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     

Angular distribution of diffracted x rays from (111) channeled electrons in Si: The effect of the band structure of energy levels

It has been shown that the inclusion of the band structure of the energy levels of channeled electrons qualitatively changes the angular distributions of x rays at the Bragg angles, which can be useful for the experimental detection of the effect.     

Laser vaporisation of absorbing liquid under transparent cover

Vaporization of absorbing liquid (water) under a transparent solid cover upon exposure to nanosecond pulses of a holmium laser (λ = 2920 nm) is studied using acoustic and optical diagnostics. The features of the optical signal reflected from the liquid–cover interface suggest that a vapor cavity appears at a submicrometer distance from this interface and exists for about one hundred microseconds. An additional acoustic signal appearing after returning the light signal to the initial level is caused by known cavitation effects accompanying vapor cavity fracture and collapse in liquid.     

Top-Antitop Pair Production Close to Threshold Synopsis of Recent NNLO Results

Using non-relativistic effective theories, new next-to-next-to-leading order (NNLO) QCD corrections to the total production cross section at the Linear Collider have been calculated recently. In this article the NNLO calculations of several groups are compared and the remaining uncertainties are discussed. The theoretical prospects for an accurate determination of top quark mass parameters are discussed in detail. An outlook on possible future improvements is given.     

Pulse acoustic microscopy characterization of the elastic properties of nanostructured metal-nanocarbon composites (Declercq/ICU'07)

New metal-nanocarbon composites were obtained by high-energy (ball milling) pre-treatment of the powder mixture followed by high-pressure/high-temperature treatment. Acoustic microscopy was used to study elastic properties and bulk irregularities of the samples.     

Bent crystal channeling of 255 MeV electrons

Charged particles channeled in a bent crystal plane are known to be deflected along the bent plane. Such studies have mainly been performed for high-energy positively-charged particles such as protons, and recently for electrons with energies from 855 MeV to 20.35 GeV. In this work, we present experimental results on the bent crystal channeling of electrons for a lower energy region (255 MeV), where the multiple scattering effect in a crystal is expected to be more dominant. Angular distributions of electrons transmitted through a bent Si crystal have been measured, which are in good agreement with the simulation results.     

Photochemical interaction of molybdenum and tungsten phosphine hydride complexes with carbon dioxide

UV, IR, and¹H NMR spectra of photoproducts obtained by irradiation of phosphine hydride complexes MH₄L₄ (M = Mo and W; L = PHPh₂, PMePh₂, PEtPh₂, PEt₂Ph, and PBuPh₂) in an atmosphere of CO₂,¹³CO₂, and C¹⁸O₂ have been studied. The photoproducts can be formed due to the insertion of carbon dioxide both into the M-H bond and M-C and M-Ph bonds.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2324–2326, September, 1996.     

ASYMPTOTIC ANALYSIS OF THE MOTION OF A LOW-VISCOSITY FLUID THAT FILLS A CYLINDRICAL CAVITY BY HALF

Journal of Applied Mechanics and Technical Physics - A problem of a plane-parallel steady motion of a low-viscosity incompressible fluid that fills a rotating cylindrical cavity by half is under...     

An ESR and Optical Spectroscopic Study of the Mechanism of Photostimulated Reactions in Hydrogen Cyanide γ-Irradiated at 77 K

Changes in the electronic absorption spectra and ESR spectra in the course of photobleaching of radiolyzed solid HCN with light of different wavelengths (236–600 nm) were studied by ESR and optical spectroscopy. Two bands at 270 and 290 nm in the optical spectrum were attributed to the presence of H₂C=N and HC=NH radicals, respectively (the molar absorption coefficients are k ₂₇₀ 2.7 × 10²l mol^–1cm^–1and k ₂₉₀ 1.5 × 10²l mol^–1cm^–1, respectively). Structureless broad bands with maximums at 313 and 465 nm, which were detected after the exposure of a sample to light with 300 nm, can belong to the cyanide ions (CN^–) and H₂C=N⁺cations (the molar absorption coefficients of the ions are k _ion= (0.4–1.0) × 10²l mol^–1cm^–1). In the photobleaching of -irradiated HCN ( = 236–280 nm), H₂C=N⁺radicals were additionally formed by the photoinduced reaction of electron transfer from the CN^–anion to the H₂C=N⁺cation. The amount of these radicals generated in the course of photobleaching is several times greater than that of the same radicals formed in the radiolysis via hydrogen atom addition to the multiple bond of HCN molecules.