Failure of the Feynman R1 gauge for the standard model: An explicit example

2016 ◽  
Vol 31 (04n05) ◽  
pp. 1650028 ◽  
Author(s):  
Tai Tsun Wu ◽  
Sau Lan Wu
Keyword(s):  
Standard Model ◽  
Correct Answer ◽  
Gauge Invariance ◽  
Higgs Particle ◽  
Great Care ◽  
Simple Argument ◽  
Incorrect Answer ◽  
Unitary Gauge ◽  
The Standard Model ◽  
Feynman Rules

The decay of the Higgs particle into two photons through a [Formula: see text] loop was calculated in a straightforward way four years ago on the basis of the standard model. This calculation was carried out in the unitary gauge. Nevertheless, all attempts to reproduce this correct answer using the Feynman rules in the [Formula: see text] gauge, or the more general [Formula: see text] gauge, have failed. In this paper, a detailed analysis is carried out to compare the unitary gauge with the [Formula: see text] gauge; through this comparison, the underlying reason is determined why the answer cannot be obtained using the Feynman rules in the [Formula: see text] gauge. This is the first example where the use of the Feynman rules in the [Formula: see text] gauge leads to an incorrect answer, and this incorrect answer cannot be ruled out by any simple argument such as gauge invariance. It means that great care must be exercised in using Feynman rules.

scholarly journals Testing the mechanism of lepton compositeness

2021 ◽  
Vol 10 (3) ◽  
Author(s):  
Vincenzo Afferrante ◽  
Axel Maas ◽  
René Sondenheimer ◽  
Pascal Törek
Keyword(s):  
Gauge Theory ◽  
Standard Model ◽  
Gauge Invariance ◽  
Bound States ◽  
Lattice Gauge Theory ◽  
Higgs Field ◽  
Left Handed ◽  
Lattice Gauge ◽  
The Standard Model ◽  
Weyl Fermions

Strict gauge invariance requires that physical left-handed leptons are actually bound states of the elementary left-handed lepton doublet and the Higgs field within the standard model. That they nonetheless behave almost like pure elementary particles is explained by the Fr"ohlich-Morchio-Strocchi mechanism. Using lattice gauge theory, we test and confirm this mechanism for fermions. Though, due to the current inaccessibility of non-Abelian gauged Weyl fermions on the lattice, a model which contains vectorial leptons but which obeys all other relevant symmetries has been simulated.

scholarly journals One Loop Corrections to Decay \(\tau\rightarrow \mu\gamma\) in Economical 3-3-1 Model

2015 ◽  
Vol 25 (2) ◽  
pp. 113
Author(s):  
Truong Trong Thuc ◽  
Le Tho Hue ◽  
Dinh Phan Khoi ◽  
Nguyen Thanh Phong
Keyword(s):  
Standard Model ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Lepton Flavor ◽  
Unitary Gauge ◽  
The Standard Model ◽  
Charged Leptons

Lepton flavor violating (cLFV) decays of charged leptons such as \(\tau\rightarrow \mu\gamma\), \(\tau\rightarrow e\gamma\), \(\mu\rightarrow e\gamma\),..., are now the subjects of experiments as signals of new Physics beyond the Standard Model (SM). In the limit of the unitary gauge, we prove that contributions from one loop corrections to the above decays are very small in the framework of the economical 3-3-1 model.

scholarly journals A RESOURCE FOR SIGNS AND FEYNMAN DIAGRAMS OF THE STANDARD MODEL

2012 ◽  
Vol 27 (26) ◽  
pp. 1230025 ◽  
Author(s):  
JORGE C. ROMÃO ◽  
JOÃO P. SILVA
Keyword(s):  
Standard Model ◽  
Feynman Diagrams ◽  
Gauge Fields ◽  
Full Calculation ◽  
The Standard Model ◽  
Feynman Rules ◽  
Gauge Couplings

When performing a full calculation within the standard model (SM) or its extensions, it is crucial that one utilizes a consistent set of signs for the gauge couplings and gauge fields. Unfortunately, the literature is plagued with differing signs and notations. We present all SM Feynman rules, including ghosts, in a convention-independent notation, and we table the conventions in close to 40 books and reviews.

