scholarly journals Some analytic results for the contribution to the anomalous magnetic moments of leptons due to the polarization of vacuum via lepton loops

2019 ◽  
Vol 222 ◽  
pp. 03007 ◽  
Author(s):  
Olga Solovtsova ◽  
Vasil Lashkevich ◽  
Alexander Sidorov
Keyword(s):  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Magnetic Moments ◽  
Mass Ratio ◽  
Mass Dependent ◽  
Made In

We present some new exact expressions for the contribution of the mass-dependent three-bubble diagrams to the anomalous magnetic moment of leptons L = e, µ and τ. A comparison with the analytic expansions in terms of the mass ratio mℓ/mL made in the literature, whenever relevant, is discussed.

scholarly journals Testing dark matter with the anomalous magnetic moment in a dark matter quantum electrodynamics model

2017 ◽  
Vol 32 (33) ◽  
pp. 1750175
Author(s):  
Ashok K. Das ◽  
Jorge Gamboa ◽  
Fernando Méndez ◽  
Natalia Tapia
Keyword(s):  
Dark Matter ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Quantum Electrodynamics ◽  
Heavy Fermions ◽  
Mass Ratio ◽  
Dark Photon ◽  
The Masses ◽  
Visible Photon

We consider a model of dark quantum electrodynamics (QEDs) which is coupled to a visible photon through a kinetic mixing term. We compute the [Formula: see text] for the dark fermion, where [Formula: see text] is its gyromagnetic factor. We show that the [Formula: see text] of the dark fermion is related to the [Formula: see text] of (visible) QEDs through a constant which depends on the kinetic mixing factor. We determine [Formula: see text] as a function of the mass ratio [Formula: see text], where [Formula: see text] and [Formula: see text] denote the masses of the dark photon and the dark fermion, respectively, and we show how [Formula: see text] becomes very different for light and heavy fermions around [Formula: see text] eV.

scholarly journals Vacuum instability due to the creation of neutral fermion with anomalous magnetic moment by magnetic-field inhomogeneities

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
T. C. Adorno ◽  
Zi-Wang He ◽  
S. P. Gavrilov ◽  
D. M. Gitman
Keyword(s):  
Magnetic Field ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Strong Field ◽  
Magnetic Moments ◽  
Particle Creation ◽  
Magnetic Field Inhomogeneity ◽  
Field Inhomogeneity ◽  
Pauli Equation ◽  
Vacuum Instability

Abstract We study neutral fermions pair creation with anomalous magnetic moment from the vacuum by time-independent magnetic-field inhomogeneity as an external background. We show that the problem is technically reduced to the problem of charged-particle creation by an electric step, for which the nonperturbative formulation of strong-field QED is used. We consider a magnetic step given by an analytic function and whose inhomogeneity may vary from a “gradual” to a “sharp” field configuration. We obtain corresponding exact solutions of the Dirac-Pauli equation with this field and calculate pertinent quantities characterizing vacuum instability, such as the differential mean number and flux density of pairs created from the vacuum, vacuum fluxes of energy and magnetic moment. We show that the vacuum flux in one direction is formed from fluxes of particles and antiparticles of equal intensity and with the same magnetic moments parallel to the external field. Backreaction to the vacuum fluxes leads to a smoothing of the magnetic-field inhomogeneity. We also estimate critical magnetic field intensities, near which the phenomenon could be observed.

scholarly journals Holographic QCD and the muon anomalous magnetic moment

2021 ◽  
Vol 81 (11) ◽  
Author(s):  
Josef Leutgeb ◽  
Jonas Mager ◽  
Anton Rebhan
Keyword(s):  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Short Distance ◽  
Axial Vector ◽  
Distance Constraint ◽  
Vector Mesons ◽  
Goldstone Bosons ◽  
Holographic Qcd ◽  
Scattering Contribution ◽  
Made In

AbstractWe review the recent progress made in using holographic QCD to study hadronic contributions to the anomalous magnetic moment of the muon, in particular the hadronic light-by-light scattering contribution, where the short-distance constraints associated with the axial anomaly are notoriously difficult to satisfy in hadronic models. This requires the summation of an infinite tower of axial vector mesons, which is naturally present in holographic QCD models, and indeed takes care of the longitudinal short-distance constraint due to Melnikov and Vainshtein. Numerically the results of simple hard-wall holographic QCD models point to larger contributions from axial vector mesons than assumed previously, while the predicted contributions from pseudo-Goldstone bosons agree nicely with data-driven approaches.

scholarly journals Explaining g − 2 anomalies in two Higgs doublet model with vector-like leptons

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Eung Jin Chun ◽  
Tanmoy Mondal
Keyword(s):  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Magnetic Moments ◽  
Higgs Doublet ◽  
Light Particle ◽  
Muon Anomalous Magnetic Moment ◽  
Negative Contribution ◽  
Doublet Model ◽  
Pseudo Scalar ◽  
Two Higgs Doublet Model

Abstract We consider the two Higgs doublet model (2HDM) along with a generation of vector-like lepton doublet and singlet to explain the observed discrepancies in the electron and muon anomalous magnetic moments. The type-X (lepton-specific) 2HDM can allow a light pseudo-scalar which is known to explain the muon anomalous magnetic moment at two-loop. Such a light particle induces a sizable negative contribution to the electron anomalous magnetic moment at one-loop in the presence of vector-like leptons evading all the experimental constraints.

