The effect of tensor correlations on isovector operators

Very simple relations between renormalization factors and corrections to the GT-type-decay operator, isovector magnetic moment and coulomb energy differences between mirror nuclei due to tensor correlations are obtained.     

Radiative corrections to the Lagrangian of the electromagnetic field

The single-loop corrections to the Lagrangian of a uniform, constant electromagnetic field are found which include the anomalous magnetic moment and electric dipole moment of the electron. The imaginary part of the effective Lagrangian, which determines the probability of electron-positron pair production is found. The asymptotic behavior of the effective action is studied for supercritical magnetic fields H » H₀ = m²/e with the dependence of the anomalous magnetic moment on H taken into account.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 37–42, March, 1987.     

Magnetic dipole moment of the Δ(1232) in chiral perturbation theory

The magnetic dipole moment of the Δ(1232) is calculated in the framework of manifestly Lorentz-invariant baryon chiral perturbation theory in combination with the extended on-mass-shell renormalization scheme. As in the case of the nucleon, at leading order both isoscalar and isovector anomalous magnetic moments are given in terms of two low-energy constants. In contrast to the nucleon case, at next-to-leading order the isoscalar anomalous magnetic moment receives a (real) loop contribution. Moreover, due to the unstable nature of the Δ(1232), at next-to-leading order the isovector anomalous magnetic moment not only receives a real but also an imaginary loop contribution.     

The effect of tensor correlations on isovector operators

Very simple relations between renormalization factors and corrections to the GT-typeΒ-decay operator, isovector magnetic moment and coulomb energy differences between mirror nuclei due to tensor correlations are obtained.     

An interpolation of the vacuum polarization function for the evaluation of hadronic contributions to the muon anomalous magnetic moment

We propose a simple parameterization of the two-point correlator of hadronic electromagnetic currents for the evaluation of the hadronic contributions to the muon anomalous magnetic moment. The parameterization is explicitly done in the Euclidean domain. The model function contains a phenomenological parameter which provides an infrared cutoff to guarantee the smooth behavior of the correlator at the origin in accordance with experimental data in e ⁺e^- annihilation. After fixing a numerical value for this parameter from the leading order hadronic contribution to the muon anomalous magnetic moment, the next-to-leading order results related to the vacuum polarization function are accurately reproduced. The properties of the four-point correlator of hadronic electromagnetic currents as for instance the so-called light-by-light scattering amplitude relevant for the calculation of the muon anomalous magnetic moment are briefly discussed. Received: 14 December 2001 / Published online: 7 June 2002     

Exchange magnetic moment form factor of the three-nucleon system

The exchange magnetic moment form factor of ³H and ³He is derived from experiment, regarding the D state probability P_D as free parameter. The isoscalar part is roughly constant. The rms radius corresponding to the isovector part increases as P_D increases.     

The Z 0-Boson Contribution to the Anomalous Moments of an Electron in a Plane-Wave Electromagnetic Field

This paper considers the Z ⁰-boson contribution to the mass of an electron moving in a plane-wave field. The dependence of the Z ⁰-boson contribution to the anomalous magnetic moment (AMM) and anomalous electric moment (AEM) of the electron on the parameters of the external field is investigated in terms of the conventional Weinberg–Salam–Glashow model.     

The spin of the electron according to stochastic electrodynamics

By making use of the method of moments we study some aspects of the statistical behavior of the nonrelativistic harmonic oscillator according to stochastic electrodynamics. We show that the random rotations induced on the particle by the zero-point field account for the magnitude of the spin of the electron, the result differing from the correct one(3/4)h ² by a factor of2. Assuming that the measurement of a spin projection may be effectively taken into account by considering the action of only the subensemble of the field with the corresponding circular polarization, the calculated value of the spin projection comes out to be the correct one within a factor of order unity. The radiative corrections give rise to both the Lamb shift and the anomalous magnetic moment of the electron, the latter being evaluated to within a factor of2. The magnetic and gyromagnetic properties of the electron come out to be in agreement with quantum mechanics. Interference effects are shown to occur when evaluating the average value of the square of the angular momentum.Fellow of CONACYT, México.     

