility of constructing more elaborate but realistic models. We then show an example of a quasirealistic SUSY SU(5) model which, by exploiting the crucial presence of an Abelian flavor symmetry, does not require any fine-tuning and predicts a satisfactory phenomenology with respect to coupling unification, fermion masses and mixings and bounds from proton decay.

scholarly journals Radiative Corrections toMhfrom Three Generations of Majorana Neutrinos and Sneutrinos

2015 ◽  
Vol 2015 ◽  
pp. 1-26 ◽  
Author(s):  
S. Heinemeyer ◽  
J. Hernandez-Garcia ◽  
M. J. Herrero ◽  
X. Marcano ◽  
A. M. Rodriguez-Sanchez
Keyword(s):  
Higgs Boson ◽  
Higgs Mass ◽  
Critical Discussion ◽  
Full Detail ◽  
Neutrino Masses ◽  
Type I ◽  
Radiative Corrections ◽  
Seesaw Mechanism ◽  
Three Generations ◽  
Majorana Neutrinos

We study the radiative corrections to the mass of the lightest Higgs boson of the MSSM from three generations of Majorana neutrinos and sneutrinos. The spectrum of the MSSM is augmented by three right handed neutrinos and their supersymmetric partners. A seesaw mechanism of type I is used to generate the physical neutrino masses and oscillations that we require to be in agreement with present neutrino data. We present a full one-loop computation of these Higgs mass corrections and analyze in full detail their numerical size in terms of both the MSSM and the new (s)neutrino parameters. A critical discussion on the different possible renormalization schemes and their implications, in particular concerning decoupling, is included.

scholarly journals Baryogenesis and dark matter in U(1) extensions

2017 ◽  
Vol 32 (15) ◽  
pp. 1740005 ◽  
Author(s):  
Wan-Zhe Feng ◽  
Pran Nath
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Lepton Number ◽  
Current Data ◽  
Neutrino Masses ◽  
Neutrino Experiment ◽  
The Standard Model ◽  
Reactor Neutrino ◽  
The Universe ◽  
Neutrino Masses And Mixings

A brief review is given of some recent works where baryogenesis and dark matter have a common origin within the U(1) extensions of the Standard Model (SM) and of the minimal supersymmetric Standard Model (MSSM). The models considered generate the desired baryon asymmetry and the dark matter to baryon ratio. In one model, all of the fundamental interactions do not violate lepton number, and the total [Formula: see text] in the Universe vanishes. In addition, one may also generate a normal hierarchy of neutrino masses and mixings in conformity with the current data. Specifically, one can accommodate [Formula: see text] consistent with the data from Daya Bay reactor neutrino experiment.

NEUTRINO MASSES AND MIXINGS IN SO(10)M

2000 ◽  
Vol 15 (01) ◽  
pp. 15-22 ◽  
Author(s):  
M. ABUD ◽  
F. BUCCELLA ◽  
F. TRAMONTANO ◽  
D. FALCONE ◽  
G. RICCIARDI
Keyword(s):  
Neutrino Masses ◽  
Solar Oscillations ◽  
Seesaw Mechanism ◽  
The Right ◽  
Neutrino Masses And Mixings ◽  
Good Agreement

Assuming a Zee-like matrix for the right-handed neutrino Majorana masses in the seesaw mechanism, one gets maximal mixing for vacuum solar oscillations, a very small value for Ue3 and an approximate degeneracy for the two lower neutrino masses. The scale of right-handed neutrino Majorana masses is in good agreement with the value expected in an SO (10)M model with Pati–Salam SU (4)× SU (2)× SU (2) intermediate symmetry.

scholarly journals Supersymmetric U(1)Y′⊗ U(1)B−L extension of the Standard Model

2017 ◽  
Vol 32 (16) ◽  
pp. 1750093 ◽  
Author(s):  
J. C. Montero ◽  
V. Pleitez ◽  
B. L. Sánchez-Vega ◽  
M. C. Rodriguez
Keyword(s):  
Gauge Symmetry ◽  
Mass Spectra ◽  
Tree Level ◽  
Neutrino Masses ◽  
Type I ◽  
Seesaw Mechanism ◽  
Active Neutrino ◽  
Supersymmetric Version ◽  
Fermion Masses ◽  
The Standard Model