The Standard Model (SM) of fundamental interactions

2021 ◽  
pp. 567-592
Author(s):  
Jean Zinn-Justin
Keyword(s):  
Standard Model ◽  
Particle Physics ◽  
Hadron Collider ◽  
Nuclear Research ◽  
Strong Interactions ◽  
Higgs Particle ◽  
Fundamental Interactions ◽  
The Standard Model ◽  
Minimal Modification ◽  
Charge Conjugation Parity

The Standard Model (SM) 2020 of weak, electromagnetic and strong interactions, based on gauge symmetry and spontaneous symmetry breaking, describes all known fundamental interactions at the microscopic scale except gravity and, perhaps, interactions with dark matter. The SM model has been tested systematically in collider experiments, and in the case of strong interactions (quantum chromodynamics) also with numerical simulations. With the discovery in 2012 of the Higgs particle at the Large Hadron Collider (LHC) at the European Council for Nuclear Research (CERN), all particles of the SM have been identified, and most parameters have been measured. Still, the Higgs particle remains the most mysterious particle of the SM, since it is responsible for all the parameters of the SM except gauge couplings and since it leads to the fine-tuning problem. The discovery of its origin, and the precise study of its properties should be, in the future, one of the most important field of research in particle physics. Since we know now that the neutrinos have masses, the simplest extension of the SM implies Dirac neutrinos. With such a minimal modification, consistent so far (2020) with experimental data, the lepton and quark sectors have analogous structures: the lepton sector involves a mixing matrix, like the quark sector (three angles have been determined, the fourth charge conjugation parity (CP) violating angle is still unknown).

scholarly journals Tests of the CPT Invariance at the Antiproton Decelerator of CERN

2019 ◽  
Vol 64 (7) ◽  
pp. 589
Author(s):  
D. Horváth
Keyword(s):  
Cosmic Rays ◽  
Standard Model ◽  
Gauge Invariance ◽  
Particle Physics ◽  
Composite Particles ◽  
Cpt Invariance ◽  
Invariance Principles ◽  
Antiproton Decelerator ◽  
The Standard Model ◽  
Cp Symmetry

The Standard Model, the theory of particle physics is based on symmetries: both the structure of the composite particles and their interactions are derived using gauge invariance principles. Some of these are violated by the weak interaction like parity and CP symmetry, and even masses are created via spontaneous symmetry breaking. CPT invariance, the most essential symmetry of the Standard Model, states the equivalency of matter and antimatter. However, because of the lack of antimatter in our Universe it is continuously tested at CERN. We overview these experiments: measuring the properties of antiprotons as compared to those of the proton at the Antiproton Decelerator and also searching for antimatter in cosmic rays.

scholarly journals Feynman rules for the Standard Model Effective Field Theory in R ξ -gauges

2017 ◽  
Vol 2017 (6) ◽  
Author(s):  
A. Dedes ◽  
W. Materkowska ◽  
M. Paraskevas ◽  
J. Rosiek ◽  
K. Suxho
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
Effective Field ◽  
The Standard Model ◽  
Feynman Rules

Higgs decay H → γγ: New theoretical results and possible experimental implications

2015 ◽  
Vol 30 (32) ◽  
pp. 1550200 ◽  
Author(s):  
R. Gastmans ◽  
Sau Lan Wu ◽  
Tai Tsun Wu
Keyword(s):  
Matrix Element ◽  
Standard Model ◽  
Decay Rate ◽  
Mass Range ◽  
Present Calculation ◽  
Atlas Collaboration ◽  
Higgs Particle ◽  
Higgs Decay ◽  
The Standard Model ◽  
Theoretical Results

The contribution of one [Formula: see text] loop to the decay of the Higgs particle into two gammas is recalculated. Since this matrix element is finite in the standard model, it should be calculated in a straightforward way without artifacts such as regularization or ghosts. The result of the present calculation differs from the previous one, giving a Higgs decay rate smaller by a factor of 2 in the mass range of physical interest. In view of the results from the ATLAS Collaboration and the CMS Collaboration, this leads to possible far-reaching experimental consequences.

scholarly journals TWIN AND MIRROR SYMMETRIES FROM PRESYMMETRY

2011 ◽  
Vol 26 (18) ◽  
pp. 3051-3063 ◽  
Author(s):  
ERNESTO A. MATUTE
Keyword(s):  
Standard Model ◽  
Mirror Symmetry ◽  
Beyond The Standard Model ◽  
Higgs Particle ◽  
Gauge Bosons ◽  
The Standard Model ◽  
Strong Sector ◽  
Left Right Asymmetry ◽  
The One ◽  
Mirror Matter

We argue that presymmetry, a hidden predynamical electroweak quark–lepton symmetry that explains the fractional charges and triplication of families, must be extended beyond the Standard Model as to have a residual presymmetry that embraces partner particles and includes the strong sector, so accounting for the twin or mirror partners proposed to alleviate the naturalness problem of the weak scale. It leads to the full duplication of fermions and gauge bosons of the Standard Model independently of the ultraviolet completion of the theory, even if the Higgs particle is discarded by experiment, which adds robustness to twin and mirror symmetries. The established connection is so strongly motivated that the search for twin or mirror matter becomes the possible test of presymmetry. If the physics beyond the Standard Model repairs its left–right asymmetry, mirror symmetry should be the one realized in nature.

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