Configurational mixing and the magnetic moment of f72-Nucleons

It is shown that, after the corrections due to deformed components in the wave functions have been removed, the new measurement of the magnetic moment of the 6⁺ state in ⁴²Ca together with the corresponding results from ⁴¹Ca, ⁴¹Sc as well as the β-decay results ⁴¹Sc → ⁴¹Ca, fit a picture in which the correction to the Schmidt magnetic moment of the $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ nucleons is pure isovector and consists of a 10 percent reduction of the 〈Σσ₂τ₃〉 and δg_l = 0.15 τ.     

Pseudo scalar contributions to light-by-light correction of muon in AdS/QCD

We have performed a holographic calculation of the hadronic contributions to the anomalous magnetic moment of the muon, using the gauge/gravity duality. As a gravity dual model of QCD with three light flavors, we study a U(3)_L×U(3)_R flavor gauge theory in the five-dimensional AdS background with a hard-wall cutoff. The anomalous (electromagnetic) form factors for the pseudo scalars, π⁰, η and η^′, are obtained from the 5D Chern–Simons term of the gravity dual, which correctly reproduce the asymptotic behavior of the form factor, dictated by QCD. We find the total light-by-light contributions of pseudo scalars to the muon anomalous magnetic moment, , which is consistent with previous estimates, based on other approaches.     

Confronting spectral functions from ee annihilation and $\tau$ decays: consequences for the muon magnetic moment

Vacuum polarization integrals involve the vector spectral functions which can be experimentally determined from two sources: (i) e ⁺ e ^- annihilation cross sections and (ii) hadronic decays. Recently results with comparable precision have become available from CMD-2 on one side, and ALEPH, CLEO and OPAL on the other. The comparison of the respective spectral functions involves a correction from isospin-breaking effects, which is evaluated. After the correction it is found that the dominant spectral functions do not agree within experimental and theoretical uncertainties. Some disagreement is also found for the spectral functions. The consequences of these discrepancies for vacuum polarization calculations are presented, with the emphasis on the muon anomalous magnetic moment. The work includes a complete re-evaluation of all exclusive cross sections, taking into account the most recent data that became available in particular from the Novosibirsk experiments and applying corrections for the missing radiative corrections. The values found for the lowest-order hadronic vacuum polarization contributions are where the errors have been separated according to their sources: experimental, missing radiative corrections in e ⁺ e ^- data, and isospin breaking. The Standard Model predictions for the muon magnetic anomaly read where the errors account for the hadronic, light-by-light scattering and electroweak contributions. We observe deviations with the recent BNL measurement at the 3.0 (e ⁺ e ^- ) and 0.9 () level, when adding experimental and theoretical errors in quadrature. Received: 27 August 2002 / Revised version: 10 January 2003 / Published online: 26 February 2003 RID="a" ID="a" e-mail: davier@lal.in2p3.fr RID="b" ID="b" e-mail: simon.eidelman@cern.ch RID="c" ID="c" e-mail: hoecker@lal.in2p3.fr RID="d" ID="d" e-mail: zhangzq@lal.in2p3.fr     

Contributions to the muon’s anomalous magnetic moment from a hidden sector

The measurement of the anomalous magnetic moment of the muon provides a stringent test of the standard model and of any physics that lies beyond it. There is currently a deviation of 3.1σ between the standard model prediction for the muon’s anomalous magnetic moment and its experimental value. We calculate the contribution to the anomalous magnetic moment in theories where the muon couples to a particle in a hidden sector (that is, uncharged under the standard model) and a connector (which has nontrivial standard model gauge and hidden sector quantum numbers).     

Letter: Antisymmetric Tensor Contribution to the Muon g − 2

We investigate the Kalb-Ramond antisymmetric tensor field as a solution to the muon g – 2 problem. In particular we calculate the lowest-order Kalb-Ramond contribution to the muon anomalous magnetic moment and find that we can fit the new experimental value for the anomaly by adjusting the coupling without affecting the electron anomalous magnetic moment results.     

