scholarly journals Anatomy of the Higgs Boson Decay into Two Photons in the Unitary Gauge

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Athanasios Dedes ◽  
Kristaq Suxho
Keyword(s):  
Decay Amplitude ◽  
Goldstone Boson ◽  
Equivalence Theorem ◽  
Loop Contribution ◽  
Four Dimensions ◽  
Three Sphere ◽  
Unitary Gauge ◽  
The Standard Model ◽  
Spatial Dimensions ◽  
Exact Equality

We review and clarify computational issues about theW-gauge boson one-loop contribution to theH→γγdecay amplitude, in the unitary gauge and in the Standard Model. We find that highly divergent integrals depend upon the choice of shifting momenta with arbitrary vectors. One particular combination of these arbitrary vectors reduces the superficial divergency down to a logarithmic one. The remaining ambiguity is then fixed by exploiting gauge invariance and the Goldstone Boson Equivalence Theorem. Our method is strictly realised in four dimensions. The result for the amplitude agrees with the “famous” one obtained using dimensional regularisation (DR) in the limitd→4, wheredis the number of spatial dimensions in Euclidean space. At the exact equalityd=4, a three-sphere surface term appears that renders the Ward Identities and the equivalence theorem inconsistent. We also examined a recently proposed four-dimensional regularisation scheme and found agreement with the DR outcome.

scholarly journals A global view of the off-shell Higgs portal

2020 ◽  
Vol 8 (2) ◽  
Author(s):  
Maximilian Ruhdorfer ◽  
Ennio Salvioni ◽  
Andreas Weiler
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Vector Boson ◽  
Effective Interaction ◽  
Goldstone Boson ◽  
High Energy ◽  
Beyond The Standard Model ◽  
The Standard Model ◽  
Higgs Portal ◽  
First Time

We study for the first time the collider reach on the derivative Higgs portal, the leading effective interaction that couples a pseudo Nambu-Goldstone boson (pNGB) scalar Dark Matter to the Standard Model. We focus on Dark Matter pair production through an off-shell Higgs boson, which is analyzed in the vector boson fusion channel. A variety of future high-energy lepton colliders as well as hadron colliders are considered, including CLIC, a muon collider, the High-Luminosity and High-Energy versions of the LHC, and FCC-hh. Implications on the parameter space of pNGB Dark Matter are discussed. In addition, we give improved and extended results for the collider reach on the marginal Higgs portal, under the assumption that the new scalars escape the detector, as motivated by a variety of beyond the Standard Model scenarios.

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 Electroweak fermion triangle loop contributions to the muon anomalous magnetic moment revisited

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Ken Sasaki
Keyword(s):  
Magnetic Moment ◽  
Top Quark ◽  
Anomalous Magnetic Moment ◽  
Ward Identity ◽  
Axial Vector ◽  
Goldstone Boson ◽  
Muon Anomalous Magnetic Moment ◽  
Feynman Gauge ◽  
Unitary Gauge ◽  
The One

Abstract The contribution to the muon anomalous magnetic moment from the fermion triangle loop diagrams connected to the muon line by a photon and a $Z$ boson is re-analyzed in both the unitary gauge and the ’t Hooft–Feynman gauge. With use of the anomalous axial-vector Ward identity, it is shown that the calculation in the unitary gauge exactly coincides with the one in the ’t Hooft–Feynman gauge. The part which arises from the ordinary axial-vector Ward identity corresponds to the contribution of the neutral Goldstone boson. For the top-quark contribution, the one-parameter integral form is obtained up to the order of $m_\mu^2/m_Z^2$. The results are compared with those obtained by the asymptotic expansion method.

scholarly journals EFT anomalous dimensions from the S-matrix

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Joan Elias Miró ◽  
James Ingoldby ◽  
Marc Riembau
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Form Factors ◽  
Effective Field ◽  
Higher Dimension ◽  
Powerful Method ◽  
Loop Contribution ◽  
Anomalous Dimensions ◽  
S Matrix ◽  
The Standard Model

Abstract We use the on-shell S-matrix and form factors to compute anomalous dimensions of higher dimension operators in the Standard Model Effective Field Theory. We find that in many instances, these computations are made simple by using the on-shell method. We first compute contributions to anomalous dimensions of operators at dimension-six that arise at one-loop. Then we calculate two-loop anomalous dimensions for which the corresponding one-loop contribution is absent, using this powerful method.

