scholarly journals HEAVY MAJORANA NEUTRINOS IN e-e- COLLISIONS

1998 ◽  
Vol 13 (14) ◽  
pp. 2363-2381 ◽  
Author(s):  
CHRISTOPH GREUB ◽  
PETER MINKOWSKI
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
Majorana Neutrino ◽  
Low Energy ◽  
Left Handed ◽  
Mixing Parameters ◽  
Heavy Majorana Neutrino ◽  
The Standard Model ◽  
Majorana Neutrinos ◽  
The Masses

We discuss the process e-e-→W-W- mediated by heavy Majorana neutrino exchange in the t- and u channel. In our model the cross section for this reaction is a function of the masses (mN) of the heavy Majorana neutrinos and mixing parameters (UeN) originating from mixing between the ordinary left-handed standard model neutrinos and additional singlet right-handed neutrino fields. Taking into account the standard model background and constraints from low energy measurements, we present discovery limits in the [Formula: see text] plane. We also discuss how to measure in principle the CP violating phases, i.e., the relative phases between the mixing parameters.

scholarly journals B-anomalies from flavorful U(1)$$'$$ extensions, safely

2022 ◽  
Vol 82 (1) ◽  
Author(s):  
Rigo Bause ◽  
Gudrun Hiller ◽  
Tim Höhne ◽  
Daniel F. Litim ◽  
Tom Steudtner
Keyword(s):  
Standard Model ◽  
Predictive Power ◽  
Planck Scale ◽  
Low Energy ◽  
Energy Parameters ◽  
Left Handed ◽  
The Standard Model ◽  
Scalar Sector ◽  
Gauge Interaction ◽  
Gauge Anomaly

Abstract$$U(1)^\prime $$ U ( 1 ) ′ extensions of the standard model with generation-dependent couplings to quarks and leptons are investigated as an explanation of anomalies in rare B-decays, with an emphasis on stability and predictivity up to the Planck scale. To these ends, we introduce three generations of vector-like standard model singlet fermions, an enlarged, flavorful scalar sector, and, possibly, right-handed neutrinos, all suitably charged under the $$U(1)^\prime $$ U ( 1 ) ′ gauge interaction. We identify several gauge-anomaly free benchmarks consistent with $$B_s$$ B s -mixing constraints, with hints for electron-muon universality violation, and the global $$b \rightarrow s$$ b → s fit. We further investigate the complete two-loop running of gauge, Yukawa and quartic couplings up to the Planck scale to constrain low-energy parameters and enhance the predictive power. A characteristic of models is that the $$Z^\prime $$ Z ′ with TeV-ish mass predominantly decays to invisibles, i.e. new fermions or neutrinos. $$Z^\prime $$ Z ′ -production can be studied at a future muon collider. While benchmarks feature predominantly left-handed couplings $$C_9^{\mu }$$ C 9 μ and $$C_{10}^{\mu }$$ C 10 μ , right-handed ones can be accommodated as well.

scholarly journals MODEL FOR SMALL NEUTRINO MASSES AT THE TeV SCALE

2002 ◽  
Vol 17 (13) ◽  
pp. 771-778 ◽  
Author(s):  
SALAH NASRI ◽  
SHERIF MOUSSA
Keyword(s):  
Standard Model ◽  
Majorana Neutrino ◽  
Lepton Number ◽  
Neutrino Masses ◽  
Mass Generation ◽  
Seesaw Mechanism ◽  
Left Handed ◽  
The Standard Model ◽  
Neutrino Mass Generation ◽  
The One

We propose a model for neutrino mass generation in which no physics beyond a TeV is required. We extend the standard model by adding two charged singlet fields with lepton number two. Dirac neutrino masses mνD ≤ MeV are generated at the one-loop level. Small left-handed Majorana neutrino masses can be generated via the seesaw mechanism with right-handed neutrino masses MR of order TeV scale.

Possibility of hadronic dark matter

2019 ◽  
Vol 28 (13) ◽  
pp. 1941001 ◽  
Author(s):  
Vitaly Beylin ◽  
Vladimir Kuksa
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Cross Section ◽  
Low Energy ◽  
Annihilation Cross Section ◽  
Strong Interactions ◽  
Charged State ◽  
Energy Potential ◽  
The Standard Model ◽  
Sommerfeld Enhancement

We consider main properties of hadronic Dark Matter (DM) candidate consisting of new heavy stable quark and the light ordinary one. This additional quark arises in chiral-symmetric extension of the Standard Model and has standard electromagnetic and strong interactions. Neutral and charged pseudoscalar low-lying states are interpreted as the DM carrier and its nearest charged partner. Their masses and lifetime of the charged state are evaluated; we also describe asymptotics of low-energy potential of the particles interactions with nucleons and each other. Annihilation cross-section is calculated and some peculiarities of Sommerfeld enhancement are analyzed.

scholarly journals A NOTE ON MAJORANA NEUTRINOS, LEPTONIC CKM AND ELECTRON ELECTRIC DIPOLE MOMENT

1996 ◽  
Vol 11 (03) ◽  
pp. 211-216 ◽  
Author(s):  
DANIEL NG ◽  
JOHN N. NG
Keyword(s):  
Dipole Moment ◽  
Standard Model ◽  
Electric Dipole Moment ◽  
Electric Dipole ◽  
Majorana Neutrino ◽  
Loop Order ◽  
The Standard Model ◽  
Majorana Neutrinos ◽  
Electron Electric Dipole Moment