Radiative tau lepton pair production as a probe of anomalous electromagnetic couplings of the tau

We calculate the squared matrix element for the process e⁺e⁻ → τ⁺τ⁻γ allowing for anomalous magnetic and electric dipole moments at the ττγ vertex. No interferences are neglected and no approximations of light fermion masses are made. We show that anomalous moments affect not only the cross section, but also the shape of the photon energy and angular distributions. We also demonstrate that in the case of the anomalous magnetic dipole moment, the contribution from interference involving Standard Model and anomalous amplitudes is significant compared to the contribution from anomalous amplitudes alone. A program to perform the calculation is available and it may be employed as a Monte Carlo generator.     

Higher-order hadronic contributions to the anomalous magnetic moment of leptons

Higher-order hadronic contributions to the anomalous magnetic moment of the electron, muon, and π lepton are considered in detail. As a main result we find a reduction by −11 × 10⁻¹¹ for the g-2 of the muon as compared to previous calculations. Analytical expressions for the kernel functions of higher-order hadronic effects are presented. We employ the method of asymptotic expansions to calculate kernel functions analytically in terms of a series expansion in the lepton mass.     

Electron resonance studies of the renner effect

The gas phase electron resonance spectra of NCO in its ground ²Π_3/2 vibronic state and in two excited vibronic states are described. Theoretical analysis of the spectra yields effective g values for the three states. In additon the ¹⁴N magnetic hyperfine and electric quadrupole coupling constants and the electric dipole moment are determined. The theory of the Renner coupling of electronic and vibrational motion is extended, and shown to account for anomalous contributions to the g values. The theory also shows that these contributions are closely related to the Renner coupling constant.     

Contributions of weak and strong interactions to the anomalous magnetic moment of the electron

Based on Weinberg - Salam weak interaction theory, we have determined the addition to the anomalous magnetic moment of the electron arising from interaction between the electron and quantum fluctuations of the vector field (the carrier of the weak interaction). We also estimate the contribution of the strong interaction to the anomalous magnetic moment of the electron due to polarization of the quark — gluon vacuum. The overall contribution of the weak and strong interactions to the anomalous magnetic moment proves to be equal to 1·10^–12, and the contribution of the weak interaction is 2.2 times greater than the contribution of the strong interaction.Kamskii Polytechnical Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 13–19, November, 1993.     

Passage of relativistic magnetic dipole moments through magnetic fields

We have solved the Dirac equation with an anomalous moment Pauli-coupling exactly for a constant magnetic field and derived the general relativistic formulas for phase changes due to translational motion and spin rotations. We also give transmission and reflection coefficients, spin rotation for tunnelling and barrier penetration. For ultrarelativistic particles the spin rotation angle on the path of lengthL is equal to (2μB L/ħc)[1 +m ² c ⁴/(E²-μ ² B ²)].

     

Anderson impurity model: Double occupancy contribution to the magnetic susceptibility

After solving the single Anderson impurity model (SIAM) within the non-crossing approximation with a finite Coulomb repulsion, U, and vertex corrections (NCAf²v), we focus on the magnetic susceptibility. Using the same diagrammatic expansion the susceptibility can be dressed with two factors, namely, the double state occupancy and the vertex corrections. In this work we analyse the effect of double occupancy on the dynamic and static susceptibility as a function of U and on the degeneracy of the total impurity angular moment, S.     

Isovector,isoscalar and Coulomb contributions to the mean field in 208Pb

We investigate the difference between the real parts of the mean fields felt by protons and neutrons in ²⁰⁸Pb, as evaluated from the iterative dispersion relation approach. This difference is decomposed into two contributions, namely a Coulomb correction to the average Coulomb potential felt by protons, and an isovector potential due to the existence of a neutron excess in ²⁰⁸Pb. It is shown that the volume integrals of these two contributions display a pronounced maximum near the Fermi energy; this feature is due to dispersive corrections to the Hartree-Fock type approximation, and mainly reflect the energy dependence of the surface properties of the isovector and Coulomb correction contributions. The energy dependence of the volume integrals of the imaginary parts of the isovector and Coulomb correction contributions is evaluated, as well as that of the real part of the isoscalar component of the mean field.