TEST OF GOLDSTONE BOSON EQUIVALENCE THEOREM

1994 ◽  
Vol 09 (11) ◽  
pp. 1025-1032 ◽  
Author(s):  
B. DUTTA ◽  
S. NANDI
Keyword(s):  
Higgs Boson ◽  
Gauge Boson ◽  
Scattering Amplitude ◽  
Goldstone Boson ◽  
Equivalence Theorem ◽  
General Proof

We study the convergence (with energy) of the exact longitudinal gauge boson scattering amplitude to that given by the equivalence theorem. For low Higgs boson masses, this convergence is rather slow, and can have significant effect at the SSC energies. We find that in addition to [Formula: see text] terms, the two amplitudes differ by terms of [Formula: see text]. We incorporate the presence of such terms in the general proof of the equivalence theorem.

scholarly journals THE HIGGS PUZZLE: EXPERIMENT AND THEORY

2002 ◽  
Vol 17 (23) ◽  
pp. 3300-3317
Author(s):  
FABIO ZWIRNER
Keyword(s):  
Higgs Boson ◽  
High Energy ◽  
Experimental Information ◽  
Electroweak Symmetry Breaking ◽  
Electroweak Symmetry ◽  
Supersymmetric Extension ◽  
Light Higgs Boson ◽  
Open Questions ◽  
The Standard Model ◽  
Spatial Dimensions

The present experimental and theoretical knowledge of the physics of electroweak symmetry breaking is reviewed. Data still favor a light Higgs boson, of a kind that can be comfortably accommodated in the Standard Model or in its Minimal Supersymmetric extension, but exhibit a non-trivial structure that leaves some open questions. The available experimental information may still be reconciled with the absence of a light Higgs boson, but the price to pay looks excessive. Recent theoretical ideas, linking the weak scale with the size of possible extra spatial dimensions, are briefly mentioned. It is stressed once more that experiments at high-energy colliders, such as the Tevatron and the LHC, are the crucial tool for eventually solving the Higgs puzzle.

scholarly journals Searches for extra spatial dimensions with the CMS detector at the LHC

2015 ◽  
Vol 30 (15) ◽  
pp. 1540017 ◽  
Author(s):  
Greg Landsberg
Keyword(s):  
Hadron Collider ◽  
Center Of Mass ◽  
New Physics ◽  
Current Status ◽  
Beyond The Standard Model ◽  
Cern Large Hadron Collider ◽  
The Standard Model ◽  
Cms Detector ◽  
Spatial Dimensions ◽  
8 Tev

The success of the first three years of operations of the CERN Large Hadron Collider (LHC) at center-of-mass energies of 7 TeV and 8 TeV radically changed the landscape of searches for new physics beyond the Standard Model (BSM) and our very way of thinking about its possible origin and its hiding place. Among the paradigms of new physics that have been probed quite extensively at the LHC, are various models that predict the existence of extra spatial dimensions. In this review, the current status of searches for extra dimensions with the Compact Muon Solenoid (CMS) detector is presented, along with prospects for future searches at the full energy of the LHC, expected to be reached in the next few years.

scholarly journals UNDERSTANDING LORENTZ VIOLATION WITH RASHBA INTERACTION

2012 ◽  
Vol 27 (24) ◽  
pp. 1250139 ◽  
Author(s):  
MUHAMMAD ADEEL AJAIB
Keyword(s):  
Condensed Matter ◽  
Lorentz Violation ◽  
Condensed Matter Physics ◽  
Coupling Constant ◽  
Standard Model Extension ◽  
Rashba Interaction ◽  
Model Extension ◽  
The Standard Model ◽  
Spatial Dimensions ◽  
Rashba Coupling

Rashba spin–orbit interaction is a well-studied effect in condensed matter physics and has important applications in spintronics. The standard model extension (SME) includes a CPT-even term with the coefficient Hμν, which leads to the Rashba interaction term. From the limit available on the coefficient Hμν in the SME we derive a limit on the Rashba coupling constant for Lorentz violation. In condensed matter physics the Rashba term is understood as resulting from an asymmetry in the confining potential at the interface of two different types of semiconductors. Based on this interpretation we suggest that a possible way of inducing the Hμν term in the SME is with an asymmetry in the potential that confines us to three spatial dimensions.

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