The hadronic corrections to the muon anomalous magnetic moment
a
μ
, due to the gauge-invariant set of diagrams with dynamical quark loop light-by-light scattering insertions, are calculated in the ...framework of the nonlocal chiral quark model. These results complete calculations of all hadronic light-by-light scattering contributions to
a
μ
in the leading order in the
1
/
N
c
expansion. The result for the quark loop contribution is
a
μ
HLbL
,
Loop
=
11.0
±
0.9
×
10
-
10
,
and the total result is
a
μ
HLbL
,
N
χ
QM
=
16.8
±
1.2
×
10
-
10
.
The light-by-light contribution from the lightest neutral pseudoscalar and scalar mesons to the anomalous magnetic moment of muon is calculated in the framework of the nonlocal
SU
(3)×
SU
(3) quark ...model. The model is based on chirally symmetric four-quark interaction of the Nambu–Jona-Lasinio type and Kobayashi–Maskawa–’t Hooft
U
A
(1) breaking six-quark interaction. Full kinematic dependence of vertices with off-shell mesons and photons in intermediate states in the light-by-light scattering amplitude is taken into account. The small positive contributions from the scalar mesons stabilize the total result with respect to change of model parameters and reduces to
.
The contribution from the axial-vector meson exchange to the potential of the muon–proton interaction in muonic hydrogen induced by anomalous axial-vector meson coupling to two photon state is ...calculated. It is shown that such contribution to the hyperfine splitting in muonic hydrogen is large and important for a comparison with precise experimental data. In the light of our result, the proton radius “puzzle” is discussed.
The light-by-light contribution to the anomalous magnetic moment of muon (
g
−2)
μ
from the hadronic exchanges in the neutral pseudoscalar meson channel is calculated in the nonlocal chiral quark ...model. The full kinematic dependence of the meson two-photon vertices from the virtualities of the mesons and photons is taken into account. It is demonstrated that the effect of the full kinematic dependence in the meson–photon vertices is to reduce the contribution of pseudoscalar exchanges comparing with the most of previous estimates and the result is
. The status of various phenomenological and QCD short-distance constraints is discussed and the comparison with the predictions of other models is performed.
We study the pair production of Bc mesons in the photon-photon interaction in the framework of perturbative quantum chromodynamics and the relativistic quark model. The production amplitudes of a ...pair of pseudoscalar and vector Bc mesons are constructed in the nonrelativistic approximation and taking into account relativistic effects. Relativistic corrections related to the relative motion of heavy quarks in the production amplitude, as well as in the wave function of the bound state of heavy quarks, are taken into account. Analytical expressions are constructed for the relativistic differential and total cross sections for the pair Bc meson production. Based on them, numerical values of the production cross sections are obtained for various energies and scattering angles.
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•Synthesis, characterization, and catalytic examination of KCoMoS/C/Al2O3 in production and conversion of alcohols.•Effect of potassium on sulfide catalyst structure and ...properties.•DFT calculations of KCoMoS system.•Reaction network of CO conversion on KCoMoS-catalyst active sites.
Catalysts with the common composition KCoMoS/C/Al2O3 were synthesized, characterized by physicochemical methods, and tested in the synthesis of alcohols from CO and H2. It was noted that carbon supported on alumina promoted alcohol synthesis by enhancing the CO conversion and the alcohols/hydrocarbons ratio in comparison to pure alumina. The addition of potassium to CoMoS/C/Al2O3 could substantially affect both the morphology of molybdenum disulfide crystallites and catalyst activity in the synthesis of alcohols. According to quantum chemical calculations, using the density functional theory approach, potassium donates electronic density onto the Co atoms of CoMoS phase active sites. Reduction of metal atoms of active sites leads to a decrease in Lewis acidity and in the CO and H2 adsorption energy as well as promoting the oxidative addition of H2. The influence of ethanol addition to synthesis gas on its conversion and the product composition was examined with a view to checking whether the alkyl intermediate interacted with CO in the presence of potassium. A sharp increase of CO conversion in the presence of ethanol was detected. A reaction network of CO conversion on KCoMoS catalyst active sites to various products depending on the catalyst composition and reaction conditions was suggested.
Abstract
The paper provides information on the causes of failures in automotive equipment and shows the ways to determine failures using digital technologies introduced into the diagnostic process. ...The implementation of forecasting as a separate stage in the process of diagnosing automotive equipment using machine learning technologies in the form of neural networks is analyzed. The results of the study reflect that the neural network while analyzing a huge amount of data received during remote diagnostics is able to more reliably predict failures of automotive equipment.
Studies in healthy adult volunteers with different levels of anxiety addressed the effectiveness of recovery of monotonous activity after brief episodes of daytime sleep. A continuous-discrete ...psychomotor test was used in which the experimental participants carried out two sequentially alternating tasks: counting to themselves from 1 to 10, accompanied by synchronous pressing of a button with the right hand, and counting to themselves without button-pressing. Subjects’ eyes were closed during the whole experiment. All subjects performed the test correctly before going to sleep. Subjects who started to make errors in the number of button presses and performed the test significantly more slowly after waking showed increases in the spectral power of EEG δ, θ, and α oscillations. These results point to marked signs of sleep inertia in the conditions in which the activity was performed. After waking, groups of subjects performing the task accurately in both experimental situations displayed no changes in the δ, θ, or α1 ranges compared with the beginning of the experiment. This fact, as well as the observation that test performance speed decreased slightly, provides grounds for suggesting that the sequelae of short-term sleep had smaller effects on performance of the psychomotor test in these subjects. We suggest that the decrease in α2 power in the caudal EEG leads reflects activatory processes supporting more effective activity in these conditions. Short-lived daytime sleep had different effects on the effectiveness of recovery of activity in healthy subjects with different anxiety levels. After waking, subjects with elevated anxiety showed greater signs of sleep inertia and performed the psychomotor test task worse than at the beginning of the experiment before going to sleep. The effect of short-term sleep on the effectiveness of test performance was significantly less marked in less anxious subjects.
This article addresses contemporary concepts of the neurophysiological mechanisms of awakening from sleep and the results of our own electroencephalographic (EEG) studies of the temporospatial ...dynamics of activity in the cortical hemispheres using an experimental model developed by ourselves for investigation of consciousness in the sleep–waking paradigm. This model is based on continuous performance of a monotonous psychomotor test carried out lying down with the eyes closed, which in a 1-h experiment allows observation of several brief episodes of sleep with subsequent spontaneous awakening and recovery of psychomotor test performance. A necessary condition for recovery of activity after spontaneous awakening is the appearance of the EEG α rhythm, and the parameters of this rhythm determine the effectiveness of recovery of the psychomotor test and, thus, achievement of a particular level of consciousness, so this can be regarded as a neurophysiological correlate of the activation of consciousness on awakening. This experimental model for studies of consciousness may be useful for analysis of the neurophysiological mechanisms of its activation in patients with chronic impairments of consciousness and for seeking effective methods for the rehabilitation of such patients.
.
In the framework of the quasipotential method in quantum electrodynamics we calculate corrections to the nuclear structure proportional to
r
N
2
from two-photon exchange amplitudes in the fine and ...hyperfine structure of
P
-states in muonic hydrogen, as well as the photon-photon interaction amplitudes, leading to the exchange of the axial vector meson. In constructing the quasipotential of the muon-nucleus interaction, we use the method of projection operators on states of two particles with a definite spin and total angular momentum. Analytical calculation of the matrix elements is performed and contributions to the fine and hyperfine structure of the
2
P
1
/
2
and
2
P
3
/
2
levels are obtained.
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