scholarly journals CPT-violating z = 3 Horava–Lifshitz QED and generation of the Carroll–Field–Jackiw term

2021 ◽  
pp. 2150081
Author(s):  
T. Mariz ◽  
R. Martinez ◽  
J. R. Nascimento ◽  
A. Yu. Petrov
Keyword(s):  
Axial Vector ◽  
Loop Approximation ◽  
The One ◽  
Vector Formula ◽  
Breaking Term

We study the new extension of the [Formula: see text] Horava–Lifshitz QED involving a CPT-breaking term, characterized by the axial vector [Formula: see text], and calculate the Carroll–Field–Jackiw (CFJ) term in the one-loop approximation. Explicitly, we use two regularization schemes and demonstrate that in our case, the CFJ term is finite but ambiguous, so that its exact coefficient depends on the used regularization.

AN IMPROVED ONE-LOOP ANALYSIS OF THE λϕ4 THEORY AT FINITE TEMPERATURE

1987 ◽  
Vol 02 (03) ◽  
pp. 713-728 ◽  
Author(s):  
SWEE-PING CHIA
Keyword(s):  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Zero Temperature ◽  
Coupling Constant ◽  
Loop Analysis ◽  
Temperature Dependent ◽  
Effective Coupling ◽  
Loop Approximation ◽  
The One ◽  
Dependent Mass

The λϕ4 theory with tachyonic mass is analyzed at T ≠ 0 using an improved one-loop approximation in which each of the bare propagators in the one-loop diagram is replaced by a dressed propagator to take into account the higher loop effects. The dressed propagator is characterized by a temperature-dependent mass which is determined by a self-consistent relation. Renomalization is found to be necessarily temperature-dependent. Real effective potential is obtained, giving rise to real effective mass and real coupling constant. For T < Tc, this is achieved by first shifting the ϕ field by its zero-temperature vacuum expectation value. The effective coupling constant is found to exhibit the striking behavior that it approaches a constant nonzero value as T → ∞.

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.

The renormalization group in perturbative quantum gravity

2021 ◽  
pp. 488-493
Author(s):  
Iosif L. Buchbinder ◽  
Ilya L. Shapiro
Keyword(s):  
Renormalization Group ◽  
Quantum Gravity ◽  
Minimal Subtraction Scheme ◽  
Loop Approximation ◽  
Renormalization Group Equations ◽  
Gauge Fixing ◽  
Perturbative Renormalization ◽  
Fourth Derivative ◽  
Perturbative Quantum ◽  
The One

This is a short chapter summarizing the main results concerning the renormalization group in models of pure quantum gravity, without matter fields. The chapter starts with a critical analysis of non-perturbative renormalization group approaches, such as the asymptotic safety hypothesis. After that, it presents solid one-loop results based on the minimal subtraction scheme in the one-loop approximation. The polynomial models that are briefly reviewed include the on-shell renormalization group in quantum general relativity, and renormalization group equations in fourth-derivative quantum gravity and superrenormalizable models. Special attention is paid to the gauge-fixing dependence of the renormalization group trajectories.

NEUTRINO SELF-ENERGY AND DISPERSION EQUATION IN DENSE MATTER

1996 ◽  
Vol 11 (28) ◽  
pp. 5093-5108 ◽  
Author(s):  
A. PEREZ MARTINEZ ◽  
A. ZEPEDA ◽  
H. PEREZ ROJAS
Keyword(s):  
Energy Gap ◽  
Vector Boson ◽  
Dense Matter ◽  
Self Energy ◽  
Dispersion Equations ◽  
Negative Effective Mass ◽  
Loop Approximation ◽  
Asymmetric Case ◽  
Type Spectrum ◽  
The One

General expressions for the neutrino self-energy and dispersion equations are found in a medium at finite temperature and density. The neutrino self-energy is calculated in the one-loop approximation and using the unitary gauge. The singularities and the absorption mechanisms are discussed. The low momentum (as compared with the vector boson masses) limit of the self-energy is obtained and from it, the dispersion equations for the quasiparticles are found. These solutions exhibit a group velocity smaller than unity which decreases with increasing density and an energy gap leading to a superfluid-type spectrum. In the particle–antiparticle asymmetric case, a negative effective mass is found for neutrinos.

scholarly journals Observables for model-independent detections of Z′ boson at the ILC

2015 ◽  
Vol 30 (16) ◽  
pp. 1550087
Author(s):  
V. Skalozub ◽  
I. Kucher
Keyword(s):  
Cross Section ◽  
Z Boson ◽  
Axial Vector ◽  
Effective Lagrangian ◽  
The Standard Model ◽  
Model Predictions ◽  
Model Independent ◽  
Vector Formula ◽  
Two Parameter