Anomalous Magnetic Moments

2004 ◽  
Vol 19 (supp01) ◽  
pp. 77-87
Author(s):  
William J. Marciano
Keyword(s):  
Dirac Equation ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Magnetic Moments ◽  
New Physics ◽  
Gyromagnetic Ratio ◽  
Small Shift ◽  
G Factor ◽  
Experimental Values

The Dirac equation explained why the gyromagnetic ratio, g factor, is equal to 2 for fundamental spin [Formula: see text] particles. Quantum loop effects were subsequently shown to induce a small shift or anomaly, a≡(g-2)/2. Anomalous magnetic moment effects have been calculated and measured with extraordinary precision for the electron and muon. Here, the Standard Model's predictions for al=(gl-2)/2, l=e, μ are described and compared with experimental values. Implications for probing "New Physics" effects are also discussed.

scholarly journals Synthesis of Metal Organic Frameworks by Ball-Milling

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 15
Author(s):  
Cheng-An Tao ◽  
Jian-Fang Wang
Keyword(s):  
Ball Milling ◽  
Large Scale ◽  
Raw Materials ◽  
Metal Organic Frameworks ◽  
Research Topic ◽  
Mass Ratio ◽  
Time Consumption ◽  
Metal Organic ◽  
Short Time ◽  
Made In

Metal-organic frameworks (MOFs) have been used in adsorption, separation, catalysis, sensing, photo/electro/magnetics, and biomedical fields because of their unique periodic pore structure and excellent properties and have become a hot research topic in recent years. Ball milling is a method of small pollution, short time-consumption, and large-scale synthesis of MOFs. In recent years, many important advances have been made. In this paper, the influencing factors of MOFs synthesized by grinding were reviewed systematically from four aspects: auxiliary additives, metal sources, organic linkers, and reaction specific conditions (such as frequency, reaction time, and mass ratio of ball and raw materials). The prospect for the future development of the synthesis of MOFs by grinding was proposed.

scholarly journals Two and three pseudoscalar production in e+e− annihilation and their contributions to (g − 2)μ

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Wen Qin ◽  
Ling-Yun Dai ◽  
Jorge Portolés
Keyword(s):  
Experimental Data ◽  
Theoretical Prediction ◽  
Pseudoscalar Meson ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Vacuum Polarization ◽  
Meson Production ◽  
The Other ◽  
Joint Analysis ◽  
The Standard Model

Abstract A coherent study of e+e− annihilation into two (π+π−, K+K−) and three (π+π−π0, π+π−η) pseudoscalar meson production is carried out within the framework of resonance chiral theory in energy region E ≲ 2 GeV. The work of [L.Y. Dai, J. Portolés, and O. Shekhovtsova, Phys. Rev. D88 (2013) 056001] is revisited with the latest experimental data and a joint analysis of two pseudoscalar meson production. Hence, we evaluate the lowest order hadronic vacuum polarization contributions of those two and three pseudoscalar processes to the anomalous magnetic moment of the muon. We also estimate some higher-order additions led by the same hadronic vacuum polarization. Combined with the other contributions from the standard model, the theoretical prediction differs still by (21.6 ± 7.4) × 10−10 (2.9σ) from the experimental value.

scholarly journals Stochastic computation of g − 2 in QED

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Ryuichiro Kitano ◽  
Hiromasa Takaura ◽  
Shoji Hashimoto
Keyword(s):  
Perturbation Theory ◽  
Numerical Computation ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Stochastic Perturbation ◽  
Higher Order ◽  
Feynman Diagrams ◽  
Perturbative Series ◽  
Physical Quantities

Abstract We perform a numerical computation of the anomalous magnetic moment (g − 2) of the electron in QED by using the stochastic perturbation theory. Formulating QED on the lattice, we develop a method to calculate the coefficients of the perturbative series of g − 2 without the use of the Feynman diagrams. We demonstrate the feasibility of the method by performing a computation up to the α3 order and compare with the known results. This program provides us with a totally independent check of the results obtained by the Feynman diagrams and will be useful for the estimations of not-yet-calculated higher order values. This work provides an example of the application of the numerical stochastic perturbation theory to physical quantities, for which the external states have to be taken on-shell.

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