1,417 research outputs found
QCD evolution of naive-time-reversal-odd fragmentation functions
We study QCD evolution equations of the first transverse-momentum-moment of
the naive-time-reversal-odd fragmentation functions - the Collins function and
the polarizing fragmentation function. We find for the Collins function case
that the evolution kernel has a diagonal piece same as that for the
transversity fragmentation function, while for the polarizing fragmentation
function case this piece is the same as that for the unpolarized fragmentation
function. Our results might have important implications in the current global
analysis of spin asymmetries.Comment: 8 pages,4 figure
Single spin asymmetry for the Drell-Yan process
We calculated the single spin asymmetries for the reaction
in the framework of twist-3 QCD for
HERA energies. The necessary imaginary phase is produced by the on-shell
contribution of the quark propagator, while the long distance part is analogous
to that providing the direct photon asymmetry calculated by J. Qiu and G.
Sterman. The asymmetry turns out to be generally of the order percent.Comment: 7 pages, 4 figures, LaTe
Topological gravitation on graph manifolds
A model of topological field theory is presented in which the vacuum coupling
constants are topological invariants of the four-dimensional spacetime. Thus
the coupling constants are theoretically computable, and they indicate the
topological structure of our universe.Comment: 3 pages, a talk delivered at the 11th Marcel Grossmann Meeting (2006
On the Spiral Structure of the Milky Way Galaxy
We consider the possible pattern of the overall spiral structure of the
Galaxy, using data on the distribution of neutral (atomic), molecular, and
ionized hydrogen, on the base of the hypothesis of the spiral structure being
symmetric, i.e. the assumption that spiral arms are translated into each other
for a rotation around the galactic center by 180{\deg} (a two-arm pattern) or
by 90{\deg} (a four-arm pattern). We demonstrate that, for the inner region,
the observations are best represented with a four-arm scheme of the spiral
pattern, associated with all-Galaxy spiral density waves. The basic position is
that of the Carina arm, reliably determined from distances to HII regions and
from HI and H2 radial velocities. This pattern is continued in the quadrants
III and IV with weak outer HI arms; from their morphology, the Galaxy should be
considered an asymmetric multi-arm spiral. The kneed shape of the outer arms
that consist of straight segments can indicate that these arms are transient
formations that appeared due to a gravitational instability in the gas disk.
The distances between HI superclouds in the two arms that are the brightest in
neutral hydrogen, the Carina arm and the Cygnus (Outer) arm, concentrate to two
values, permitting to assume the presence of a regular magnetic field in these
arms.Comment: 21 pages, 14 fugures; accepted for publication in Astronomichesky
Journal (Astron. Rep.
Seasonal Change of the Ozone Layer State over Yakutia
The ozone layer state in the stratosphere over Yakutia depending on the year
time is considered. It is shown that the layer thickness is maximum in
February-March (450 Dobson's units) and it is minimum in July-September (300 -
350 DU). Measurements indicate that the ozone layer thickness was significantly
decreased in the 1990's. A problem of change of ozone layer state is discussed.Comment: 3 pages, 2 figure
Evolution of twist-3 multi-parton correlation functions relevant to single transverse-spin asymmetry
We constructed two sets of twist-3 correlation functions that are responsible
for generating the novel single transverse-spin asymmetry in the QCD collinear
factorization approach. We derive evolution equations for these universal
three-parton correlation functions. We calculate evolution kernels relevant to
the gluonic pole contributions to the asymmetry at the order of . We
find that all evolution kernels are infrared safe as they should be and have a
lot in common to the DGLAP evolution kernels of unpolarized parton
distributions. By solving the evolution equations, we explicitly demonstrate
the factorization scale dependence of these twist-3 correlation functions.Comment: 28 pages, 17 figures, new materials and references adde
Single Transverse-Spin Asymmetries at Large-x
The large- behavior of the transverse-momentum dependent quark
distributions is analyzed in the factorization-inspired perturbative QCD
framework, particularly for the naive time-reversal-odd quark Sivers function
which is responsible for the single transverse-spin asymmetries in various
semi-inclusive hard processes. By examining the dominant hard gluon exchange
Feynman diagrams, and using the resulting power counting rule, we find that the
Sivers function has power behavior at , which is one power
of suppressed relative to the unpolarized quark distribution. These
power-counting results provide important guidelines for the parameterization of
quark distributions and quark-gluon correlations.Comment: 20 pages, 4 figure
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