We build a supersymmetric version with [Formula: see text] gauge symmetry, where [Formula: see text] is a new charge and [Formula: see text] and [Formula: see text] are the usual baryonic and leptonic numbers. The model has three right-handed neutrinos with identical [Formula: see text] charges, and can accommodate all fermion masses at the tree level. In particular, the type I seesaw mechanism is implemented for the generation of the active neutrino masses. We obtain the mass spectra of all sectors and for the scalar one we also give the flat directions allowed by the model.

scholarly journals Heavy right-handed neutrino dark matter in left–right models

2017 ◽  
Vol 32 (15) ◽  
pp. 1740007 ◽  
Author(s):  
P. S. Bhupal Dev ◽  
Rabindra N. Mohapatra ◽  
Yongchao Zhang
Keyword(s):  
Dark Matter ◽  
Mass Range ◽  
Neutrino Masses ◽  
Seesaw Mechanism ◽  
Leptonic Sector ◽  
Active Neutrino ◽  
The Standard Model ◽  
The Stability ◽  
The Universe

We show that in a class of non-supersymmetric left–right extensions of the Standard Model (SM), the lightest right-handed neutrino (RHN) can play the role of thermal Dark Matter (DM) in the Universe for a wide mass range from TeV to PeV. Our model is based on the gauge group [Formula: see text] in which a heavy copy of the SM fermions is introduced and the stability of the RHN DM is guaranteed by an automatic [Formula: see text] symmetry present in the leptonic sector. In such models, the active neutrino masses are obtained via the type-II seesaw mechanism. We find a lower bound on the RHN DM mass of order TeV from relic density constraints, as well as a unitarity upper bound in the multi-TeV to PeV scale, depending on the entropy dilution factor. The RHN DM could be made long-lived by soft-breaking of the [Formula: see text] symmetry and provides a concrete example of decaying DM interpretation of the PeV neutrinos observed at IceCube.

scholarly journals NEUTRINO PHYSICS (THEORY)

2005 ◽  
Vol 20 (22) ◽  
pp. 5254-5265 ◽  
Author(s):  
PAUL LANGACKER
Keyword(s):  
Neutrino Physics ◽  
Standard Model ◽  
Neutrino Masses ◽  
Bottom Up ◽  
Basic Framework ◽  
The Standard Model ◽  
The Status ◽  
Neutrino Masses And Mixings

Nonzero neutrino masses are the first definitive need to extend the standard model. After reviewing the basic framework, I describe the status of some of the major issues, including tests of the basic framework of neutrino masses and mixings; the question of Majorana vs. Dirac; the spectrum, mixings, and number of neutrinos; models, with special emphasis on constraints from typical superstring constructions (which are not consistent with popular bottom-up assumptions); and other implications.

scholarly journals Natural Higgs inflation, gauge coupling unification, and neutrino masses

2020 ◽  
Vol 35 (21) ◽  
pp. 2050117
Author(s):  
Heng-Yu Chen ◽  
Ilia Gogoladze ◽  
Shan Hu ◽  
Tianjun Li ◽  
Lina Wu
Keyword(s):  
Top Quark ◽  
Gauge Coupling ◽  
Neutrino Masses ◽  
Type I ◽  
Mass Generation ◽  
Vacuum Stability ◽  
Seesaw Mechanism ◽  
Quark Masses ◽  
The Standard Model ◽  
Neutrino Mass Generation

We present a class of nonsupersymmetric models in which the so-called critical Higgs inflation [Formula: see text] can be naturally realized without using specific values for Higgs and top quark masses. In these scenarios, the Standard Model (SM) vacuum stability problem, gauge coupling unification, neutrino mass generation and Higgs inflation mechanism are linked to each other. We adopt in our models Type I seesaw mechanism for neutrino masses. An appropriate choice of the Type I seesaw scale allows us to have an arbitrarily small but positive value of SM Higgs quartic coupling around the inflation scale. We present a few benchmark points where we show that the scalar spectral indices are around 0.9626 and 0.9685 for the number of [Formula: see text]-folding [Formula: see text] and [Formula: see text], respectively. The tensor-to-scalar ratios are of the order of [Formula: see text]. The running of the scalar spectral index is negative and is of the order of [Formula: see text].

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