THE TAU-LEPTON AND TESTS OF THE STANDARD MODEL

1993 ◽  
Vol 08 (26) ◽  
pp. 2491-2496 ◽  
Author(s):  
MARK A. SAMUEL
Keyword(s):  
Standard Model ◽  
Tau Lepton ◽  
Tau Neutrino ◽  
The Standard Model ◽  
B Factory

Using a new value for the mass of the tau-lepton we reconsider various tests of the Standard Model (SM) for the tau. The agreement with the SM is much improved. All tests agree within 1.2σ or smaller and the so-called “tau-lifetime problem” has disappeared. We also obtain bounds on the mass of the tau-neutrino. It is shown that an improved bound [Formula: see text] MeV at 95% C.L. can be obtained at the τ-charm factory in Spain or at a proposed B-factory.

scholarly journals The SHiP physics program

2018 ◽  
Vol 179 ◽  
pp. 01002
Author(s):  
Giovanni De Lellis
Keyword(s):  
Standard Model ◽  
Theoretical Models ◽  
Mass Range ◽  
Beyond The Standard Model ◽  
Beam Dump ◽  
Tau Neutrino ◽  
Physics Program ◽  
Weakly Coupled ◽  
Physics Potential ◽  
The Standard Model

The discovery of the Higgs boson has fully confirmed the Standard Model of particles and fields. Nevertheless, there are still fundamental phenomena, like the existence of dark matter and the baryon asymmetry of the Universe, which deserve an explanation that could come from the discovery of new particles. The SHiP experiment at CERN meant to search for very weakly coupled particles in the few GeV mass domain has been recently proposed. The existence of such particles, foreseen in different theoretical models beyond the Standard Model, is largely unexplored. A beam dump facility using high intensity 400 GeV protons is a copious source of such unknown particles in the GeV mass range. The beam dump is also a copious source of neutrinos and in particular it is an ideal source of tau neutrinos, the less known particle in the Standard Model. Indeed, tau anti-neutrinos have not been directly observed so far. We report the physics potential of such an experiment including the tau neutrino magnetic moment.

scholarly journals Exploring CP-Violation Through B Decays

2003 ◽  
Vol 18 (21) ◽  
pp. 1413-1433 ◽  
Author(s):  
Robert Fleischer
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
B Meson ◽  
Model Description ◽  
B Decays ◽  
Unitarity Triangle ◽  
The Standard Model ◽  
B Factory ◽  
Meson System

The B-meson system provides many strategies to perform stringent tests of the Standard-Model description of CP-violation. In this brief review, we discuss implications of the currently available B-factory data on the angles α, β and γ of the unitarity triangle, emphasize the importance of Bsstudies at hadronic B experiments, and discuss new, theoretically clean strategies to determine γ.

ELECTROWEAK THEORY AND THE NEUTRINO-MASS AND NEUTRINO-OSCILLATION QUESTIONS

2007 ◽  
Vol 22 (12) ◽  
pp. 853-865 ◽  
Author(s):  
G. ZIINO
Keyword(s):  
Standard Model ◽  
Neutrino Oscillation ◽  
Neutrino Mass ◽  
Parity Violation ◽  
Crucial Role ◽  
Tau Lepton ◽  
Electroweak Theory ◽  
Mass Eigenstates ◽  
The Standard Model

It is shown that both conjectures of neutrino mass and neutrino oscillation can be made really well-grounded within the Standard Model provided that one adopts a recent new version of the electroweak scheme spontaneously giving also a fundamental explanation for the so-called "maximal parity-violation" effect. A crucial role is played by the prediction of two distinct, scalar and pseudoscalar, replicas of (electron, muon, and tau) lepton numbers that could fully account for an actual non-coincidence between neutrino mass-eigenstates and gauge-eigenstates.

Detectors for collider experiments at the luminosity frontier

2015 ◽  
Vol 30 (14) ◽  
pp. 1530029
Author(s):  
Peter Križan
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
Transition Matrix ◽  
Data Acquisition System ◽  
New Physics ◽  
Accelerator Complex ◽  
The Standard Model ◽  
Belle Ii ◽  
B Factory ◽  
Event Rates

In experiments at the luminosity frontier, New Physics is being searched for in precision studies of rare processes. The most important example of such an effort is experiments at B factories and super B factories. While B factories have fully established the CKM quark transition matrix as the only source of CP violation in the Standard Model, the next generation of B factories, the so-called super B factories, will look for departures from the Standard Model. To collect a 50 times larger data sample, needed to reach the required sensitivity, a substantial B factory upgrade is being carried out. The SuperKEKB accelerator complex is designed for an increase in luminosity by a factor of 40. The upgraded Belle II spectrometer is being constructed to operate at considerably higher event rates, as well as higher backgrounds, accompanied by an increase in occupancy and radiation damage. Higher event rates also require substantial modifications in the trigger scheme, data acquisition system and computing. The paper discusses the detectors at B factories, the motivation for SuperKEKB/Belle II, the super B factory at KEK, as well as the requirements for the new accelerator and for the new detector. The present status of the project will be presented together with plans for the future. We will also discuss its competition, the LHCb experiment at the LHC.

