4,122 research outputs found
Monte-Carlo Generator Photon Jets for the process e+e- -> gamma gamma
Monte-Carlo generator with photon jets radiation in collinear regions for the
process \eegg is described in detail. Radiative corrections in the first order
of are treated exactly. Large leading logarithmic corrections coming
from collinear regions are taken into account in all orders of by
applying the Structure Function approach. Theoretical precision of the cross
section with radiative corrections is estimated to be 0.2%. This process is
considered as an additional tool to measure luminosity in forthcoming
experiments with the CMD-3 detector at the collider VEPP-2000.Comment: 6 pages, 5 figure
The running of the electromagnetic coupling alpha in small-angle Bhabha scattering
A method to determine the running of alpha from a measurement of small-angle
Bhabha scattering is proposed and worked out. The method is suited to high
statistics experiments at e+e- colliders, which are equipped with luminometers
in the appropriate angular region. A new simulation code predicting small-angle
Bhabha scattering is also presentedComment: 15 pages, 3 Postscript figure
Parton distribution functions from the precise NNLO QCD fit
We report the parton distribution functions (PDFs) determined from the NNLO
QCD analysis of the world inclusive DIS data with account of the precise NNLO
QCD corrections to the evolution equations kernel. The value of strong coupling
constant \alpha_s^{NNLO}(M_Z)=0.1141(14), in fair agreement with one obtained
using the earlier approximate NNLO kernel by van Neerven-Vogt. The intermediate
bosons rates calculated in the NNLO using obtained PDFs are in agreement to the
latest Run II results.Comment: 8 pages, LATEX, 2 figures (EPS
Methodological aspects of advertising activity efficiency evaluation
© Medwell Journals, 2016.The study describes the methodological approaches to the essence of advertising effectiveness. Theoretical and methodological basis of advertising activity evolution is given and its specificity in various stages of operation is determined. It is substantiated that advertising as it changes in the social and historical conditions and the development of commodity production transformed from a special type of information in the field of advertising as a specific market segment with a developed infrastructure. Supplemented and refined classification of advertising as a system of education is based on different criteria. The features display advertising in a modification of the competition, consisting of individualization advertising and changing its forms; the interactive nature of advertising; the concentration of the individual segments of the advertising market. The factors and methodological approaches of the effectiveness of advertising are determined
Branching ratios of the decays of psi(3770) and Upsilon(10580) into light hadrons
Taking into account the new data on the full width of D^{\ast\pm}(2010) and
the mass difference of the charged and neutral beauty mesons B^\pm, B^0,\bar
B^0, the branching ratios of the decays psi(3770), Upsilon(10580) to pi^+pi^-,
K bar K, rho(omega)pi, rho(omega)eta, rho(omega)eta^prime, K^ast bar K+ c.c,
rho^+ rho^-, and K^ast bar K^ast are re-evaluated in the model in which the
Okubo-Zweig-Iizuka rule is violated due to the real intermediate state D\bar D
in case of psi(3770) and B\bar B in case of Upsilon(10580). The inclusive
annihilation of psi(3770) and Upsilon(10580) into light hadrons is discussed.Comment: 10 page
Hadronic Vacuum Polarization and the Lamb Shift
Recent improvements in the determination of the running of the fine-structure
constant also allow an update of the hadronic vacuum-polarization contribution
to the Lamb shift. We find a shift of -3.40(7) kHz to the 1S level of hydrogen.
We also comment on the contribution of this effect to the determination by
elastic electron scattering of the r.m.s. radii of nuclei.Comment: 7 pages, latex, 1 figure -- Submitted to Phys. Rev. A -- epsfig.sty
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The running mass at low scalefrom the heavy-light meson decay constants
It is shown that a 25(20)% difference between the decay constants
and occurs due to large differences in the pole
masses of the and quarks. The values , recently observed in the CLEO experiment, and
, obtained in unquenched lattice QCD, can be
reached only if the running mass at low scale is GeV) MeV. Our results follow from the analytical expression for the
pseudoscalar decay constant based on the path-integral
representation of the meson Green's function.Comment: 6 pages, no figures; revtex
New high order relations between physical observables in perturbative QCD
We exploit the fact that within massless perturbative QCD the same Green's
function determines the hadronic contribution to the decay width and the
moments of the cross section. This allows one to obtain relations
between physical observables in the two processes up to an unprecedented high
order of perturbative QCD. A precision measurement of the decay width
allows one then to predict the first few moments of the spectral density in
annihilations integrated up to with high accuracy.
The proposed tests are in reach of present experimental capabilities.Comment: 7 pages, Latex, no figure
Tangling clustering of inertial particles in stably stratified turbulence
We have predicted theoretically and detected in laboratory experiments a new
type of particle clustering (tangling clustering of inertial particles) in a
stably stratified turbulence with imposed mean vertical temperature gradient.
In this stratified turbulence a spatial distribution of the mean particle
number density is nonuniform due to the phenomenon of turbulent thermal
diffusion, that results in formation of a gradient of the mean particle number
density, \nabla N, and generation of fluctuations of the particle number
density by tangling of the gradient, \nabla N, by velocity fluctuations. The
mean temperature gradient, \nabla T, produces the temperature fluctuations by
tangling of the gradient, \nabla T, by velocity fluctuations. These
fluctuations increase the rate of formation of the particle clusters in small
scales. In the laboratory stratified turbulence this tangling clustering is
much more effective than a pure inertial clustering that has been observed in
isothermal turbulence. In particular, in our experiments in oscillating grid
isothermal turbulence in air without imposed mean temperature gradient, the
inertial clustering is very weak for solid particles with the diameter 10
microns and Reynolds numbers Re =250. Our theoretical predictions are in a good
agreement with the obtained experimental results.Comment: 16 pages, 4 figures, REVTEX4, revised versio
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