172 research outputs found
Foreign trade of Russia and Vietnam: modern trends and prospects of development
The subject of this study is trade between Russia and Vietnam. The purpose of the study is to identify historical features, prevailing trends, development trends, current status and prospects for the development of international trade between the specified countries. The research method is based on the logistics function of P.F. Verhulst and consists of: 1) selecting predicted values, initial value and indicators used for forecasting; 2) calculating the indicators necessary for compiling a system of equations; 3) forming a system of equations and solving it; 4) calculating forecasted indicators; 5) building a graphical forecasting model; 6) formulating conclusions. The paper presents a historical overview of trade relations between Russia and Vietnam. The study develops a mathematical model for forecasting exports and imports of Russia and Vietnam by individual indicators until 2025. The authors perform the calculation using statistical data for the period 2011–2018. The article presents the results of calculations graphically. Based on the results of calculation the paper formulates the main directions, trends and prospects for the development of foreign trade of both countries until 2025. The results of the study can be used to teach disciplines that deal with trade issues between Russia and Vietnam. The research materials may be of interest to business companies and government agencies dealing with issues related to international trade and forecasting
METHODICAL RECOMMENDATION ABOUT SUPPLY CHAIN MANAGEMENT IN THE FASHION INDUSTRY
In article methodical recommendations about supply chain management in the fashion industry are made. Methods effectively are considered to work in such difficult market conditions as high variability of the market, a high assortment, short product lifecycles which are characteristic of this industry
METHODICAL RECOMMENDATION ABOUT SUPPLY CHAIN MANAGEMENT IN THE FASHION INDUSTRY
In article methodical recommendations about supply chain management in the fashion industry are made. Methods effectively are considered to work in such difficult market conditions as high variability of the market, a high assortment, short product lifecycles which are characteristic of this industry
The massive analytic invariant charge in QCD
The low energy behavior of a recently proposed model for the massive analytic
running coupling of QCD is studied. This running coupling has no unphysical
singularities, and in the absence of masses displays infrared enhancement. The
inclusion of the effects due to the mass of the lightest hadron is accomplished
by employing the dispersion relation for the Adler D function. The presence of
the nonvanishing pion mass tames the aforementioned enhancement, giving rise to
a finite value for the running coupling at the origin. In addition, the
effective charge acquires a "plateau-like" behavior in the low energy region of
the timelike domain. This plateau is found to be in agreement with a number of
phenomenological models for the strong running coupling. The developed
invariant charge is applied in the processing of experimental data on the
inclusive lepton decay. The effects due to the pion mass play an
essential role here as well, affecting the value of the QCD scale parameter
extracted from these data. Finally, the massive analytic running
coupling is compared with the effective coupling arising from the study of
Schwinger-Dyson equations, whose infrared finiteness is due to a dynamically
generated gluon mass. A qualitative picture of the possible impact of the
former coupling on the chiral symmetry breaking is presented.Comment: 13 pages, 7 figures, revtex
The gluon content of the and mesons and the , electromagnetic transition form factors
We compute power-suppressed corrections to the \eta\gamma and
\eta^{\prime}\gamma transition form factors
Q^2F_{\eta(\eta^{\prime})\gamma}(Q^2) arising from the end point regions x \to
0,1 by employing the infrared-renormalon approach. The contribution to the form
factors from the quark and gluon content of the \eta,\eta^{\prime} mesons is
taken into account using for the \eta-\eta^{\prime} mixing the SU_f(3) singlet
\eta_1 and octet \eta_8 basis. The theoretical predictions obtained this way
are compared with the corresponding CLEO data and restrictions on the input
parameters (Gegenbauer coefficients) B_2^q(\eta_1), B_2^g(\eta_1), and
B_2^q(\eta_8) in the distribution amplitudes for the \eta_1,\eta_8 states with
one nonasymptotic term are deduced. Comparison is made with the results from
QCD perturbation theory.Comment: 25 pages, RevTeX4 used. 9 figures as EPS files. Text significantly
changed to include variation of theoretical parameters. Figures modified.
Corrected typo in equation (34) and trivial mistake in -coefficient.
