On a semi-analytical and realistic approach to e+e− annihilation into fermion pairs and to Bhabha scattering within the minimal standard model at LEP energies

1993 ◽  
Vol 401 (1-2) ◽  
pp. 3-66 ◽  
Author(s):  
Guido Montagna ◽  
Fulvio Piccinini ◽  
Oreste Nicrosini ◽  
Giampiero Passarino ◽  
Roberto Pittau
Keyword(s):  
Standard Model ◽  
Realistic Approach ◽  
Bhabha Scattering ◽  
Fermion Pairs ◽  
Minimal Standard

scholarly journals Lorentz Violation of the Photon Sector in Field Theory Models

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Lingli Zhou ◽  
Bo-Qiang Ma
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Degrees Of Freedom ◽  
Lorentz Violation ◽  
Detailed Structure ◽  
Standard Model Extension ◽  
Model Extension ◽  
The Standard Model ◽  
Minimal Standard

We compare the Lorentz violation terms of the pure photon sector between two field theory models, namely, the minimal standard model extension (SME) and the standard model supplement (SMS). From the requirement of the identity of the intersection for the two models, we find that the free photon sector of the SMS can be a subset of the photon sector of the minimal SME. We not only obtain some relations between the SME parameters but also get some constraints on the SMS parameters from the SME parameters. The CPT-odd coefficients(kAF)αof the SME are predicted to be zero. There are 15 degrees of freedom in the Lorentz violation matrixΔαβof free photons of the SMS related with the same number of degrees of freedom in the tensor coefficients(kF)αβμν, which are independent from each other in the minimal SME but are interrelated in the intersection of the SMS and the minimal SME. With the related degrees of freedom, we obtain the conservative constraints(2σ)on the elements of the photon Lorentz violation matrix. The detailed structure of the photon Lorentz violation matrix suggests some applications to the Lorentz violation experiments for photons.

HIGGS BOSON DISCOVERY POTENTIAL BEYOND THE MINIMAL STANDARD MODEL

1994 ◽  
Vol 09 (11) ◽  
pp. 1747-1785 ◽  
Author(s):  
ANDRÉ SOPCZAK
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Mass Parameter ◽  
Mass Range ◽  
Higgs Bosons ◽  
The Standard Model ◽  
Charged Higgs ◽  
Discovery Potential ◽  
Decisive Test ◽  
Minimal Standard

Detailed studies of neutral and charged Higgs boson pair production with full statistic detector simulations around [Formula: see text] with 500 pb−1 are presented in the context of a review of the Higgs boson discovery potential at LEP200. Already in the first phase of LEP200, a significant increase of the mass parameter space compared to LEP1 for the discovery of nonminimal Higgs bosons will be possible, while the mass range for the discovery of the minimal Standard Model Higgs boson will increase only marginally. The requirements for a decisive test of the Minimal Supersymmetric extension of the Standard Model (MSSM) at a later stage of LEP200 are discussed. A sensitivity mass range is given for charged Higgs bosons.

scholarly journals NEUTRINO MASS AND THE STANDARD MODEL

2013 ◽  
Vol 28 (05) ◽  
pp. 1350010 ◽  
Author(s):  
F. R. KLINKHAMER
Keyword(s):  
Standard Model ◽  
Neutrino Mass ◽  
Grand Unification ◽  
Neutrino Masses ◽  
Ultimate Explanation ◽  
The Standard Model ◽  
Interaction Term ◽  
Minimal Standard ◽  
First Time ◽  
Higgs Fields

It is pointed out (not for the first time) that the minimal Standard Model, without additional gauge-singlet right-handed neutrinos or isotriplet Higgs fields, allows for nonvanishing neutrino masses and mixing. The required interaction term is non-renormalizable and violates B-L conservation. The ultimate explanation of this interaction term may or may not rely on grand unification.

THE USE OF NEURAL NETWORK CLASSIFIERS FOR HIGGS SEARCHES

1992 ◽  
Vol 03 (04) ◽  
pp. 611-636 ◽  
Author(s):  
ALESSANDRO PETROLINI
Keyword(s):  
Neural Network ◽  
Higgs Boson ◽  
Standard Model ◽  
High Energy ◽  
Multidimensional Analysis ◽  
Standard Model Higgs Boson ◽  
Delphi Detector ◽  
Higgs Search ◽  
Minimal Standard ◽  
Neural Network Classifiers

Neural Network Classifiers are used to separate the signal from the background in a High-Energy Physics problem. The basic principles of Multidimensional Analysis by means of Back-Propagation Neural Network Classifiers and the application to the Higgs search are discussed. A search for the Minimal Standard Model Higgs boson, through the reaction [Formula: see text], using the data collected in 1990 by the DELPHI detector at LEP is made. The technique used allows to reach good detection efficiencies and no evidence of the Minimal Standard Model Higgs boson with mass less than 37 GeV is found. The use of Neural Network Classifiers proves to be a very powerful classification method. A comparison of the method with standard analysis techniques is presented.

scholarly journals LIMITS ON EXTENSIONS OF THE MINIMAL STANDARD MODEL FROM COMBINED LEP LINESHAPE DATA

1995 ◽  
Vol 10 (13n14) ◽  
pp. 1057-1063 ◽  
Author(s):  
ANDRÉ SOPCZAK
Keyword(s):  
Standard Model ◽  
Z Boson ◽  
Higgs Model ◽  
Z Decays ◽  
Minimal Standard ◽  
Z Boson Decays

The high statistics of the combined LEP lineshape data are used to derive constraints on hypothetical extensions of the minimal standard model. The data comprises about eight million visible Z decays, recorded between 1989 and 1993. This letter gives limits for simple tests on models which predict additional Z boson decays or modified Z-couplings. As an application, the two-doublet Higgs model is considered.

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