1,547 research outputs found
Quark orbital angular momentum: can we learn about it from GPDs and TMDs?
It is known how to access information on quark orbital angular momentum from
generalized parton distribution functions, in a certain specified framework. It
is intuitively expected, that such information can be accessed also through
transverse momentum dependent distribution functions, but not known how. Now
quark models provide promising hints. Recent results are reviewed.Comment: proceeding of the "4th Workshop on Exclusive Reactions at High
Momentum Transfer," 18-21 May 2010, Jefferson La
Surface Polar Phonon Dominated Electron Transport in Graphene
The effects of surface polar phonons on electronic transport properties of
monolayer graphene are studied by using a Monte Carlo simulation. Specifically,
the low-field electron mobility and saturation velocity are examined for
different substrates (SiC, SiO2, and HfO2) in comparison to the intrinsic case.
While the results show that the low-field mobility can be substantially reduced
by the introduction of surface polar phonon scattering, corresponding
degradation of the saturation velocity is not observed for all three substrates
at room temperature. It is also found that surface polar phonons can influence
graphene electrical resistivity even at low temperature, leading potentially to
inaccurate estimation of the acoustic phonon deformation potential constant
Parton distribution functions and quark orbital motion
Covariant version of the quark-parton model is studied. Dependence of the
structure functions and parton distributions on the 3D quark intrinsic motion
is discussed. The important role of the quark orbital momentum, which is a
particular case of intrinsic motion, appears as a direct consequence of the
covariant description. Effect of orbital motion is substantial especially for
polarized structure functions. At the same time, the procedure for obtaining
the quark momentum distributions of polarized quarks from the combination of
polarized and unpolarized structure functions is suggested.Comment: 17 pages, 2 figures, 1 table. Paper is accepted for publication in
Eur.Phys.J.
Transverse momentum dependent distribution functions in a covariant parton model approach with quark orbital motion
Transverse parton momentum dependent distribution functions (TMDs) of the
nucleon are studied in a covariant model, which describes the intrinsic motion
of partons in terms of a covariant momentum distribution. The consistency of
the approach is demonstrated, and model relations among TMDs are studied. As a
byproduct it is shown how the approach allows to formulate the non-relativistic
limit.Comment: 16 page
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