The electric dipole moment of the electron, de, is known to vanish up to three-loop in the standard model with massless neutrinos. However, if neutrinos are massive Majorana particles, we obtain the result that de induced by leptonic CKM mechanism is nonvanishing at two-loop order, and it applies to all massive Majorana neutrino models.

scholarly journals THE THIRD TYPE OF FERMION MIXING IN THE LEPTON AND QUARK INTERACTIONS WITH LEPTOQUARKS

2012 ◽  
Vol 27 (11) ◽  
pp. 1250062 ◽  
Author(s):  
A. V. KUZNETSOV ◽  
N. V. MIKHEEV ◽  
A. V. SERGHIENKO
Keyword(s):  
Lower Bound ◽  
Standard Model ◽  
Low Energy ◽  
Minimal Extension ◽  
The Third ◽  
Model Based ◽  
Mixing Parameters ◽  
The Standard Model

The low-energy manifestations of a minimal extension of the electroweak standard model based on the quark–lepton symmetry SU(4)V ⊗SU(2)L ⊗GR of the Pati–Salam-type are analyzed. Given this symmetry the third type of mixing in the interactions of the SU(4)V leptoquarks with quarks and leptons is shown to be required. An additional arbitrariness of the mixing parameters could allow, in principle, to decrease noticeably the lower bound on the vector leptoquark mass originated from the low-energy rare processes, strongly suppressed in the standard model.

scholarly journals Low-Energy Effective Field Theory below the Electroweak Scale: dimension-8 operators

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Christopher W. Murphy
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
Effective Field ◽  
Low Energy ◽  
Electroweak Scale ◽  
Left Handed ◽  
The Standard Model ◽  
Two Generations ◽  
Charged Leptons

Abstract We construct a complete basis of dimension-8 operators in the Low-Energy Effective Field Theory below the Electroweak Scale (LEFT). We find there are 35058 dimension-8 operators in the LEFT for two generations of up-type quarks and three generations of down-type quarks, charged leptons, and left-handed neutrinos. The existence of this operator basis is a necessary prerequisite for matching to the Standard Model Effective Field Theory at the dimension-8 level.

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 Flavour Anomalies in a U(1) SUSY Extension of the SM

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 191
Author(s):  
Alexander Bednyakov ◽  
Alfiia Mukhaeva
Keyword(s):  
Standard Model ◽  
Parameter Space ◽  
Gauge Boson ◽  
New Physics ◽  
Low Energy ◽  
Effective Theory ◽  
The Standard Model ◽  
Meson Mixing ◽  
Additional Anomaly ◽  
Lepton Flavour

Flavour anomalies have attracted a lot of attention over recent years as they provide unique hints for possible New Physics. Here, we consider a supersymmetric (SUSY) extension of the Standard Model (SM) with an additional anomaly-free gauge U(1) group. The key feature of our model is the particular choice of non-universal charges to the gauge boson Z′, which not only allows a relaxation of the flavour discrepancies but, contrary to previous studies, can reproduce the SM mixing matrices both in the quark and lepton sectors. We pay special attention to the latter and explicitly enumerate all parameters relevant for our calculation in the low-energy effective theory. We find regions in the parameter space that satisfy experimental constraints on meson mixing and LHC Z′ searches and can alleviate the flavour anomalies. In addition, we also discuss the predictions for lepton-flavour violating decays B+→K+μτ and B+→K+eτ.

NOTE ON THE MEASUREMENT OF y-DEPENDENCE IN NEUTRINO-ELECTRON SCATTERING: A SENSITIVE TEST OF THE STANDARD MODEL

1993 ◽  
Vol 02 (04) ◽  
pp. 915-921 ◽  
Author(s):  
C. RANGACHARYULU ◽  
A. RICHTER
Keyword(s):  
Standard Model ◽  
Differential Cross Section ◽  
Cross Section ◽  
Electron Scattering ◽  
Differential Cross ◽  
Sensitive Test ◽  
Testing Ground ◽  
The Standard Model ◽  
Sensitive Testing

It is pointed out that the y-dependence of the differential cross-section for various types of neutrinos on the electron promises to be a sensitive testing ground of the electroweak Standard Model at KAON in Vancouver. Estimates of the flux requirements are given and the feasibility of such experiments is discussed.

scholarly journals STANDARD MODEL HIGGS COMBINED RESULT FROM CDF

2001 ◽  
Vol 16 (supp01b) ◽  
pp. 825-827
Author(s):  
◽  
JOÃO GUIMARÃES DA COSTA
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
Z Boson ◽  
Decay Channel ◽  
Vector Boson ◽  
Associated Production ◽  
The Standard Model ◽  
The Individual ◽  
Cross Section Limit

The Tevatron is expected to be most sensitive to the Standard Model Higgs in its associated production with a W or Z boson. The Collider Detector at Fermilab (CDF) has performed individual searches for such production in each decay channel of the vector boson, assuming that the Higgs decays to [Formula: see text]. These searches use data collected by CDF during the 1992-95 run. The individual results are reviewed, and a combined cross section limit is presented.

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