References added. Conclusions unchange
DVCS amplitude at tree level: Transversality, twist-3, and factorization
We study the virtual Compton amplitude in the generalized Bjorken region (q^2
-> Infinity, t small) in QCD by means of a light-cone expansion of the product
of e.m. currents in string operators in coordinate space. Electromagnetic gauge
invariance (transversality) is maintained by including in addition to the
twist-2 operators 'kinematical' twist-3 operators which appear as total
derivatives of twist-2 operators. The non-forward matrix elements of the
elementary twist-2 operators are parametrized in terms of two-variable spectral
functions (double distributions), from which twist-2 and 3 skewed distributions
are obtained through reduction formulas. Our approach is equivalent to a
Wandzura-Wilczek type approximation for the twist-3 skewed distributions. The
resulting Compton amplitude is manifestly transverse up to terms of order
t/q^2. We find that in this approximation the tensor amplitude for longitudinal
polarization of the virtual photon is finite, while the one for transverse
polarization contains a divergence already at tree level. However, this
divergence has zero projection on the polarization vector of the final photon,
so that the physical helicity amplitudes are finite.Comment: 34 pages, revtex, 1 eps figure included using epsf. Misprints
corrected, one reference adde
Diffractive neutrino-production of pions on nuclei: Adler relation within the color-dipole description
Effects of coherence in neutrino-production of pions off nuclei are studied
employing the color dipole representation and path integral technique. If the
nucleus remains intact, the process is controlled by the interplay of two
length scales. One is related to the pion mass and is quite long (at low Q^2),
while the other, associated with heavy axial-vector states, is much shorter.
The Adler relation is found to be broken at all energies, but especially
strongly at \nu > 10 GeV, where the cross section is suppressed by a factor
~A^{-1/3}. On the contrary, in a process where the recoil nucleus breaks up
into fragments, the Adler relation turns out to be strongly broken at low
energies, where the cross section is enhanced by a factor ~A^{1/3}, but has a
reasonable accuracy at higher energies, where all the coherence length scales
become long.Comment: 9 pages, 5 figure
Dirac neutrino magnetic moment and a possible time evolution of the neutrino signal from a supernova
We analyze the influence of neutrino helicity conversion, ,
on the neutrino flux from a supernova caused by the interaction of the Dirac
neutrino magnetic moment with a magnetic field. We show that if the neutrino
has a magnetic moment in the interval and provided that a magnetic field of G exists in the supernova envelope, a peculiar kind of time evolution
of the neutrino signal from the supernova caused by the resonance transition
in the magnetic field of the envelope can appear. If a
magnetar with a poloidal magnetic field is formed in a supernova explosion,
then the neutrino signal could have a pulsating behavior, i.e., a kind of a
neutrino pulsar could be observed, when it rotates around an axis that does not
coincide with its magnetic moment and when the orientation of its rotation axis
is favourable for our observation.Comment: 9 pages, LaTeX, 2 EPS figures, based on the talk presented by A.V.
Kuznetsov at the XVI International Seminar Quarks'2010, Kolomna, Moscow
Region, June 6-12, 2010, to appear in the Proceeding
Operator product expansion in QCD in off-forward kinematics: Separation of kinematic and dynamical contributions
We develop a general approach to the calculation of target mass and finite
t=(p'-p)^2 corrections in hard processes which can be studied in the framework
of the operator product expansion and involve momentum transfer from the
initial to the final hadron state. Such corrections, which are usually referred
to as kinematic, can be defined as contributions of operators of all twists
that can be reduced to total derivatives of the leading twist operators. As the
principal result, we provide a set of projection operators that pick up the
"kinematic" part of an arbitrary flavor-nonsinglet twist-four operator in QCD.
A complete expression is derived for the time-ordered product of two
electromagnetic currents that includes all kinematic corrections to twist-four
accuracy. The results are immediately applicable to the studies of
deeply-virtual Compton scattering, transition gamma^*-> M gamma form factors
and related processes. As a byproduct of this study, we find a series of
"genuine" twist-four flavor-nonsinglet quark-antiquark-gluon operators which
have the same anomalous dimensions as the leading twist quark-antiquark
operators.Comment: 68 pages, 2 figures. Misprints in Eq.(5.64) and several equations in
Sec.6 are corrected. For readers' convenience all corrections are marked in
re
Twist-3 contribution to the amplitude in the Wandzura-Wilczek approximation
We have calculated the Wandzura-Wilczek contribution to the twist-3 part of
amplitude. It describes interaction of the
longitudinally polarized virtual photon with the real one, and it is suppressed
by 1/Q, where is the virtuality of the , as compared to the
twist-2 contribution. We have found that, in the Wandzura-Wilczek
approximation, factorization applies to the twist-3 amplitude.Comment: 13 pages, 4 figure
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