Multiloop contributions to the on-shell-$$ \overline{{\mathrm{MS}}}$$ heavy quark mass relation in QCD and the asymptotic structure of the corresponding series: the updated consideration

The asymptotic structure of the QCD perturbative relation between the on-shell and $$\overline{{\mathrm{MS}}}$$ MS ¯ heavy quark masses is studied. We estimate the five and six-loop contributions to this relation by three different techniques. First, the effective charges motivated approach in two variants is used. Second, the results following from the large-$$\beta _0$$ β 0 approximation are analyzed. Finally, the consequences of applying the asymptotic renormalon-based formula are investigated. We show that all approaches lead to corrections which are qualitatively consistent in order of magnitude. Their sign-alternating character in powers of the number of massless quarks is demonstrated. We emphasize that there is no contradiction in the behavior of the fine structure of the renormalon-based estimates with other approaches if one use the detailed information about the normalization factor included in the renormalon asymptotic formula. The obtained five- and six-loop estimates indicate that in the case of the b-quark the asymptotic character of the studied relation manifests itself above the fourth order of PT, whereas for the t-quark it starts to reveal itself after the seventh order. This allows to conclude that like the running masses, the pole masses of the b and especially t-quark in principle may be used in the phenomenologically-oriented studies.

Electrical Characterization of Positively Charged SiO Coatings for MOS Solar Cells

This article discusses fabrication, characteriza-tion and studies of the C-V characteristics of SiO layers depos-ited by PVD on Si-p <100> substrates with doping around 1x1016 cm-3. MOS capacitors (Metal-Oxide-Semiconductor) with Al/SiO2/Si-P, Al/SiO/Si-P and Al/SiO/SiO2/Si-P structures were manufactured. It was observed the presence of negative charges in the structure with SiO/SiO2 with density of effective charges Qf ≈ -1x1012 cm-2 and relative permittivity of the die-lectric εr = 2.9. After sintering in ultrapure Ar and N2+H2(10%) the relative permittivity changed to εr = 4.52 and the layers stayed positively charged (Qf = (0.5-1.6)x1012 cm-2), which is adequate for positively charged anti-reflective (AR) coatings of MOS solar cells.

Investigation of the Quadrupole Moment and Form Factors of Some Ca Isotopes

Nuclear shell model is adopted to calculate the electric quadrupole moments for some Calcium isotopes 20Ca (N = 21, 23, 25, and 27) in the fp shell. The wave function is generated using a two body effective interaction fpd6 and fp space model. The one body density matrix elements (OBDM) are calculated for these isotopes using the NuShellX@MSU code. The effect of the core-polarizations was taken through the theory microscopic by taking the set of the effective charges. The results for the quadrupole moments by using Bohr-Mottelson (B-M) effective charges are the best. The behavior of the form factors of some Calcium isotopes was studied by using Bohr-Mottelson (B-M) effective charges.