The integral observables for model-independent detections of Abelian Z′ gauge boson in e+e- → μ+μ-(τ+τ-) process with unpolarized beams at the ILC energies are proposed. They are based on the differential cross-section of deviations from the standard model predictions calculated with a low energy effective Lagrangian and taking into consideration the relations between the Z′ couplings to the fermions derived already. Due to these relations, the cross-section exhibits angular distribution giving a possibility for introducing one- or two-parameter observables which effectively fit the mass mZ′, the axial-vector [Formula: see text] and the product of vector couplings vevμ(vevτ). A discovery reach for the Z′ is estimated for two of introduced observables. Determination of the basic Z′ model is discussed. Comparison with other results and approaches is given.

scholarly journals SCALAR EFFECTIVE ACTION IN KREIN SPACE QUANTIZATION

2011 ◽  
Vol 26 (01) ◽  
pp. 31-41 ◽  
Author(s):  
A. REFAEI ◽  
M. V. TAKOOK
Keyword(s):  
Effective Action ◽  
Krein Space ◽  
Physical Interaction ◽  
Running Coupling ◽  
Loop Approximation ◽  
Running Coupling Constant ◽  
Kreĭn Space ◽  
Β Function ◽  
The One ◽  
Krein Space Quantization

In this paper, the λϕ4 scalar field effective action, in the one-loop approximation, is calculated by using the Krein space quantization. We show that the effective action is naturally finite and the singularity does not appear in the theory. The physical interaction mass, the running coupling constant and β-function are then calculated. The effective potential which is calculated in the Krein space quantization is different from the usual Hilbert space calculation, however we show that β-function is the same in the two different methods.

scholarly journals THE TOROID DIPOLE MOMENT OF THE NEUTRINO

1998 ◽  
Vol 13 (30) ◽  
pp. 5257-5277 ◽  
Author(s):  
VLADIMIR M. DUBOVIK ◽  
VALENTIN E. KUZNETSOV
Keyword(s):  
Dipole Moment ◽  
Mass Shell ◽  
Dipole Moments ◽  
Form Factors ◽  
Dispersion Method ◽  
Anapole Moment ◽  
Electromagnetic Interactions ◽  
Loop Approximation ◽  
The Standard Model ◽  
The One

We discuss the third electromagnetic characteristic of the neutrino, i.e. the toroid dipole moment (TDM), in the framework of the Standard Model. The TDM's distinctions from and similarities to an anapole moment are mentioned. The calculations of toroid dipole moments of νe,μ,τ neutrinos have been done by the dispersion method in the one-loop approximation of the SM for the Majorana case and generalized to the Dirac one. We found them to be different from zero in the case of massive as well as massless neutrinos. The behavior of the νe,μ,τ toroid form factors is also presented in the [Formula: see text] range. All external particles are on the mass shell and there are no problems with the physical interpretation of the final result. Some manifestations of the electromagnetic interactions of neutrinos, induced by their toroid moments, are also remarked on.

Bc SPECTROSCOPY IN THE SHIFTED l-EXPANSION TECHNIQUE

2008 ◽  
Vol 17 (04) ◽  
pp. 669-691 ◽  
Author(s):  
SAMEER M. IKHDAIR ◽  
RAMAZAN SEVER
Keyword(s):  
Ground State ◽  
Heavy Quarkonium ◽  
Scaling Relation ◽  
High Agreement ◽  
Model Potentials ◽  
Ground State Spin ◽  
Expansion Technique ◽  
The One ◽  
State Spin ◽  
Vector Formula

In the framework of static and QCD-motivated model potentials for heavy quarkonium, we present a further comprehensive calculation of the mass spectrum of [Formula: see text] system and its ground state spin-dependent splittings in the context of the shifted l-expansion technique. We also predict the leptonic constant fBc of the lightest pseudoscalar Bc, and [Formula: see text] of the vector [Formula: see text] states taking into account the one-loop and two-loop QCD corrections. Furthermore, we use the scaling relation to predict the leptonic constant of the nS-states of the [Formula: see text] system. Our predicted results are generally in high agreement with some earlier numerical methods. The parameters of each potential are adjusted to obtain best agreement with the experimental spin-averaged data (SAD).

scholarly journals Chiral condensate beyond the one-loop approximation

2017 ◽  
Vol 80 (3) ◽  
pp. 465-468
Author(s):  
V. G. Ksenzov ◽  
A. I. Romanov
Keyword(s):  
Chiral Condensate ◽  
Loop Approximation ◽  
The One
Sign in / Sign up

Export Citation Format

Share Document