1,179 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
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
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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