scholarly journals Tau-neutrino as a probe of nonstandard interactions via charged Higgs and W′ contribution

2014 ◽  
Vol 29 (07) ◽  
pp. 1450040
Author(s):  
Ahmed Rashed
Keyword(s):  
Standard Model ◽  
Cross Sections ◽  
New Physics ◽  
Mixing Angles ◽  
Tau Neutrino ◽  
Standard Model Cross Section ◽  
The Standard Model ◽  
Charged Higgs ◽  
Reactor Mixing ◽  
The Impact

We discuss the impact of the presence of a charged Higgs boson and a W′ gauge boson on the tau-neutrino nucleon scattering ντ+N→τ-+X and [Formula: see text]. We show the effect of the new physics on the quasielastic, Δ-resonance and deep inelastic scattering. The measurements for the atmospheric and reactor mixing angles θ23 and θ13 in the appearance analyses νμ →ντ and [Formula: see text] are based on the Standard Model cross-section of the above processes. The measured mixing angles are changed when considering the new physics contributions to those reactions, assuming the Standard Model cross-sections. We include form factor effects in the new physics calculations and find the deviations of the mixing angles can be significant and can depend on the energy of the neutrino.

scholarly journals Leptonic decays of the tau lepton

2019 ◽  
Vol 212 ◽  
pp. 08004 ◽  
Author(s):  
Matteo Fael
Keyword(s):  
Standard Model ◽  
Weak Interaction ◽  
Tau Lepton ◽  
Decay Modes ◽  
Leptonic Decays ◽  
The Standard Model

In these proceedings we review the SM prediction for the tau leptonic decays, including the radiative $ (\tau \to \ell \lambda \nu \bar \nu ) $ and the five-body $ (\tau \to \ell \ell '\ell '\nu \bar \nu ) $ decay modes, which are among the most powerful tools to study precisely the structure of the weak interaction and to constrain possible contributions beyond the V–A coupling of the Standard Model.

IMPLICATIONS OF A MODEL WITH A LONGER TAU LIFE-TIME

1992 ◽  
Vol 07 (31) ◽  
pp. 2921-2930
Author(s):  
R. FOOT ◽  
H. LEW
Keyword(s):  
Standard Model ◽  
General Model ◽  
Life Time ◽  
Tau Lepton ◽  
Standard Cosmology ◽  
The Standard Model ◽  
Weyl Fermion

It is possible that the tau lepton may have a longer life-time than that predicted by the Standard Model. The simplest extension to the Standard Model incorporating a longer tauon life-time involves the addition of a gauge singlet Weyl fermion. We consider the most general model of this kind and evaluate the experimental constraints on the various parameters of this model. We show that the model is consistent with the standard cosmology model for a range of parameters. We then examine possible signatures of the model in certain experiments searching for heavy neutral leptons.

scholarly journals New method for beyond the Standard Model invisible particle searches in tau lepton decays

2020 ◽  
Vol 102 (11) ◽  
Author(s):  
E. De La Cruz-Burelo ◽  
A. De Yta-Hernandez ◽  
M. Hernandez-Villanueva
Keyword(s):  
Standard Model ◽  
Tau Lepton ◽  
New Method ◽  
Beyond The Standard Model ◽  
The Standard Model ◽  
Invisible Particle ◽  
Lepton Decays

A TESTABLE MODEL OF A 17 keV TAU NEUTRINO

1992 ◽  
Vol 07 (06) ◽  
pp. 459-465
Author(s):  
DANIEL NG
Keyword(s):  
Standard Model ◽  
Branching Ratio ◽  
Life Time ◽  
Local Symmetry ◽  
Global Symmetry ◽  
Tau Neutrino ◽  
The Standard Model ◽  
Near Future ◽  
Breaking Scale ◽  
Testable Model

We discuss an extension of the standard model with a local symmetry of Le−Lμ and a global symmetry of Lτ to incorporate a 17 keV Dirac tau neutrino. A massive neutral gauge boson (AX) and a majoron (J) are present by breaking the symmetries spontaneously. The tau neutrino, with a life-time of the order 10−3 s, will decay by emitting an electron and a majoron. Tau will also decay into an electron and a majoron with a branching ratio as large as 10−4. The breaking scale of Le−Lμ symmetry can be as low as 700 GeV. Hence, AX can be produced in LEP II in the near future.

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